Update - looking for more suggestions

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clarnibass
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Update - looking for more suggestions

Post by clarnibass »

Hi

Just had a few more tests. I'm still using about x2 magnification to test lighting before I try the x5 objective.
These bugs are in bad condition, only used for the tests, so there's lots of dust, etc. even after cleaning.

The lens is a Nikon 105mm micro with 80mm of extension tubes.
The magnification is actually x1.76 (according to the calculator). I rounded to x1.8 to check step size, which gave 0.099mm, so I've used 0.090mm and 0.095mm steps which I think should definitely be ok.

Rail is very rigid so should be good. Lights are still small flashes, but I've changed the setup to be able to use 1/16 or 1/8 power (previously had to resort to 1/2). There is a cone diffuser over the lens and two additional diffusers on the sides. Three lights - one from top front and one on each side.
ISO 100 and noise in background is from stacking (haven't used the other stack for the background) and anyway this is temp background for the tests.

I have a feeling it should be better but I'm wondering if that's true and why it's not as good as I think it should be.

Looking at the eye of the first bug (wasp?), part of it seems much sharper. Is that because of the angle to the lens? Can too much diffusion cause that?
I can try just one layer of diffusion and that depends on the bug anyway (first bug I tested had extreme highlights from "fur" and dirt/dust so maybe it's overkill now).
Crops are 1:1.

Some parts look hazy (not the outer edges which is partly from the stacking). The originals at ISO 100 surprisingly have quite a bit of grain...
Is this what I can expect from that lens/tubes setup?
The objective I have is a Mitutoyo x5. Assuming it's not defective, should it be better?
For some of the eventual photos I would need lower magnification than x5 on full frame, so I planned to use the x2 on the APSC camera (which is what these examples are from).

Thanks for any suggestions

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clarnibass
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Joined: Fri Jun 10, 2016 11:33 pm

Post by clarnibass »

Some additional info, not sure why I haven't tried this before... but I just checked the setup at different apertures taking photos of some text.
f/5.6 (approximately f/16 actual aperture) was best, with a visible improvement over f/4 (approx f/11) and f/8 (approx f/22).
Bug photos were taken at f/4. I will definitely use f/5.6 with this setup from now on.
The test was done with the APSC camera. Can I assume the same for the full frame camera (f/5.6 being best)?
Though the improvement is very noticeable, it's not significant enough to "solve" the issues shown above.
Thanks again

ChrisR
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Post by ChrisR »

The first thing that hits me is colour/color balance. In Photoshop I found +41% on Green gave a neutral background (RGB 80,81,82).

Noise - may be from Pmax whcih enhances all detail, including noise!
If you start with DMap and retouch with Pmax, it should be better

What's the camera? My Canon 700D ( which is something like a t5i) is quite noisy.

[Edited due to misreading]
Last edited by ChrisR on Sun Jan 27, 2019 9:52 am, edited 1 time in total.
Chris R

rolsen
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Post by rolsen »

Might be that the 105 Micro Nikkor ain't in its comfort zone when extended 80mm, that's quite a lot based on my own tests. Just my two cents.
- Rane

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Post by ChrisR »

rolsen wrote:Might be that the 105 Micro Nikkor ain't in its comfort zone when extended 80mm, that's quite a lot based on my own tests. Just my two cents.
Certainly true - I misread....:oops:
If you screw the Mitutoyo 5x on the front of your 105mm it'll vignette (probably) but it should be sharper in the middle!
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hero
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Post by hero »

None of the consumer 100mm 1:1 macro lenses do that well (compared to simpler designs or microscope objectives) using extension to bring them up to 2:1, because the amount of extension needed is substantial. I've personally pushed the Canon EF 100/2.8L macro IS with tubes plus a teleconverter to get to 2:1, which actually does better than tubes because the extension is less. But the corners are bad and it is not suitable for stacking in my opinion. Chromatic aberrations are the main problem.

To be clear, one puts the extension between the lens and teleconverter--NEVER between the teleconverter and camera body. Canon's TCs have a protruding element...so I use the extension tube mainly to just allow for enough space to attach the TC.

Once I got the MP-E, I forgot about these "Frankenlens" setups. And then after getting my first objective, I was reintroduced to a whole world of rings, adapters, and flocking that made my early experiments in macro look like child's play.

You'd almost certainly do better to get a short focal length lens and reverse it on the 100mm macro if 2:1 is the range you want to be in; or certain other lenses reversed on bellows could do much better. These autofocusing 100mm macros just aren't made for higher magnification. Other manufacturers, like Venus Optics, have been designing lenses that go to 2:1 natively, but if you want even more magnification, it's probably best to get a lens that does NOT have the ability to focus to infinity, because it's a lot to ask design-wise to make a lens that is well-corrected for aberrations in both regimes, not to mention the effective f-number of such a design at its MFD.

clarnibass
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Post by clarnibass »

ChrisR wrote:The first thing that hits me is colour/color balance.
I'm colourblind, the colours for this eventual project are purposely not going to be completely natural/realistic and specifically for the background, it was a random "black" (very dark gray) with some other colours near by reflecting on it. So doesn't matter for now :)
ChrisR wrote:Noise - may be from Pmax whcih enhances all detail, including noise!
If you start with DMap and retouch with Pmax, it should be better
Wow... I just looked it up and saw the retouching videos on Zerene's website. I can't believe I didn't know about this before. I used to do this in Photoshop and although I'm used to it and it's probably a better retouching program overall, it seems more convenient to do at least most of it in Zerene. I never thought to stack several DMAPs at different settings!
ChrisR wrote:What's the camera? My Canon 700D ( which is something like a t5i) is quite noisy.
This was a Nikon D5500, which is supposed to have pretty good low ISO noise for an APSC. My other camera is a D600. Both are 24mp. I compared them a lot as far as low and high ISO noise, resolution vs. noise with croipped FF vs. APSC, etc.
ChrisR wrote:If you screw the Mitutoyo 5x on the front of your 105mm it'll vignette (probably) but it should be sharper in the middle!
I plan to use the Mitutoyo x5 on a 200mm lens, actually I just tried it, without a rail... difficult... but could get a tiny fraction of a target to seem sharp.
A nice bonus was that the focus was best with the 200mm lens exactly where the focus ring stops at infinity, so less fiddling than if it was almost there.
If I understand, using it on the 105mm would basically give lower magnification, with (probably) some vignetting? Is it nearly half (same ratio as the FLs)?
rolsen wrote:Might be that the 105 Micro Nikkor ain't in its comfort zone when extended 80mm, that's quite a lot based on my own tests. Just my two cents.
hero wrote:None of the consumer 100mm 1:1 macro lenses do that well (compared to simpler designs or microscope objectives) using extension to bring them up to 2:1...
I was really hoping this wasn't the issue but knew that it might be... :)
Though I'm not sure what you mean by consumer... At least at 1:1 it seems to be pretty much the same as some older manual focus lenses... but it definitely could be worse beyond that. What macro lenses aren't "consumer" other than the Canon 65 (which isn't something I'm interested in)?
hero wrote:You'd almost certainly do better to get a short focal length lens and reverse it on the 100mm macro if 2:1 is the range you want to be in; or certain other lenses reversed on bellows could do much better.
I won't use bellows, but I'll look into the reversed lens.
Can you help me understand this calculator a bit better http://extreme-macro.co.uk/extreme-macr ... calculator

Let's say I use the 105mm micro, I put 105mm in the first field right?
Then if I reverse a 55mm 1:2 lens, I put 55mm and 0.5 right?
So I get about x2.4 magnification. I can use that on the FF to get roughly similar to what I got with the 105mm + extensions and on the APSC for a step below the x5.

Is that likely to be significantly better than the 105mm with extensions?
hero wrote:These autofocusing 100mm macros just aren't made for higher magnification.
Definitely possible, though as mentioned above, I think the one I have, which is the previous 105mm micro (not the G), is more or less similar to some of the older MF micro lenses (maybe). I guess quality at 1:1 doesn't mean anything for this, but it does extend, etc. unlike the new lenses.
hero wrote:Other manufacturers, like Venus Optics, have been designing lenses that go to 2:1 natively, but if you want even more magnification, it's probably best to get a lens that does NOT have the ability to focus to infinity, because it's a lot to ask design-wise to make a lens that is well-corrected for aberrations in both regimes, not to mention the effective f-number of such a design at its MFD.
Interesting. I read about their 25mm x2.5-x5 and 60mm x2. In theory those two lenses would cover what I need, but I already have the Mitutoyo so I can't see getting both. I'll consider one of them, likely the 60mm, if it's really good at x2?

I guess it was designed to get to x2 so should be better than my current (approx) x2 setup, but I don't see how it is less "consumery"?

Thanks again!

NikonUser
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105 mm Nikon, an OK lens

Post by NikonUser »

The Nikon 105mm Micro, older manual f/2.8 lens, is quite capable of giving decent 2x images on a 24mm sensor.
lens fully extended (i.e., to give 0.5x) on 130mm extension, f/8 on lens; FOV 11 mm wide; D90
Zerene stack
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Nikon camera, lenses and objectives
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clarnibass
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Re: 105 mm Nikon, an OK lens

Post by clarnibass »

NikonUser wrote:The Nikon 105mm Micro, older manual f/2.8 lens, is quite capable of giving decent 2x images on a 24mm sensor.
lens fully extended (i.e., to give 0.5x) on 130mm extension, f/8 on lens; FOV 11 mm wide; D90
Zerene stack
Thanks. Can you post a 100% crop of an eye/face part, without sharpening? That full photo looks to have quite a bit of sharpening, but still seems like there are more details than in mine. It's not the camera since it's actually lower res.

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Post by Chris S. »

Clarnibass,

The micro-Nikkor 105mm series are excellent lenses. Not sure why anyone would label them consumer-level, whatever that means. My specimen is a micro-Nikkor 105 f/2.8 AF-D. At 1x, it comes surprisingly close to (though does not quite equal), my Printing Nikkor 105, which is, deservedly, a legend--but is semi-rare and expensive.

This said, for magnifications over 1x, I would reverse the micro-Nikkor 105, just as I would reverse any similar lens for magnifications above 1x. At 2x, I think you'll see improvement from your 105mm if you reverse it. Reversing a lens with a 105 focal length isn't as mechanically easy as reversing a macro lens with a shorter macro length. But if you can do this, I suspect you'll see improvement in the 2x performance of your 105mm micro-Nikkor.

Cheers,

--Chris S.

hero
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Post by hero »

Apparently, the meaning of my post has become twisted in a way that was not my original intent.

I did not, for example, say "consumer level." I used the word "consumer" to refer to lenses that are available for the general photographer, with a native system mount, as opposed to, for example, a microscope objective or a lens not originally made for a modern camera system, that needs some kind of adapter or custom solution to mount. In this regard, "consumer" is not to be mistaken for low or mediocre imaging quality. It is meant to refer to lenses that are designed for a wider range of shooting situations than just high magnifications.

Second, I stand by my statement that imaging performance is not optimized for these ~100mm lenses when used with enough extension to get to 2:1 (the implication being that these are extended in the normal orientation). It may be good in the center, but the corners--at least on a full frame sensor--do not fare well, and this was one of the main reasons why I eventually got the MP-E, because I simply couldn't get to the magnifications I wanted to, with the image quality I desired, by extending my 100/2.8, which I believe to be comparable to the Nikkor 105/2.8 VR.

Also keep in mind that not all tubes are created equal--it was only after seeing how necessary it was to have a rigid setup with the Mitutoyo 10x that I went back and realized just how much play my bayonet EF mount extension tubes actually have! It may not have that much of a real-world impact at 2:1 but there is no such issue with a lens that's designed for that magnification regime. Had Venus Optics released their competitor to the MP-E earlier, I might have gotten it instead.

I suspect it is not a coincidence that these 5x-capable lenses are not made at long focal lengths--granted, they don't even focus at infinity, and when the 100 mm lenses are at MFD, their focal length is substantially shorter due to their internally focusing design. Reversing a wide-angle lens can provide better performance at a given magnification than putting tubes behind a lens with a long focal length.

clarnibass
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Post by clarnibass »

Thanks.

I'm used to the world of machining where "consumer" is often used by "real" machinists to mean lower quality and cheaper tools... also it's my second language :)
With these lenses it's more confusing, the "special" macro lenses are often cheaper (e.g. Venus vs. the regular Canon or Nikon). Also part of the advantage with Nikon is that very old manual lenses still fit the mount, so they are "consumer" in that sense.

The Nikon 105mm VR is equivalent to the Canon 100mmL. I don't know if it's different (optically) from the regular 100mm. Mine is neither, it is the older Nikon, I think first model with AF (not sure), but still extends like the older manual lenses. If that means anything to its quality when extended beyond 1:1... I don't know. It could be just like you are saying, and it's just not that great at close to 2:1.

Re tubes, I've tried many, and got rid of all except the older Nikon ones which are the most rigid I've found.

The Mitutoyo x5 being smaller diameter is a bit better for lighting and hopefully at least as good or better than the Venus... Otherwise I could have bought both Venus lenses and save a lot of hassle... hopefully I get something in return for that hassle...

Basically I have excellent 1:1 and 5:1, both on APSC and FF with same MP which gives a bit more flexibility. x2 or x2.5 is exactly what I need in addition to that so I'll try a few more things and if not I'll consider one of the Venus lenses.

I read this (which might be reliable or not) http://extreme-macro.co.uk/coupled-reverse-lens/
They say if lenses are good, this is usually better than just reversing a lens with an extension (which I'll try too).
I ordered an adapter and I'll try the 105mm lens with a reversed 55mm lens, which should give about x1.9.
I don't know if the working distance would be very small that way.

clarnibass
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Post by clarnibass »

OK finally was able to do a (rough) comparison between the 105mm with 80mm extension tubes (x1.76 according to the calculator) and the 105mm with a reversed 55mm (x1.9 according to the calculator).

First thing that is weird, in spite of those supposed magnification, the 105mm with extensions has a higher magnification. I think the coupled lenses are less than what they are supposed to be.

Another huge difference is the working distance. About 90mm for the lens with extensions, barely 40mm for the coupled lenses.

I don't think my test subject is good enough but it's really hard to find something. Maybe a part of a coin would be good?
These are stacks. Even though I glued the text to an extremely flat ground steel part it was too hard to get it in focus in one photo.
I don't have a stand that put it perpendicular to the camera and don't need to do that outside this test anyway.

I think the coupled lenses give a slightly better result but since the other version gives a slightly higher magnification maybe it compensates a little when they are eventually viewed at the same size.
Also the working distance might turn out to be more important, I'll see.

I'll try to see if I can find something else to test.

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clarnibass
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Post by clarnibass »

Tried hopefully better comparisons.
From top to bottom:
105mm extended by 52.5mm at f/4
105mm extended by 52.5mm at f/5.6
105mm extended by 80mm at f/4
105mm extended by 80mm at f/5.6
Coupled lenses 105mm and 55mm

Coupled lenses came out warmer, slightly adjusted it to match more or less (being colourblind, I'm not sure how accurate it is).

Not sure why the coupled lenses give magnification somewhere between the two other options. According to calculators it should be slightly more than even the 80mm extension.

Extending by 52.5mm at f/4 seems worse to me. f/5.6 is much better.
Extending by 80mm, the difference is much smaller, but I think f/5.6 is still better.
Comparing the two f/5.6 photos, I think the shorter extension might be better, but I'm not sure and even harder to compare because of the different magnification and how they would compare at the same size.
The coupled lenses seems best and overall more crisp, but have to check if lighting is an issue for actual subjects.


I'm interested to know what others see.

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Post by rjlittlefield »

clarnibass wrote:OK finally was able to do a (rough) comparison between the 105mm with 80mm extension tubes (x1.76 according to the calculator) and the 105mm with a reversed 55mm (x1.9 according to the calculator).

First thing that is weird, in spite of those supposed magnification, the 105mm with extensions has a higher magnification. I think the coupled lenses are less than what they are supposed to be.
I expect it's the other way around. That is, the 105 plus extensions is giving you more magnification than you calculate via 80/105 = 0.76.

In general, it is an accurate calculation that added_magnification = added_extension / effective_focal_length

However, you have to plug in the effective focal length of the lens as it is configured at the time it's being extended. Turning the focus ring on a macro lens usually shortens its focal length in addition to adding some internal extension. A macro lens that is 105 mm at infinity focus is typically more like 75 mm when its focus ring is turned to closest focus.

From there, the formula about added_magnification does apply, but using the new shorter focal_length.

The formula actually provides a good method to determine just what value the new focal length is. Add some extension, measure the magnification in both cases, and invert the formula to get:
effective_focal_length = added_extension / added_magnification

--Rik

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