Hi

I am looking at buying a cheap consumer camera. Does any body know of a way to increase their low light performance and the light range it can work over (at set aperture and gain)?

I've looked at the MX500 (953) for instance, at low light is an underexposed mess, and you just can't have a external window view in proper exposure at the same time, unlike professional models, so it is a bit useless.

I don't know enough about optics but I was thinking that an attachable lenses assembly with 4 times + the lense surface area will collect four times more light, and increase the low light capability by at least double. I am also wondering if there is a method/filter out there that will increase the light range by directly passing dim light and progressively dimming bright light, so as not to under expose or overexpose the CCD?

Would anybody be able to help?

By the way, does anybody know of any home made professional camera projects out there (like www.pixelmonger.com did)?


Thanks.

Wayne.

I'm not sure what you are looking for exactly, but not even
professional cameras usually have such a latitude. What they
do is:

- use a gradient filter so you can bring down a part of the image
- add extra light to the room to also lower the contrast
- put nd (neutral density) on the window
- add a silk or other equipment outside to cut the light that comes in through the window

Also you cannot use a lens with a larger surface because your
CCD chips have a fixed surface. If the light levels are too low,
add light!

If you want a better performance, just get a better camera. For a wider exposure range -- get one with larger chipset and ND filter(s) built in.

Thanks Robin and Joseph for your help

I wanted to aviode buying a very expensive professional camera or lots of extra lighting. My reasoning was that you could focus a larger lense on the same CCD area. Maybe a better camera like the JVC GY DV 5000 will be reduced to a cheap enough price eventually.

Thanks

Wayne

Many wide angle convertors improve low-light sensitivity somewhat.
I'm not sure if one can improve it by four times, but I've seen about a half-stop improvement.
Basically, convertor might increase the effective aperture. Not all of them do, but some.
In any case, the improvement I've seen was not that big to compensate for serious low-light deficiency of some cameras.

Vladimir.

Wide angle lenses do seems to add a little light, as the front of the lenses are generally much wider. However, the WA lenses themselves are not perfect, being made of glass, and it'll absorb a little light.

I use the Fujifilm 0.79x WA (meant for the Fujifilm Finepix S602Zoom Digital Camera) on my MX350. Good results and unnoticeable vignetting. The scenes with or without the WA has some difference in lighting, but it's probably just in the range of + or - 1db (in digital gain mode).

I've seen more than 1db improvement. May be as much as 3-4db. The converter I tried was x0.5-0.6. I dont remember its brand, it was some 5 years ago.
In any case, if it makes 15 Lux camcorder capable to shoot at 10 Lux, it's not that big deal.

one more thing i dont think has been mentioned ....

One thing ive come across when doing alot of "repairs" is that alot of videogrpahers arent using the backlight compensation of the camera.

most cams these days have a backlight compo featrue.. not many people use it...


under the stabilizer button, theres a backlight compo button.. mess around with it.. it might help...

<<<-- Originally posted by Vladimir Koifman : I've seen more than 1db improvement. May be as much as 3-4db. The converter I tried was x0.5-0.6. I dont remember its brand, it was some 5 years ago.
In any case, if it makes 15 Lux camcorder capable to shoot at 10 Lux, it's not that big deal. -->>>


Thanks Vladimir, this sounds fantastic, imagine what it would do to a VX2000?

I'm curiouse though, when they say that the JVC HD10 is 35 Lux and the Panasonic 953 is 15 Lux, is that before gain and lolux mode or after?

I have been told that trying to put an attachement on the lense ruins the optical design (like the JVC DV 3000 is designed to make diferent colours focus at the same distance, instead of using three chips). Does the lense have to be specially designed for the camera?

I have heard of adaptors to attach bigger 35MM lenses to a camcorder, does anybody know of any of these?


Thanks

Wayne.

By the way. Thanks Yow and Peter for your help.


Peter, thanks for the suggestion, I do intend to use the backlight compensation feature, but it makes the outside go completely overexposed. I was hoping some genuise would have figured out a light sensitive filter designed to progressively dim brighter light. It would help "crippled" cameras a lot, along with increased apeture.

Thanks

Wayne.

Wayne, a compressed dynamic range is the "backlight cure" that some CMOS sensors manufacturers offer. For instance, see this:

http://www.smalcamera.com/technology.html

This solves backlight problem, sort of. However, the resulting image looks flat and lacks "punch" of linear CCD camera.

I'd like to see some brave manufacturer delegates to us control over compression ratio. So we could optimize it for our tastes.
Even gamma control in one form or another would be nice.

Dear Vladimir

This is more like it, I have seen a near $20000AU Sony Camera that would do something like this.

I see some wash out there, but, in the example picture, if they matained the same brightness for inside and gave more range to the outside, instead of brightening all of it the picture would be a lot better. You should check out the page on there altrawide 3000 security model (1920*480 pixels), wow you could do a cheap 2.35:1 ration film ;), joking, there probably is a lot of quality isues still to be worked out, but amazing. What I was suggesting would get even better results than this (and closer to film). As you can see if I was to film a scene like this I would have to add so much in store lighting or window tint on the window as to make it very awkward.

http://www.smalcamera.com/w3000wide.html

With 100 Meter firewire, you think they could make a camera with 720p firewire output.

Thanks Vladimir, that was really great.

<<<-- Originally posted by Vladimir Koifman :
I'd like to see some brave manufacturer delegates to us control over compression ratio. So we could optimize it for our tastes.
Even gamma control in one form or another would be nice. -->>>

Yeah, DVCPRO50 tape would be good with it aswell. They will probably have to change the codec standard to support it though. Gama control would be good for the cheap cameras.

I read, a few years ago, that MiniDV could go upto 10 (maybe 100, I forget) times more capacity, the technique was already developed, so JVC gives us HD25 MinDV instead. Also the DVCPRO tape is also developed to give playback many more times than MiniDV that degrades after 7-12 times play/record.

Thanks for the help

Wayne

final thought.. feel like jerry springer now.. LOL

the old fashioned way to remove shadows and backlighting issues during daylight is to use a light...
A small 50 to 100w should be sufficient for close shots.... anything up to about 10 metres..

You can also use a large reflector to fill the shadows.

As to low lux rating of a camera, it is always with gain up.

"As to low lux rating of a camera, it is always with gain up."

Or, shoot in more light.

If nothing else helps, try light color sets and white makeup -- that should be worth a few lux/dB. Just don't quote me on it. Quote Frank. :)

http://www.dvfreak.com/lux.htm

Thanks guys, but I was looking for a way around having to set up big lights, bounce board, make up and sets all the time. Vladimir advice looks useful.

I tried a TRV22 yesterday and noticed that it was much better at rendering the outside scene in the background then the 953 (shame). There is a cheap DV3000 available (with some re-work it would be all right).

I am actually considering what would happen if I bought a cheap second hand 35 MM lense, and mount that to a camera (probably need intermediatory lense or something as well). I might try to experiment with my old camcorder in the next week or two.

Joseph, thanks, you wouldn't think that the JVC HD could possibly be 35 Lux with gain up, pity because otherwise it would get to nearly 4 lux with gainup (where it should have been). This lux thing is interesting because theorectically, a one lux camera should produce very usuable video, better than the human eye, with just one candle; has this been anybody's experience, at all? But most lux ratings aren't worth the soap there written on. On the other hand I have seen the JVC GY DV5000 at 0.4 lux, even two lux settings down from that it was producing low light vision as good (or better) than what I was seeing and no niose, without pixel combining that low lux modes can use as well as gainup and slow shutter. If anybody wants to work out the lux of their cameras it can be worked out from the db (I have been told about double for every 6db), slow shutter speed and cameras pixel combining scheeme. I looked at some cameras and figured that they were between 30-40 lux unasisted.

Anyway thanks everybody, from what I can tell knowbody makes an attachments to do this, but it should be possible. I know enough to look at doing it myself in future. I have also been offered a second hand VX9000 (pro VX1000) I think there 4 or 5 lux, and the VX2000 might come down to $4000AU eventually and that would be nice to improve. Unless somebody can tell me where I can get lense 35mm adaptors from that should be about all. Thanks for everybodies help, and hopefully there is a way around the crippled camera modle syndorme we have been seeing.

Thanks

Wayne.

Wayne, as to the Lux rating, let me give you an example. DVX is rated 3 Lux. In progressive it becomes 24 lux. The chips have the same sensitivity, but there is no gain up in progressive, for reasons unknown, since it would not cost Panasonic anything to include it. The extra video amplifier gain ads sensitivity but also noise. Unless you do some testing, the Lux ratings are meaningless.

>> Wayne, as to the Lux rating, let me give you an example. DVX
>> is rated 3 Lux. In progressive it becomes 24 lux. The chips
>> have the same sensitivity, but there is no gain up in
>> progressive, for reasons unknown,

Probably a marketing consideration for the higher Cinema series of cameras. Pity a 24fps shutter speed could be used to halve the lux, and people could tune the gainup to suit their preference.


>> the Lux ratings are meaningless.

They are, we could allways work backwards from the slow shutter speed, gainup and pixel combining functions, but we still need to see the footage to see how bad the niose is.

Somebody has pionted me to an interesting site:

http://www.tiffen.com/contrast_filters.htm

Not exactly what I'm looking for but seems good.

http://www.tiffen.com/digital_lenses.htm #Wide Angle Lenses

the 0.54 WA convertor seems to make the brightness double. They also have some interesting DV filter sets.

Well thanks Jospeh

Wayne.

Wayne,

it takes a lot of effort to find information, or people, who are interested in the progression of the art rather than restort to the standard. It takes so much time and hassle to get true answers I don't even bother to ask difficult questions, the simple ones I usually can find out myself

It's time to put some facts in this discussion and to paraphrase Indiana Jones, Truth is down the hall in the philosophy class.

There are no attachments that will add light to your camera, short of powered light amplification devices. If there were, every newspaper photographer and photojournalist in the country would be running around with one attached to their lens. Any changes to light levels brought about by attaching a WA convertor is due to the increased angle of view bringing an additional light source into the frame. If anything performance will be decreased because of increased reflection and optical defects brought into the optical system.

There are no adapters to attach 35mm lenses to cameras with fixed (nonremovable) lens systems. The least expensive series of cameras with a removable lens is the Canon XL1 series. Panasonic had some older, 1 chip designs with removable lenses, WV-3260, I believe. By today's standards a poor performer. Why no adapters? There are many reasons, added glass would cause loss of light, AF would perform poorly, and the aperture mechanism would not couple, to name a few. It would also result in extreme telephoto focal lengths.

In answer to your question, there is no magic pill or magic filter or any other magic device to add light where it doesn't exist. Well, except for the obvious one, a light.

Joseph summed it up when he suggested that you buy a camera with better specs. I've read your reply and I understand it. But the facts are the camera manufactures have stacked the deck against you. Better performance (lower lux ratings) come with the higher priced models. In the future the lower end models will get some of those high end feature sets. The trickle down theory. It's the way camera manufactures have always done it. It's unfortunate, but it's the way the manufactures do it.

None of this is meant to "knock or subvert" you in your search for answers. But many before you have been down this same path. What you seek does not exist or the effort to produce it, exceeds the value of your camera.

If anyone has something new to ask feel free to post. There is no need to restate the past.

<<<-- Originally posted by Wayne Morellini :
The 953 is a toy non toys virtually start at the PD150, the challenge is to make a 953 (for example), decent enough (fit for purpose/s), to give an edge to everybody that owns a cheaper cam. -->>>

Now you have to be careful, Wayne, because I am using a toy called MX350 and making some money with the toy. I also know of at least 4 other people using toys to make money. For these people, and their clients, your toys are tools of the trade.

I agree that a good camera would start at the VX2000, the PD150, the DVX100 or the even XL-1. But the 'prosumer' label is applied to cameras in the 3CCD range, manual controls, optical stabiliser, zebra (maybe) and audio input control. These qualities are all found on the MX500. So the MX500 may be the lowest of the prosumers in terms of quality. But even the XL-1 is nowhere near broadcast quality video, or film cams, at best, a prosumer cam with interchangeable lens and XLR input.

I use to own the MX8, a consumer 'toy'. I normally call it the highest possible consumer cam, though, as the images are good and the OIS is wonderful. It's not as sharp and not as beautifully coloured as 3CCD cams, but at 1 lux rating, it captured light where most other cams see nothing. And at +18db gain, the grain is so much less prominent than the XL-1 at +9db gain. So you can save $2000 from buying the XL-1 and pay $800 for the MX8, if low light is your only concern.

To tell you the truth, I'll prefer to use both the MX8 and a better cam (my MX350 for now) to shoot. Switching from the nice colours of 3CCD in good lights, to the less-grainy and brighter but greyish footage of the MX8 in very low lights. It's interesting that my clients are not too concern about colours, but whether the events were well covered and the key shots taken.

BTW, I shoot cheap commercials, training videos, church productions, weddings and cheap documentaries. some paid jobs, some free.

Frank, Jeff,

Let me disagree with you that it's impossible to improve low-light sensitivity with lens attachments. The reason is that among other factors, the sensor light level depends on lens aperture. Once an adapter is attached to the lens, the aperture of such a combination is not necessarily same, as naked lens. It can be more or less. In the first case, the light intensity measured at the sensor plane would increase, it we neglect the light loss from additional glass surfaces.

In short, the lens attachment can change the amount of light reaching the sensor. Theoretically, it's not necessarily should be WA convertor. It can be made a convertor that does not change the focal length, but just increase an effective aperture.

Jeff, you are right in your assertion that WA converter collects more light because of increased field of view. Then this light is distributed between available number of pixels, with each pixel getting more light. The angular resolution is sacrificed here, but so it is in any WA lens. This can be compensated if object is placed closer to the camera.

I'm not saying that ANY WA converter would increase light sensitivity. It depends on its optical design, its antireflective coating quality, and on camera lens as well. If some camera naked has aperture 1:0.7, I doubt this can be improved. But if camera maximal aperture is 1:1.8, this opens some possiblities.

Saying all this, I dont think this way to increase light sensitivity is worth the trouble. In my opinion, the possible gain is too small to justify a huge and heavy convertor on the camera. But for the sake of theoretical purity we should agree that it could be done.

It's worth repeating that the way to get your camera to perform better in low light is to remove all filters and converter lenses and to film at maximum wide-angle. Remember that all camcorders loose a stop as you zoom towards telephoto and some - like the Canon GL2 loose closer to two stops.

What this means is that if you can correctly expose a grey card using the wide-angle end of the zoom with one lamp on in the room, then you'll need to have four such lamps lit to expose correctly at full telephoto. This is quite a penalty. The losses are directionally proportional to focal length, i.e. the more zoom, the more losses.

My MX300 is even worse as full telephoto has the in-built ND firmly in place, covering a good third of the maximum aperture. No wonder it carries the banner of being crap in low light, yet at max wide it's pretty good.

Remember that every piece of glass you put in front of your lens absorbs some light and reflects some light, however beautifully coated it is or however thin the glass is. Some wide-angle converters use 4 elements and this introduces 8 extra surfaces for the reflections to take place.

Never was the term 'less is more' more apt.

tom.

Vladimir, please find a link or article that describes such an optical device. I am very curious to read about it.

Remember that all camcorders loose a stop as you zoom towards telephoto and some - like the Canon GL2 loose closer to two stops.

Tom, not all camcorders have variable aperture lenses. An F number is an F number no mater what lens or focal length. In other words F2.0 is F2.0 on any lens at any focal length. F2.0 is not unique to a particular lens, focal length or camera.

Very true Jeff, though domestic camcorders exhibiting such lenses are very few and far between, which is why I felt I could say that. My 10x zoom on my Canon 1014E Super8 camera had a maximum aperture of f1.4 throughout the zoom range, so it's perfectly possible for this to be made more widely available today.

It isn't only for cost, size and weight reasons, it's also competition. If Panasonic hasn't seen fit to supply that need then Sony are happy to remain in step.

I also agree with you that f2.0 is f2.0 whatever the lens or format. My real point is that T stops are never quoted and that Panasonic, with their in-built ND, can remain very quiet about the transmission at full telephoto.

tom.

<<<-- Originally posted by Jeff Donald : Vladimir, please find a link or article that describes such an optical device.

Well, I don't have a link. I've seen a clear low-light improvement by my own eyes a few years ago. The best reference I was able to find is Century claiming "no light loss" for their adapters:

http://www.centuryoptics.com/products/dv/4/chart.htm

I think what happens here is that aperture gets bigger, but surface reflections eat most of the gain. The net result is "no light loss".

With what cam and adaptor did you see "a clear low-light improvement by my own eyes?"

I doubt it was with a MX5/PV-DV953.

<<<-- Originally posted by Frank Granovski :
I doubt it was with a MX5/PV-DV953. -->>>

You are right. It was some 5 years ago. DVcams were in their infancy then.

Thanks Vladmir for introducing some sense. Over here , there has been lots of people, in the past, who just want to be negative rather than find a solution. It has been prolific, many people have been sent broke trying to prove, or invent something, that was right. That is one reason America does so much, better there is an interest in sucess, rather than failure. Admitedly, on average, inventors and creative people can reach higher hieghts here because of the opposition, they have to be good, but America reaches a much bigger bulk and heights. I can smell this from a mile off.

An wide angle convertor is actually not what I really want, but it is needed anyway, as the normal angle is to low for tight situations.


<<<-- Originally posted by Vladimir Koifman : Frank, Jeff,

Let me disagree with you that it's impossible to improve low-light sensitivity with lens attachments. The reason is that among other factors, the sensor light level depends on lens aperture. Once an


Jeff, you are right in your assertion that WA converter collects more light because of increased field of view. Then this light is distributed between available number of pixels, with each pixel getting more light. The angular resolution is sacrificed here, but so it is in any WA lens. This can be compensated if object is placed closer to the camera.

justify a huge and heavy convertor on the camera. But for the sake of theoretical purity we should agree that it could be done. -->>>

Jeff thanks for your comments. I don' think it is a magic pill, it will cost a bit of money, not as much as many would think, but still alright.

> Joseph summed it up when he suggested that you buy a
> camera with better specs. I've read your reply and I understand
> it. But the facts are the camera manufactures have stacked the
> deck against you. Better performance (lower lux ratings) come
> with the higher priced models. In the future the lower end
> models will get some of those high end feature sets. The trickle
> down theory. It's the way camera manufactures have always
> done it. It's unfortunate, but it's the way the manufactures do it.

Well that is a good reason to attempt it. The problem is that cartels, or anti trust behavour, in some Asian countries aren't regulated like they are in the States (where there illegal), so they can set the trend for the market. Any accesory manufacturer can produce trouble for themselves if they buck the trend as well.

> None of this is meant to "knock or subvert" you in your search
> for answers. But many before you have been down this same
> path. What you seek does not exist or the effort to produce it,
> exceeds the value of your camera.

I appreciate that, and I also appreciate your much more graciouse reply compared to some. But the fact that a particular answer is being looked into, and is possible, is a reason to explore that rather than getting stuck in avioding it by restating opposing answers that are obviouse but aviode the issue asked, over and over again, like some had. I didn't expect to find an easy answer, it was either going to cost money or time.

Yow Cheong Hoe:

Thanks Yow. I'm sorry for the toy camera remark, it is a quote of professional opinion I have come across. Over here we have moved to HDTV broadcasting and standards have risen for years to high levels. They only want to accept threee chip footage. The definition of braodcast is probably 4:2:2 from a digi beta camera to some. They define broadcast interms of variouse signal level, resolution, colour requirements etc etc. I have got to admit aswell the footage from the JVC GYDV5000, Digital Beta, JVCPRO cameras does look a lot better than what is produced by the XL1 and the VX which probably fails these tests. My guess is that they probably have some filtering mechanism that takes prosumer 3CCD footage and adjusts the levels to suit and quality standards, and prefer not to spend the time on it. I don't particularly need to buy a pro camera, but if I am going have to be cheap, I prefer not to look good at it.

Tom Hardwick:

> It's worth repeating that the way to get your camera to perform
> better in low light is to remove all filters and converter lenses
> and to film at maximum wide-angle. Remember that all
> camcorders loose a stop as you zoom towards telephoto and
> some - like the Canon GL2 loose closer to two stops.

Thanks Tom most appreciated.


Frank:

I have been advised of 33% inprovement, I have shown you a link that looks like a 100% improvement.

http://www.tiffen.com/digital_lenses.htm #Wide Angle Lenses

It is theorectically, and practically possible. It is only a complicated design issue (for somebody that knows optical engineering) the issues are image distortion not light gain, that is obviouse, the lens collects the amount of light not the CCD and effects the Lux. Bigger lense and focused right = more light. Lenses don't ussually absorb most of their light but only a fraction of it. If the 10 piece (or 8) DV3000 passes 70% of it's light that averages to around 3% light loss. If it has four times the area and collects 400% light 3%-16% (good coating, thick lense) light loss, plus corection lenses, doesn't make much of a difference. Let alone side tracking the issues.

Well thanks everybody, I have to get going, a lot to do lately, I won't be back for a while, so until the future have a good day.

Thanks

Wayne.

http://www.dvfreak.com/lux.htm

I work as an instructor at a local University. I printed out this thread and took it to several trusted associates: Engineering Professors (and a Dean who is also a cutting-edge optics consultant); folks who, collectively, have over 100 years of experience and knowledge in Optical, Electrical, and Computer Engineering. They all gave me the same answer. Some professed being mystified at why there was a question about this in the first place.

Put simply, you cannot gain LUX without actually replacing the lens, the CCD, the electronics, or all three. You cannot ADD a lens, any lens of any design, and increase LUX sensitivity.

I suggest you go to a good University with this printed thread in hand. Ask someone in Optical Engineering, etc. to take a look at your argument. They will tell you, based on universally respected FACTS of physics, why this is impossible as you argue it.

I'm still feel unconvinced about the technical side of this discussion. Let me put things upfront - I have absolute zero experience in optics. But even risking to lose my face in this discussion, I still like to learn something.

Let's look on telescope stricture. It has two basic peices - the large diameter lens-objective and small eyepiece. The eyepice is just like camera lens, just optimized for viewing by human eye, instead of CCD. It's also interchangable (usually).
Now, the larger the main lens-objective, the better telescope ability to see weak stars.
Assume someone attaches video camera to the telescope instead of eyepeice. Assume that front lens or mirror of the telescope is very large, say 10 feets. Does this improve the camera low-light abilities?
I'm understand the focus length will be huge and that front lens would make upside-down picture. If somebody values low lux abilities above all, he might use his camcorder upside down to compensate - just joking.

Charlie, you know, after you referenced to professors and 100 years of combined experience, I'm not sure in anything. I'm ready to lose this argument. Please, just explain me where is my mistake.

No mistake Valimir, just a misunderstanding of the way a lens's maximum aperture is formulated.

If you have a 50mm lens and it has a maximum aperture of f2 then the diaphragm blades (the 'aperture' through which all the light must pass) has to be 25mm in diameter. This is optical law and is a simple mathematical equation. If you look at this argument you'll realise that two identical 50mm lenses could both be f2 yet one could be made with the purest glass to be found, the other made with scratched, yellowing plastic.

They'd both be f2 lenses, but one would transmit a lot more light than the other. Welcome the T stop (T for transmission). This is a much more accurate way of measuring the light that exits the lens on the way to the chip, and is the way professionals set up their shots.

Sony have designed the 12x zoom on the VX to have a maximum aperture of f1.6 at the 6mm end. But with production tolerances, 13 elements, three beam splitting prisms and two plane parallel elements in the OIS you'll realise that the T stop is probably some way away from f1.6.

No matter. Increasing the size of the front element (as in your telescope analogy) won't affect the T stop of the lens, only a complete re-design could do that. In the same way adding a wide-angle converter won't help either - in fact it will very slightly decrease the amount of light that finally exits the lens.

tom.

Tom,

Thank you for your reply. I understand what you are saying about loss of light in the lens elements. So the light loss is unevitable. Theoretically, this can be improved by multilevel coating, if lens cost is no issue. For example, some Hoya UV filters promise 97% of light transparancy. Also, mirrors can be used instead of glasses.

But there is one thing in your explanations I don't understand. In telescopes the eyepiece size is something more-less simalar in all telescopes. I mean, even huge telescopes have relatively small eyepiece. However the bigger the front lens or mirror, the weaker stars the telescope can detect - at given eyepiece size.
I understand there is a flaw in my speculations. In the end, if everybody says I'm wrong, most probably I am. I'm just trying to find a peace of mind and understand why adapters (wide or tele) with lens do not work in a same manner as telescope eyepiece-front end.
Please help me on this.

Yes, multi-layer coating can indeed improve light transmission. Plain uncoated glass reflects back about 8% whereas as you say MC coating can mean that only 0.2% gets reflected (at each air to glass surface) - all the rest goes through. I would suspect that mirrors suffer the same losses as glass, even sufrace silvered ones. Nothing is perfect.

I'm not a telescope man but I'd suspect that larger front elements on telescopes mean more light gathering power, in the same way as wide aperture photographic lenses have bigger front elements. This light is then passed through the eyepiece to the human eye which can vary its own iris diaphragm to expose the retina correctly. If you look through a pinhole all will be dark as you eye is at it's max f1.4 and still there's not enough light to see by. Look through a huge telescope and the eye is fed enough information to sensitise the retina (or film or CCD, whatever).

tom.

Tom,

Now you put it in even more straight way than I did.
A human eye have f1.4 aperture - I did not know this, thank you for the info.
The ability of eye to see weak stars is extended by telescope, right?
So, if one attaches camcorder instead of eye to the telescope eyepiece, the camcorder will see weaker stars as well, right?
I feel I messed up things somewhere, but I don't see where. Any help?

Absolutely correct.

Tom,

Does this mean that if one buys telescope as a tele-adapter for his camera (albeit huge, expensive and inconvenient), one can improve the camera low-light capability? I still think there is a catch here, it cant be that professors are wrong here.

Tom's quote, " I'm not a telescope man but I'd suspect that larger front elements on telescopes mean more light gathering power, in the same way as wide aperture photographic lenses have bigger front elements."...This light is then passed through the eyepiece to the human eye which can vary its own iris diaphragm to expose the retina correctly."

You forget that Wayne's argument was that NO INTERNAL CAM MODIFICATION is ncessary, save adding an attachment Lens system. Where does this 'wide aperture photographic lens' obtain its 'wide aperture? FROM AN INTERNAL MODIFICATION, that's where.

Vladimir siad:
"Now you put it in even more straight way than I did.
A human eye have f1.4 aperture - I did not know this, thank you for the info.
The ability of eye to see weak stars is extended by telescope, right?
So, if one attaches camcorder instead of eye to the telescope eyepiece, the camcorder will see weaker stars as well, right?
I feel I messed up things somewhere, but I don't see where. Any help?"

Tom: "Absolutely correct."

Um, no.

The cam cannot change how it 'sees' in the same manner the human eye does so reflexively WITHOUT BEING MODIFIED at its lens, CCD, electronics, and/or software. Without said cam modifications, it is technically impossible to increase the cam's LUX sensitivity. There are losses at every step, from Telescopic front lens to CCD, and these losses are what prevent a sum LUX gain by only adding more glass to the front of any cam.

This, Vladimir, is precisely why it will always remain a tantalizing theory and not be a practical solution- cams are not human eyes, and even if they were, 'attaching' a cam to a huge telescope is tantamount to attaching the cam to an external light source, rather than an 'add-on' lens system. In this case, it's the CAM that's being added to the light source, not the other way around.

Good luck on your search for the answers, fellas...

Oh, yeah...as I recall, basic physics would also dictate that, no matter how much a telescopic device 'gathers light' it's in the service of 'passive transmission, i.e., a small star appears bigger, but the light-gathering serves the magnification of the image, not the modifcation of the device attahced to it- a cam, etc. In other words, at some point, the cam attached to a telescope would be the BOTTLENECK to its light transmission back to a CCD, including whatever technical limitations are built into the CCD itself!

My final 2 cents as a 'lay' observer...

Howdy from Texas,

<< a telescopic device... i.e., a small star appears bigger, >>

As an amateur astronomer who has built his own Newtonian reflector (a type of telescope), I can assure you that telescopes do not make small stars appear bigger. All stars (with the exception of our own sun) appear through all telescopes (without exception, including Hubble) as tiny points of light with the single dimension of brightness. Some are brighter than others, which is usually an indicator of age and flavor, not size... and some resolve into binaries (twin stars)... and some resolve into double binaries (two sets of twins). But they're all just points of light, no matter what telescope you're using, no difference in "size," only in brightness.

To steer this back on topic, please note that I've had to edit a few recent responses. It is a rule here that we have NO FLAMING of any kind, so please be nice to each other. Daddy is watching. Many thanks,

See, this is what I mean. I'm not a 'Telescope Guy', either, Tom. Glad to see a reply from one though!

I'll add one more thing: that adding any apparatus to a cam doesn't make it inherently more sensitive to light; it may, at best, increase the amount of light transmitted to the cam itself. This only means that the cam, once again, is the bottleneck of light sensitivity- you ARE stuck with the LUX rating of yer cam until you ebay it and buy a more sensitive one!

Point taken on the 'no flaming' Chris- I get a little carried away sometimes...again, I'm demonstrating a firm grasp of the obvious!

Thank you Chris for calming the flames. I saw the relevant post and thought it harsh. And hey Charlie, I thought I had put up a defence of what I was about to write when I started the paragraph with, "I'm not a telescope man but I'd suspect that ... " I certainly didn't mean to mislead, but bow to your greater knowledge on the subject. And I hope Valadimir now knows that adding anything in front of his front element will soak a bit of light...

tom.

Sorry, Tom. Point well taken; I looked back over the posts and indeed, that's easy to see now...

8-month old son with MAJOR sleep problems got me CCI (Cranky, Confused, and Ill-mannered)...

Thanks for setting me striaght, guys.

*yawn, sniff*

<<<-- Originally posted by Charlie Higgins :
I'll add one more thing: that adding any apparatus to a cam doesn't make it inherently more sensitive to light; it may, at best, increase the amount of light transmitted to the cam itself. This only means that the cam, once again, is the bottleneck of light sensitivity- you ARE stuck with the LUX rating of yer cam until you ebay it and buy a more sensitive one!
-->>>

Charlie, sorry for my insistance, but I'll ask again. It looks there is something basic that I don't understand.
On one hand you say that one can add something that increase the light coming to the cam. I mean something passive, not night vision tube or like.
Then you say, I'm stuck with LUX rating anyway.
I'm failing to connect these two statements. Could you please build a logic chain in between for me? I understand you have it in your mind, and it looks that Tom agrees with you, but I still can't understand.
Sorry for my ignorance, but I'd like to understand it. Is it at all possible without reading an optics textbook?

Vladimir, I'm sorry.

My posts seem contradictory; my first assertions are based on scientific principles as related anecdotally to me by people who have forgotten more about optics, etc., than I will ever know. My latter post, the one to which you so perceptively refer, seems to undercut my previous posts because, and this is my again my fault, it seems more based on semantics ('the LUX of the camera itself is not altered, even if more light is introduced to its outer optics by an additive lens system' kind of argument). What I meant to say, and again please forgive my very basic understanding of what I was told by my collegues, is that any 'more' light that arrives at the front lens of a cam is absorbed by the lens glass, distance to the CCD, and various other losses that preclude a net gain of LUX in any cam. The cam itself, in order to become more light-sensitive, must be modified per my previous (and others') posts: i.e., modification or replacement of cam lenses, CCD, software or electronics. I am given to understand that the design and construction of a cam does not allow it to become more sensitive to light (LUX rating). One reason is that the lens dispersion and distance losses in both the attachment and the cam optics apparently absorb any incrementally increased light to the outer lens of the cam.

Now whether this is a theoretical or a practical limitation is what I don't understand myself. In other words, what about a huge Parabolic Mirror funneling light to the cam lens? Now, obviously, that would increase the light into the cam, no? Why doesn't this work on a smaller scale? Vladimir, I'm with you on this. I do not understand the (dis?) connection, if any, between one scenario and the other

I also wonder, and wish I'd thought to ask at the time, whether an attachment system such as 'Night Vision', an ACTIVE light amplification system of electronics and optics, might introduce light to the cam in such a way that would allow the cam, with the rest of its sytems intact and unchanged, to successfully record footage via the 'Night Vision' attachment.

Vladimir, I am at this point in optical water deeper than I can swim. I hope this helps in some small way, but if it doesn't, I understand, and my apologies!

I am pure amateur on this, but I think noone really cares if you can increase camera LUX or not, so to say... The practical thing is what it's of interest, so the real question is not if you can increase camera LUX (it's obvious you can not if you don't change the camera itself), BUT can one record at low lights with better results (with better image quality)? It's seems simple logic, that if you "attach" telescope in front of camera you can. E.g. recorded stars at night will appear much brighter and if you'd, say, point telescope to a city you'd get a much brighter city at night -- it's the telescope which collects light, camera per se does nothing new... So, wouldn't be possible to make lenses (prob. would be quite big), which would collect more light to pass to camera to say record at nights with good results even when light is relatively low...? Ohhh all this might sound stupid, I apologize if so...

Adding a tele and pointing it to a spot of light like a star isn't an example of decreasing LUX requirements with a cam.

wouldn't be possible to make lenses (prob. would be quite big), which would collect more light to pass to camera to say record at nights with good results even when light is relatively low.

These types of lenses (or adaptors) are available at the cost of an average person's year's salary. It's good for about 15 feet and produces a nice grainy green colour. Sometimes you can see their use on CNN. I used to have a couple of links written down somewhere about them.

Hi

I've been away for a long time, I was amazed to see the discussion. The university professors had me worried though. I did some lecturing at uni once. First thing, only the guys with optical experience I would bother to ask, and only if they are paying attention and not just trying to get you out the door (as I said I have worked at university). One of my best freinds was the top electrical engineering student of his year (in the country) I wouldn't ask him anything about optical stuff though, just electrical/electronic. We both have simular intelligence (but not in spelling). I am a sickly computer scientist actually, and I wouldn't ask most IT people a single thing about optics.

Unfortunately the closet university, that has the relavent experience, is 3 1/2 hours away.

I saw a couple of flaws earlier on and that is the way the arguement went.

When you asked them about whereever puting a lense infront of the camera would increase it's lux sensitivity, did they think you were asking about a single lense and the light resolving factor, not the amount of light? I appreciate your comments though, it explains why the single lense won't work, something I thought might be the case, and needed a proper lense system to bend and foucus the light correctly at the front lense of the camera, so it passes through with minimal loose and hits the CCD correctly. I have tried a SLR lense (without adaptor) and have seen a increase in brightness (though I need a video card to prove the values), but at a slight telephoto :(. I had to dim the lights and put the old panasonic to 1/6000 of a second to keep auto iris at maxium to prove what could be seen at normal light levels, and pionted it at a white peice of paper with evenly reflected light off the the ceiling, took ages (eventually used frame capture button to compare 5% to %10 light). That is why I was unconvinced enough in it's accuracy to share it here (to much niose to be completely objective).


Of course, if it were not possible to increase the lux gathering power of the camera, then attaching it to the hubble telescope would produce little different image then pionting it directly (except for maginifaction with the same net brightness). Attaching a lense system to the front of the camera is infact changing the camera optical system by addition. My origional thought was that it would be an multi-lense engineering feet to get the light to come into the lense properly, so as to not loose light down the optical path through dispersion and "fractional" ansorption in the optics, this I would still like to know how to do.

Well thanks for all your comments they have been well thought out, correct in what they were talking about, and answers a few things.


Wayne.



<<<-- Originally posted by Charlie Higgins : Vladimir, I'm sorry.

I work as an instructor at a local University. I printed out this thread and took it to several trusted associates: Engineering Professors (and a Dean who is also a cutting-edge optics consultant); folks who, collectively, have over 100 years of experience and knowledge in Optical, Electrical, and Computer Engineering. They all gave me the same answer. Some professed being mystified at why there was a question about this in the first place.

Put simply, you cannot gain LUX without actually replacing the lens, the CCD, the electronics, or all three. You cannot ADD a lens, any lens of any design, and increase LUX sensitivity.

I suggest you go to a good University with this printed thread in hand. Ask someone in Optical Engineering, etc. to take a look at your argument. They will tell you, based on universally respected FACTS of physics, why this is impossible as you argue it.

-----

My posts seem contradictory; my first assertions are based on scientific principles as related anecdotally to me by people who have forgotten more about optics, etc., than I will ever know. My latter post, the one to which you so perceptively refer, seems to undercut my previous posts because, and this is my again my fault, it seems more based on semantics ('the LUX of the camera itself is not altered, even if more light is introduced to its outer optics by an additive lens system' kind of argument). What I meant to say, and again please forgive my very basic understanding of what I was told by my collegues, is that any 'more' light that arrives at the front lens of a cam is absorbed by the lens glass, distance to the CCD, and various other losses that preclude a net gain of LUX in any cam. The cam itself, in order to become more light-sensitive, must be modified per my previous (and others') posts: i.e., modification or replacement of cam lenses, CCD, software or electronics. I am given to understand that the design and construction of a cam does not allow it to become more sensitive to light (LUX rating). One reason is that the lens dispersion and distance losses in both the attachment and the cam optics apparently absorb any incrementally increased light to the outer lens of the cam.

Now whether this is a theoretical or a practical limitation is what I don't understand myself. In other words, what about a huge Parabolic Mirror funneling light to the cam lens? Now, obviously, that would increase the light into the cam, no? Why doesn't this work on a smaller scale? Vladimir, I'm with you on this. I do not understand the (dis?) connection, if any, between one scenario and the other

I also wonder, and wish I'd thought to ask at the time, whether an attachment system such as 'Night Vision', an ACTIVE light amplification system of electronics and optics, might introduce light to the cam in such a way that would allow the cam, with the rest of its sytems intact and unchanged, to successfully record footage via the 'Night Vision' attachment.

Vladimir, I am at this point in optical water deeper than I can swim. I hope this helps in some small way, but if it doesn't, I understand, and my apologies! -->>>