Blowfly (Calliphora sp.) bits and pieces

Charles Krebs · Post by **Charles Krebs** » Wed Feb 25, 2009 12:28 am

I posted a couple of "portraits" of this same species a while back:
http://www.photomacrography.net/forum/v ... php?t=3770

But this time we're looking at some details. The first shot is of the trailing edge of the wing. The colorful iridescence was a bit of a surprise. The second shot is from the leading edge of the wing. The third shot shows a section of a large "bristle" on the thorax. (If you look at the first picture of the link above, this was in the group of bristles that is close to the haltare, just in front of the wing). This was also surprising in that they normally appear black, but in the bright light from the vertical illuminator they seem to be showing some sort of interference colors. These bristles are not smooth, but have a grooved surface running the full length.

All three photographed at a magnification of 50X on sensor. Nikon D300. Olympus BHA with BH2-UMA vertical illuminator. 20/0.46 Olympus M SPlan objective and 2.5X NFK photo-eyepiece. Each were from stacks of about 20 images.

NikonUser · Post by **NikonUser** » Wed Feb 25, 2009 5:28 am

Fantastic shots.

All those bits and pieces on the head and thorax have names, even the setae (bristles) have names - entomologists have to do something during the winter.

That vertical line of grooved bristles in front of the wing are "anepisternal setae".

The fly is a female Calliphora vicina the very common blue bottle fly; recognized by the orange cheeks (genal dilation) below the eye and the orange anterior spiracle posterior to the eye.

Charles Krebs · Post by **Charles Krebs** » Fri Feb 27, 2009 11:01 am

NU,

Thanks for the positive ID and the official names of the "parts".

With many of my subjects I'm usually happy I can get it down to the genus, and leave the species to more knowledgeable individuals.

lauriek · Post by **lauriek** » Fri Feb 27, 2009 12:37 pm

Wow, that vertical illuminater certainly works nicely! These recent microscope-bugs of yours are amazing, even by your normal high standard!

How does this device send the light down onto the subject, is it around the lens, as with the Nikon BD objectives which have a kind of round prism around the actual lens, or does it actually bounce the light down through some sort of prism arrangement /through/ the lens itself?

Plus another techie question!

Surely at 50x on a crop sensor cam, with an objective with NA of 0.46 you should be well into diffraction territory? So firstly are you, and we're just not seeing at this size (I suspect not)? Or does the fact that you are shooting through a photo eyepiece change the equations? If so could you explain roughly how that affects the calculation? (Or have I just worked it out wrong in the first place?)

Charles Krebs · Post by **Charles Krebs** » Fri Feb 27, 2009 2:34 pm

Laurie,

With "brightfield" the light comes in from the side and is deflected downward through the objective by use of a beamsplitter mirror. The objective optics become a "condenser" of sorts, focusing the light onto the subject. It's then reflected off of the subject, back through the objective, through the beamsplitter mirror and then goes to the eyepieces/camera. The beauty of this is that you can put bright light onto a subject even if the working distance is fractions of a mm. There are a couple "downsides". Regardless of how well the mirror and other optics are coated there is a higher internal flare situation. The light very direct. So if the subject is very reflective it's a little like standing facing a big mirror and taking a flash picture. (And often direct head-on light is not very aesthetically pleasing.) Using crossed polarizers is a big help.

With darkfield the light passes around the objective optics and is reflected onto the subject by a built-in annular collar on each objective (as with the Nikon BD -- "brightfield/darkfield" -- objective you referenced). I've not yet tracked down all of the pieces I need to do darkfield yet. When the pieces are assembled I suspect I'll find it to be more useful than brightfield in many instances.

Yes, we're "into" diffraction. Unavoidable with visible light microscopy. The "aperture" is fixed, and can only resolve a certain amount of detail. In this case the camera, as set up, is far more than capable of recording all of the detail produced so I am not really hurting myself due to the sensor size. Play around with this spreadsheet to see what is required of a camera sensor for microscope use:
http://krebsmicro.com/relayDSLR/relay_micro.xls

A larger format would not be able to record any more resolution.

Aynia · Post by **Aynia** » Tue Mar 03, 2009 12:35 pm

These are amazing.

I love the last one.

lauriek · Post by **lauriek** » Mon Mar 09, 2009 10:56 am

Thanks for the clarification!

I had a feeling that illuminator sent the light down through the lens but I did think this would lead to flare problems, however it doesn't seem to be a problem with these images... I have to say you've done a better job of capturing the irridescence on this beetle in this shot and the previous post than I think I've ever seen before.

Those shiny beetles are an absolute /nightmare/ with my current flash setup!