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Old July 19th, 2005, 10:56 AM   #16
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Andy,

Would the single PCX lenses from OptoSigma be a better choice than their cemented Achromatic Doublets?

Seems like two 120s would be the sweet spot for no distortion and just a little hotspot correction (if that's all you need)?

How far do these need to be placed from the front of your achromat and how far from the GG? As it stand, I've got a shorter 2" anodized tube (which I use now), and a longer 3" tube -- will this be enough room?

And, lastly, did you purchase the AR coated lenses or the uncoated? (big price diff.)

Any chance we can see some side-by-sides with your two 120mm PCX's versus without?

Thanks again,

- jim
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Old July 19th, 2005, 06:23 PM   #17
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With versus without there is a massive difference. Without there is a huge hotspot (didn't see the point taking sample shots of that), with it's pretty much zero, you can only see it if you're really looking for it, I thought I had eliminated it altogether as I couldn't see it on a blue sky, I only noticed it on a bright beach shot, but it's still very subtle. The good thing about my set up is I have larger than 36 x 24mm image size, almost the maximum possible with a 50mm dia GG, so it minimises narrowing the FOV.

I've posted some samples on another site, which will get removed if I mention it by name :). Suffice to say I have a GS-400.... with my set up I have no achromat or macro lens. There was still a hotspot with two 120s until I moved the cam back and zoomed in to a bit more than 2x. Total adapter tube length = 100mm, lens is Takumar 1.4, so it's around 50mm from GG to step ring. My design is basically a 56mm dia 3mm thick PVC tube with 50mm dia spacers that fit tightly inside and can be slid up and down into position. Glued a 55-58 step ring on the end which allows things to slide out, then a 43-55 to cam. Glued 50mm pipe direct to the Takumar to slide it in the front of the tube. It's a lot better looking than any other homemade static I've seen. He said modestly.

Not sure the exact distance from GG to condnesers (), I had slight distortion so I moved them back a little, I think it's around 15mm or so from GG to () at the outside edge. They are uncoated, Optosigma part no. 011-3480. I put a single layer of tape around the outside edge to hold them together and make them fit more tightly in the tube, friction is sufficient to keep them in place.

Singles are cheaper than the cemented doublet and you can try this set up as well |)(. I think Anchor Optics might be good enough, they have 50mm dia 97mm FL for about half the price of Optosigma.

You need to be very careful handling the PCX lenses, any tiny chip will show up in the image, my 80s tapped together on the curved surface and are no good now.

Last edited by Andy Gordon; July 19th, 2005 at 07:08 PM.
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Old July 23rd, 2005, 10:57 PM   #18
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This thread seems to hav gotten pretty technical, but people are still encouraged to comment on the video I posted that the thread is supposed to be about :)
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Old July 25th, 2005, 01:40 AM   #19
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Hi Noah,

I especially liked your natural wipes. I think they add production value to the film, and are not too obtrusive. Good work with the GL2, it hasn't looked better.

Along with you and others, I have been questing for a better 35mm adapter. Is it correct to say you used a static gg? Over at dvxuser.com, most are concerned with the motorized version. I have made headway with the static version, but can't get the grain fine enough. Are you using wax or a polished gg?

-andrew
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Old July 25th, 2005, 03:42 AM   #20
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thank you, and yes it is a static GG adapter based on the http://www.ideaspora.net/oldskool/ concept and using an optosigma 1500 grit 50mm ground glass. I found the grain almost unnoticeable at large apertures. But then this setup also created a lot of diffusion in the out of focus areas which has an unusual look to it, so wax or moving coarse gg might be better. I didnt even realize dvxuser.com had a lot of people discussing 35mm adapters, I'll have to start looking at the forums there.
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Old July 25th, 2005, 09:56 AM   #21
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Great stuff Noah,

Even in the darker scene, there is no noticeable vignetting and I couldn't see any artifacts when you panned on the shots. That looks amazing!
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Old July 26th, 2005, 12:49 AM   #22
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Noah,

Thank you for such gracious info.

You may have already found that dvxuser.com now has a "DIY" section where old adapter threads are available. We have developed pretty nice wax versions, static that is. I am concerned that a major pitfall of wax is temperature. In northern california it was 104 degrees far. today. My wax gg has shown promise in quality, but "sunk" in the heat. It caused the wax to become clumpy and blotchy.

Even though the wax has great properties, I am now interested in a non- wax option.

Keep tinkering,

andrew
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Old July 26th, 2005, 07:12 PM   #23
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Noah,
Which Mic did you use for the movie?
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Old July 31st, 2005, 08:43 AM   #24
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I'm not sure actually, it was whatever the school had. Why do you ask? I could ask the sound guy.
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Old August 2nd, 2005, 01:29 PM   #25
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It just occurred to me that while I dont have the adapter to take pictures of, I do have production stills that show it. Here it is:

http://ase.tufts.edu/turbo/noah/adapter.jpg

As you can see my crappy paint job didnt take wear and tear well, I guess thats how you learn that spraypaint doesnt like to stick to pvc even with primer.

Anyway, you can sort of tell from the picture there are several pieces to the adapter, on the front there is a screw in piece that mounts the 35mm format lens. Then there is a big piece that houses the GG and condenser, which itself is made of two parts that screw together so the GG and condenser can be swapped out (useful if your GG gets way too dirty or splotchy (which happened) and you need to put in a new one and it makes the optics easier to take out and clean. And then at the other end there is another piece that screws into the rest of the adapter and connects it to the GL2 with the proper filter thread size. The two filter thread mount and the FD mount ends both screw onto the center part with a standard 2.5" PVC thread. I just really like the idea of having modular design so I could easily make a mounts to attach the adapter to any 35mm format lens (using different mounts) or any camcorder (with different filter thread sizes). In the end I never ended up using the adapter on anything but FD lenses and the GL2, but that was mainly because I find oscillating adapters to be more interesting lately. If I do make an oscillating adapter, I really want it to be easily dissasembleable (to replace or clean the GG/condensers) and capable of interchangeable lens and filter thread mounts.
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Old August 2nd, 2005, 09:53 PM   #26
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Noah, how is your adapter with panned shots? Since it is static, that always seems to be the problem. Did you notice problems with yours?
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Old August 3rd, 2005, 07:38 AM   #27
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What kind of problem do you mean? I havent found any problems with panning.
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Old August 3rd, 2005, 08:13 AM   #28
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The grain sometimes 'bleeds' when panning quickly across shots - this happens with alot of early static adapters.
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