Still no joy
Gene,
The
third image in my previous post was
not taken using my current setup. It was taken using a CH2; same slides and similar subject (but no meteor storm or starfield).
I'm beginning to suspect, that in addition to my ineptitude, there may be something physically
out-of-wack with the condenser. All the instruction I have received and read seems to indicate I should be seeing better results; but I am yet to achieve true darkfield.
The information below was provided by a supplier of darkfield stops (and echoes one of Charlie's suggestions):
"This item is placed in the filter holder located underneath the condenser.
The condenser iris should be fully opened and the flip-top lens in the top position."
hmmm... I've done that too.
Might need to look at a dedicated Darkfield condenser, oil or dry, whichever comes first, or a general purpose alternative to the flip-top condenser (I went with the flip-top (swing-out) condenser initially, because it plays well with the lower power objectives; but apparently not in darkfield. The BH2 is more complex than the CH2 and obviously the complexity requires more finely tuned or dedicated components for specific applications.
I have tried different 'slides' to see if slide thickness and glass properties may be having an undesirable effect; short answer = yes.
I need to solve this riddle, for my own satisfaction and for future projects. It may sound like I am a bit
scattered (I am at times); but that is usually the case when learning something new that doesn't quite turn out as expected. I scramble for answers.
Tom, thanks for sharing your experiences. I have taken onboard all the information you provided and also Rik's nifty tissue paper calculator and placement of the stop in the "optics chain".
I've just located a couple of alternate Olympus condensers for the BH series, not dedicated darkfield (that may take another 5 days or so), but they should enable me to compare results.
Thanks for all the assistance. Loads of good advice in this thread.
Charlie wrote:Also (regardless of brand) you really need to clean the slides and covers scrupulously.
Can anyone suggest a practical approach to the 'cleaning' process? My coverslips are exceptionally brittle due to the nature (and purpose) of their construction.
Craig