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Mineral PhotographyExposure problems caused my fluorescence?

30th Jul 2017 15:59 UTCLarry Eicher

00394240016015759225163.jpg
Sirs:


Occasionally I come across samples which present exposure nightmares. I am currently working on gypsum which is posing this problem

There are, perhaps two crystals in the upper right which are causing the problem. I exposed this one at ec -3. I used one Neewer led light on low setting. The light had a diffuser mounted. The light also had to go through a white plastic tubular diffuser/reflector. I held almost all detail in the "two" crystals. I pushed up "fill" light and "brightness" to help compensate for the under exposure. Could this "hot" spot be caused by UV light? I don't see how since I can't see UV light, but I am at a loss.


Regards,

Larry

30th Jul 2017 21:21 UTCDoug Daniels

I doubt it has any UV problems. It is likely the orientation of those two crystals with respect to your light source. Notice how the crystals along the lower part are much brighter than the main part of the specimen?

31st Jul 2017 16:42 UTCLarry Eicher

-- moved topic --

7th Nov 2017 18:09 UTCLarry Eicher

Doug,


Thanks for your reply and apologies for my tardy reply. I have since come to the same conclusion. I was just beginning to consider UV light at the time I asked. I have learned enough to know that I needn't worry about UV light until my camera is modified so as to capture light in that range.


I have since modified my setup adding the option to rotate the subject until the faces are aligned such that we get no blown out highlights. I don't yet have an image of the "new" setup but if you are interested, I will create one and post it.


Regards,

Larry
 
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