Microstar IV Camera Adapter

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BrianBurnes
Posts: 37
Joined: Sat Feb 08, 2020 5:05 pm

Microstar IV Camera Adapter

#1 Post by BrianBurnes » Thu Sep 24, 2020 4:25 am

Following on the discovery of the chromatic aberration correcting doublet by hans, I've decided to make a more permanent afocal camera adapter for my Microstar IV that incorporates the correcting optics, eyepiece and a firmly mounted camera lens.

It consists of a combination of 3D printed parts, metal inserts, threaded rings and a standard camera helicoid. For robustness I removed the original dovetail on the trinocular port of the Microstar and bolted the adapter to the head directly.

The adapter contains an entire eyepiece holder (scavenged from a different microstar head) and a #181 eyepiece. The adapter helps align all the pieces and contains a few design features to absorb and reflect away stray light, and stably mounts the eyepiece as close as possible to the lens.

I've documented the parts and assembly of the adapter in a Youtube video for those interested. Below are a few images:

ImageImage

ImageImage

I'm quite happy with the result. The images are much improved and the tube is quite robust. The weakest part of it right now is the helicoid, which can tilt slightly under weight. I may add an external camera mount eventually to fix the camera even more firmly, but for now this will work quite nicely.

hans
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Location: Southern California

Re: Microstar IV Camera Adapter

#2 Post by hans » Thu Sep 24, 2020 7:10 am

Beautiful work, I think 3D-printed designs often look haphazard and poorly-thought-out because of the lack of constraints, but it is clear you have put a lot of effort into designing around the strengths and weaknesses of 3D printing.

What size Phillips bit are you using for those set screws in the outer part of the eye tubes? I never found a size that worked well and they drove me crazy until I eventually bought a bag of hex set screws and threw out all the original Phillips ones.

PeteM
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Joined: Tue Dec 06, 2016 6:22 am
Location: N. California

Re: Microstar IV Camera Adapter

#3 Post by PeteM » Thu Sep 24, 2020 7:13 am

Very nice build. Thanks for sharing it.

Curious what correcting optics you used?

Hobbyst46
Posts: 4277
Joined: Mon Aug 21, 2017 9:02 pm

Re: Microstar IV Camera Adapter

#4 Post by Hobbyst46 » Thu Sep 24, 2020 8:28 am

Impressive project !

Hopefully images recorded with the setup will be posted !

Questions if I may.
may add an external camera mount eventually to fix the camera even more firmly, but for now this will work quite nicely..

1. I wonder about the feasibility of mechanical stabilization of the camera on two separate supports ?
2. Is the hellicoid needed for parfocality ?
3. Does the top clamp adapter part, that accepts the camera lens and is tightened by means of the thumbscrew, enable lateral alignment of the camera to make it coaxial with the optical train ?
Last edited by Hobbyst46 on Thu Sep 24, 2020 1:13 pm, edited 1 time in total.

apochronaut
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Joined: Fri May 15, 2015 12:15 am

Re: Microstar IV Camera Adapter

#5 Post by apochronaut » Thu Sep 24, 2020 12:50 pm

hans wrote:
Thu Sep 24, 2020 7:10 am
Beautiful work, I think 3D-printed designs often look haphazard and poorly-thought-out because of the lack of constraints, but it is clear you have put a lot of effort into designing around the strengths and weaknesses of 3D printing.

What size Phillips bit are you using for those set screws in the outer part of the eye tubes? I never found a size that worked well and they drove me crazy until I eventually bought a bag of hex set screws and threw out all the original Phillips ones.
Phillips can be a problem because there are so many "improved" versions of cross head screws , that look similar but have slightly different dimensions and locking areas. Phillips screwdrivers will destroy similar looking JIS screws quite quickly . Most "Phillips" screws in use now are in fact Pozidriv. Phillips screwdrivers will damage them quickly and are generally incapable of loosening tight ones. Pozidriv screwdrivers will work on Phillips screws but also quickly round them out making repeated use impossible......and those aren't the only cross drive screw types.

apochronaut
Posts: 6272
Joined: Fri May 15, 2015 12:15 am

Re: Microstar IV Camera Adapter

#6 Post by apochronaut » Thu Sep 24, 2020 12:52 pm

That's a really nice settup, Brian. It looks like you are using it afocally?

BrianBurnes
Posts: 37
Joined: Sat Feb 08, 2020 5:05 pm

Re: Microstar IV Camera Adapter

#7 Post by BrianBurnes » Thu Oct 22, 2020 3:35 pm

hans wrote:
Thu Sep 24, 2020 7:10 am
What size Phillips bit are you using for those set screws in the outer part of the eye tubes? I never found a size that worked well and they drove me crazy until I eventually bought a bag of hex set screws and threw out all the original Phillips ones.
From what I can tell they are hex grub screws, but not even the smallest allen key I have would fit. A PH000 phillips bit has just enough bite to get them moving - it's not pretty but it's the only thing I could find that works.
Hobbyst46 wrote:
Thu Sep 24, 2020 8:28 am
1. I wonder about the feasibility of mechanical stabilization of the camera on two separate supports ?
2. Is the hellicoid needed for parfocality ?
3. Does the top clamp adapter part, that accepts the camera lens and is tightened by means of the thumbscrew, enable lateral alignment of the camera to make it coaxial with the optical train ?
The helicoid is mostly for focus fine adjustment. I usually dial it in once at the start of a session in liveview to be fully parfocal and then don't need to touch it again. For stabilization I was thinking a DYI mount that is attached to the microscope body and slides vertically, and allows me to clamp the camera firmly to the body once the helicoid is dialed in.

The top clamp adapter currently does not have any built-in lateral alignment. Because the lens is focused at infinity this is less critical. The lens currently has about 0.5mm play to allow for the clamp to move.
apochronaut wrote:
Thu Sep 24, 2020 12:52 pm
That's a really nice settup, Brian. It looks like you are using it afocally?
Yes. I could not get it to work with direct projection (mentioned in another thread) and afocal will have to do for now. I will try to find a fully mechanical lens at some point that is a bit more stable than the prime lens I use now.

I can still see slight asymmetric CA that does not seem to change when I shift the adapter or camera. This asymmetry has been present since I got this scope, and I'm starting to think that either the nosepiece or the condenser are misaligned. I have a second body that I can try this setup on before I post conclusive results (available free time has been the limiting factor so far).

hans
Posts: 986
Joined: Thu May 28, 2020 11:10 pm
Location: Southern California

Re: Microstar IV Camera Adapter

#8 Post by hans » Sun Oct 25, 2020 7:39 pm

BrianBurnes wrote:
Thu Oct 22, 2020 3:35 pm
hans wrote:
Thu Sep 24, 2020 7:10 am
What size Phillips bit are you using for those set screws in the outer part of the eye tubes? I never found a size that worked well and they drove me crazy until I eventually bought a bag of hex set screws and threw out all the original Phillips ones.
From what I can tell they are hex grub screws, but not even the smallest allen key I have would fit. A PH000 phillips bit has just enough bite to get them moving - it's not pretty but it's the only thing I could find that works.
I looked at one with my stereo microscope and they are neither Philips nor hex, something else. I started a new topic asking if anyone knows what they are.

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