Microscope Photo Accessories

When Lukey and I were using the microscope a week or so ago, I noticed a few nagging problems that needed to be resolved before I attempted another microscopy session and especially a session that included photography and/or videography.  I spent the past week or so trying to resolve these problems and thought it would be best to document it all here.

My first problem was that what I was seeing on my camera (and on the 32" monitor connected to my camera) was not nearly as crisp as what I was seeing visually in the binocular eyepieces.  This was really frustrating.  I had been using my Sony a6000 camera in a prime focus configuration.  Prime focus imaging involves no additional lenses including eyepieces.  This type of imaging works very well in astronomy but I was not liking what I was getting in microscopy.  The images and video were very soft, sort of mushy, un-crisp.  They looked really terrible on the 32 inch monitor.

The next problem was figuring out what I actually needed to fix this problem.  There really is very little information online about microscope adapters in general.  There seems to be even less information online about photography adapters for microscopes.  I couldn't find the information I needed even years ago when I first started looking for options.  Over the years, I would occasionally search again and again, finding nothing useful.  I would find a general statement here or there in forums but this wasn't helping me in the least.  The bulk of videos on YouTube seemed more geared toward purchasing a dedicated microscope camera.  I already have a dedicated microscope camera (designed specifically for microscope use) and I have experienced even more problems with that camera than with my everyday Sony cameras so I wasn't ready to go that route just yet (with a far better microscope camera).  

I even searched through a few online retail stores that carry microscope adapters but the number of available products and information was severely lacking.  The product descriptions didn't address the purpose of the particular adapter.  The product descriptions didn't specify thread sizes and thread pitches.  And, I quickly noticed that there really are very few adapters available for microscopy especially when compared to astronomy.  

I was also a bit confused about the spacing that would be needed between the microscope and the camera.  I was pretty sure I would need to figure this out simply by trial and error because this can vary from one microscope to the next and from one camera to the next.  What the best distance is was information that was elusive though.  Common sense was telling me that I would need a way to adapt the total length of these adapters and extension tubes easily in case I wanted to use different microscopes or different cameras so, at the moment, I wasn't all that concerned about a finite distance if I was going to adapt for variable distance.

So, first I needed to figure out if maybe my choice of camera was causing the problem of a kind of mushy view on my monitor.  I tried other cameras with different sensors...  four-thirds sensors, 1/2" sensors, 1/1.8" sensors, dedicated microscope cameras, dedicated astronomy cameras...  I found that my Sony a6000 with its APS-C sized sensor was the best camera of everything I had on hand and evaluated.  So, how could I make my view sharper?  At least I felt that I had ruled out that the camera was the problem. 

Since my views through my eyepieces were noticeably crisper than what I was seeing on my camera, I decided that I should try imaging through a microscope eyepiece in between the camera and the microscope rather than prime imaging with no eyepiece or lens.  Any photographic adapters would be placed on the trinocular port of my microscope.  This was another issue I found...  different microscopes have different thread sizes for the trinocular port and I have no idea what any of these thread sizes are nor could I find any information online.  

I had a few adapters on hand already because I had already tried a cheap Celestron microscope camera as well as my astronomy cameras.  So this got me started in the right direction.  An adapter that came with a 0.5x lens assembly I had previously purchased to use with these small-sensored microscope and astronomy cameras (around the 1/2" sensor size) actually fit my microscope perfectly so that is the first part I decided to use.  Smaller sensors significantly magnify the views so a reducing lens of 0.5x was needed for the smaller sensors.  It turns out that there were all sorts of other issues with these smaller sensors too just like in regular photography so I abandoned that option rather quickly but the supplied adapter connection to the microscope would be my starting point.  

The adapter that came with the microscope camera was made specifically for my brand of microscope so that was good news.  This adapter was actually in two parts.  One part threads into my microscope and then an adapter slides into that to make a nice 23.2mm eyepiece holder.  My microscope uses 23.2mm eyepieces which is a whole other issue I've overcome in the recent past.  This was the same adapter combo I was using for my Sony a6000 when having it arranged in the less-than-impressive prime focus configuration so I knew I could start with that.  I now needed to figure out how I was going to stick a microscope eyepiece in-between this two piece adapter and my camera.

I have an eyepiece projection adapter for astronomy but the overall sizing and spacing is larger in astronomy than what my microscope needs.  I figured that maybe a similar eyepiece projection adapter would be available for microscopy.  Unfortunately, I couldn't find one so this meant I would need to figure out how to adapt my astronomy eyepiece projection adapter to use on my microscope.  (More on that later, below.)

I would also need a way to adjust the spacing between the microscope and the dedicated microscope eyepiece as well as the spacing between this dedicated eyepiece for photography and the camera.  The astronomy eyepiece projection adapter provides some adjustment in length but it was already starting out being too long even adjusted to its shortest length.  If I could find a way to shorten it while still allowing length adjustments, I could make it work.  I still needed to figure out the spacing between the microscope and the eyepiece used for photography so that the camera and the microscope eyepieces on my binocular head were focused at the same time (parfocal).  I didn't want to have to refocus whenever I went from observing through the binocular eyepieces and photographing with the camera which would be mounted on the trinocular port.  So, I went searching for "adjustable extension tubes".  

Fortunately, during my extended and thorough online searches, I stumbled upon a helical m42 extension tube on Amazon!  This would definitely work!  This helical extension tube would allow a very easy way of focusing the camera so it would be parfocal with the binocular eyepieces.  It is available in different length ranges so I needed to choose the best minimum and maximum length for my particular situation.  When I figured out the best range, I ordered the part.  

It was time to work on somehow shortening my astronomy eyepiece projection adapter.  The first thing that was limiting me from shortening this adapter in adjustment was the inside tube.  This tube was too long.  I took a hacksaw to it and cut about an inch of length off it.  Now it was a better length but I noticed that one of the thumbscrews was now blocking the adapter from collapsing to a shorter length.  The outside tube was now jamming against this thumbscrew.  I decided to make a notch in the outside tube to allow the outside tube to collapse down and around the thumbscrew that was in the way (see photos below).  First I punched a divot so I could easily drill a hole for the rounded top of the notch.  Then I pulled out my Dremel tool with a cutting wheel and cut my notch.  Now this eyepiece projection adapter could be adjusted to an appropriate minimum length but which would also add some control to magnification as I expanded the adapter.

Previously, I had been using the in-camera "Clear Image Zoom" function to handle proper magnification (to eliminate vignetting).  This Sony implementation of Clear Image Zoom is actually excellent but I wanted to eliminate all possibilities of anything that could soften my images.  This is why I chose to handle magnification by expanding or contracting the eyepiece projection adapter instead of using the Clear Image Zoom function of the camera.  Handling magnification in this way was just like moving a projector farther from the screen...  the image gets larger.   

Now I planned to put an eyepiece in-between my camera and the microscope.  I have some old eyepieces that didn't work so well for me when using them visually.  They were wide field which is good...  they were 10x magnification which is a good magnification...  and, honestly, they are just as sharp as my current eyepieces (the blue eyepieces in the top photo) but they were difficult to use with eyeglasses and uncomfortable to use.  I need a lot of eye relief because of my eyeglasses plus I prefer a large top eye lens.  I find smaller top eye lenses like looking through a straw.  My old 10x eyepieces didn't have enough eye relief and they were only about 2/3 the diameter of my new (blue) eyepieces.  The sharpness through these older eyepieces was fine but the lack of eye relief and the smaller size rendered them useless for me visually.  I decided that one of these two 10x eyepieces would be my donor eyepiece to secure inside the eyepiece projection adapter.  The good news here is that I didn't need to go on another search for eyepieces nor would I have to spend any money on another new eyepiece.  I already had one that would work for this project.  The donor eyepiece is a WF10x 18mm eyepiece with a 23.4mm mounting nosepiece.  

Microscope eyepieces, especially the ones used in my microscope (23.2mm), are smaller than astronomy eyepieces.  This meant that my 10x donor eyepiece that I planned to use in this photographic setup needed to be adapted to fit perfectly into my astronomy eyepiece projection adapter.  If I just used the single thumbscrew to mount this small eyepiece in the eyepiece projection adapter, it would be very off-center.  If the eyepiece is off-center, then my views would be compromised and I would end up with images that are blurry on one side (most likely).  It turns out that I had the perfect thickness of styrene that I use for building model railroad structures on hand already.  I cut a small piece of styrene to wrap around the eyepiece to use as a centering spacer.  This fit was so perfect that I actually could have gotten away with no thumbscrew to hold it in place!  I still set the thumbscrew firmly against the eyepiece so it has no way to slipping out or moving inside this adapter.  

At this point, I had my whole photography adapter assembled and ready for imaging.  This new configuration with the widefield 10x microscope eyepiece in the optical train was working just great!  It required a lot of trial and error but the results are very nice.  I decided to document it here in this blog for two reasons.  First, I would need some sort of documentation to refer to whenever I wanted to image my microscopy sessions again otherwise I would likely forget how I set it up.  The other reason for documenting it here in this blog is so others can see what I did and adapt it to their own microscopes and cameras.  

I photographed this entire adapted imaging train and numbered each part as an exploded view.  (See photo below.) 

Part #1:  This is the part that screws into the trinocular port of the microscope.  From what little I have been able to find online, the exact size of this port will vary from microscope to microscope so you'll need to figure out your own thread sizes for your own needs.  This part that I obtained has a locking ring that I can snug down to the microscope housing so that this part is firmly secure when threaded into the microscope trinocular port.  The thread is long enough that some length can be varied on this end of the optical train.  The opening at the top of this part is 23mm so my 23.2mm eyepiece nosepiece does not fit directly into this part.  Adapting the opening of Part #1 is the main purpose of Part #2.

Part #2:  This part has a 23mm nosepiece to fit snugly into Part #1 and converts to a 23.2mm opening to accept standard 23.2mm eyepiece nosepieces.  This part also extended the total length of my Part #1 which is good because I needed some extra length here between the eyepiece and the microscope.  The 23.2mm eyepiece holder has three set screws.  Having three thumbscrews around the circumference of the eyepiece holder allows you to secure connections while keeping parts centered.  

Part #3:  This part is a standard 23.2mm nosepiece with an m42 thread on the other end.  The 23.4mm end fits into the eyepiece adapter (Part #2) and the m42 male threads connect to the bottom of the helical extension tube (Part #4).  

Part #4:  This part is a helical m42 (female) to m42 (male) extension tube.  My tube has a range of 15mm to 26mm by turning the helical ring.  This range works for me but other microscopes and other eyepieces might require a different range of length.  This part is available on Amazon in different lengths.  I suspect most photography stores would stock this part too (ie, B&H Photo).

Part #5:  This part is the adapted astronomy eyepiece projection adapter.  The bottom of this adapter has a female m42 thread and the top of this adapter has a male m42 thread.

Part #6:  This part is a standard T-ring (shown mounted on my camera).  My T-ring fits my Sony e-mount camera but T-rings are available for many different camera mounts.  The T-ring has a female m42 thread on one side and the e-mount on the other.  Worth noting is that T-rings are also available with an m48 thread.  In this situation, I needed an m42 thread.

In the following photo, you can see the WF10x 18mm microscope eyepiece mounted inside the bottom of the eyepiece projection adapter.  Also worth noting is that this eyepiece is perfectly centered in the adapter after using my improvised styrene centering ring that I mentioned above. 

The following photo is a closer view of the adaptations I made to the astronomy eyepiece projection adapter.  

First, I disassembled the adapter so I could cut an inch off the inside tube of the adapter.  The length of the inside tube was limiting how much I could collapse this adapter to a shorter length so I needed to cut off some of this length.  The bottom end of this adapter is threaded (m42) but the top end is not threaded so I cut an inch off the top of the adapter.  

This photo also shows the notch I cut into the outside tube so that the tube can collapse down shorter without being stopped by the eyepiece thumbscrew.  This thumbscrew holds the eyepiece securely in place inside this adapter.  Now the bottom end of the outside tube can slide down below this thumbscrew making the total length of this adapter much shorter.  

Expanding the length of this eyepiece projection adapter will increase the magnification.  Conversely, contracting its length will reduce the magnification.  I contracted this adapter enough so that I no longer see dark vignetted corners.  Also, within reason, I can increase magnification if I want without having to change objectives as well as any other accessories I may be using simply by expanding the length of this eyepiece projection adapter.  That is a nice option to have available.   

I have a lot of different gradient universal filters, darkfield stops, colored filters and oblique filters.  Trying to figure out which ones work best on my microscope can be frustrating so the next photo shows the filters and stops I have found most useful for providing added contrast, providing darkfield illumination, and deflecting light for oblique illumination.  The different color stops provide alternate colors for the background.  The colored filters enhance the overall color.  

This next photo is a sample image using this photographic setup on my microscope.  This specimen is table salt at 200x (20x objective and a 10x eyepiece in the eyepiece projection adapter = 200x magnification).  Table salt isn't a great specimen to evaluate sharpness across the frame because each grain of salt has a different height.  Different heights focus at different settings of the focus knob so you can never get the whole frame perfectly in focus.  For this sample photo, I chose to focus on the one grain of salt right in the middle of the frame.  Because of the 3d depth to table salt and because it is crystalized, it is a good specimen to demonstrate different illumination techniques.

For this photo, I used a blue filter stop in the condenser and a deep blue glass filter placed on top of the bottom light lens.  I inserted the larger gradient universal filter in the filter drawer as well.  This gradient universal filter just slides in between the filter holder and the condenser and then I slide it in and out and side to side to get the type of effect I find most pleasing.

The following photo shows why having different colored stops on these filters can be useful.  This is the same table salt specimen except that I used a yellow stop and the smaller gradient universal filter.  This time I opted to use no color filter on the lighting lens.  The background color is coming from the yellow stop filter.  The background brightness is controlled by the gradient universal filter.  

Overall, I am now very happy with this microscopy photographic setup.  It required a lot of research, a lot of adaptation of parts and a lot of trial and error but things are looking good now.  

If I ever forget how to set this up, I can always come back to this blog entry.  Hopefully, other people will stumble upon this blog entry if they are searching for ways to connect their camera to their microscope.  As I said at the beginning of this blog entry, there isn't nearly enough information online about this sort of stuff so having this info available here should be useful for at least a few people.

Next, I'll need to write another blog entry detailing and documenting how to use my microscope with polarized illumination.  

POST EDIT - 6 May 2022:  Late last night, I had the bright idea to try using a couple of my astronomy eyepieces in the eyepiece projection adapter rather than using a microscope eyepiece.  It was too late to start messing with that project last night so I started on this little project this morning.  

A 24mm or 25mm astronomy eyepiece will provide approximately the same 10x magnification that my microscope eyepiece provides so I tried the two astronomy eyepieces that I have that match that focal length range.  

First was a 25mm Plossl...  I disassembled my eyepiece projection adapter...  then installed the 25mm Plossl into it...  reassembled...  not bad.   I'd say it was about equal to the microscope eyepiece.  

Next, I tried my Baader Hyperion 24mm eyepiece.  This is a pretty nice astronomy eyepiece and it even has threads on it for eyepiece projection.  Since it already had threads on it for eyepiece projection, there was no need for the eyepiece projection adapter.  This big eyepiece wouldn't fit into the eyepiece projection adapter anyway!  I simply screwed the appropriate adapter rings and extension tubes directly to the eyepiece.  I slipped it into my microscope...  turned it on...  again, the view was nice but it was no better than using my microscope eyepiece.  

I then reassembled everything to the way it was described in this blog entry above.  The WF10x 18mm microscope eyepiece is just fine for this purpose so I'll continue using that for now.  

It is worth noting, however, that it might be best to find a microscope correcting eyepiece to use instead of the standard microscope eyepiece.  Right now, I'm not seeing a need for a correcting eyepiece but sometime down the road I might find a situation where the correcting eyepiece would improve the view.  For now, however, I'll stick with what I have on hand as described above.