Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Just bought that first macro lens? Post here to get helpful feedback and answers to any questions you might have.

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kirshmedia
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Location: Toronto, ON

Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Post by kirshmedia »

Hi everyone,

I'm looking to set up my Sony A7iii with a microscope objective to capture extreme macros of minuscule details of flowers.

I have the following lenses:

Tokina Macro 100 F2.8D AT-X Pro
(with a Sigma Mount Converter MC-11 Canon EF-E)
Sony 70mm-200mm G Master
Sigma 24mm-70mm


I inquired with a contact at RAF camera who mentioned the following (NOTE: I excluded my macro lens as I didn't have it when I inquired):
Your lenses have 82mm and 77mm filter threads correspondingly.
We make 77mm step-down rings to different microscope objectives, but you did not tell what thread your microscope objective has.
Also, I can't give you good advice on building your setup since I don't shoot myself.

1. Which of my 3 lenses mentioned above would be best to use with a microscope objective/adapter setup?

I'm assuming the Macro as it will allow for maximum magnification but i'm relatively new to this so I'm seeking guidance

2. Which adapter should i be purchasing which will fit my camera and a suggested microscope objective?

I've found this shop which sells a number of options for the Sony E-Mount, but without an objective currently in my inventory and without an idea of which lens would be best for these purposes, i'm unsure which adapter I should be purchasing. I'm just unsure of the different terminology used for the adapters in terms of thread sizes and how they fit into eachother etc. (male/female)
3. Which microscope objective would be best/most compatible moving forward?
I've found some relatively expensive objectives as recommended by a colleague, but he wasn't able to help much more than recommending: https://www.edmundoptics.ca/p/20x-mitut ... tive/6625/

Are there any other comparable alternatives? Or more affordable alternatives which might get the job done?

4. If I decided to move forward with the 20x Mitutoyo objective linked in #3, how would you recommend I go about understanding the thread sizes / female / male terminology required to purchase the appropriate parts? Anyone have the knowledge to help me understand a little better? Any resources/formulas/calculations etc might be useful (i.e. Sizes i need to consider, diameter, where I can find these dimensions

Pau
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Re: Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Post by Pau »

For Full frame you need a long tube lens (the Sony 70mm-200mm G Master at 200mm in your case*) and one of the objectives capable of covering that sensor like some Mitutoyo M Plan Apo like the linked 20X and some Nikon CFI

You need one adapter from the objective thread to the filter thread of your lens.
Take a look at: https://www.photomacrography.net/forum/ ... 29&t=11710
For example the Mitutoyo M Plan Apo has a 26mm x 36tpi thread

*Not sure if it would be adequate, some similar lenses like the Canon EF are.
Pau

kirshmedia
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Location: Toronto, ON

Re: Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Post by kirshmedia »

Pau wrote:
Wed Jun 15, 2022 9:37 am
For Full frame you need a long tube lens (the Sony 70mm-200mm G Master at 200mm in your case*) and one of the objectives capable of covering that sensor like some Mitutoyo M Plan Apo like the linked 20X and some Nikon CFI

You need one adapter from the objective thread to the filter thread of your lens.
Take a look at: https://www.photomacrography.net/forum/ ... 29&t=11710
For example the Mitutoyo M Plan Apo has a 26mm x 36tpi thread

*Not sure if it would be adequate, some similar lenses like the Canon EF are.
Thank you for your help! This has been the most helpful response i've gotten from all forums i've tried (reddit included). Just curious, when you say "*Not sure if it would be adequate", what would be inadequate about this setup? Also, when I search up the 26mm x 36tpi on Raf Camera, 3 options pop up. Which version would be the one I should use? I'm unsure of the differences but it seems to be something to do with Male/Female vs Male/Female

Just trying to understand a little more. Thank you

rjlittlefield
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Re: Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Post by rjlittlefield »

kirshmedia wrote:
Wed Jun 15, 2022 10:01 am
"*Not sure if it would be adequate", what would be inadequate about this setup?
Some telephoto lenses vignette when used with an objective. Whether this happens depends on details of the lens design that are never published and are not addressed by ordinary test reports. So, the only way to know for sure is to find a specific report for that model of lens, or try it yourself. You can get a good indication, without an objective, by making a 10 mm diameter hole in the middle of a black card, holding the card in front of the lens, and shooting a distant scene. If the lens vignettes when used this way, then it will also vignette when used with an objective. This is because the distant scene plus the hole in the card closely mimics the rear aperture of an infinite objective.

If your camera lens does vignette too much, then an alternative is to use an assembly such as described at https://www.photomacrography.net/forum/ ... 01#p283201 and the references that it links.

Also, when I search up the 26mm x 36tpi on Raf Camera, 3 options pop up. Which version would be the one I should use? I'm unsure of the differences but it seems to be something to do with Male/Female vs Male/Female
"Male" threads are external threads, like on the end of a microscope objective. "Female" threads are internal threads, like the filter threads at the end of a lens. The adapter(s) you need must have a 77 mm male thread to mate with the camera lens, and a 26mm female thread to mate with the objective.

When I search rafcamera.com for 26mm x 36tpi, the site responds with three hits, as follows:

https://rafcamera.com/adapter-sm2m-to-m26f "SM2 male to M26x0.75 (36tpi) female thread adapter (SM2 to 26mm step-down ring)"
The small interior thread will fit your objective, but the other threads are designed to work with ThorLabs' SM2-series tubes. Getting from SM2 to your telephoto's filter threads would be challenging.

https://rafcamera.com/adapter-m49x0-75m-to-m26x0-75f "M49x0.75 male to M26x0.75 female thread adapter (49mm to 26mm step-down ring)"
The small interior thread will fit your objective, and the large exterior thread will fit standard step rings to go from the adapter's 49 mm to your lens's 77 mm threads.

https://rafcamera.com/adapter-m26x0-7m-to-m40x0-7f "M26x0.7 male to M40x0.7 female thread adapter for Mitutoyo"
This adapter is not relevant to your application. It is designed to allow using a Mitutoyo BD-style objective that has 40 mm threads, on a system that already accepts ordinary Mitutoyo objectives that have 26 mm threads.

So, you want the second one, plus a "77-49 mm step down ring" like https://www.ebay.com/itm/265706760675 , or a short combination of step down rings such as 77-55 (https://www.amazon.com/Step-Down-Compat ... B089FZP3GW) plus 55-49 (https://www.amazon.com/Fotodiox-Adapter ... B001G43POM).

It may be tempting to get a full set of step down rings such as https://www.amazon.com/Fotasy-Anodized- ... B008TC1RS0 from which you can assemble a long sequence to get 77-49. But this should be avoided because it moves the objective farther away from the telephoto lens, which makes vignetting more likely.

I hope this helps (and welcome aboard!).

--Rik

kirshmedia
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Re: Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Post by kirshmedia »

Your responses have been the most help i've found online! I really appreciate all your assistance with this!

To clarify, you're saying if I choose to move forward with my Sony 70mm-200mm lens as my lens of choice for this, then you'd recommend purchasing the following two items:

1. https://rafcamera.com/adapter-m49x0-75m-to-m26x0-75f "M49x0.75 male to M26x0.75 female thread adapter (49mm to 26mm step-down ring)"
The small interior thread will fit your objective, and the large exterior thread will fit standard step rings to go from the adapter's 49 mm to your lens's 77 mm threads.

+

2. A "77-49 mm step down ring" like https://www.ebay.com/itm/265706760675 or a short combination of rings.

What would the benefit be of the combination of rings? Would that not move the objective further away from the lens as mentioned in your last point re:what to avoid?

blekenbleu
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Re: Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Post by blekenbleu »

M42 (or T2) are a common denominators among camera adapters for both microscopes and telescopes.

Here is a M42 x1mm TO M26*36tpi (Mitutoyo Nikon BD ) adapter:
https://cnscope.com/new-m26-female-for- ... ad-adapter

.. and here is an M42 to M77 adapter:
https://www.wemacro.com/?product=m42-to-m77-adapter

I now see that WeMacro also offers an M26(Mitutoyo) to M42 (42mm x 1)
https://www.wemacro.com/?product=m26mit ... -1-adapter

.. so both rings could be acquired from one source.

For infinity objectives, rays to your telephoto (focused at infinity) are parallel;
small distance differences do not much matter.
Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope

rjlittlefield
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Re: Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Post by rjlittlefield »

kirshmedia wrote:
Tue Jun 28, 2022 1:41 pm
Your responses have been the most help i've found online! I really appreciate all your assistance with this!
You're very welcome.
2. A "77-49 mm step down ring" like https://www.ebay.com/itm/265706760675 or a short combination of rings.

What would the benefit be of the combination of rings? Would that not move the objective further away from the lens as mentioned in your last point re:what to avoid?
There would be no benefit except for availability.

As mentioned by blekenbleu, small distance differences do not have much effect on image quality. More separation makes vignetting worse, but adding one extra ring is a good tradeoff if it means you can get your system working sooner.

The ideal adapter would be M26 to M77 in a single ring, but apparently that would be a custom part. RafCamera might be willing to make one and add it to his product line, but doing any transactions with RafCamera may be difficult at this time anyway. (See their notes at https://rafcamera.com/news .)

The M42 approach described by blekenbleu may be the best approach at this time, though shipping out of China can be problematic also. I would love to list a North American source for adapters like this, but I don't know of one.

--Rik

blekenbleu
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Re: Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Post by blekenbleu »

rjlittlefield wrote:
Tue Jun 28, 2022 4:15 pm
The M42 approach described by blekenbleu may be the best approach at this time, though shipping out of China can be problematic also. I would love to list a North American source for adapters like this, but I don't know of one.
WeMacro orders in May were delayed, for which I was promptly notified and offered the option to cancel.
WeMacro shipments resumed mid-June.
Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope

Lou Jost
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Re: Please Help - Set up Macro Rig w/ microscope objective on Sony A7III

Post by Lou Jost »

"It may be tempting to get a full set of step down rings such as https://www.amazon.com/Fotasy-Anodized- ... B008TC1RS0 from which you can assemble a long sequence to get 77-49. But this should be avoided because it moves the objective farther away from the telephoto lens, which makes vignetting more likely."
There is a way to avoid vignetting from stacking step-down rings. You can put some of the rings on the back side of the larger rings instead of in front. You can completely avoid any extra extension. In fact, using this method, you can sometimes get the limiting ring closer to the front element than you could by using a single 77-26 ring.

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