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Old April 19th, 2004, 09:45 AM   #16
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I haven't paid much attention to the work done on the Hubble but you cannot increase the amount of light gathered by using smaller lenses and I did not say that. The only way to increase the light gathering is by increasing the size of the front element.

I say light gathering because you cannot increase the amount of light, or magnify it, any other way. A wide angle lens only takes the available input of light and places it on a different area of the ccd or film. That amount of light does not increase or decrease because you would be creating light with a lens which is impossible.

Light travels in a straight line. The number of "light lines" is a constant unless the scene or light source changes. It's what makes depth of field work. By stopping down a lens you are cutting off scattered "light lines" which can't be focused....man, I really am not in the mood to go into all of this. I've been up all night.
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Old April 19th, 2004, 09:55 AM   #17
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Quote: Rob
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...only way to increase the light gathering is by increasing the size of the front element.
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so we agree that the front element increases the light gathering.

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I say light gathering because you cannot increase the amount of light, or magnify it, any other way.
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if you are "gathering" more light you get more light. you are contradicting yourself here.


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A wide angle lens only takes the available input of light and places it on a different area of the ccd or film.
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do you mean your CCD becomes larger? haha =)
and since you "gather more light" you get more light to put (focus) on the same CCD on the same elements.

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That amount of light does not increase or decrease because you would be creating light...
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the focused light does increase when you have a larger gathering element...


I can see you've been up all night =) you make no sense =)

(again.. talk is cheap)
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Old April 19th, 2004, 11:23 AM   #18
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No I am not contradicting myself. You are confusing "gathering" light with "magnifying" it. Magnifying means to increase the amount while gathering means collecting what is there.

Think like this: when it's raining you can set a bucket out to collect the rain. You can set a larger bucket out to collect more rain. In neither case does the size of your bucket make more rain.

Placing light on a different part of the ccd does not make the ccd larger and I don't know how you got that idea.

When light shines on an object, a certain number of photons strike and, presumably, reflect off that object and head in various directions. If all the light at one point equaled 10 photons, just to pick a number, the angle of the lens does not change that. That is why the inverse square law does not apply to the distance to the camera, only to the placement of the light source.

All of this is simple optics and physics.
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Old April 19th, 2004, 12:03 PM   #19
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Rob... buddy... think for a second... =)

are you teling me that when you put wide angle lense your CCD gets larger? =))

Quote:
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Think like this: when it's raining you can set a bucket out to collect the rain. You can set a larger bucket out to collect more rain. In neither case does the size of your bucket make more rain.
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but in the end of the day you have the same size CCD. that means that you have to pour the "water" you gathered from the larger bucket into the smaller one. and what matter here is the depth of the water you gathered. (your CCD's area surface does not change)


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Placing light on a different part of the ccd does not make the ccd larger and I don't know how you got that idea.
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you cannot place the light on a larger area (as in the given examples by you). like in the larger bucket -> that has larger bottom surface. if you use this as anology to light and CCD, you mean that the light in second case hits larger surface (larger CCD). and this is not the case.
you get that more light has been focused on the same area, same CCD.


-----------
When light shines on an object, a certain number of photons strike and, presumably, reflect off that object and head in various directions. If all the light at one point equaled 10 photons, just to pick a number, the angle of the lens does not change that. That is why the inverse square law does not apply to the distance to the camera, only to the placement of the light source.
-----------

ok.. so say we have 100 photons hitting an apple =)
and they are reflected by the surface of the apple in different directions.

the case of the "light colector"

case A:
Lets say we have lens A with surface light collecting area of "Sa"
and we get 10 photons collected and focused on a CCD with fixed surface area, with our normal lense.

caseB:
lets say we add a larger light collector B with double the surface area. Assuming a even photon distribution we will now gather (about) 20 photons coming from that apple, which will be focused on the same CCD.

so in case A we get 10 photons on our CCD, in case B we get 20.
(more photons -> more light)

=====================

the case of the "open eye" =)

similar to above we collect 10 photons from the apple.

if we have wide angle lenses, the "apple" will look smaller on our image. this is because the lenses have focused the apple on a fewer number of CCD photo sensor elements.

so in CaseA (no extra lenses) we have 10 photons hitting 10 photo sensors, or
1 photon per sensor.

in CaseB (with the larger lenses attached) we have 10 photons hitting 5 photo sensors. Or we have
2 photons hitting each element.
======================
bottom line:
no matter type of optics you attach to your cam, if you have larger lense infront, extra light gathered from the lens will reach your CCD and lower the lux.

I call this elemental logic =)
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Old April 19th, 2004, 01:19 PM   #20
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Once again: at no time did I say your ccd gets larger. The buckets are an analogy for lenses, not ccds.

When you use a larger front end on a lens you gather more photons but you are assuming these photons all reflect and are focused on the same point. This does not happen unless you increase the source light.

Take a garden hose with a spray attachment. Aim it at the aforementioned bucket. Say a quick spray releases 100 droplets (photons) and 10 land randomly inside the bucket. Using a wider bucket may catch 20 droplets. You have captured more drops (light) but, reverting back to the lens, the lens will attempt to focus the photon spray at the ccd. It cannot focus all the photons perfectly since they are all different distances from the ccd. 10 droplets in the smaller bucket (lens) can be brought together (focused) better than 20 droplets in the wider bucket. (See circle of confusion, sort of).

The light reflected at any point on the apple never changes just like the water from the hose never changes but you can collect more of it. However, no point in the bucket will get any wetter just by using a larger bucket. Equally, no point on the ccd will get any brighter just because you use a wider angle bucket, er, lens, which, I thought, the original question was.
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Old April 19th, 2004, 02:01 PM   #21
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Rob, I don't think I can explain this any simpler... =/

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When you use a larger front end on a lens you gather more photons but you are assuming these photons all reflect and are focused on the same point. This does not happen unless you increase the source light.
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when you use larger front end lens you DO gather more photons... (which means you gather more light), I agree... the next part makes no sense.
I do assume you focuse them on the same "point" (i would say area) .. - the CCD
the more photons you have the more photons you focus on the CCD, the more light you get on the CCD.

----------------
Take a garden hose with a spray attachment. Aim it at the aforementioned bucket. Say a quick spray releases 100 droplets (photons) and 10 land randomly inside the bucket. Using a wider bucket may catch 20 droplets. You have captured more drops (light) but, reverting back to the lens, the lens will attempt to focus the photon spray at the ccd.
-----------------
at least you agree that you will capture more light.
now you have to tell me how you will lose part of this gathered light.
in the example you need half of the light to somehow "diasppear" in order to have only 10 of the 20 droplets reach the CCD.


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10 droplets in the smaller bucket (lens) can be brought together (focused) better than 20 droplets in the wider bucket.
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what you are saying is that you can focus better 10 photons than the 20, and that when you focus the 20, 10 somehow disapear?
I hope you see how fallacious this suggestion is....
(even if you were out of focus you'll still get 20 photons on the CCD, even if they are not arranged well - blury image)

I would suggest you go back to my previous post and think about it a bit more. I hope you get it this time...

good luck.

ps. i was trying to figure out what exactly you are thinking...
you should know, you don't "focus" photons you redirect them. so if you redirect them. maybe you think that you cannot redirect them all on the CCD?... and half of them "spil" outside the CCD?
(this of course does not happen...)
i give up... g'luck again, i don't think there's a point of more examples.
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Old April 19th, 2004, 03:29 PM   #22
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I hope you weren't trying to explain anything to me! I was trying to explain this to you. You're previous post is inaccurate. But since you choose not to read any further I, too, will stop posting.
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Old April 19th, 2004, 04:28 PM   #23
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yep.. there's no point of going on about this.

I just wanted to see a test, so if anyone has the ability to make it, please try it and post the pics.
10x in advance

ps. Rob, I see that you were only explaining it to me. Thats why you didn't even think about what I was saying. No point to continue on that path.

ps2. for those who are still following.. and still confised.. you can try thinking it this way: when you gather more light you gather more energy, unless yout lens charge the battery pack, they'll transmit... project the higher light energy onto the CCD. And even "unfocussing" cannot make you lose the gained energy.
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Old April 19th, 2004, 04:58 PM   #24
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George, your original question was this: "Is there any change in the LUX sensitivity of 953/gs100k if you use large wide angle lenses? (like Aspheron)?" And your answer is, no.
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Old April 19th, 2004, 06:07 PM   #25
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Frank, did you try it? or you are taking a blind leap of faith? =)
(since what Rob says is incorrect)


make 3 shots,
1-original setting, lens
2-attach the wide angle lens, and make a shot from the same location
3-with wide angle lens, move the cam closer so you get more or less the same scene in the frame

do this in low light conditions, and post the pics =)

post the pics...

be the one who shows some facts :)

ps. the change and increased light will be there, but it may not be enough to have visible difference in this specific case of dv953 and Ashton lens, but untill you test it you'll never know.
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Old April 19th, 2004, 06:48 PM   #26
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I had already mentioned that I didn't notice a LUX improvement when I was trying wide angle adaptors on my cams in Leo's dimmly lit downtown store. I tried the Tiffen wide (37mm and 43mm), and a couple of Raynox models. If I discovered that a wide would improve the LUX requirements of my cams, I would have bought a couple of wide angles years ago. If you're not happy with your PV-DV953's LUX requirements, sell it, and buy a MX3000 or better, a VX2000. I'm sure they're both easy to find in the used market. Just a couple of weeks ago there were 2 MX3000's up on e-bay; someone posted these links here, several threads down from this one. If you don't want to spend that kind of money, look for a used Panasonic PV-DV852 or an Optura 100MC. That's what I would do, but I still have my old but trusty DVL9500's for "low light" shooting. :-))

See: http://www.dvinfo.net/conf/showthrea...threadid=24781 - I'm asking too. But the trick isn't with in an adaptor but with the cam instead. :-))
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Old April 19th, 2004, 06:57 PM   #27
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Frank, the idea was to have mush larger lens, not one thats about the size of your cams. I think 37mm is about your cam own lens (even if it's a wide-angle, there will be no change at all, same size - same light collector).

Thanks for the suggestion, but I'll probably get GS400 =)
and then if I have to, I'll make a camp-fire on the living room's floor, for extra light :)
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Old April 19th, 2004, 07:04 PM   #28
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Quote:
I'll make a camp-fire on the living room's floor, for extra light :)
Actually, placing yourself or your subject or one or two 60 watt light bulbs in the right place can make all the difference with your footage. Never mind the campfire in the living room. I did that, and my aunt who was baby sitting me and my brother at the time thrashed us real good, after she put out the fire. My Aunt's still alive, bless her soul. :-))
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Old April 19th, 2004, 07:15 PM   #29
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=) too bad you hadn't had a cam setup for the "camp-fire" that day :))
it would had been something
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Old April 19th, 2004, 07:18 PM   #30
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That was 46 years ago. No miniDV back then. :-))
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