Canon 200mm 2.8 II as tube lens for FF

kirispupis · Post by **kirispupis** » Wed Jan 30, 2013 9:58 am

Hello everyone,

I have been playing on and off with microscope objectives on my camera, but really haven't taken any interesting photos yet. I am debating getting a bit more serious about it and I was wondering if anyone has any experience with the Canon 200/2.8 II on a FF (5D3) camera.

I currently have a Nikon 10x .25 10.5 WD and a Mitutoyo 20x. For a tube lens I am currently using a 100mm/2.8 macro with a 2x extender and 68mm of extension tubes. I ordered various adapters on EBay to allow both objectives to fit on the end of the lens. With this setup I have verified both objectives work, but the whole thing is rather long. Also, I am worried about loss of image quality due to the 2x.

My main interest in the 200/2.8 II is the ability to get rid of the extender and I hope the extension tubes, but I am worried that this combo will vignette on a FF camera. Of course, if you know of a cheaper lens that will work I am all ears.

I have verified that my 70-200/2.8 II does not work well.

I am still very much a newbie in this area and I have other problems to solve like stabilization and lighting, but I have found other posts on this forum that will help me there.

rjlittlefield · Post by **rjlittlefield** » Wed Jan 30, 2013 11:57 am

I have no personal experience with any 200/2.8.

However, I note that 200/2.8 = 71 mm entrance pupil. Since the diagonal of a full frame camera is less than 44 mm, the exit pupil of those objectives is less than 12 mm, and 44+2*12 is less than 71, I can't imagine how the beast could vignette.

On the other hand, that same calculation should apply to your 70-200/2.8, when used wide open at 200.

So I am curious: what does it mean that your "70-200/2.8 II does not work well" ?

--Rik

Charles Krebs · Post by **Charles Krebs** » Wed Jan 30, 2013 12:49 pm

I am currently using a 100mm/2.8 macro with a 2x extender and 68mm of extension tubes.

I am curious... why the extension tubes? Normally you want the "tube lens" to be focused at infinity. (At least to initially start off that way to establish some sort of "base" image quality).

kirispupis · Post by **kirispupis** » Wed Jan 30, 2013 6:47 pm

The problem with the 70-200/2.8 II is too much vignetting when either of the objectives are attached. The 100/2.8 + 2x has much less vignetting - but still has some. When I add the extension tubes the vignetting goes away.

rjlittlefield · Post by **rjlittlefield** » Wed Jan 30, 2013 8:58 pm

kirispupis wrote:The problem with the 70-200/2.8 II is too much vignetting when either of the objectives are attached.

I assume this is with the 70-200/2.8 II set to shoot wide open at f/2.8.

Could you do me a favor, please?

Zoom the lens clear out to 200 mm and stop it down to f/16 or so using the DOF preview button. Then look into the front of the lens while pointing the camera's eyepiece toward something light, so that you can see the lens diaphragm.

What I want to know is where the diaphragm appears to be. Is it someplace inside the lens, or perhaps inside the camera, or is it far behind the camera and if so, how far?

Thanks!

--Rik

abpho · Post by **abpho** » Sat Feb 02, 2013 6:14 pm

I use the 200mm f/2.8L II with my infinitely corrected objective lenses. I use this combo on a FF camera body. No vignetting that I feel is a problem. I'll go get a sample image for you.

This is the re-sized full image. Taken with a Mits 5x objective, the 200mm 2.8L II and a 5D2. Hope that helps.