Calculating vignette, cropping on tube lens?

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harisA
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Post by harisA »

rjlittlefield wrote:
harisA wrote:With the exception of Mitutoyo objectives the only way to achieve FF frame coverage is to use a tube lens with a focus distance significant higher than the objective's designation.
I am curious to know what experience is the basis for that statement.

I re-checked just now, and I get good full frame coverage on Nikon D800E using Raynox DCR-150 with Nikon CFI 10X NA 0.25 (part number MRL00102); with Nikon CFI BE 10X NA 0.25 (part number MRN70100); and with Nikon CFI BE 4X NA 0.10 (part number MRN70040), hood removed as shown at http://www.photomacrography.net/forum/v ... hp?t=18182 .

--Rik
Rik ,with all the respect,my statement is a result of personal experience.Your paradigms are correct (nikon10x MRL00102 actually has a big image circle even with the official nikon tube lens-almost covering FF-same is true for nikon CFI 20X/0.75 PLAN APO) but these are rather exceptions that verify the rule:The majority of nikon and olympus objectives can't cover a full frame sensor using a tube lens of 200mm or 180mm respectively.

harisA
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Post by harisA »

cube-tube wrote:@harisA I have both Nikon and Mitutoyo objectives and I get similar vignetting with all of them.

Also @Pau I have that Nikon 10x (the one in my profile photo?) and get a vignette.
If you can't cover a FF frame sensor with a mitutoyo objective and your 180mm tube lens then the problem is definately your lens.Try to use some other lenses which were tested here with good coverage results like Q nikkor 200mm or raynox DCR-150.Sometives a High end expensive telephoto lens proves to be a horrible tube lens .

rjlittlefield
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Post by rjlittlefield »

harisA wrote:Rik ,with all the respect,my statement is a result of personal experience.Your paradigms are correct (nikon10x MRL00102 actually has a big image circle even with the official nikon tube lens-almost covering FF-same is true for nikon CFI 20X/0.75 PLAN APO) but these are rather exceptions that verify the rule:The majority of nikon and olympus objectives can't cover a full frame sensor using a tube lens of 200mm or 180mm respectively.
I agree that the majority of objectives cannot cover full frame. My concern was with the strength of the statement "With the exception of Mitutoyo objectives the only way to achieve FF frame coverage is to use a tube lens with a focus distance significant higher than the objective's designation" (emphasis added). Based on my personal experience, and for my own quality criteria, that bit about "only" is simply not correct. The specific Nikon objectives that I listed work fine on rated extension.

If you agree that some Nikon objectives can cover full frame, including those in particular, then the conflict is resolved. If you don't agree that those objectives give adequate full frame coverage, then I assume we have different criteria.
cube-tube wrote:Also, is there a consensus on whether a forward or reversed raynox is better?
In my most recent tests, focusing on full-frame corner sharpness, I do not see much difference between forward and reversed. However, in both orientations the corners were significantly sharper with 35 mm total separation between the mounting flanges of Raynox DCR-150 and objective. That was better than with just an adapter ring (7 mm separation). I did not test with longer extensions. The adapter chains have fewer parts in front forward, and the chain of parts seems easier to flock and mask. My usual setup has been reversed, but now I am coming to think that forward would be better. So, there is no consensus even within my one head. People show good results both forward and reversed and it does not seem to make a big difference. Having at least that small amount of extra separation does matter, though.

--Rik

Vector1968
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Post by Vector1968 »

rjlittlefield wrote:
cube-tube wrote:Also, is there a consensus on whether a forward or reversed raynox is better?
In my most recent tests, focusing on full-frame corner sharpness, I do not see much difference between forward and reversed. However, in both orientations the corners were significantly sharper with 35 mm total separation between the mounting flanges of Raynox DCR-150 and objective. That was better than with just an adapter ring (7 mm separation). I did not test with longer extensions. The adapter chains have fewer parts in front forward, and the chain of parts seems easier to flock and mask. My usual setup has been reversed, but now I am coming to think that forward would be better. So, there is no consensus even within my one head. People show good results both forward and reversed and it does not seem to make a big difference. Having at least that small amount of extra separation does matter, though.

--Rik
In my opinion, forward DCR-150 is also better than reverse, interestingly, the situation of DCR-250 is just to the contrary. Besides, I don't use extensions between objective and Raynox lens, but added a fixed iris (about f9) at the rear mount of Raynox lens, which can also significantly increase the full-frame corner sharpness.

JH
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Post by JH »

I just tested Nikon TU Plan Fluor 10x, Nikon Plan Fluor ELWD 20x and 40x. The corners do not vignette with an ITL 200 mm tube lens on a Canon 6D FF sensor. I used a Nikon Optiphot so the distance between the tube lens and the objectives was approx. 5cm. The quality of the corners is a different story. The TU plan is marked OFN 25 I have interpreted this to mean that the best image circle is 25 mm. The ELWD:s hava a smaller best image circle.

Edit: I used a Nikon BP 6 bellows. I have tubes, prime-lenses and teleconverters that makes my lenses look like they vignette.

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

JohnyM
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Post by JohnyM »

This is rough test of Nikon CFI Plan Apo 20x/0,75 on various tube lenses on Sony A7RII full frame sensor. Those are handheld images of cellphone display, just to show the coverage:

Raynox DCR ~210mm:
Image

Agfa Repromaster 135mm F9:
Image

Minolta AF100mm F2.8 Macro:
Image

Works great in aps-c mode, but not good enough for full frame.


My initial judgement is that (within my conditions) IQ is excellent corner to corner with 135mm (better than any 10x centers).


Other lenses from nikon that i've tested (ie: mentioned CFI BE plans) have no problems with 200mm coverage, and some (again BE plans) are good with ~150mm or less tubes

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