AmScope 4X Infinity Objective

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LewTwo
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AmScope 4X Infinity Objective

Post by LewTwo »

Before I found this forum and when I was too ignorant to know that it was not supposed work I tried something. I have a simple portable inspection microscope similar to this (a few decades older): https://www.amazon.com/dp/B004E8W8WW

I purchased an "AmScope PA4X-INF 4X Infinity Plan Achromatic Microscope Objective" and screwed into the bottom of said scope. Then I stuck my Pentax M42 microscope adapter on the top (without an eyepiece). Lastly I attached my Sony A6000 camera via an heliod focusing NEX to M42 adapter. The whole thing was a bit top heavy, precarious and focusing was course. However it did work. The light portion in the middle may be due to the desk light shining through the slot in the front of microscope stand. The target is a black metric steel scale.

Sony A6000, ISO 200, 1/5 second, aperture priority
Tube length (shoulder to sensor): 250mm
Working distance: 30mm
Image width: 6.25mm (almost 4:1)

Now I know I am supposed to have a tube lens but .... I have to get a more stable setup.
Sample Micro 4X infinite (notes 1024x682).jpg
Sample Micro 4X infinite (crop).jpg

rjlittlefield
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Re: AmScope 4X Infinity Objective

Post by rjlittlefield »

LewTwo, welcome aboard.

To understand your results, it may help to know that optically your 4X NA 0.10 infinity objective is just a fairly ordinary 50 mm f/5.0 lens, mounted in a barrel that has standard threads and focus position so that it plays well with other objectives when mounted in the frame of a microscope. With this sort of objective, presence/absence of a tube lens makes little difference except for changing the amount of extension that you need to get the same magnification.

I notice in your other post that you mention "Novoflex M42/M39 bellows, extension tubes, several EL-Nikkor enlarger lense". You could get results that are similar to the objective, with more flexibility, by reversing a 50 mm EL Nikkor lens in front of bellows / extension tubes.

The main value of microscope objectives kicks in at 10X and above, where the objective is designed to cover only a small field but at high quality. A 10X NA 0.25 infinity objective corresponds to a 20 mm f/2 lens, optimized to run wide open, over a field that is only about 3 mm wide. Paired with a standard 200 mm tube lens, the combination nets out as almost the same as a 10X NA 0.25 finite objective, which is also equivalent to a roughly 16mm f/1.8 lens, again optimized to run wide open over a small field. So, at 10X and above, you can do things with microscope objectives that you cannot do with ordinary camera or enlarger lenses.

The sample image that you show looks heavily diffracted, evidenced by lack of fine detail and presence of halos around bright highlights. This appearance is typical for a metal target illuminated by highly directional light. You would see finer detail, without those halos, by using more heavily diffused illumination that makes light strike the subject from a wide range of angles.. This does not need to be anything fancy. I do most of my work with simple paper diffusers, often just a Kleenex tissue held around the subject to form a light tent.

I hope this helps!

--Rik

LewTwo
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Location: Houston, Texas

Re: AmScope 4X Infinity Objective

Post by LewTwo »

rjlittlefield wrote:
Sun Nov 22, 2020 6:29 pm
LewTwo, welcome aboard.
Thank thee
rjlittlefield wrote:
Sun Nov 22, 2020 6:29 pm
I notice in your other post that you mention "Novoflex M42/M39 bellows, extension tubes, several EL-Nikkor enlarger lense". You could get results that are similar to the objective, with more flexibility, by reversing a 50 mm EL Nikkor lens in front of bellows / extension tubes.
I plan to do to exactly that when some of the bits and pieces arrive from China (40.5mm reversing ring among others).

I have cobbled together a vertical macro work stand by bolting a 240mm Arca-Swiss type rail to a an old stereo microscope stand.
I added a Neewer focusing rail for finer adjustment. I also ordered a 400mm rail for lenses that might require a bit more elbow room.

Lighting is a problem I have not worked out yet and with the little stand microscope there really are not many options.

Lou Jost
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Re: AmScope 4X Infinity Objective

Post by Lou Jost »

with the little stand microscope there really are not many options.
The diffusing options that Rik mentioned are applicable to just about any front-illuminated set-up. It is not complicated. Split ping-pong balls are also useful.

lothman
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Re: AmScope 4X Infinity Objective

Post by lothman »

LewTwo wrote:
Sun Nov 22, 2020 10:16 am

Sony A6000, ISO 200, 1/5 second, aperture priority
Tube length (shoulder to sensor): 250mm
Working distance: 30mm
Image width: 6.25mm (almost 4:1)

Now I know I am supposed to have a tube lens but .... I have to get a more stable setup.
Sample Micro 4X infinite (notes 1024x682).jpg
Sample Micro 4X infinite (crop).jpg
Robert O'Toole show excellent results with the same lens and a similar camera.
https://www.closeuphotography.com/seven ... -objective

If your lens is labeled with 160/0,17 you don't need a tube lens, just 160mm distance between lens and sensor.
Your example shows a "hot spot" in the center, so by flocking you could eliminate stray- light. Often also the lightning can cause crisp detail or blurr, as others have said try to diffuse the light.

Be careful against vibrations, use 10 sec. selftimer and electronic shutter. If the results are better than you have suffered from motion blurr.

LewTwo
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Location: Houston, Texas

Re: AmScope 4X Infinity Objective

Post by LewTwo »

lothman wrote:
Mon Dec 07, 2020 8:51 am
If your lens is labeled with 160/0,17
It is not.
It Is Not.JPG

lothman
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Re: AmScope 4X Infinity Objective

Post by lothman »

LewTwo wrote:
Mon Dec 07, 2020 9:33 am
It is not.
sorry then I was on the wrong track, the finite Amscope 4x Robert was demonstrating is quite good. But in this magnification range the Laowo 2,5-5x lens might be worth to think about. Very flexible and optically also very good (even on full frame). If you buy it used you probably won't loose money once you resell it.

Lou Jost
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Re: AmScope 4X Infinity Objective

Post by Lou Jost »

I second Lothman's recommendation. The ability to change magnification easily between 2.5x y 5x is very useful, and there aren't many objectives in that range which cover full frame.

LewTwo
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Joined: Sun Nov 22, 2020 4:49 am
Location: Houston, Texas

Re: AmScope 4X Infinity Objective

Post by LewTwo »

lothman wrote:
Mon Dec 07, 2020 10:11 am
sorry then I was on the wrong track, the finite Amscope 4x Robert was demonstrating is quite good. But in this magnification range the Laowo 2,5-5x lens might be worth to think about. Very flexible and optically also very good (even on full frame). If you buy it used you probably won't loose money once you resell it.
https://www.venuslens.net/product/laowa ... a-macro-2/

That is an interesting option. Actually I have just received the "Venus Optics 'Laowa' 65mm f2.8 Macro 2:1 lens"
https://www.venuslens.net/product/laowa ... macro-apo/
https://www.youtube.com/watch?v=6fL7Aa2QCcI

That lens will likely suit my walk-about needs just fine. However I started a project with bellows, enlarger lens and microscope objectives prior to finding out about that lens. My intent was to do a "head to head" comparison between different options. I have invested enough time, money and effort into the project that I intend to complete it.
Neigbors Flowers.JPG
Lou Jost wrote:
Mon Dec 07, 2020 10:53 am
I second Lothman's recommendation. The ability to change magnification easily between 2.5x y 5x is very useful, and there aren't many objectives in that range which cover full frame.
I am holding out a lot of hope for the Edmund Optics Microscope in that regard. The objective zoom range is 0.75X to 3X (primefocus). With 5X, 10X and 20X eyepieces for eyepiece projection the range is extended quite a bit. I have discovered that a 1-1/4 Telescope camera adapter has an inside diameter of 28.5mm. It fits perfectly over the Edmund optics 28.0mm outside diameter eyepiece tube (reversed so the M42x0.75 pitch threads face up). I plan to epoxy it to the microscope. That makes it simple to use T2 extension tubes and a camera adapter for either prime focus or eyepiece projection.

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