Consolidated XL1 35mm Adapter Thread

[Bob Hart]

Rai.

The Cosmicar is a television lens. It was sold to me in 1969 as a film lens for a Bolex. I onsold it to the TV station I bought an Auricon off. It went into their museum. I went and bought another secondhand 11 years ago. This one is a little more battered but performs as did the other.

Here are the details :-

COSMICAR TELEVISION LENS.
25MM
1:1.9
No. 21094.

The f-stop range is f 1.9 to f 22.

[Kevin Burnfield]

Okay, I think it's time to talk agenda.

the primary focus of this thread (as long as everyone agrees) is to:

Develop, as a group, a simple and inexpensive Aldus35 (spinning ground glass) device for the XL1, XL1S and the XL2 Canon camera. I believe that after this configuring for a static version would me much easier.

This includes figuring out the best lenses or type of lens to be used, the focal lengths, ect and materials needed for the optimum design.

Most specifically, this thread is to find solutions to specific issues such as lens adapters and use our group discoveries, finding vendors and possibly making group purchases to lower the cost to each of us for these solutions.

[Stephen Birdsong]

Yes, sounds good to me.
One comment. I would say that we are going for a static gg, because once we achieve that, we can work with people with other cameras to achieve the moving gg, since it has nothing to do with the xl1. In other words, the dilemma faced with the xl1/s/2 is the relay lens. The vibrating gg, is another dilemma that every 35mm adapter faces. Our biggest resource at this point is collaboration, so lets target this in a way that utilizes those resources to their fullest.

my 2 euros.
stephen

[Kevin Burnfield]

so you think that it would be easier to create a static gg option then a spinning one?

I would have thought the opposite but I trust your opinion on this more then my own since I haven't built any of them

[Bob Hart]

For the database a bit of tech spec. I rang Canon here to see if they had any dead, drowned or wrecked XL1s to do some match engineering on. = No go. They crush them if the customers don't want them back. They gave me the flange to focal plane distance which appears below with others.

Canon XL1 - 20mm.
C Mount - 17.5mm.
CS mount - 12.5mm.

Given that the C Mount lens has to be brought forward about 3mm - 4mm to get it to focus close enough on the GG, the adaptor would have to be sunken in the middle to position the C Mount lens back far enough but the actual flange face for the close-up function being asked of it would be close enough to the same as the Canon face.

Being positioned furthur away from the focal plane, even the 1/3" lenses may throw a big enough image to be adequate.

[Stephen Birdsong]

Bob, that is interesting, I did not realize this was the case. I was under the impression that c-mount had a deeper (longer) flange depth than xl mount. So could it be said that the larger the format, the closer the flange depth?

You are correct about the focus distance, the engineer I spoke with at schnieder optics mentioned that if I needed to focus closer than 6 inches, than I needed to add a spacer to increase flange depth, which will allow me to focus closer. He gave me a number to work with to calculate exactly, but since I am not at home, I don't have access to that info. Will post when I have access to it.

stephen

Is anyone doing any physical expirements, or are we just discussing theoretical possibilities?
If the answer is no (to the first question) get out there!!!! pvc pipe is cheap, gg is cheap, and im sure you have some lenses out there, whether they are ideal or not, get your hands dirty! (but not your lenses)

[Roger Moore]

<<<-- Originally posted by Stephen Birdsong : Bob, that is
Is anyone doing any physical expirements, or are we just discussing theoretical possibilities?
-->>>

Oh, I'm totally theoretical, hypothetical, whimsical. My feet are hovering 20 feet from the battle ground because I don't own a XL2 to anchor me down and allow me to take the next step. It's fun having a excuse to slack.

[Keith Kline]

Okay I know this isn't the cheapest version out there, but is there a certain reason against using a 35mm prime lens and a lens adapter for the relay as Dino did with his static adapter? I picked up a 24mm f2.8 off brand eos lens and am working on a eos to xl mount now. Is the reasoning for looking at c mount options optical or the price? Also does anyone have access or know of a place to get body caps for the XL? I've looked and fount front lens caps, but no body cap. I'm working on a mount and trying to avoid wrecking the one that came with my camera for the mount prototype.

[Dino Reyes]

i think this is good to have a consolidated xl thread, now we have some brains (Bob Hart) and some fresh ideas under one roof. there are probably a number of issues we can handle collectively and reduce the costs and r&d associated with the complexities of a lens adapter for xl systems.

Rai is right on with that S&K lens setup (pg. 8). that would be an example of the "ideal" relay lens, there are a couple of vendors, one in india and the other in the UK i was communicating with about fabricating basic components to build xl "kits" also. my india contact never responded back with a quote. i also worked at pricing out a few, because some people asked the constuction costs, you can make them in a range of a few hundred dollars for cheap ones, if you happen to have one or two good (wide fast) lenses around, or for as much as $1300 or so, which is what my present unit roughly costs, and it costs much more than that in testing and equipment that i bought and it didn't even work. but in the end, i'm not really a lens maker, or seller, i'm more, just a guy who shots his own films and i just want to make my camera better, so i can tell a better story.

i got most of my stuff from hardware stores, ebay, and optical places. i put all my lense models i built, 1 Agus & 2 Aldus', in my kitchen or sitting on my coffee table lens grinding while i watched orson welles movies.
you need 4 things, a dremel tool, goggles, cement glue, and a glue gun, the rest, i think, is just part$.

i was thinking of sending a note to my UK contact, who makes xl to eos and xl to nikon adapters. he makes the cheapest around (like $120 usd) and i think would be sure to consider a bulk deal if we went and purchased from him, so i will inquire.

my only other question that hasn't been answered from my last posts was talk of anamorphic lenses for the xl lens adapter. i'm not sure if anyone has any info on that, who would like to share, but i would be interested getting 1:85 porportions. i'll probably look into making a smaller version of the lens adapter, anamorphic in the coming months.

[Bob Hart]

Regarding getting hands dirty. I did some C-Mount lens tests into a single CCD crimcam. I have an old Bolex with vintage Schneider-Kreusnach lenses on it so I might re-do the tests. I originally published the results here on one of the Aldo or XL1 threads but I have got such a slow landline speed here I haven't gone looking for that post.

From memory, I think the 25mm lens had to be too far away from the GG to be useful onto a 1/3" CCD for a 24mm x 18mm 4:3 frame. For the larger still-camera format it might be usable.

The Century Optics 16:9 anamorphic lens works fine on front of a 55mm Micro-Nikkor, so-so on a 135mm telephoto (Auto-Tamron) also so-so through a cinemascope lens (Proskar Anamorphic.) With the longer lenses distance focus to infinity seems to go off. Closer focus out to about 60 feet seems to be adequate. Those tests are viewable as .jpg files on www.dvinfo.net/media/hart.

[Stephen Birdsong]

Dino, glad to see your still around, we could use your expertise.

You can probably immediately solve one of our first obstacles.
What focal length (in 35mm lenses) have you found to be ideal in capturing the 36x24mm image off of the gg, and at what distance.

do you have the hotspot problem? If so, what measures have you taken to reduce the undesired effect? Have you any experience with condensor lenses? If so, what have you found?

I am planning on purchasing some lenses ie:
achromatic doublets to test as relay lens:
http://www.optosigma.com/miva/mercha...matic+Doublets
condensor lenses one in front, one behind gg:
http://www.optosigma.com/miva/mercha...herical+Lenses

as for housing, I will probably stick with pvc. I may look into purchasing that fine tuning housing that someone posted about a few days ago.

stephen

[Dino Reyes]

hey stephen,
let me see if i can help any address your questions.... as far as focal length, since i am not technical i'm not sure how to answer that. everything i've done i've just "eyeballed". if your asking me how far my relay lens is to my Acromat is roughly 2 inches. i'm using a 24mm f2 with 1 +4 and 1 +2 close-up lenses that get me the closeup image on the Acromat. From the Acromat to my GG is roughly less than 1 inch. i prefer the acromat over any condesor lens because it not only color corrects but the quality is tops. condensor lenses are much cheaper but acromatic diopters are better all the way around.

i got my Acromat off of ebay for $50, it originally came from Newport Optical, they have 7 - 50.8mm versions. and 50.8 also fits perfectly in a 52mm ring! so pick up a couple of Skylight brand clear 52mm filters, they also unscrew nicely-and come in handy more often than not. so i'm not sure of the focal length or which 50.8 version i bought since it didn't have any papers.

i see you are considering trying a theoretical approach, sandwiching two condesor lenses between the GG. in theory it should work, acording to papers i've read. i would stick with PVC, i believe 2 inch will fit a 52mm reversal ring to perfection. if you can find an internal reducer for the 2 inch PVC (2inch to 1.5) a reversal ring cemented firmly will fit like a glove. with it's strong metal threads it will hold firmly.

here is another "field" test i did with my 2nd lens adapter shooting some graffiti in williamsburg. i didn't use any support rods and had everything hot glue gunned together so at the end of the shoot my heavy 55mm lens slipped out of the casing (i had not glued it at the time because i wanted to see if i adjusted it correctly) and it fell to the ground and got banged a little-but it still works. you will notice my lens is dirty as i was just shooting and moving, testing out how one might use and hold the unit. check it out here (warning: 15fps, 75meg download!!! as i wanted to not put so much compression on there and try to keep it raw so you can see how it works)
http://www.dinoreyes.com/images/graff_seq.mov

here is the page link also: http://www.dinoreyes.com/images/lensadapter.html

i've since improved the GG and have a better 3rd version because i did some good testing so far. as far as hot spots, i believe, but i'm not certain that good grinding will take care of any problem like that. also, adjusting lighting can also help. and, ever so slightly you can see a bit of vignetting on the edges, but it actually looks a bit stylized if you like that sort of thing.

also, bob, what i am refering to as far as anamorphic lenses is, instead of using a standard GG that i use a "circular cylinder lens" and grind the flat side. because there is so MUCH unused image on the GG, being the CCDs pick up such a small amount of the image of the GG, it would be nice to put a cylinder lens inside to make a true 1:85. do you have any knowledge on the amount of cylindrical bend one might need to get close to the 1:85 porportions??

[Bob Hart]

Dino.

You be a braver man than I in taking the AO up to a precision piece of glassware. My understanding and very inexpert at that, is the cylinder lens in an anamorphic adaptor is only one half of a matched pair.

I see no advantage in aquiring an anamorphic image off the back of a "groundglassed" cylinder lens versus having the lens in front of the SLR lens. Any defects from the groundglass texture still get stretched in reproducing the image. But don't trust my opinion on this.

[Dino Reyes]

stephen,
check out this link from edmund industrial optics. i also had a bit of a dialogue with them on understanding and trying to improve the optics of a lens adapter system. in the end, they said it would run in the neighborhood of 5-10k to have a professional take a look at the problem xl systems face. but this article covers the technique you described for your system. i chose the achromat type system because of it's one piece and reduces adjusting.

http://www.edmundoptics.com/techsupport/displayarticle.cfm?articleid=267&search=1

-d

[Kevin Burnfield]

That's pretty intersting Dino.

Okay... let's try putting together a shopping list-- or at least bounce some ideas off each other for components.