Nikkor 200 mm as tube lens and a short extension tube

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JH
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Nikkor 200 mm as tube lens and a short extension tube

Post by JH »

If you use a Nikkor 200mm as a tube lens with a FF camera you will have dark corners.

I have said:
JH wrote:I use a short empty tube with my Nikon 200mm on a FF Canon. This helps with the corners.
https://www.photomacrography.net/forum/ ... 928#236928
JH wrote: In the few occasions when I used a short empty tube with a Nikon 200 mm the quality looked the same with and without the empty tube - even though the focus was not at infinity. At least in the centre of the picture you can probably be off by a few centimetres with a 200 mm tube lens before you see disturbing degradation with the Canon cameras I use.
https://www.photomacrography.net/forum/ ... 928#236928

To what extent is the help with the corners true, and how much does the use of an extension tube actually affect the image quality?

Here is a series of screen grabs, subject Euro, 1 cent, camera Canon 5D II FF, objective Mitutoyo MPlan apo 10x. I tried to have the crossing scratches in focus.

OBS! I wanted to show the exact same area of the subject so I used my Optiphot microscope. This means that there is approx. 5 cm distance between the back of the Mitutoyo and the front of the Nikkor. With less distance between the objective and the Nikkor the dark corners are smaler than what I show here.

When I use the Nikkor I have the lenses closer together, this makes the corner problem less severe, but you must find an empty tube that does not add to the vignetting. I use a cheap approx. 1 cm eBay tube.

#1 Nikkor 200mm at infinity - clearly problems with the corners OBS 5 cm distance between objective and tube lens.
Image

#2 Extension tube 12mm tube. Better corners but still some problems here with 5cm distance. If you look at picture #3 you can see that you do not need an extension tube for this you can just change focus.
Image

#2 Nikkor 200mm at closest focus.
Image

#3 Nikkor 200mm at infinity with 36mm extension tube, little problems with corners, clearly degraded image quality.

Image

If you already have a Nikkor 200 mm, wants to use a FF sensor and do not want to crop out the corners you could change focus from infinity or use a short extension tube. An extension tube or a closer focus makes the corners better but affects the image quality. The longer the extension tube the larger the effect on the image quality.

#4 Raynox DCR-150 as a reference. Still 5 cm between tube lens and objective.
Image

Best regards
Jörgen Hellberg
Jörgen Hellberg, my webbsite www.hellberg.photo

svalley
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Post by svalley »

Jörgen, I have been using a 200mm micro-nikkor as my tube lens with Mitutoyo objectives.

With the objective mounted in the normal configuration (62-52mm step-down ring mounted on the lens, then a CNS ring screwed into that and then the objective screwed into that) the rear of the objective is 28mm from the front element of the 200mm. The image results were not good.

I screwed the CNS ring into the back of the 62-52 step-down ring, so it was closer to the 200mm front element and then the rear of the objective was only 14mm from the front element. The image quality is good and there is only a slight bit of vignetting, mostly not noticeable.

You did not say whether your 200mm is a macro lens or a normal 200mm.

Steve
"You can't build a time machine without weird optics"
Steve Valley - Albany, Oregon

mjkzz
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Post by mjkzz »

Hi Jörgen,

I can confirm it, mine is a Nikkor Q Auto 200mm. A Mitutoyo 10x on it produces pretty bad vignetting on my Sony A7III in full frame mode, no vignetting in crop mode.

This is mine

Image

Chris S.
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Post by Chris S. »

mjkzz wrote:I can confirm it, mine is a Nikkor Q Auto 200mm. A Mitutoyo 10x on it produces pretty bad vignetting on my Sony A7III in full frame mode, no vignetting in crop mode.
Peter, I'll venture a guess that it is not the Nikkor lens producing the FF vignetting, but rather, the Nikon-to-Sony adapter. Is it possible to source such an adapter with a larger inner diameter? Or to assemble a simple tube of greater diameter and proper length, and appropriate adapters front and rear? Such a tube would require flocking, of course. But my bet is that if its diameter is sufficiently large, it would not vignette

I could be wrong, but I've been taught by others on this forum, and by my own frustrating experience, that a vignette with a reasonably abrupt edge is likely not caused by a lens alone, but by apertures arguing with one another. In a case of mine, the vignetting aperture was the inner diameter of a short extension tube that resembles your Nikon-Sony adapter.

Like Jörgen, I've used the micro-Nikkor 200mm f/4 IF-ED to converge Mitutoyo objectives on full frame without vignetting. And I think I recall at least a couple of forum members using the older Nikkor Q-series 200mm successfully as converging lenses on full-frame Nikon bodies--this furthering my suspicion that the culprit in your case is the adapter.

Cheers,

--Chris S.

mawyatt
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Post by mawyatt »

Chris,

I've used the old Nikkor 200mm "Q" as a tube lens for various Mitutoyos. Also used the flat adapters to the Mitutoyo, as I was informed that the "cone" type adapters can cause some vignetting. I don't recall seeing significant vignetting on a FF Nikon camera, although some was present.

Curious to what those mounting clamps are on the Nikkor??

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

mjkzz
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Post by mjkzz »

Hi Chris, here are two images, one is using Sony A7III with adapter (as shown in my last post), one is using Canon 6D II (full frame) with Nikon to Canon adapter. Both look about the same in terms of vignetting -- if you put both in a graphic application and flip back and forth, you will see severity of vignetting does not change much (ignore exposure difference). This means the adapter for Sony is at least as good as the adapter for Canon.

The adapter for Canon is a thin one, the thickness is the difference between flange distance for Canon and Nikon, so I do not think it would cause vignetting.

Image

Image

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