Another step forward...

I seem to have taken a few steps toward a better understanding of my system and perhaps even the broader subject of photomicrography. I belong to a couple of microscope related forums and a couple of helpful suggestions were made. The first was offered by Pau who thought I should mount a camera to a tripod and take a picture through one of the eyepieces (afocal setup). Good idea, so I found an old tripod, mounted an old point and shoot camera on it and set it up to shoot through an eyepiece. After finding the bright sphere on the LCD monitor I zoomed into the image until all vignetting had disappeared. I set the shutter on self-timer , pressed the shutter release and waited for my digital image to appear. Not bad. I could just see the punctae on the image and it was much better than previous attempts. A step forward.

PH2 Neofluar 40/0.75 with Pentax Optio s5i afocal

OK, so the objective is doing it's job, the room is not shaking (or the microscope is shaking in sync with the camera) but the 40D images are just poor. The problem must lie with the camera system, whether from movement, optics or just bad technique. At this point one of my forum queries received an interesting observation from Brian who suggested that just possibly the camera sensor wasn't getting enough magnification to properly record the detail required. A light went on...I had read that maximum useful image information seldom exceeds 1000 x N.A. but also that maximum resolution requires minimum magnification of 500 x N.A. Was my sensor getting an image that had been magnified 500 x 0.75 or about 375X? I wasn't sure but Brian suggested that if I set my optovar multiplier to 2X I might notice an immediate improvement, especially with the Neofluar 40/0.75. As circumstances usually go, I had the adapter off the microscope and apart to see if anything unusual could be found. Later that evening, after getting everything back together (and with no leftover parts) I was able to try the test that Brian suggested.

Neofluar 40/0.75 with 40D

Neofluar 25/0.60 with 40D

This is a large improvement over previous attempts and has me convinced I'm on the right track. I still need a better way to adapt my camera to the microscope but at least I have a setup that will allow me to start learning all the stuff I have to learn. As I write this blog a blizzard has swept in from the north-east and has obliterated all thoughts of getting out to collect some of those pond specimens I so desperately desire.