Problem: Intersecting ring pattern at higher magnifications?

Bruce Williams · Post by **Bruce Williams** » Tue Nov 21, 2006 2:57 pm

Hi Folks,

I would really appreciate some help/information to explain if not reduce/illiminate the annoying intersecting ring patterns that I get when I take photographs at high magnification (say 200X and 400X).

I don't see these rings when I look through the eyepiece (I have a bino scope so the camera/adapter is in the other eyepiece). The pattern rotates when I turn the camera/adapter (so I assume the problem is unlikely to be related to the microscope itself).

The attached photo of an unidentified algae (taken with 40X objective) illustrates what I mean.

Bruce

.

Ken Ramos · Post by **Ken Ramos** » Tue Nov 21, 2006 5:28 pm

You are probably going to get bombarded by tons of technical solutions about this, I used to have this problem until I switched to directly photographing my subjects through an eyepiece instead of a camera adapter designed specifically for my camera. What I did was place a 10X eyepiece in my photo tube, attached my camera via an Orion SteadyPix digital camera adapter, which is nothing more that just a mounting bracket to hold your camera directly over the eyepiece, no other optics are involved with this adapter. I adjusted the hight and all while viewing the field on the cameras LCD, when I had it centered, I tightened everything down and that was it. Not to say that this would solve your problem but anyway that is the set up I use and I do not have anymore rings like I had when I used those expensive camera adapters. The Orion SteadyPix is about $39.00 US and can be obtained from http://www.telescope.com/jump.jsp?itemI ... =HOME_PAGE

I should also add that this adapter is for cameras like the Fuji FinePix, Sony DSC series, Nikon CoolPix, and Canon Powershot consumer type digital cameras.

Bruce Williams · Post by **Bruce Williams** » Wed Nov 22, 2006 1:59 pm

Thanks Ken,

Yes, my camera adapter comes with it's own (apparently fixed) 10X eyepiece and it could well be that it is the adaptor eyepiece that is causing the problem. I am going to contact the supplier and see if they have any suggestions. If not I'll remove their eyepiece (if it can be done - I'll check) and replace it with an eyepiece that hopefully will not have that problem.

Bruce

gslaten · Post by **gslaten** » Wed Nov 22, 2006 9:10 pm

Hi Bruce,

This looks exactly like the artifacts produced by certain Nikon Coolpix cameras and in particular like a CP4500 I used to use. I think it has more to do with the camera lens than the relay lens, and is most apparent at high zoom ratios. There has been a lot of discussion of artifacts like this on the Yahoo microscope forum and in particular by Gordon Cougar.

Try searching for lens artifacts here.
http://tech.groups.yahoo.com/group/Microscope/

Regards,

Gary

Ken Ramos · Post by **Ken Ramos** » Thu Nov 23, 2006 3:17 am

You know, now that you brought it up Gary, those rings do appear more frequently if one uses the cameras zoom. I rarely use mine in the zoom mode and crop out the image that I want or sometimes just settle for the "shotgun" image.

Bruce Williams · Post by **Bruce Williams** » Thu Nov 23, 2006 1:28 pm

Hi Gary,

Thanks for the excellent advice. I did as you suggested via the links you posted and subsiquently followed several onward links to related sites. From what I've now read and from the artifact photos that I've seen there can be no doubt that the rings are a product of the camera lens system used in conjunction with the microscope optics.

It appears to be an extremely common problem with compact cameras when used to take photos via a microscope eyepiece or adapter optic. The technical explanations got a bit heavy however it seems that the problem is "caused" by the way the various camera lens elements are manufactured.

I have confirmed that the problem is not the Brunel adapter by taking a photo through the eyepiece and getting the same (or at least very similar) results.

Picking up the point you made about the effect of zoom ratio (also observed by Ken) I will carry out some tests varying the zoom, exposure and condenser iris setting (I have noticed that the rings become more evident as the iris is shut down).

Bottom line seems to be that to guarantee artifact-free images I will need to change the method I'm using to one not involving the use of the camera lens - ie, a DSLR setup of some type. As I'm still very new to photomacrography I think short term (maybe even medium term

) I'll persevere with my Olympus SP-350.

Bruce

Bruce Williams · Post by **Bruce Williams** » Fri Nov 24, 2006 5:02 am

Hi folks,

Just for completeness - I'm pretty sure the algae is a Pandorina species (possibly P. morum). I have read that the number of colony cells is fixed at 8, 16 or occasionally 32 (makes sense as powers of 2). A visual count confirms that there are 16 daughter cells in this colony.

Bruce