Bee's head

[scitch]

Here's my first shot at using a microscope objective as my camera lens. I took the adapter that connects my camera to my microscope and attached the 4X objective to the other end. I cut a hole in a water bottle lid and put the objective in that. Then I stuck it inside the adapter. Then I taped up the end with black tape to keep out light. I took the microscope head out of my stereo setup and put the camera in its place. Then I used the microscope's focus knob to move the camera up and down. The insect was held by a needle passed through the corner of a cork. The built in halogen light from the microscope was used with a tissue paper diffuser and a soda can reflector. I used the 10-second countdown mode to reduce vibration.

In playing with this setup, I think I figured out why my shots through the microscope were so bad. The inside of the adapter tube is very reflective. All of my objective-lens shots had a fuzzy bright spot in the middle. When I looked through it with my eye, I saw a lot of reflection. So, I lined the tube with black construction paper and the problem disappeared. I think it will help greatly once I go back to the microscope too.

I'm still waiting for my portable light to arrive to ease my lighting problems.

Here's my first try, Zerene stack of 47 pictures:



Any idea why there are stars all over the place, particularly near the simple eye? These showed up in the DMap version as well.

[rjlittlefield]

Any idea why there are stars all over the place, particularly near the simple eye?

Those are due to astigmatism in the lens. This defect turns up pretty commonly when you use a lens outside its design space. What happens is that away from the lens's optical axis, points of light in the subject turn into sharp radial lines or sharp tangential lines or fuzzy ellipses depending on focus depth. In the stacking process, the fuzzy ellipses get weeded out, but both of the sharp lines get preserved. As a result every bright spot on the subject ends up being rendered as a cross with one arm radial and the other tangential.

In the image here, I think there are a couple of things going on. First, the radial/tangential pattern seems to indicate that the optical axis is centered in the lower portion of the picture, possibly a bit left of center. Ideally, it would be centered in the middle of the frame. The axis will move off-center if your lens is tipped, so I suspect the problem here is that your water bottle lid adapter is a bit misaligned. Second, the field of view of a 4X objective is typically about 5 mm, and I suspect that you're asking it to cover more than that by running it at less than its rated magnification. I notice in the lower part of the frame that both sides are clean, so you ought to be able to make significant improvement by just un-tipping the lens so that the optical axis becomes centered on the frame.

--Rik

[scitch]

"so I suspect the problem here is that your water bottle lid adapter is a bit misaligned"

Absolutely possible with this setup. The objective has a flat face, so I should be able to stand the whole thing on the table and see how far off the alignment is Leaning Tower of Pisa style.

"Second, the field of view of a 4X objective is typically about 5 mm, and I suspect that you're asking it to cover more than that by running it at less than its rated magnification."

And the magnification is controlled by the length of the tube? That's not adjustable in this case. I do have a cheap bellows but cannot find an adapter to get my camera lens on it. Maybe I should play with an objective at the end. I cannot find a male T to female maxxum/sony adapter.

"I notice in the lower part of the frame that both sides are clean"

Yes, and the lower left looks best. So, I'll try to straighten it and improve the lighting so that there aren't as many bright spots. But first, I think I'll go back and try through the microscope with the construction paper insert in the tube.

Thanks, your analyses are always right on. It's amazing what you can tell about the setup by looking at the image.