Using a ZWO CMOS camera for microscopy

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rpsfam1
Posts: 4
Joined: Tue May 05, 2020 7:19 pm

Using a ZWO CMOS camera for microscopy

#1 Post by rpsfam1 » Fri Jan 01, 2021 5:15 am

Hi Everyone,


I am new to imaging through a microscope and am having some problems. I have a ZWO ASI385MC CMOS camera (used mainly for astrophotography) with the following specs:


Sensor: Sony 1/2″ CMOS IMX385 color
Diagonal: 8.35mm
Resolution: 2.12 MP
Pixel Array: 1936 x 1096
Pixel Size: 3.75 µm x 3.75 µm
Minimum Exposure: 32 µs


I have an AmScope Stereo Zoom Trinocular (https://www.amazon.c...1?ie=UTF8&psc=1) and

a Swift Compound Trinocular (https://www.amazon.c...0?ie=UTF8&psc=1)


Images through the eyepieces on both scopes are truly beautiful - razor sharp, colorful and full of contrast. However, when I try to image in either one with my ASI385MC, the images are soft (I cannot seem to get a tight focus at all) and the colors are way off. I've tried playing with the white balance and the gain/exposure settings but nothing helps (using sharpcap for this). Both scopes came with "photo-tubes" to attach the camera to the trinocular but they do not have any optical elements in them. Any ideas what I'm doing wrong? tried calling tech support but answer and no reply to my messages.



Thanks in advance for any and all help/advice.



Patrick

MichaelG.
Posts: 3980
Joined: Mon Apr 10, 2017 8:24 am
Location: North Wales

Re: Using a ZWO CMOS camera for microscopy

#2 Post by MichaelG. » Fri Jan 01, 2021 6:08 am

Welcome, Patrick

Your camera should be excellent for microscopy
... so the problem ‘must’ be either vibration or optics.

Could you please share some of your results

I am not familiar with either of those microscopes, but there will surely be someone here that knows them.

If you can take some photos of a stage micrometer, or some reasonable substitute, that would be most helpful.

MichaelG.

.
Ref. https://www.microscopemaster.com/micros ... ments.html
Too many 'projects'

Scarodactyl
Posts: 2775
Joined: Sat Mar 03, 2018 9:09 pm

Re: Using a ZWO CMOS camera for microscopy

#3 Post by Scarodactyl » Fri Jan 01, 2021 6:35 am

A 1/2 inch sensor is 8mm on a diagonal. Your stereo microscope's eyepieces probably have a field number of at least 20mm, probably more. So from the start you are cropping out most of your image, which is like doubling the magnification while keeping the same resolution. Stereo microscopes tend to walk the line on having just enough resolution for the magnification they give, so this kind of cropping can be problematic. You probably want to get a .5x reducing lens as a first step.
The eye is also a lot more forgiving than a camera, and this goes doubly on stereo microscopes. The true 3-D view that a stereo gives means your eyes and brain are getting more information about the subject than just the nominal image resolution, which can make it look better yet. The camera only gets one half of this.
Is the camera parfocal with the eyepieces (in focus without having to do any refocusing?)

rpsfam1
Posts: 4
Joined: Tue May 05, 2020 7:19 pm

Re: Using a ZWO CMOS camera for microscopy

#4 Post by rpsfam1 » Fri Jan 01, 2021 2:15 pm

Hi Scarodactyl,

Thank you for your reply. No, the image is not parfocal between the camera and the eyepieces - not even close-on either the AmScope Stereoscope or the Swift Compound. As far as a reducer goes, I will try that and see if it helps. I would order one to go between the trinocular tube and the camera,correct ? I also recall reading some where that there is an important correlation between the n.a. of an objective and the eyepiece used with it. They said that a "mismatch" between the 2 is the main reason reason why an image viewed with a 10x eyepiece and a 100x oil objective will be better than the same object viewed with a 25x eyepiece and a 40x non-oil objective, even though they will be at the same magnification. Could that be the same problem I'm having with the camera and the trinocular port? Also, if this helps, I can see some sort of lens in the trinocular port on each scope.

Patrick

rpsfam1
Posts: 4
Joined: Tue May 05, 2020 7:19 pm

Re: Using a ZWO CMOS camera for microscopy

#5 Post by rpsfam1 » Fri Jan 01, 2021 2:18 pm

Hi Michael,

Thank you for your reply. I do not have a stage micrometer but will post some pics of something later on today.

Patrick

Scarodactyl
Posts: 2775
Joined: Sat Mar 03, 2018 9:09 pm

Re: Using a ZWO CMOS camera for microscopy

#6 Post by Scarodactyl » Fri Jan 01, 2021 5:23 pm

rpsfam1 wrote:
Fri Jan 01, 2021 2:15 pm
No, the image is not parfocal between the camera and the eyepieces - not even close-on either the AmScope Stereoscope or the Swift Compound.
This can be one source of trouble. The image is optimized for a particular magnification and working distance, so having to refocus a lot is pushing the optics out of spec. You really want to be able to get the camera in focus at the same time as the eyepieces. Could you show us how it's hooked up?
rpsfam1 wrote:
Fri Jan 01, 2021 2:15 pm
I also recall reading some where that there is an important correlation between the n.a. of an objective and the eyepiece used with it. They said that a "mismatch" between the 2 is the main reason reason why an image viewed with a 10x eyepiece and a 100x oil objective will be better than the same object viewed with a 25x eyepiece and a 40x non-oil objective, even though they will be at the same magnification.
That's not as technical as it seems, that's just a matter of resolution. A 40x dry objective will have a significantly lower numerical aperture (which caps resolution) vs a 100x oil objective. The eyepiece can't increase the resolution of the image given to it--you can certainly blow it up with a higher power eyepiece but it's the same as zooming in on a digital image. It's a similar issue, since the field of view you get with a 1/2" sensor camera with no reducer is similar to what you'd get with 25x eyepieces.

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