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Microscope Photography --- What's a 'T Mount"?

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A T-mount is a standard lens mount for cameras and other optical instruments. Depending on the camera and the instrument (microscope in your case) you will have a different specification. The T-Mount, on one side attaches to the camera (M42, SA bayonet, etc), and on the other end, to the instrument, replacing the eyepiece (providing the eyepiece is removable).

Edmund Scientific; B&H; Adorama, etc sell adapters or T-Mounts. Relatively easy to find for Nikon and Canon, not so for Sigma.

If you want to use your Sigma, I would get an adapter (SA bayonet to M-42) and then a T-Mount (M-42 to whatever the diameter of the eyepiece is).

If you find the right combination I am pretty sure you will be able to use your Sigma.

Good Luck

PD if you google T-Mount you will see many photos and examples.
 
Hello

In case of use I used a Sigma SD14 for some time on a microscope and shared the experiences at article below (compared to a Nikon D5000). This shows a typical T2 mount setup with camera directly coupled to a Zeiss research microscope using a T2 photomicro adapter off eBay to couple to vertical photo tube on microscope.

Some microscopists prefer to independently support an SLR camera from the scope to avoid vibration but can depend on the type of scope, shutter range and objective mags as to whether vibration is likely. The Sigma's mirror lock will help reduce this.

The Sigma photomicrography workflow wasn't as straightforward as with a DSLR with Live View and remote control and/or tethering but very capable of good results.

As an aside the most serious vibration I've experienced for photomicroscopy is with mirrorless cameras not digital SLRs, they can give a real old kick to even a large research scope despite their lack of mirror. I believe it may be because they start with open shutter, so there's a shut/open cycle at start of exposure.

regards
Dave

http://www.microscopy-uk.org.uk/mag/artaug10/dw-sigma.html
 
William,

I bought a t-mount adapter for a zeiss microscope and konica camera back in the 80's. I don't remember that it was the same as the t-mount lens adapters you can get for some older generic lenses. It was essentially like a macro extension spacer, with one side that mounts to your camera, and the other than will fit in the eye-piece holder of the microscope. If I remember correctly, I put the microscope eye piece inside the adapter as well. So I guess you need the microscope t-mount adapter with some camera mount that you can adapt to fit on the sigma (which is where m42 would be a logical choice - or a pentax k-mount should also work, but your focus would be off, if it works the same way the pentax lenses work on the sigma mount.

Good luck - I really enjoyed photographing through a microscope - it opens up new worlds!
-John
--
http://www.johnlindroth.com/
[email protected]

My future starts when I wake up every morning ...
Every day I find something creative to do with my life.
--Miles Davis
 
rick decker said:
What about for astronomical photography - in my case, shooting the moon mainly as I have a 10" Dobsonian reflector with a 2 inch helical focuser.
Click to expand...
I have an 8" Cat with a 1.25" focuser. My old Pentax T-mount worked okay (a little loose) with this rig and the SD mount Sigma cameras.

Some Dobsonians have the prime focus too close to the tube to allow for the additional length of the T-mount and registration distance of the camera and so are effectively eyepiece only rigs. Conversely, some Dobs have a removable extension tube and eyepiece holder, these are designed to work with a T-mount and camera for prime focus astrophotography.

Incidentally, the "eyepiece only" Dobs can be used for eyepiece projection photography using an eyepiece and the proper adapters. Eyepiece projection astrophotography is comparable to using a tele-converter with a camera lens. It can give much more magnification but at the expense of longer exposure times and some image degradation.

-Jerry
 
T2 is a M42 thread with a 0.75mm pitch & used in many optical systems, astronomy & microscopy etc.
The M42 is a M42 thread with a 1.0mm pitch & used in camera lens systems.
They both are the same diameter M42 but don't match together !

For connecting your Sigma camera to the microscope or telescope systems you need the T2 to Pentax adapter http://www.ebay.com.au/itm/T2-T-Mount-Mirror-Telephoto-Lens-Pentax-PK-K-DSLR-SLR-Camera-Ring-Adapter-/320845288651?pt=AU_Lenses&hash=item4ab3de94cb

It has an adjustable inner ring that allows the camera to be rotated to align with the optics.
Cheers
Col
 
Thanks, Dave, for the extremely valuable article. I have just started doing this and it isn't that easy. First, is finding a microscope to camera adapter that will fit the microscope eye tube (What you have after removing the eyepiece, which may be held in by a set screw).

My school microscope has a 25mm inside diameter eye tube. Not everything fits. Finally, got an old manual era Minolta microscope adapter to work, and the eyepiece will drop back inside the adapter. But old school camera company microscope adapters were longer than many sold today. You may not be able to focus at every eyepiece/objective combination.

I plan on investing in a 20x plan objective, which is the most corrected. If you buy adapters off eBay, be sure there is a return privilege—and good luck. Besides Edmund, there is a place called Surplus Shed to look at. Maybe, all I needed was a T2 microscope adapter that would drop into the eye tube???
 
Dave Walker 56 said:
Hello

In case of use I used a Sigma SD14 for some time on a microscope and shared the experiences at article below (compared to a Nikon D5000). This shows a typical T2 mount setup with camera directly coupled to a Zeiss research microscope using a T2 photomicro adapter off eBay to couple to vertical photo tube on microscope.

Some microscopists prefer to independently support an SLR camera from the scope to avoid vibration but can depend on the type of scope, shutter range and objective mags as to whether vibration is likely. The Sigma's mirror lock will help reduce this.

The Sigma photomicrography workflow wasn't as straightforward as with a DSLR with Live View and remote control and/or tethering but very capable of good results.

As an aside the most serious vibration I've experienced for photomicroscopy is with mirrorless cameras not digital SLRs, they can give a real old kick to even a large research scope despite their lack of mirror. I believe it may be because they start with open shutter, so there's a shut/open cycle at start of exposure.
Click to expand...
That shut-open cycle does not occur in Sony's NEX cameras. The shutter is used only to end the exposure.

But I would still prefer the camera to be on a stand and not in physical contact with the microscope. Use extension tubes.
 
Yes, some have suggest using a camera stand because of camera vibration, but some have stated much, if not all, of that can be eliminated by using mirror lock-up. (Perhaps is't a good thing that I don't have mirror-less cameras! ;) ) Regardless, I'll be getting a trinocular microscope.)
--
William Wilgus
 
Mostly Lurking said:
I may have to get into microscopy and trying to learn if there's some way I can use my Sigma dSLR's for the photgraphic work.
Click to expand...
Yes, there is.

The best way, when using a "high vibration" camera like the Sigma, is what has come to be know as the "Charles Krebs" method, mount the camera on a sturdy stand behind the camera, lower a black lined shroud over the scope's draw tube (aka "photo tube" or "photo port") and do not let the camera or shroud actually touch the microscope .

http://micropix.home.comcast.net/~micropix/microsetup/index.html

http://www.krebsmicro.com/microsetup2/index.html

In those tutorials, Charles uses a $200 bellows as the "shroud", but I made one from a length of PVC tubing and black flock paper for a cost of about $15.

Check out some of the other tutorials on his site, and his galleries. Charles Kreb has multiple Nikon and Olympus microscopy awards, he knows his way around a scope.

http://www.krebsmicro.com/

Make sure your scope has a photo projection eyepiece mounted in the draw tube already. They tend to disappear. If it doesn't, that's going to be your biggest cash outlay for this, $50-200 for the common 4x, $300-500 for the 2.5x or 1.7x that would work better with an APS or sub-APS Sigma.

Oh, and incidentally, the "T" mount is the "Tamron" universal mount, although several other lens makers in the 60s and 70s copied it. There were three versions, then came T4, the "Adaptall" bayonet.

--
Rahon Klavanian 1912-2008.

Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.

Ciao! Joseph

http://www.swissarmyfork.com
 
Mostly Lurking said:
I thought about doing something like that.
Click to expand...
It's the next best thing to a "vibration free" system, like the temperamental leaf shutter unit that sits between my scope and camera (my scope is a Nikon Optiphot-88, the leaf shutter is a Nikon UF-X), or using a vibration free camera, like a Canon 5D II or Sony NEX 7 on a T-mount.

Oh, and I made a minor error in my earlier post. The 2.5x photo eyepieces are relatively affordable. I checked my notes: I paid $120 for mine. 4x and 10x are dirt cheap, but skip them, all they do is give you a ton of empty magnification. They were made for medium format and large format work. No one does large format on a scope, anymore. It's the 2X Nikon or the 1.67x Oly that will kill you. I don't know Leica scopes well enough to make recommendations there.

--
Rahon Klavanian 1912-2008.

Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.

Ciao! Joseph

http://www.swissarmyfork.com
 
Mostly Lurking said:
Thanks for the additional info.
Click to expand...
You're very welcome.
Mostly Lurking said:
I'll need a 10X as I'll need 1,000X over-all.
Click to expand...
You can't really get it, at least in any way that's meaningful.

You can get 1000x to the eye, in a fashion, because the eye doesn't have as big a "field" as the camera, and it processes information a lot better.

The fastest 100x microscope objectives have a "numerical aperture" of 1.40, which is about f0.5 (yes, that's not impossible in wet microscopy). That's a resolution of 0.2 microns on the subject.

You can see this on the resolution calculator

http://www.microscopyu.com/tutorials/java/digitalimaging/pixelcalculator/index.html

Use the "objective magnification" and "numerical aperture" sliders, set the "video coupler magnification" to 1, because it can't go any higher, and read the "optical resolution" and "required pixel size" results. The pixel size is output as monochrome, not Bayer, so it's directly applicable to Foveon cameras. As you can see, the best you can do with the fastest wet 100x is
  • 0.2um on the subject. That is half a wavelength of visible light, you can't go below that without going to UV microscopy, which explains why no one tries to make wet objectives above NA 1.4. There literally isn't anything to see beyond 0.2um
  • 10um on the sensor. We halve the subject resolution, assuming that a subject "detail" is a "transition" from light to dark or vise verse, and needs two pixels to pick it up, so, the 100x objective mag * 0.2um / 2 = 10um.
I seem to recall you shooting an SD-14. That has 7.8um pixels, already smaller than the highest resolution of the best 100x objective.
  • Now, if you have a 10x projection eyepiece, that expands the smallest detail that the best 100x objective can resolve all the way up to 100um. It will cover 12 pixels on the Foveon sensor. We call that "empty magnification". All you're doing is magnifying blur, and making "bigger blur". I won't get into Foveon vs. Bayer "pixel sharpness", because with the camera's resolution 12x higher than the scopes, you're simply overpowering the objective, no matter what sensor you use.
That's why the 10x projection eyepieces were only used for 4x5 large format and for Polaroids. Those formats gave you images in 10 minutes (for a 4x5 negative, rushed through the lab) or 2 minutes (Polaroid), which was useful in a lab setting, but has no artistic merit, because the resolution is so bloody low.

You can get exactly the same empty magnification effect by taking the image from the 2.5x eyepiece and scaling it up. At 2.5x, you're still spreading the smallest detail the scope can resolve across 3 pixels, so you're getting all the dynamic range advantages of overmagnifying, but your resolution isn't totally out-of-control.

The 2.5x photo eyepiece will make your camera so much easier to handle on the scope.
  • It makes the view in the scope's 10x eyepieces more similar to the camera's view, so the shot is easier to compose. With 10x in the viewing eyepieces, you're seeing pretty much all the scope's 20mm "field" with your eyes (scope fields range from 16mm to 25mm, but we'll just call it 20mm for discussion) and with a 2.5x photo eyepiece, you're taking that up to about 50mm, and your camera's diagonal is 25mm, so you can visualize a rectangle with a diagonal half the diameter of the circle you see in the scope's eyepieces when you compose. 10x would mean the rectangle you have to "hit" is only 1/8 the size of the eye view.
  • It makes the view in the camera's finder 16x (four full stops) brighter. That helps with final focusing and composition. You would not believe how dim the view through a 10x projection eyepiece is on a low-end DLSR, not fitted with a semi-transparent "aerial image" microscope focusing screen. Even the 2.5x isn't all that bright or easy to see.
We have a saying in microscopy: "physics bites".

Seriously, if you know someone with a scope already, get them to show you.

--
Rahon Klavanian 1912-2008.

Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.

Ciao! Joseph

http://www.swissarmyfork.com
 
Joseph S Wisniewski said:
You can get exactly the same empty magnification effect by taking the image from the 2.5x eyepiece and scaling it up. At 2.5x, you're still spreading the smallest detail the scope can resolve across 3 pixels, so you're getting all the dynamic range advantages of overmagnifying, but your resolution isn't totally out-of-control.

The 2.5x photo eyepiece will make your camera so much easier to handle on the scope.
  • It makes the view in the scope's 10x eyepieces more similar to the camera's view, so the shot is easier to compose. With 10x in the viewing eyepieces, you're seeing pretty much all the scope's 20mm "field" with your eyes (scope fields range from 16mm to 25mm, but we'll just call it 20mm for discussion) and with a 2.5x photo eyepiece, you're taking that up to about 50mm, and your camera's diagonal is 25mm, so you can visualize a rectangle with a diagonal half the diameter of the circle you see in the scope's eyepieces when you compose. 10x would mean the rectangle you have to "hit" is only 1/8 the size of the eye view.
Click to expand...
If you want to get an idea of what this looks like, go back to the resolution calculator site, and set the sliders like this:
  • objective magnification = 100x
  • numerical aperture = 1.4
  • field number = 22mm
  • CCD format = 2/3 inch
  • video coupler magnification = 1
What you see on the center display is a rectangle with an 11mm diagonal in a field of 22mm. The circular image is what you see through the scope eyepiece, the rectangle is the picture you get with your DSLR. With the rectangle 0.5x the field size, it's pretty easy to work the scope. And again, that's about what you get from an APS DSLR on a 2.5x photo eyepiece.

Now change
  • field number = 26mm
  • CCD format = 1/3 inch
That's a 6mm diagonal rectangle in a 26mm field. The rectangle has a diagonal 0.23 of the circle you see looking into the scope's eyepieces. Notice how small the "picture" is compared to what you see. That's hard to visualize and shoot. Even if you had a marked "photo reticule" in the viewing eyepiece, it would be hard.

That's actually the limit of that particular scope simulator. With a 10x projection eyepiece, you're dealing with something even worse. A scope with a 22mm field (the first example) and a 10x projection eyepiece projects a 220mm (10x22mm) circle, and the picture is a 25mm diagonal rectangle cut out of that.

Aside from how much light this wastes, you have a rectangle that's 0.11 of the eyepiece image. Try to picture a rectangle less than half the size of the one we just simulated.

--
Rahon Klavanian 1912-2008.

Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.

Ciao! Joseph

http://www.swissarmyfork.com
 
Thanks for helping me out again. While most of what you wrote went way above my comprehension, I gathered the following:

When viewing with my eyes through the eyepieces, a 100X objective lens with 10X eyepiece lenses will work just fine, but when using a camera, the strongest lens I would want to use (in the trinocular port) would be a 2.5X lens and I'd be just as well off---if not better off---to use no lens at all.

Do I have at least that part right?

By the way, if I haven't mentioned it, I would be using it to look at bacteria, etc. from water and sewer plants.
--
William Wilgus
 
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