Wrap-around midge eyes

Charles Krebs · Post by **Charles Krebs** » Wed Nov 14, 2007 11:36 pm

Last fall I posted a shot of a midge in which I found the eye structure intriguing.

They are really quite tiny, but since I've been playing around with some higher magnifications with my "tabletop" setup, I decided to have another look.

This specimen wasn't anywhere near as pretty as the one I worked with last fall, but it had similar interesting eye structure.
After taking the shots, I carefully measured the subject. The width of the head, as seen here, is .022" (0.56mm).

rjlittlefield · Post by **rjlittlefield** » Thu Nov 15, 2007 12:11 am

Lovely! So, was this shot with a 40X objective or something else?

--Rik

Charles Krebs · Post by **Charles Krebs** » Thu Nov 15, 2007 12:39 am

Rik, this was with a 10X objective. It was actually shot as a vertical, so this is a pretty significant crop. I did a "full frame" shot with a 20X and while I liked the overall eye better, I didn't care for the rendition of the face texture and the eye "facets" behind the antenna. Still sort of hit-and-miss with the 20X for subjects like this.

DaveW · Post by **DaveW** » Thu Nov 15, 2007 12:59 am

Great shot Charles again. I found it interesting that male hoverflies have larger more wrap around eyes than the females too. Presumably it must just be to spot females because obviously if the females smaller eyes were a disadvantage from the predation point of view, meaning they got eaten more often, hoverflies would have died out!

DaveW

RobertoM · Post by **RobertoM** » Thu Nov 15, 2007 1:02 am

Incredible!!!
RobertoM

rjlittlefield · Post by **rjlittlefield** » Thu Nov 15, 2007 9:00 am

Charles Krebs wrote:Rik, this was with a 10X objective. It was actually shot as a vertical, so this is a pretty significant crop. I did a "full frame" shot with a 20X and while I liked the overall eye better, I didn't care for the rendition of the face texture and the eye "facets" behind the antenna. Still sort of hit-and-miss with the 20X for subjects like this.

That's encouraging news! 10X objective is a lot easier to work with than 20X, for sure. And I was wracking my brain trying to figure out how you might be managing to illuminate around a 40X.

Was this midge with standard extension, so that 0.56 mm subject turns out to be 5.6 mm on sensor? Then we're seeing about 1/3 frame width? The image quality looks very good for such a tight crop.

--Rik

Charles Krebs · Post by **Charles Krebs** » Thu Nov 15, 2007 10:57 am

Rik,

Probably easiest to show you the full frame:

As you can see it was a pretty significant crop. It was actually taken as a "test" comparison between two optics (as well as a comparison to the 20X shot), but it looked pretty neat so I thought I would post it. As such, I agree that it held up pretty nicely. The objective was on a "maxed out" Olympus bellows plus some additional fore and aft extension, but I have not calculated the magnification.
(... just after I wrote the above sentence, I realized you might start counting pixels and get out your calculator , so I calculated the magnification recorded on sensor based on this image. It worked out to 14.8X).

I screwed up the 20X shot... "over-lit" the antenna (at least in the jpegs) and lost detail. Also, at that magnification the centrally placed antenna "expanded" greatly as focus was moved to the back, so the top of the eye around the antenna doesn't look very good. (But the bulk of the eye looks great). Always a trade-off somewhere!

JoanYoung · Post by **JoanYoung** » Thu Nov 15, 2007 6:09 pm

Once again a superb image Charlie.

rjlittlefield · Post by **rjlittlefield** » Thu Nov 15, 2007 8:32 pm

Charles Krebs wrote:... just after I wrote the above sentence, I realized you might start counting pixels and get out your calculator , so I calculated the magnification recorded on sensor based on this image. It worked out to 14.8X.

Who, me? What a silly idea!! I hate calculators. I always use a spreadsheet.

Thanks for the extra information -- very helpful.

--Rik