New microscope and photo problems...

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RobertoM
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Joined: Thu Jul 05, 2007 6:21 am

New microscope and photo problems...

Post by RobertoM »

Hi, today I buy a tronocular microscope, and I connect the Canon 30 D to the adapter tube.
The adapter tube have two magnification (2,5X and 4X)
Only for a little test, I shot this:

Image

But I'm not satisfied, because is not I see that I watch in the ocular...
When I see in the ocular, the image is brillant, clean, this photo is dark, not clean...
Before do a shot, I move the selector for give the image on the photo tube.
What's the mistake?
How can I do for shot better photos?
Thanks in advance
Roberto

Charles Krebs
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Post by Charles Krebs »

Roberto,

Congratulations on your new microscope. Don't worry, it takes some time to get things working as you would like.

Two things come to mind first.

For photography, the tungsten bulb will need to be turned up to near full voltage. You want it to be close to 3200 degrees Kelvin. The camera should be set for "tungsten" white balance. I don't recommend leaving it on "AWB" (auto white balance).

If the bulb is turned down too low, the results will be very "red" and all colors will be off by a large amount. (With some power supplies it is also possible to "overdrive" the bulb, and in that case the results will have a blue color cast).

The picture you have posted here looks too red to me, but obviously I can't see the actual subject.

As for exposure, until you get some more experience you should "bracket" exposures. The camera meter will often be "off" by a constant amount because of the unusual (for the camera!) set-up. Also keep in mind that "brightfield" microscope scenes have a great deal of bright white areas which will often result in the meter giving darker than desired exposure.

Check these things first, and then let us know what problems you might still be having.

Charlie

RobertoM
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Post by RobertoM »

Thanks a lot Charlie, I forget the white balance.. (and leave the set AWB) in this test shot in manual mode (RAW + Jpeg).
I have a question:
If I put the tungsten bulb (50 W) near full voltage, the image is too bright... I must do somethings with the condenser?
Today I try some modifications.
Regards

Roberto.

rjlittlefield
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Post by rjlittlefield »

RobertoM wrote:I must do somethings with the condenser?
Probably not -- most condensers do not have adjustments that will reduce the brightness alone. Adjusting the aperture diaphragm will reduce brightness, but will also reduce resolution.

When the image is too bright to look with your eyes, it is probably still good to photograph -- you will just need a faster shutter speed.

Try turning the brightness up when you move the slider to take a picture, then turn it back down to look again by eye.
Charles Krebs wrote:..."brightfield" microscope scenes have a great deal of bright white areas...
Shooting brightfield is a lot like shooting a snow scene -- lots of white and a little dark. The meter in your camera tries to make the picture gray on average. Bracketing is a good approach. It may also help to set your camera's exposure compensation.

--Rik

RobertoM
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Joined: Thu Jul 05, 2007 6:21 am

Post by RobertoM »

I try to change some parameters to RAW file.
This is the result..

Image

After I try some new test with your suggestion.

When I shot this photo, in the ocular the subject look like made of glass, but in the photo don't look glass...

I think this photo is better than that at the beginning of this post, but is not a good photo.

Roberto

Charles Krebs
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Post by Charles Krebs »

Roberto,
If I put the tungsten bulb (50 W) near full voltage, the image is too bright... I must do somethings with the condenser?
Yes, while you may find the 50W bulb too bright for viewing at full voltage when using brightfield, it will be greatly appreciated when you try other illumination methods where more light is a big help. As Rik said, you can try you get into the habit of viewing at a lower level and then turning it up only for photography. For photography it is best if the bulb is run at proper voltage. If desired you can reduce the light intensity by placing some sort of neutral density filter or film over the light port at the base of the microscope stand.

(BTW.... when you "switch" to take a picture, does all of the light go into the trinocular tube, or can you still see the images through the eyepieces at the same time?)

You don't want to try to vary the illumination"brightness" with the substage condenser!
That setting will determine the contrast and resolution provided by the objective. If you close it down too far in order to reduce the brightness through the eyepieces, you can dramatically decrease the resolution of the image. When starting out, the best way to determine the proper setting for the diaphragm of the substage condenser is to temporarily remove one eyepiece and look down the eyepiece tube at the back of the objective. Then gradually close the condenser diaphragm. While looking down the eyepiece tube, you will begin to see the diaphragm blades come in from the sides. Adjust the condenser diaphragm to the point where it comes in from the sides and "blocks" about 30% of the full aperture area you could see down the tube. It should look something like this:

Image
http://micro.magnet.fsu.edu/primer/java ... index.html

rjlittlefield
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Post by rjlittlefield »

RobertoM wrote:When I shot this photo, in the ocular the subject look like made of glass, but in the photo don't look glass...

I think this photo is better than that at the beginning of this post, but is not a good photo.
Roberto, can you tell us more about what is different between picture and ocular?

The brightness and color of this new image look good to me.

But it is maybe a little fuzzy, more fuzzy in some places than others.

I wonder if you have focus or depth of field problems. Your eyes will adjust for small differences in focus. The camera will not.

How do you set focus? Have you tried taking several pictures with the focus moved just a little bit up and down?

--Rik

RobertoM
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Joined: Thu Jul 05, 2007 6:21 am

Post by RobertoM »

Thanks a lot.
I do other test, set white balance to tungsten, use bracket exposure.
The results is little better, but I'm not satisfied.
For shot a photo, switch the selector and all the light go to the camera.
But there are some problems....
When I watch from two oculars (10X) with 4X or 10X objective, the image is very good, bright and not fuzzy, but when change the switch and I see on camera, I must search a new focus, and the image is more dark, little fuzzy and not easy to put on focus.
The image I can see on camera is more bigger than when I see in oculars.
The tube adapter for reflex have two kind of magnifications: 2,5X and 4X.
How can I do?
There is a very bigger difference between the image from oculars and the image that I see on camera.
The image that I post, rappresent the real image I see on camera, but not that in oculars.
Thanks for your help.
Roberto

Charles Krebs
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Post by Charles Krebs »

Roberto,

Let's go back a little. I am assuming that you have properly adjusted the lighting for Koehler illumination. If not, see:
http://www.meditec.zeiss.com/C1256F8500 ... orner1.pdf

The 2.5X magnification in the trinocular tube is more fitting for a full frame 35mm camera. (the 4X is too much for a SLR). Since the sensor of the D30 is smaller than 24x36mm you will record a smaller part of the field (about 1/2 left to right) you see through 10X eyepieces. Lower power photo-eyepieces are very rare.

The focusing screens on most SLR's are simply not designed to give a nice clear image when used in this manner. It is difficult to focus and the viewfinder image is "grainy" and dark. That is why I have gone to great effort to make my camera focus at the same point as my eyepieces.

Why not post a couple shots of the trinocular tube, and the way your camera is now set up.

RobertoM
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Joined: Thu Jul 05, 2007 6:21 am

Post by RobertoM »

This after adjusted the lighting for Koehler illumination...

Image

I think is better than the first two shot...

Roberto

RobertoM
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Post by RobertoM »

This is another test:

Image

Roberto

rjlittlefield
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Post by rjlittlefield »

RobertoM wrote:This after adjusted the lighting for Koehler illumination...
----
I think is better than the first two shot...
Yes, definitely better.

But I am not sure that Koehler is making the difference.

What I see is that the new image is sharper than the earlier one. This is either better focus, or opening the condenser diaphragm to use more of the objective's aperture. (As mentioned earlier, stopping down the condenser diaphragm too far will cause worse resolution. Charlie's diagram is how you want it.)

One more idea about color balance... Remove the subject, and set custom white balance using just illumination with a blank slide. Then when you shoot a subject, what you get will be the subject's real color.

Also, be sure to give enough exposure that the bright field becomes almost white. In your last image, you are giving away about 20% of tonal range because the background is gray.

--Rik

RobertoM
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Post by RobertoM »

Thanks.
I do a simple test, I modify with photoshop camera raw and this is the result:
Image

I try to connect the camera to the third tube with a simple empty tube (without lens) and not with a tube adapter (that with a lens and 2,5X or 4X).
The image is more bright and more easy to put on focus.
Another try I made... I connect the camera with a simple empty tube to the ocular tube (without ocular).
And the image is more bright...
The shot is not very better than I shot with to tube adapter with lens 2,5X, but is more easy put on focus.
Unfortunately I can't fix the empty tube to the third tube or to ocular tube, and the photography aren't good.
And maybe not in focus near the edge.
Can you help me?
Excuse me for my complicated explanation, but English in not my primary language...
Roberto

Charles Krebs
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Post by Charles Krebs »

Roberto,

It would be helpful if you would give us some photos of the trinocular tube and any of the pieces you are using to attach the camera. Or perhaps there is an online link that describes and has pictures of the microscope and the pieces you have.

With a DSLR you can use "direct projection" from the objective into the camera body if it is possible to position the camera close enough so that the sensor is at the plane of the image formed by the objective. With some trinocular heads this will be impossible. With others it can be done, but generally you will need to make a custom adapter.

The "normal" method for a SLR (film or digital) is using a projection type photo-eyepiece. 2.5X is about right for a 35mm camera. It's little strong for a "reduced frame" DSLR, but really not that bad. A 1.67X or 2X would be a little better for a reduced frame size DSLR.

The post you made on Jan 31 looked to me like you were on the right track.

In my experience the photo will never looks quite as good as the view that appears through the eyepieces. And practically no light microscope photo will ever have the super fine details that you may be accustomed to seeing in pictures of buildings or landscapes.

But you should be getting results that you are pleased with. However I can't really make any further recommendations until I know what you are using, and how you have it set up.

RobertoM
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Joined: Thu Jul 05, 2007 6:21 am

Post by RobertoM »

This is my setup

Image


Image

Next days I put the setup in other room...

Roberto

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