Is this Chromatic Abberation? Lens flare?

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Crumble
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Is this Chromatic Abberation? Lens flare?

Post by Crumble »

Hey guys,

I am using a camera set up afocally on my microscope tripod, and am having trouble with some strange purple/blue artifacts in my images. A detailed rundown of my setup, maybe someone can spot the problem: Zeiss Universal with Neufluar objectives, KPL compensating eyepiece, and Darkfield Ultracondensor. Camera is a Panasonic G9 with 25mm f/1.8 manual lens set to f/4 and focused to infinity. This picture was taken at iso 200 and 1/500 shutter speed. As you can see in the image, there are purple/blue halos that seem to be in areas that are just out of focus. Anyone know what I'm doing wrong here? Chromatic Abberation from lens? Lens flare?

Thanks in advance for any insight!

Colin
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Ichthyophthirius
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Joined: Thu Mar 07, 2013 5:24 am

Re: Is this Chromatic Abberation? Lens flare?

Post by Ichthyophthirius »

Hi Colin,

Are you using immersion oil for the condenser front lens? I assume you do, otherwise you won't get darkfield illmination.

Regards, Ichty

seta666
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Re: Is this Chromatic Abberation? Lens flare?

Post by seta666 »

If looks like a rainbow are you are not using polarizer chromatic aberration it is. Some microscopic illumination techniques make them worse, I am finding it the hard way

Pau
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Re: Is this Chromatic Abberation? Lens flare?

Post by Pau »

To me it looks like longitudinal chromatic aberration.
The main suspect is the objective* but it could also be due to the condenser, illuminator and less likely other optics like the eyepiece and camera lens. If you are referring to the 1.2/1.4 oil DF condenser (the ultracondenser in Zeiss literature) it will not be the guilty.

If you do use LED as light source, be very careful setting it up for Kölher as most of them have a blue peak that could enhance the issue

* fluorites of this vintage have good radial CA correction but not good longitudinal CA correction in many cases
Pau

zzffnn
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Re: Is this Chromatic Abberation? Lens flare?

Post by zzffnn »

Those are CA. Darkfield makes CA more obvious, compared to other illumination techniques.

I would like to know if your immersion darkfield condenser's height is set optimally (move it up and down to see if that makes a difference) and if your condenser is properly centered.

If not, you will get quite a lot more CA.

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