Euglena and Cosmarium

Olympusman · Post by **Olympusman** » Thu Aug 15, 2013 9:03 am

Euglena Phacus pleuronectes

Dividing Cosmarium. The pair on the right appear to be the "daughter."

Cyclops · Post by **Cyclops** » Fri Aug 16, 2013 8:48 am

Fabulous!

Franz Neidl · Post by **Franz Neidl** » Fri Aug 16, 2013 10:29 am

You have interesting pictures, but I am asking me why they are so grainy. What is the reason for it?

Franz

Cyclops · Post by **Cyclops** » Fri Aug 16, 2013 11:26 am

Franz Neidl wrote:You have interesting pictures, but I am asking me why they are so grainy. What is the reason for it?

Franz

Overmagnification or zooming / cropping perhaps?

Olympusman · Post by **Olympusman** » Mon Aug 19, 2013 8:09 am

Franz
The graininess is the result of the notoriously poor performance of Olympus Four Thirds cameras at high ISOs. The sensor noise is compounded by Zerene Stacker, which does an excellent job of preserving image quality for good or evil.
For some time I had been running my E-420 at ISO 1600. Now that you have brought this to my attention, I'm going to drop the ISO to 400 for awhile and see how it goes.
I recently replaced the Swift field condenser on my scope with an Olympus condenser from a BHR focusing block I bought a few years ago which draws in far more light than the Swift ever did, so I should be able to use a lower ISO than 1600. I also have far less chromatic abberation than I did with the Swift field condenser.
For the most part, I get pretty good results down to a 20X objective, but the 40X and 60X condensers pipe in a lot less light, so the high ISO performance results in longer shutter speeds and and more sensor noise.

Cyclops · Post by **Cyclops** » Mon Aug 19, 2013 8:23 am

Why on earth would you use iso1600 for micro shots? Tho I must say for such a high EV they are very good!

Olympusman · Post by **Olympusman** » Mon Aug 19, 2013 8:30 am

Primarily to stop the action. Shutter speeds might range from 1/8 second to 1/200 second. When you shoot in darkfield, the shutter speeds get very slow.

Franz Neidl · Post by **Franz Neidl** » Wed Aug 21, 2013 1:14 am

Hello Michael,

I think you could reduce the graininess with an objective with a higher Numerical Apertur (maybe with an apochromatic corrected objective) and with an eyepiece with a lower magnification.

Franz

Olympusman · Post by **Olympusman** » Wed Aug 21, 2013 7:38 am

Franz, I have tried numerous eyepieces on my camera tube, and the one I'm using is giving me the best results. I even have a full set of Olympus NFK photo eyepieces that don't perform very well through my OM 28 mm f3.5 relay lens.
What I have done since this graininess topic has come up is dropped the ISO to 800. Also, when I'm viewing I have the brightness on the light source set lower for comfort, but when I shoot I crank the brightness all the way up.
As I have said in previous posts, I replaced the original Swift condenser with a filed condenser from an Olympus BH2 focusing stand. The Swift did not pull in nearly enough of the available lamp brightness. The Olympus covers a much wider area above the lamp so I am getting about three times more efficiency out of the light source.
We'll see how it goes.

Franz Neidl · Post by **Franz Neidl** » Wed Aug 21, 2013 12:08 pm

Hello Michael,

I dont think that you can eliminate all these problems only with the light source. Maybe there is also a problem with the so called conducive magnification. The conducive magnification is the range between the 500-fold and 1000-fold of the numerical aperture.
The Olympus E-420 has a focal lenght multiplier of 2x.
An example: If you use an objective 10x with the numerical aperture 0,10 than the conducive magnification is between 50 and 100.
You can make your calculation adding to the magnification of the objective also the magnification of the eyepiece and of your camera.
Therefore I wrote you could use an objective with a higher numerical aperture or reduce the magnification of the eypiece.

Franz

Euglena and Cosmarium

Euglena and Cosmarium

Grainitude

High ISO

Grainess