Calcium sulfate crystals stack

Corehead

The hydrated calcium sulfate crystals shown below are my pathetic efforts to capture and process a measly 4-frame stack (with Alan Hadley's CombineZX, which is still available FREE). The core sample these crystals were taken off of came from an oil exploration well somewhere in Oklahoma, from about 5,600 feet (cores from over 20,000 feet down are getting more and more common these days, FYI).

Equipment used: a Zeiss petrographic microscope with polarizing filters and set at 250X, and images captured from the left eyepiece with an old Canon A540 on manual mode, aperture f8.0, exposure times as short as 1/160 sec, and ISO 400 equiv. speed.

Alas, after much pre-processing of each frame and then stacking, I think the final image looks a little, uh, "cartoony". Any hot tips from you stacking experts out there will be appreciated and implemented (if possible).

DaddyO

I'm curious. How is your camera attached to the microscope? I take it you tried shooting in manual mode with lowest ISO and longer exposure speed.

Corehead

Believe it or not:

• camera was hand-held about 1/2-inch from the left eyepiece--about what the eye would be at
• Yes, in spite of earlier reported "aperture priority", I was shooting in manual mode ("my bad")
• ISO set at 400 to allow shorter exposure times. Too bad for the noise, though, ayy?
• Aperture set at f8.0, the tightest that most compact digicams go
• Exposure times nominally 1/125 sec to 1/160 sec

I haven't make a camera mount yet; though the petrographic microscope does have a (rather large) port for a camera mount, I couldn't get the dinkty Canon A540 to work there. I DO have access to two Nikon D200s (and a Mamiya medium-format camera [no digital back though]), but coming up with mounting for them will take time.

(Taking a deep breath here) Have I slaked your curiosity any?

DaddyO wrote:

I'm curious. How is your camera attached to the microscope? I take it you tried shooting in manual mode with lowest ISO and longer exposure speed.