Relay Lenses

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rsb
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Relay Lenses

Post by rsb »

Hi, I'm brand new to Photomacrography though I have a lot general photo experience. I do want to say how great this forum is. I don't think I've seen a forum where the experienced members are so helpful to newcomers. Based mostly on what I've learned here, I'm putting together a horizontal macro setup. I will use a full frame Nikon camera. I will purchase a Nikon CFI 10x, NA.25 wd10.5 lens. I have several questions relative to relay lenses for this objective.

Relay Lens Quality:from what I've seen there seems to be little concern for relay lens quality. People are using cheap primes from ebay and average zooms. Does relay quality not effect the final product? I have a number of good old Nikkor primes between 100-300mm which are optically better than my modern AF 70-300mm zoom. But if it doesn't matter, I would use the 70-300 zoom for convenience.

Focal length: People seem to group around 200mm for these infinity objectives though I did see someone using a 135mm to reduce magnification and another statement that 100-300mm is the general range for relay lenses. Can I use my 70-300mm Nikkor to zoom the 10x objective from 3.5x to 15x without loss of quality? Seems too good to be true.

Thanks
Robert

johan
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Post by johan »

Hello rsb,

It is too good to be true. You'd normally use the zoom only at the long end. For other lengths you'd switch to a prime of that length.

I've personally done ok using both old primes and raynoxes as relay lenses, but there are also bespoke relay lenses available.

Someone else maybe in a better position to explain what these give you that primes and raynoxes don't!
My extreme-macro.co.uk site, a learning site. Your comments and input there would be gratefully appreciated.

jazzper
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Post by jazzper »

Most people use some prime for work like this and a few use a dedicated tube lens. I believe Rik has made a test showing only minimal difference in quality.
I only use old primes, in part because they are real easy to mount, work well and are readily available but mostly because of the price: If you should have a 100mm, 135mm 150mm 200mm and 300mm bespoke tube lens you would have to shell out a fortune, and that is if you could get them at all.

I'm quite satisfied with the quality I get from the ordinary "cheap" old primes.
Jesper - Flickr

ChrisR
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Post by ChrisR »

If there's a 100 - 200mm zoom which works fairly well as a tube/relay/converging lens, I don't think we know about it yet.
From six that I can remember trying, some are OK at the long end, most or all vignette badly at the short, or more than just the short. One, a promising projection lens, was awful with CA all through.
Those zooms vignette because they move the entrance pupil a long way back. There may be some zoom construction which doesn't do that.
Some are OK from say 200 down to 150mm (on APS) which is useful. You'll have to experiment with yours.

Old Nikkor primes like a 200mm f/4, or 135mm f/2.8 or f/3.5, are good, as are many enlarger lenses. Also good, considering their simple construction, are the Raynox close-up lenses and a couple or more simple achromats (search on "morfanon" here.
Anecdotally, better primes do work a little better as tube lenses. Eg, at 100-105mm, a micro Nikkor is a little better than a $10 Rodagon enlarger lens which noticeably better than a Nikkor Series E (cheap) prime.

I've tried four other cheap primes which weren't very good for definition, though they didn't vignette.

If you want the optimum at near 200mm, you can get Mitutoyo, Nikon Olympus or Thorlabs "proper" tube lenses, and scratch your bonce over how to arrange them remembering that some are somewhat fussy about the distance between the tube lens and the objective, or maybe that depends onthe objectives more. Sure, they can be very good.

Rik's comparison gives an indication of how much better one is than another, though whether you'll notice it before you get the rest of your technique optmised, is another matter! It's pretty exacting to set up reliable tests.

I've tried, but not "tested" the zooms, plus about 6 primes, 4 enlarger lenses, a couple of close-ups and 3 tube lenses. But with random Nikon and Mitutoyo tube lenses from 2x to 50x... Thoroughly unreliable.
But the optics is the easy bit.

Blame
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Post by Blame »

Uh Uh. There has been a lot of success using prime camera lenses and mixed results using zooms at longest focal length. However that is with APS-c cameras.

With FF just about any camera lens is going to vignette. What you need is a physically short lens like an enlarger lens. Probably you won't do better than the 3 element raynox DCR-150.

Why? because light follows a different path from the intended when a lens is used as a relay lens. The physically shorter the optics, the less chance the light will stray too far.

ChrisR
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Post by ChrisR »

What's "Uh uh"?

The coverage on the sensor has much to do with the FL of the lens used, and the subject-side image circle of the objective.
If the combination give too small an image-side circle, you'll get vignetting regardless of how physically short your tube lens is.

Eg if a 10x objective subject-side image circle is 4mm, and you use a 100mm tube lens, you get a 20mm image-side circle (4 * 10 * 100/200), which won't cover APS.
Whereas, if you use a 300mm camera lens, including some zooms, it'll cover full frame. I believe I have shown that on the forum.
Last edited by ChrisR on Thu Apr 03, 2014 4:45 pm, edited 2 times in total.

Beatsy
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Post by Beatsy »

I'm not sure where I read it, possibly on this forum, but I believe the Canon 70-200 IS f/2.8 L set at 200mm works well as a tube lens, even though not a prime (obviously).

I hope this is true as I already have the 70-200 (and FF DSLR) and intended to attach a Mitutoyo or Nikon infinity objective as soon as funds will allow...

Am I mistaken?

marceppy
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Post by marceppy »

Good question, Beatsy. So, following that thought and the concept that the quality of the tube lens will not affect the IQ of the resulting image, would a Canon Zoom Lens EF 80-200mm 4.5-5.6 be as good as an EF 70-200mm f4 (as a tube lens)?

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Post by rjlittlefield »

Beatsy wrote:I'm not sure where I read it, possibly on this forum, but I believe the Canon 70-200 IS f/2.8 L set at 200mm works well as a tube lens, even though not a prime (obviously).

I hope this is true as I already have the 70-200 (and FF DSLR) and intended to attach a Mitutoyo or Nikon infinity objective as soon as funds will allow...

Am I mistaken?
Take a look at http://www.photomacrography.net/forum/v ... hp?t=18255. I'm not sure that's the same lens, though.

--Rik

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Post by Pau »

The Canon 70-200 f4 L IS USM is a good tube lens paired with the Nikon CFI 10X 0.25. I can go down to 140mm without vignetting on Canon APSC, so likely it will work well on FF at 200mm but not much shorter.
Pau

Blame
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Post by Blame »

ChrisR wrote:What's "Uh uh"?

The coverage on the sensor has much to do with the FL of the lens used, and the subject-side image circle of the objective.
If the combination give too small an image-side circle, you'll get vignetting regardless of how physically short your tube lens is.

Eg if a 10x objective subject-side image circle is 4mm, and you use a 100mm tube lens, you get a 20mm image-side circle (4 * 10 * 100/200), which won't cover APS.
Whereas, if you use a 300mm camera lens, including some zooms, it'll cover full frame. I believe I have shown that on the forum.
Well I dunno about 300mm. Strikes me that it will be a rare objective that won't be subject to empty magnification at that focal length. Much above f/16 and it all gets a bit pointless. However most camera lenses offer up at least a little vignetting even with APS-c. If you can name any that will add NO vignetting at around 200mm with FF then fair point. I can't.

Now I know that there is the view that some tube lens induced vignetting is acceptable in the corners but I am not convinced. It takes quite a lot to be visually annoying but think. What is happening is that the objective is being stopped down in the corners. If it is stopped down the diffraction is worse.

When I did some checks with camera lenses I found that 1 stop down circle often didn't even reach the top and bottom sides. Just a shade of darkening but 1 stop turns a 0.28 NA objective into a far cheaper 0.20 NA. Why take the hit when a DCR-150 offers such a good 210mm?

rsb
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Post by rsb »

Thanks so much for all your help. It was a real education. I will definitely start out with Nikkor primes, 100mm f3.5 macro, Q 135mm f3.5, 200mm f4, and 300mm ED f4.5. Hoping for some results in a week or two when I get the kinks out.
Robert

ChrisR
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Post by ChrisR »

The objective you mention has about a 5mm image circle, and you're trying to cover 24 x 36 (which I'd missed) which has approximately a 42mm diagonal so you will get hard vignetting at anything below 8x. Even then the edges "fall off" some, before that. Which is why most folk use DX or APS sensors. If you lose more in the internals of the lens then you're down again.

Diffraction is less of a constraint with bigger pixels, which may come with your FF sensor, unless you're using a D800E? If that's so the cost of a "proper" tube lens would be comparatively modest. After a camera lens the other options all require more fiddling with tubes/bellows/adapters.

Blame
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Post by Blame »

The 200/4 is your best bet with that selection. It will certainly give usable results. If, as I suspect, there is some vignetting give up and buy a raynox + adapters to reverse.

You should do well with a FF camera. The additional dynamic range counts.

The APS-C sensors are easier to find tube lenses for and they work better with finite lenses. However as there are decent options for tube lenses and the best deals seem to be in infinite lenses you have a camera to be proud of.

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Post by rjlittlefield »

ChrisR wrote:After a camera lens the other options all require more fiddling with tubes/bellows/adapters.
Definitely more, but with the Raynox DCR-150 it's simple to buy and screw together everything that's needed. See http://www.photomacrography.net/forum/v ... 195#143195 for illustration.

With the other tube lenses (Mitutoyo, Nikon, Thorlabs), some custom fittings may be needed.

--Rik

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