Microscope photography question

GaryB · Post by **GaryB** » Fri Apr 21, 2017 10:47 pm

I'm trying to figure out why the only consistently decent photos I get are when I take the head off my zeiss and hang the camera body directly over the image plane with no lens. I've tried taking photos with/without lens, with/without eyepiece, different settings, cameras etc. yet nothing comes close to using no lens, no eyepiece and no head. Just objective > sensor, and the pics come out just as I normally see things through the eyepieces.

I can get great pics at 1\1600th second at iso 200 with no problems apart from the fact it's a clumsy and inconvenient way to take pics, especially if I go onto stacking. Is there something amiss here or should I just go ahead and make an adapter to do it properly so my sensor can be fixed at 160mm? Everyone else seems to manage fine with regular setups so I'm guessing I'm doing something wrong, not entirely unusual with me

zzffnn · Post by **zzffnn** » Sat Apr 22, 2017 6:58 am

Do you know if vibration and amount of light play roles in your case? You can try some comparisons, using long exposure, for example.

GaryB · Post by **GaryB** » Sat Apr 22, 2017 10:58 am

Hi Fan,

yeah, with the normal setup I had the camera mounted on a stand with a small space from the eyepiece and took exposures from 1\250 up to 2 seconds. It seems the quality appears to drop just going through all the optics. It's not blurry with vibration, there's a lack of contrast, definition.. I don't know, they just don't look good.

zzffnn · Post by **zzffnn** » Sat Apr 22, 2017 11:22 am

Another possibility is that the lenses you have in between objective and sensor magnifies too much, for your sensor size. Or they add optical distortion (which should not happen with well matched optics).

As you know, lenses will reduce light throughput, but longer exposure or more light should take care of that.

75RR · Post by **75RR** » Sat Apr 22, 2017 12:32 pm

What setup do you have? Can you post some photos?

Olympusman · Post by **Olympusman** » Sat Apr 22, 2017 2:25 pm

A couple of possibilities:
The eyepiece you are using may not be a photo grade eyepiece. I have many 10x eyepieces and a set of Olympus NFK photo eyepieces. I tested all of my 10X eyepieces and an unlikely candidate that provided the best image was a non-photo copy.
You may have to mount a relay lens between the eyepiece and the camera body. On one of my scopes I am using a 50mm Olympus OM lens as a relay lens and it is doing a fine job. However, on my hybrid polarization setup, I am projecting the image straight to the sensor with an Olympus NFK and no relay lens.
Some of us have piles of optics laying around our labs, so we have the opportunities to test various setups. Sometimes the most unlikeloy combinatiojns yield the best results.

Mike

GaryB · Post by **GaryB** » Sat Apr 22, 2017 2:42 pm

it's a bog standard Zeiss standard 14 and an old Nikon D40, nothing complex. I use a 50mm f1.8 lens on the camera. I also have a 23mm adapter that slips into the eyepiece socket. Eyepices.. 10-18 Cpl and Kpl.

I've done the afocal thing with the eyepiece set at '0' and lens to infinity, placing the camera over the eyepiece (no camera lens), remove lens and eyepiece and just use the eyepiece adapter. None seems to work very well.

As a contingency in case I don't find a solution I drew up plans to make an adapter. This works out to objective shoulder to head plate =40mm, new adapter shoulder to top =55mm, camera plus 23mm adapter =65mm for a total of 160mm from objective shoulder to sensor plane. I can make it from black engineered plastics and I've built in some height adjustability.

Is there an advantage to using an eyepiece (corrections) or would the adapter work fine as-is? I can modify things to suit and it's not like I can use the camera and eyepiece at the same time as things are, also, no live view.

zzffnn · Post by **zzffnn** » Sat Apr 22, 2017 2:56 pm

Your Nikon D40 has crop factor of about 1.5 and your Zeiss objectives use kpl eyepiece for correction. So in theory, your afocal method (camera - 50mm lens - Zeiss Kpl eyepiece - Zeiss objective) has the correct settings and should work the best. Are you sure direct project produce better images?

Edit:
How did you judge image quality? Sometimes we tend to favor brighter image, even though it may have more optical distortion. You cannot use the same camera exposure setting and compare afocal vs direct projection, as afocal image will be darker.

GaryB · Post by **GaryB** » Sat Apr 22, 2017 4:05 pm

I adjust the exposure to keep the images lit about the same. The afocal method works, the images just look bland or a bit washed out and are incredibly difficult to focus properly. The direct method has more contrast and definition. Sharpness is generally about getting that focus right on, when it's right, both are similarly sharp. Subjectively, the direct pics look better, they look like what I see when using the scope, the afocal method always looks worse. Which method is objectively better is hard to say. Doing an exact 'like for like' is problematic at best given how much changes between the two very different setups.

zzffnn · Post by **zzffnn** » Sat Apr 22, 2017 5:33 pm

GaryB wrote:I adjust the exposure to keep the images lit about the same. The afocal method works, the images just look bland or a bit washed out and are incredibly difficult to focus properly. The direct method has more contrast and definition. Sharpness is generally about getting that focus right on, when it's right, both are similarly sharp. Subjectively, the direct pics look better, they look like what I see when using the scope, the afocal method always looks worse. Which method is objectively better is hard to say. Doing an exact 'like for like' is problematic at best given how much changes between the two very different setups.

Sometimes when you are used to seeing images made by achromat objectives (which seem to provide more contrast but actually more chromatic aberration, compared to apo objectives), better corrected images will look bland or "lack contrast". If you zoom in onto those " high contrast" achromat images, you will see some fake edge contrast is actually dark purple CA. Camera also mistakes those dark CA as real contrast and "focuses better".

I thought that way a few years ago, until I get used to cleaner "bland" apo images. Then I went back to my achromat objective and found those purple CAs very quickly.

Directly projection is easier to focus, because it takes away less light, compared to afocal method. I suggest focusing afocal camera lens to infinity, then manually turn microscope fine focus to focus camera image. Most auto lens focusing does not work well under microscope light.

GaryB · Post by **GaryB** » Sun Apr 23, 2017 4:08 am

zzffnn wrote:

Sometimes when you are used to seeing images made by achromat objectives (which seem to provide more contrast but actually more chromatic aberration, compared to apo objectives), better corrected images will look bland or "lack contrast". If you zoom in onto those " high contrast" achromat images, you will see some fake edge contrast is actually dark purple CA. Camera also mistakes those dark CA as real contrast and "focuses better".

I thought that way a few years ago, until I get used to cleaner "bland" apo images. Then I went back to my achromat objective and found those purple CAs very quickly.

Directly projection is easier to focus, because it takes away less light, compared to afocal method. I suggest focusing afocal camera lens to infinity, then manually turn microscope fine focus to focus camera image. Most auto lens focusing does not work well under microscope light.

That could all be true, and it does make sense. I really need to get an apo to play with. The main problem with focusing afocal is that the camera viewfinder on the D40 is totally rubbish. It's small, dim and very hard to get right because the screen is made of concentric rings that are all but useless without large amounts of light, hard to achieve with polarized COL and oblique. Brightfield is fine but I rarely use it like that.

I'll certainly give it a few more tries and see if I can improve things. I guess a trinocular head would help, but like Apo's, out of reach for now.

Thanks for the info and advice

zzffnn · Post by **zzffnn** » Sun Apr 23, 2017 5:40 am

For Zeiss, you may be able to get a beam splitting teaching prism and add a mono head just for afocal camera. That way, two visual eyepieces are usually tightly parfocal - when it is sharp to eyes, it must be sharp to camera.

Ichthyophthirius · Post by **Ichthyophthirius** » Sun Apr 23, 2017 2:03 pm

zzffnn wrote:For Zeiss, you may be able to get a beam splitting teaching prism

Yeah, that's what it looks like. http://www.mikroskopie-forum.de/index.php?topic=9773.0 If you get one cheaply, it's an interesting alternative to a trinocular tube. The black cube is also available in gray.

As we said previously, using a Canon, even the most basic 1000D, allows you LiveView and camera control through a computer. http://www.photomacrography.net/forum/v ... hp?t=33739 It really makes the task so much easier. You can even keep your Nikon camera objective.

Pau · Post by **Pau** » Mon Apr 24, 2017 2:21 am

Gary, could you post images illustrating the difference you're getting between afocal and direct projection? (same subject, illumination, objective...etc to be fair)

I use Zeiss Standards and I always do photomicrography afocally. It works very well. I've tested Zeiss and Leitz objectives for direct projection and the amount of chromatic aberration outside the center is unacceptable (worse on Zeiss).

If you want to do direct projection you need objectives that are designed for use of non compensating eyepieces, and the only well proven ones for 160 microscopes are Nikon CF.

75RR · Post by **75RR** » Tue Apr 25, 2017 2:45 pm

Ichthyophthirius wrote:

Yeah, that's what it looks like. http://www.mikroskopie-forum.de/index.php?topic=9773.0 If you get one cheaply, it's an interesting alternative to a trinocular tube. The black cube is also available in gray.

This is my version of Ichthy's alternative head - It has a 50/50 split.

I have used both projection and afocal. I find both work quite well. Though both have minor issues.
The projection method, when using a raised normal KPL eyepiece does not produce more CA.
I found however that fine tuning the height was more of a pain, particularly since the way I have my camera connected to a tripod means
I have to remove it to change the batteries!
With afocal one has to watch out for flare issues, but setting the camera up after changing the batteries is easier and more importantly
that much more consistent.

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