Mitutoyo 2.5X 0.28NA (warning click bait)

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mjkzz
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Mitutoyo 2.5X 0.28NA (warning click bait)

Post by mjkzz »

Following the fundamental design of an infinite objective, I am pushing a Mitutoyo 10x 0.28NA down to 2.5x with a 50mm tube lens focused to INFINITY on a MFT camera (Panasonic G7). Beside vignetting even with a small sensor and it seems to have some kind of swirling pattern at out of focus area, particularly if you have some bright dots, sort of like those old Russian photography lenses. These distortions will definitely affect final images and those out of focus area just looked so weird , I guess I am pushing it too much over its design points. Nonetheless, this could be a good reference for others. My next experiment is to fix my Raspberry Pi HQ camera and put that on this setup (50mm + infinity objective) and see what happens.
NA28_2.jpg
NA28.jpg

Lou Jost
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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by Lou Jost »

Interesting, but you don't mention the exact 50mm lens. This kind of pushing down is VERY sensitive to the exact model of tube lens used. Could you let us know what you used?

Somewhere on this foum I posted a set of tests of very short tube lenses on MFT with the Mitutoyo, and got some good results with some but not with others. Beatsy has also posted exceptionally good results with some very short Pentax tube lenses on FF or APS.
Last edited by Lou Jost on Sat Dec 18, 2021 6:21 am, edited 1 time in total.

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by mjkzz »

Lou,

The tube lens used was a Canon 50mm f/1.4, focused to infinity. I do not think this combination produce good result as it has some swirling patterns in out of focus area, very bad, but final stacked image seems OK, especially in the center area. What amazed me is that, I can just use my video lights to light the scene with about 1/10s exposure time. I have also tried with Canon 50mm f/1.8, you know that nifty-fifty black plastic one, similar result. Also tried the El-Nikkor enlarge lens, failed, too and I think my M39 to M4/3 adapter is not well made, it is not focusing to infinity after mounting it (it does not have focus ring, so I assume it should focus to infinity if properly mounted)

My goal here is to demonstrate a "systematic" way of hacking, ie, follow theory, respect design of INFINITE objective, even if it fails which illustrates that there is a limit you can push the theory and design (engineering). If it succeeds, it shows the theory is right :D
50mm.jpg

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Adalbert
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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by Adalbert »

Hi Peter,

I have already tested all my Canon lenses reverse
and as tube-lens for the microscope-lenses corrected to infinity.

Really nice was EF 17-40L reverse with the range 1:4 till 4.2:1.
M3_EF17_40_small.jpg
The best tube-lenses are EF70-200L and EF100L macro.

Best, ADi

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by mjkzz »

Hi ADi, very cool, very cool, are you trying to get a variable magnification macro lens? I used a 70-300 zoom as back lens and some other lenses, even 4x objectives, as front lens to achieve that :D

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by mjkzz »

With my setup, putting on a 5x mitty gives you 1.25x 0.14NA, swirling pattern is much less severe, might even be usable, after cropping out vignetting.

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by mjkzz »

FWIW, here is a crazy setup, 35mm T/1.0 (probably f/0.95) cinematic video lens, focused to infinity at max aperture, 10x 0.28NA. This gives 1.75x 0.28NA. Heavily vignetting, but strangely, those swirling patterns seem to be gone, or maybe the image circle is too small to notice, anyway, less noticeable. Now I regret I did not get the 50mm one for the whole set (35, 25, 17, missing 50). I do not have a 85mm portrait lens, it could be interesting to see how that plays out. Anyone?
35mm.jpg
10_35mm.jpg

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by JKT »

Adalbert wrote:
Sat Dec 18, 2021 7:58 am
Really nice was EF 17-40L reverse with the range 1:4 till 4.2:1.
If that one is good, I definitely have to test the EF 16-35mm f/4. Though the use of full frame camera could be an issue.

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by mjkzz »

FWIW and giving back to this community, here is a video shot with Panasonic G7 in 4K mode but converted to HD. When shooting 4K with that camera, there is slight crop, therefore, when shooting stills, the vignetting is worse than shown in this video. Tube lens is a 35mm f/2.0 standard photographic lens, set at max aperture and focused to infinity, objective is 10x 0.28NA. It is amazing that I was forced to use 1/100 exposure time for the video, so it does not look "cinematic".

The reason for 1.7x digital zoom is to "crop out" vignetting.
The reason for 2.5x digital zoom is to show transition to 3x
The reason for 3.0x digital zoom is to show almost vignetting free, "swirl" free
The reason for 4.0x digital zoom is to show that spot pointed by red arrow where it seems to be "alive" as we go in and out of focus.

This also is a precursor for experimenting with a Raspberry Pi HQ camera, we might not need to crop things (or maybe just a little) -- the HQ camera has SONY IMX477 sensor, 1/2.3 type. Unfortunately, I think it will be diffraction limited with this configuration. Lets see.

Here is the video

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by Macro_Cosmos »

I'm seeing the same very weird, mosaic pattern which resembles over sharpening artefacts when I decided to push my 10x down to around 3x just for fun. I wonder what's the cause of this weirdness.
Another fun comparison would be pushing down, for example, a 10x to 5x, then compare it to a native 10x but digitally shrunken (downsampled?) to match the magnification of the 5x. I'd like to say the 10x is better but on a screen, it could be more or less similar.

There's this practice in microscopy which I don't feel confident to recommend. The user would use a 5x projection eyepiece -- usually the highest magnification available, for panorama stitching. The logic behind this method is that the 5x projection eyepiece will extract any and every bit of resolution the objective has to offer, going far into empty magnification category. I think this is wishful and the lack of detail due to empty magnification from experience creates a lot more stacking issues.

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by mjkzz »

I believe the blockiness of image is due to 1. lighting and surface 2. "excessive sharpening" on less diffracted image - so far, the combinations I showed are all very well under diffraction limit for the sensor, they tend to have high contrast than heavily diffraction limited images. The 10x 0.28NA has such high resolving power, it is like using a fine tipped pencil to fill a grid vs a chalk sized pencil that is almost or over the size of grid to fill it.

As for eyepiece idea, I am not a microscopy person at all, but my basic understanding is that the eyepiece is designed to present the image obtained by objective better to human eyes, it really has nothing to do with empty magnification. It is like a focus puller using magnifying glass over the LCD screen on camera or using a large external monitor for better focus, they know there is no more details, but with those equipment, it is easier to see. Or put it this way, an objective with 20x magnification and resolving power of 1um, after the objective, that 1um becomes 20um, this is probably very hard for the eye to distinguish, but with a 5x eyepiece, it is 100um in size, much easier to see. But this has NOTHING to do with empty magnification, which is a totally different concept.

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by Scarodactyl »

Projection eyepieces go straight to a camera sensor and aren't suitable for viewing through. The 5x is actual final optical magnification, not like the '10x' of a typical viewing eyepiece which is then demagnified by your eyelens onto the retina.

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by Pau »

mjkzz wrote:
Mon Dec 20, 2021 10:00 pm
...
But this has NOTHING to do with empty magnification, which is a totally different concept.
Well, as generally accepted, empty magnification is a magnification factor (could be visual or on screen, print, etc...) that does not improve resolution on the subject over a smaller one.
For example, if a person with good eyesight uses a 20X eyepiece on a microscope with a 100X objective he/she will not be able to see smaller details than with a 10X eyepiece, or if you use a 300mm tube lens with a 50X/0.55 objective with a modern DSLR you can't capture more detail than with a 200mm tube lens. Many zoom stereomicroscopes produce empty magnification at the higher zoom ratios...and so on
If you sit too close to the cinema screen the image you see is bigger but you couldn't see more detail than from the right distance.

What's your empty magnification concept?
Pau

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by mjkzz »

Pau wrote:
Tue Dec 21, 2021 12:55 am
mjkzz wrote:
Mon Dec 20, 2021 10:00 pm
...
But this has NOTHING to do with empty magnification, which is a totally different concept.
Well, as generally accepted, empty magnification is a magnification factor (could be visual or on screen, print, etc...) that does not improve resolution on the subject over a smaller one.
For example, if a person with good eyesight uses a 20X eyepiece on a microscope with a 100X objective he/she will not be able to see smaller details than with a 10X eyepiece, or if you use a 300mm tube lens with a 50X/0.55 objective with a modern DSLR you can't capture more detail than with a 200mm tube lens. Many zoom stereomicroscopes produce empty magnification at the higher zoom ratios...and so on
If you sit too close to the cinema screen the image you see is bigger but you couldn't see more detail than from the right distance.

What's your empty magnification concept?
Hi Pau,

My concept of "empty magnification" is EXACTLY same as yours.

However, "seeing better" vs "see more" are two different concepts. If I use some philosophical terms to describe them as metaphor, empty magnification, negation of "seeing more" is a (pseudo) priori knowledge, it is constrained by physics, on the other hand, "to see better" by raising magnification is a posteriori knowledge, one should not expect to be certain to get what one wants.

Adding an eyepiece to your system is to "see better", rather than trying to "see more". Pau, from what I read here, you are an expert in this field, I am pretty sure this is the main reason for microscope manufacturers to do this (adding eyepiece), these experts would be stupid to claim that the eyepieces would allow people to "see more" in the sense seeing more details (vs seeing thing more clearly) because they know "empty magnification" as priori knowledge. So the function of eyepiece is to see better but it is a totally different concept from "being empty magnification", the negation of "seeing more"

The bottom line is, adding eyepiece is to help us to see better and it is the intended goal, it really has nothing to do with "empty magnification" unless some lab intern wants to "see more" by trying to use higher magnification eyepieces, in that case, "empty magnification" concept can be used to stop him/her from doing it, but that is different from relating the concept of eyepieces to concept of "empty magnification"

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Re: Mitutoyo 2.5X 0.28NA (warning click bait)

Post by mjkzz »

What I am just trying to say is this: being empty magnification has NOTHING to do with using (an excessive) eyepiece (in an attempt to getting more details) only seeing better.

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