Film resolution with the XL1S?
 

Greetings folks!

I still digging information about the XL1S and it's production options!
Recently I read an article on the mini35 adapter for the XL1 on Cinematographer magazine.The article states that the use of the much sharper 35mm primes made the XL1 footage look better than high end 2/3 cameras. That's really exciting since the XL1 produces the most film like color on the industry and also shoots 25fps (PAL).
The adapter is sure too expensive but you can rent it.
You can find some 35mm zoom lenses for around $2,000 (if you have a long shot, it would be cheaper buy the lens and rent the adapter only).
So I have some questions:

1)On the article test they used a prime lens (sharper than zoom lenses).Would a zoom degrade the image in a noticeble way?

2)I know the adpter keeps the 35mm depth of field, but regarding sharpness, would the use of a 16mm motion picture zoom lens increase sharpness in a similar way? Or 16mm lenses are not as sharp as 35mm?

3)If a 16mm lens would also significanttly increase sharpness, A cheaper set up to increase sharpness and image quality would be the use of the Optex PL adapter with a 16mm zoon lens.It would increase the focal length in around 2.6 times (but if you get a 12mm-120mm for example you would still getting a 32mm wide end which is around the same as the stock XL1 lens).You wouldn't have the shallow depth of field as in 35mm but it would cost you round $2000 to get the adapter and a 16mm zoom lens.Far short form the money you would spend renting the mini35 and lens.

Any thought about those questions?I would love to hear form you guys!

Cheers!

Adam

Justin Chin is our local expert on the mini35 adapter. He has one and has been getting some hands-on experience with it. Hopefully he'll chime-in here.

The depth of field is a function of the format size (as well focus distance and lens aperture, aka f/number) the lens was designed for. Ergo, a 16mm lens will be somewhere (in depth of field) between 35mm and ~8mm(the canon CCD). Sharpness??? not sure what you mean, in a technical sense, by that adjective. Lens resolution is a function of the lens design, and generally is independent of design format size. As for aesthetic look, well, only you can decide that.

Hmmmm. Focal length is focal length, no matter the format size. Depth of field is a factor of focal length and aperture. Changing format size changes the field of view, it does not change the depth of field. It is this field of view effect that appears when a 35mm lens is installed on the XL1. The 7.2x factor with EOS lenses is essentially saying taht when you use an EOS lens on the XL1 the field of view is equivalent to a 7.2x longer lens on a 35 mm camera. That is because the smaller CCD is using only the center part of the image formed by the lens

In general zoom lenses will not be as sharp over their zoom range as a fixed focal length lens. But there are significant variations in quality among makes and models. A high quality zoom may produce a better image than a cheap prime.

f/#=FL/aperture
I don't know if you're agreeing or disagreeing, Don. So, let me explain it this way....the depth of field is related to aperture, i.e. the bigger the diameter of the lens, the less depth of field. Stopping down reduces the effective diameter (aperture), thereby increasing the depth of field. A lens designed for 35mm format is larger in diameter (aperture) than a lens designed for 8mm format(1/3 inch). While a 1/3 inch ccd only fills a part of the 35mm focal plane, it still has the depth of field characteristics of the 35mm lens. My comments re: "focus distance" are not a reference to focal length, but, distance to the object of interest. I should have been more precise.

Thanks for replying folks!

I was just trying to find out if the use of a good 16mm lens would increase the sharpness of the image produced by the XL1S. Is reported that the use of 35mm lens (with the P+S adapter) on the XL1S improved very much the image sharpness . I was wondering if the same would happen if you used a 16mm with the Optex PL adapter.
I know that using the PL you would still getting the same depth of field of a normal 1/3 CCD camera.The PL also makes the focal length 2.6 times longer when used on the XL1S.
My point is get some extra sharpness.Justb wondering what the results would be but seems like nobody out there has tried the PL adapter on the XL1(S).

Cheers,

Adam

Bill. Just trying to be more precise, and I believe that we agree. A 35mm foramt lens will have the same depth of field as an 8mm format lens - if they are zoomed to the same focal length (e.g., 50mm), set to the same aperture (e.g., f/4) and same subject distance (e.g., 10 feet). But on the 8mm format the field of view is much less giving it a telephoto effect rather than a normal lens on the 35mm camera.

An of course the aperture is the effective size of the hole letting light through. The f-number being the ratio of the hole diameter to the focal length.

With regards to DoF:
The key term here is Circle of Confusion (CoC). Everyone has explained the principles of DoF calculations pretty well. I use a Palm Pilot program to calculate DoF and by just switching formats (size of film plane) but keep all other elements the same (Distance to subject, aperture, and focal length), you end up with different DoF and CoC. The larger the format the smaller the CoC and thus DoF.

As for sharpness in lenses:
You will have to look at each individual lens for an real confirmation on that. The lenses that the AC article used were Arri Zeiss Ultra Primes and they are pretty much top of the line. Any other used lens you buy should be tested with a sharpness chart so you can compare them. My Zeiss lenses don't appear to be as sharp as the Arri Zeiss'. But my lenses are at least 10 years old. I used the same sharpness chart (thanks ZGC!) and I wasn't able to resolve the center circle. Obviously, the weak link is the lens.

In short, you have to find the sharpest lenses you can find. Not all 35mm lenses are equal. I went through 3 sets of lenses before I settled on the much more expensive Zeiss. But I wouldn't have it any other way.

Also, zooms are great for versatility, but you'd be hard press to find one that is faster than T3. And thus you stop short your DoF and you'll need more light.

Hope this helps.

Thanks for all replies once more! This board really rocks!

Hey Justin, the lenses I am looking at are all 16mm.I wanted to use the Optex PL adapter.All I want is increase resolution.
You seem to have a lot of experience in using film lenses with the XL1.Would you mind I contact you in private to get some advices?
I would really appreciate that.
Please let me know.

Best regards,

Adam

Adam, sure I don't mind you contacting me. Keep in mind that I am going through the same process as you might be. Perhaps, I'm a little ahead of the game but that remains to be seen.

Let me know how I can help.

And yes this board rocks!

all the sharpness/resolution of lens at some point becomes useless when it ends up in NTSC ... i'm not sure if you can see the difference between a lens that has 200 lines resolution and one that has 75 line resolution on a XL 1 ?? i know you can see the difference on 16/35mm film ...

in FILM the smaller the film format the more resolution you need
... 16 mm lens need to have MORE resolution then 35mm lens ... 65 mm have less resolving then 35mm ... a 65 mm lens might only have 40 lines of resolution ... a 35 mm might have 75 ... a 16mm might have 100 .... if you look at resolution charts you will see that the larger the format the less resolution the lens will have for that format ... 4x5 still camera lens may only have 25 lines of resolution ....

"The article states that the use of the much sharper 35mm primes made the XL1 footage look better than high end 2/3 cameras"

as far as resolution/sharpness i can't see it ... BUT as for the image looking BETTER than a 2/3" video ..YES i can see it .. if you want the "film look " then i would agree that using the mini dv 35mm adaptor will give you that look more then a video camera with 2/3 " CCD"S ....

since i went to showbiz expo i've had a turn around of the mini dv 35mm adaptor ... before i thought it was a waste of $$ to be used on the XL 1 BUT not anymore .. i've seen the mini 35 at 2-3 other shows. i've always have had to look thru VF or they had a LCD attached to it ..at showbiz they had a GOOD NTSC monitor hooked up to it PLUS nearby they had a XL 1 with normal lens and a NTSC monitor hooked to it ... comparing them is where you see the BIG difference .. the mini had a 75mm lens on it ..on the normal lens that would be around 10mm ..at 10 mm everything is in focus and the enhancement detail circuits are doing their electronic sharpening to all infocus edges ..while over on the mini 35 you can focus on head/shoulders and the back ground goes out of focus... while over on the mini 35mm a head/shoulders shot - you focus on persons eyes and the shoulders are a little soft ..with less in focus you don't get all that "crisspening " ( that outline ) or all the electonic sharpening also much less stair stepping ( which usually happens on sharp focus angle lines) ....

on another monitor they were running clips from a german DP ( who was at the show but i can't recall name) .. some of the clips were shot with 35mm anamorphic lens and viewing was at 2:35 letterboxed ..excellent images/lighting ... if walking past IMO one would never guess they were shot on XL1 ...

the mini 35 might seem expensive BUT you get a FILM look on tape that is far less $$ then shooting film -transfer to tape ..
or shooting 24P ( which you would not get the shallow DOP )

to get the FULL impact of the images -view the mini 35 images on a good NTSC monitor not the VF or a 5" LCD screen

Yes, I agree, having seen the Mini 35 at Showbiz and NAB this year I'm pretty sold that right now it is perhaps the best look in digital. When a version becomes available for 2/3", that will be worth seeing. And the Viper 8:8:8 system is clearly the future of high-end digital image capture, and I understand it accepts 35mm lenses with the same field of view--or does it?

In the meantime, I think the images I saw that had been made with the Mini 35 are exceptional. Justin, are you fighting the ground glass issues? Are you tending to use the spinning feature, and if so have you found ways to hide the vortex in the middle?

Your glowing remarks about the P+S mini 35 adapter, and Justin's reports on its use, beg the following question >

Which would you rather use for documentary and/or dramatic production:
- an XL1s with a mini 35 and good primes, or
- a Sony DSR570 (2/3", 16:9 ccd's) with a very good lens?

I realize that each involves trade-off's in performance characteristics, et.al. But if the costs were equivalent which would you select?

Good question Ken. My vote:

Documentary--no brainer. The Mini 35 is cumbersome, and having to deal with a 35mm lens set for fast, unpredictable work would be a nightmare (a zoom with a range anywhere near that of a video lens would be impossible to handhold). The Sony wins.

Dramatic production: I haven't used the high end Sony DV cameras, but if I can substitute the DVW-700 (Digi-beta) which is in some ways stacking the deck in favor of the Sony; I think it would probably still prefer the XL1 with the Mini-35. I already feel that the XL1 in Frame movie mode has a pretty cinematic look, partially due to the softening inherent in that technology and also the way the camera renders the color palette. Adding the depth-of-field characteristic and increased resolution of the 35mm lenses only improves on that look (and significantly so, IMHO).

This is assuming a finish to video. If the piece in question were being blown up to film for projection, I would want to do some tests before stating a preference.

Choice of cameras:
I agree with Charles on this one. I did test a 20-60mm Cooke on my rig and it wasn't horrible. But it would be tiring during a long shoot. For Docs, it's better to have a nice ENG rig where you can zoom and focus when needed in a lighter package. Plus, you're not limited to a shallow focus.

I am going to shoot some live doc type stuff with the mini35, but I'm going to use one 35mm lens and just move to my shots. It'll have a much different feel. Perhaps it'll suck.

And of course I'd rather use the mini35 for dramatic pieces. It's just artistically better. Of course that's MHO.

About the ground glass:

You always use the spinning glass. If it doesn't spin, you can see the grain of the glass. Not a desirable look.

There are two speeds. I just use the fastest speed all the time. I don't really know why they bothered with the slow speed. Battery? Nah, you can run the thing full time on high for 8 hours or more with one brick battery. That's what I do. Just keep it on.

Closing down long lenses at around T8 will allow the glass to show up on tape. You can definitely see the makeup of the glass spinning on screen. It is less apparent on shorter lenses and you have more leeway. Using a high res or fine pitch monitor is your best bet. This is were the P+S Technik guys were brilliant. They added an aperture control between the units prisms just before the image hits the ccd's of the XL1. And you can use this to eliminate any apparent grain by opening up the 35mm lens' iris and the stopping down the image with the mini35's own iris, to arrive at the desired exposure level.

Unfortunately, it's a bit harder to gain extra focus range but it's not horrible.

I have yet to write anything up about the whole rig. But I'm way too busy. The good thing is that I am putting it through some paces. I don't have an editing system running so I can't even capture stuff. I'm shooting 3 shorts and a feature in a month. Another test session is coming up this week.