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Red-Eyed Fly

 
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scitch



Joined: 29 May 2010
Posts: 461

PostPosted: Sun Jul 11, 2010 10:18 am    Post subject: Red-Eyed Fly Reply with quote

Here's a small fly that I caught at the park yesterday. This is at approximately 15X on the scope. I don't know what it is on sensor, a little more than that. It was taken with the photo tube of my stereo scope on a Sony a200 with the built in halogen diffused with tissue paper and an LED flashlight not diffused. It is a Zerene PMax stack of 27 photos.



Mike
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scitch



Joined: 29 May 2010
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PostPosted: Sun Jul 11, 2010 5:40 pm    Post subject: Reply with quote

And here's my first experiment using cheap ebay bellows. I cannot get very smooth motion out of it, so I can see that I missed some areas of the eye. But it also appears that the parts that are in focus aren't great either. What do you think? Cheap optics on the eyepiece I'm using? Bad light? Aberration?
Because of the course movement of the bellows, this is only a stack of 8 photos with the bellows at about 75% extension and a 10X objective. 75% extension is about 15 cm from the face of the camera to the face of the objective. The working distance is about 7 mm.



Mike
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Sun Jul 11, 2010 7:53 pm    Post subject: Reply with quote

scitch wrote:
And here's my first experiment using cheap ebay bellows

I'm a little confused about this second setup. You ask "Cheap optics on the eyepiece I'm using?" But I don't understand what eyepiece, since from other parts of the description I think this is objective on bellows, with no other lenses. 15 cm from camera to objective is in the right ballpark and should work OK with a 10X objective.

I agree with your concern -- the image is seriously lacking in quality even at best focus. I'm not sure what to make of this. Most of the eye appears to be smeared horizontally but it varies from place to place. I'm wondering about vibration, and possibly it's different from frame to frame??

--Rik
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scitch



Joined: 29 May 2010
Posts: 461

PostPosted: Sun Jul 11, 2010 9:14 pm    Post subject: Reply with quote

Sorry, I meant the quality of the objective itself. I accidentally typed "eyepiece" when I meant "objective." The objective came from a cheap, educational microscope. Certainly is not Nikon, no correction at all (i.e. Plan or Achromat).

In order to reduce vibration, I used the 10-second timer. The camera was set to ISO 100 and a fraction of a second, I don't remember the time exactly. The camera was on a tripod separate from the table that the subject was on. Certainly not vibration-proof, but I did take some measures to reduce vibration.

I have another set of pictures on my memory card right now that I'll stack and post later that were taken with the same setup.

Thanks again for your support,
Mike
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rjlittlefield
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PostPosted: Sun Jul 11, 2010 10:33 pm    Post subject: Reply with quote

No problem -- all makes sense now. That's an easy typi...uh...typo.

The objective probably is at least an achromat. I don't think anybody has made less than that since early last century. Central resolution should be a lot better than this no matter what it is. (See HERE, panel #3. That aus Jena objective is certainly nothing to write home about.)

But I'm worried by your words about "a fraction of a second", because that's just about the worst possible range for vibration. Much better to be either very short (flash, less than 0.001 second) so that motion gets frozen, or much longer (say, greater than two seconds) so that shutter shock has a chance to die out before most of the exposure happens.

If you're using a horizontal setup, one handy way to reduce vibration is with beanbags. I'm talking literally, plastic bags of dried beans right off the supermarket shelf. I use lentils. Pile 'em around the camera and around the front standard of the bellows. They're remarkably good at absorbing shock so that vibrations die out very quickly.

--Rik
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scitch



Joined: 29 May 2010
Posts: 461

PostPosted: Sun Jul 11, 2010 10:47 pm    Post subject: Reply with quote

OK, so dimming the lights and leaving the shutter open longer should help. I checked the photo info and it said ISO 100, 1/3 of a second. I had three lights on this subject to try to get light from all around. I like the bean bag idea and I could certainly take measures to try to stabilize everything.

Below is another set that I took of the same subject, but of it's simple eyes, not the compound eyes. I took it before I got this message, so I haven't had time to try any of the vibration reduction. This is the same setup, but 1/2 second at ISO 100. The bellows were at about 13 cm and the subject about 5 mm from the objective.

Again, there are areas that got skipped over and the areas that were in focus still did not look good. When I look all the way to the left of the image, it appears that there are some vibration echoes. It could also be OOF hairs, though. Maybe the reflections in the eye will help determine that.

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rjlittlefield
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PostPosted: Sun Jul 11, 2010 11:03 pm    Post subject: Reply with quote

It's hard to tell for sure. I do notice, though, that in this one there are some sharp pointlights, for example at Photoshop x=353,y=314. Those bode well for overall sharpness when you get the vibration killed.

--Rik
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