Tube Lens tests - medium format and full frame

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nathanm
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Post by nathanm »

Here are some examples of the test target shots

We took a Thorlabs test target and turned it around so that it was viewed through the glass. That way it could be put against a paper card so the paper texture would also be there.

The optical bench set up used an improvised bellows between the tube lens and camera. At the end of a very long day we found there was a bit of a light leak that hurt the contrast across the lower left part of the frame. But we didn't feel like reshooting. We have subsequently confirmed that was the source of wash out, but these images are what I have to show now.

The images below are JPEGs from the PhaseOne. Actual comparisons were made on TIFFs after stacking.

Here is the best case for the Raynox 5320 AB set, forward with objective very close to the tube lens front element.

I think that it covers the frame pretty well. When you look closer the corners are not quite as sharp as the center, but when are they?

Image

Here is the same combination, but with the objective further away

Image

The corners are brighter in the one that is very close, which is why we bothered to make the adopter to put it close.
nathanm

nathanm
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Post by nathanm »

To answer Chris S., I have the Mitutoyo 5X, 7.5X, 10X, 20X and 50X. I am not that interested in turning my 5X into a 10X, which is why I chose to try focal lengths near 200mm for the tube lens.

If I had not found a tube lens that worked in that ballpark, then I would retreat to longer focal lengths. But I didn't need to.

As to the "low quality" field of view... well, compared to what? I have a bunch of other macro lenses for the PhaseOne but it is unclear that I have a better choice at 5X.

I say unclear because I frankly haven't tested alternatives all that closely.

Having done the optical bench tests I will try it all "for real" with a much more solid set up. But not until December....

You are right that other people have different visual criteria - and more power to them. The point of this test was not to be the definitive final word - I was just happy to find something that didn't have a white circle with black corners (many combinations did). I also wanted to have reasonable performance. It seems to first blush that I have it.
nathanm

nathanm
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Post by nathanm »

a couple other points...

To judge FF 35mm format, we took crops from the PhaseOne shots. That has the downside that it is not exact, but if anything it oversamples.

You'll have to trust me that the lower contrast across the bottom half was due to a light leak. It was, but until I am back and can shoot new images feel free to be skeptical.

We viewed close ups to see the actual pixels to judge results, but in the small jpeg that isn't possible.

The test target is used simply to have a standard image. It is not one designed for measuring resolution in the corners quantitatively.

I am sure there are other forum members more expert than I in this area. If one of you can suggest which Thorlabs (or other) test target to use for the best tests, great. I will shoot it in December with at least a couple of the best choices.

Rik suggested trials with the 10X mitutoyo. I will do some of that when I get back, and maybe sooner depending on what my colleague has on the to-do list.

I am also willing to try some other tube lenses (within reason). Obviously my main interest is taking pictures, not lens testing. But if there is some tube lens that forum members feel really must be tried, I am game. It would help of course if they are obtainable, and not too hard to mount.

You may notice that many of the tube lenses are large diameter - that seemed to be important to avoiding vignetting. Indeed that seems to be reason that the Raynox 5320 AB set does better for me than the more commonly used Raynox 150 or 250.

My personal goal (which others have no need to agree with) is to get a tube lens combo that will:

1. Let me use my Mitutoyos at close to their rated magnification. I don't want to turn the 5X into a 10X because I already have a 10X.

2. For most of my subjects (food!) lower mag is often better. I love the insect photos that other forum members shoot, but I don't have much call for that, unfortunately. So I dont' mind being a little bit lower than rated mag.

3. Cover PhaseOne sensor with as few compromises as are practical. Which to be pragmatic, must be better than other alternative lenses.

4. Or cover the FF 35mm sensor of Canon 5DSR or similar. Again, to be pragmatic if there is no way to get good quality on PhaseOne I will switch back to Canon in a heartbeat. But so far that has not seemed necessary.

I hope that explains some of my choices. But I am always happy to learn so please enlighten me if they seem screwy!
nathanm

austrokiwi1
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Post by austrokiwi1 »

I am finding this thread really interesting. I do have a question, perhaps it is silly:

If you are looking at low magnification shots ( 5X and under for medium format) Wouldn't coupling large format lenses be a better approach? I have always wondered if it were possible to couple a 35mm large format lens with a, now out of production, Schneider Kreuznach 180mm f/5.6 Makro-Symmar HM.

I realize immediately there one significant hurdle , that being cost. the SK ( and I assume there is a rodenstock equivalent) cost second hand a good part of US$2000.00 and a suitable 35mm lens would probably be double that
Still learning,
Cameras' Sony A7rII, OLympus OMD-EM10II
Macro lenses: Printing nikkor 105mm, Sony FE 90mm F2.8 Macro G, Schneider Kreuznach Makro Iris 50mm , 2.8, Schnieder Kreuznach APO Componon HM 40mm F2.8 , Mamiya 645 120mm F4 Macro ( used with mirex tilt shift adapter), Olympus 135mm 4.5 bellows lens, Oly 80mm bellows lens, Olympus 60mm F2.8

nathanm
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Post by nathanm »

There are two different points here.

One is whether a ~200 mm large format lens would work as a tube lens. Possibly it would.

Most of them are quite slow however, and I wonder how that would be with vignetting. The Raynox 5320 AB set is ~200 mm and it is 72mm front element (probably 68-70 clear aperture). So it is f/2.6 - f/2.8. In general, larger lenses did better in my tests with respect to vignetting.

The second point is I think you are suggesting that I combine lenses rather than using the Mitutoyos. That might also work.

I have the Canon 35mm macrophoto lens, the SK 28mm m-componon, and several other m-componons that could get me into the same mag range, without stacking lenses.

You are suggesting that I stack lenses. Maybe it would be great but I don't have much experience with it, and a lot of people on this forum do well with Mitutoyos. Including me...I am just trying to change to a larger format.

I think that I already own the Macro Symmar back from when I shot with a Sinar.
nathanm

Andy Davies
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Post by Andy Davies »

Could you list the Thorlabs components required for mounting the Raynox 5320 to the camera?

Many thanks

Andy

nathanm
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Post by nathanm »

Here is a basic parts list for a system based on the SM3 optical tubes from Thorlabs

http://www.photomacrography.net/forum/v ... t+thorlabs

The difference with the new set up is that the Raynox 5320 screws into a generic filter step down ring (72mm filter on 77mm lens)

The other difference is that you need to buy one of the Thorlabs variable length SM3 tubes. I don't have the part number but it is on the site. That will be used to focus the SM3.
nathanm

Andy Davies
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Post by Andy Davies »

Do you need just one SMSL20 (54.6mm length) Thorlabs tube plus the SM3V10 (21mm) with this new setup?

nathanm
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Post by nathanm »

The tube lens has approximately a focal length of 200 mm. canon flange focal length is 44 mm (Nikon is similar). So you will need more than one of the 54mm tube and perhaps a 25mm tube. I am away from the studio at the moment and I don't recall the actual count.
nathanm

Andy Davies
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tube length

Post by Andy Davies »

If the measurement for the tube lens start from the sensor and ends at the back of the Mitty then:

1. Raynox is 58mm
2. Thorlabs helicoid max extension 33mm
3. Thorlabs tube 54mm
4. camera flange distance 47mm

Giving an approx sum of 192mm which is what you arrived at at 4.8x

Does this make sense?

Lou Jost
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Post by Lou Jost »

In case Nathan is away at the moment, Andy, I can answer that with a "no". The 200mm is from the Raynox to the sensor.

nathanm
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Post by nathanm »

Correct, the ~200 mm (192 mm) is from the exit pupil of the Raynox to the sensor.

Just where the exit pupil is, I am not totally sure. The Raynox 5320 A&B is about ~50 mm back to front, and it's likely somewhere in there.

So what you do is put it on the SM3 tubes, and use the variable length SM3 tube to focus on something at infinity (or far away, I use trees on a mountain near my studio). Then lock it with locking ring.

I will send picture when I am back - still in Australia
nathanm

rjlittlefield
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Post by rjlittlefield »

nathanm wrote:Correct, the ~200 mm (192 mm) is from the exit pupil of the Raynox to the sensor.
A minor correction: rear focus would be measured from the rear principal plane of the Raynox, which may be at a different location from the exit pupil. Position of the principal plane is determined only by the refracting elements; the exit pupil is also determined by placement of the aperture. For a tube lens, the exit pupil of the tube lens by itself is not relevant, because in use there will be a different limiting aperture due to the objective.

--Rik

nathanm
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Post by nathanm »

Yes, sorry, Rik is correct...
nathanm

mawyatt
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Post by mawyatt »

nathan,

I've got the Raynox 150 and 250 and use them (reversed) with various Mits on a Nikon D800E (Full Frame FX) and D500 (APC DX) cameras. I usually image silicon chips at high resolutions, with somewhat large stacks.

Do you think it is worthwhile to get the Raynox DCR-5320 pair you are using for my application since I am using the D800E and D500 cameras?

Any comments and details on how the Raynox 150 & 250 fared with the Raynox 5320 pair on your Canon camera is appreciated.

Thanks,

Mike

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