Botryococcus, golden algae.

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Wim van Egmond
Posts: 440
Joined: Fri Apr 08, 2005 5:17 am
Location: Rotterdam, the Netherlands

Post by Wim van Egmond »

Thanks Jens en Rene,

I have now tried the Zeiss KPL and it does work better. Placing it a bit higher does not make difference, it seems.

I'll let a friend of mine, who is more experienced with optics, take a look at it! I am not very systematic and not very technical.

I have now used DIC with the digital camera and the result looks better than when I photograph with brightfield. Perhaps the closing of the condensor with brightfield causes more CA. With DIC you use the full NA.

best regards,


Posts: 125
Joined: Thu Mar 17, 2005 4:14 am

Post by rene »

I suppose we can go on and on on this subject, but I leave it after my last remark: using a normal eyepiece (for 'virtual' use) for projection on a chip or film, introduces spherical abberation. I've got tables for the correction in tubelength needed for that, maybe that's what Jens was referring to. Now, the clue: how bad is it? You might see it with a high dry like a 40/0.95, luckily this generally has a correction collar for that. You know yourself how much leeway you (seem to) have when using the correction collar, so I find it far more practical to set tubelength for parfocality only and don't worry about abberations. Good luck with your new setup: what's the chipsize you use now?