TOPICAL TIPS : CALIBRATING A CONDENSER.

 

By Ian Walker.

 

I recently started using a black and white video camera with my Russian Bimam microscope and started to find it very tedious pulling out the camera every time I changed objectives to set the condenser for optimum aperture.

On larger condensers like the Bimam R13 it can be very useful to calibrate the condenser for your particular objectives, this would not be feasible for the spiral type or small condensers where the diameter is too small to put markings on.

The great thing about this is you can take into account different style objectives on the same turret, I have one Zeiss, one Leitz and two Lomo, the older Zeiss and Leitz run best at 70% of full aperture and the Lomo's 85% of full aperture - you can calibrate the markings to suit!

 

All the tools you need.......

Use an old video or cassette label with a sticky  back, they even come with guide lines!

Cut a long strip about 1mm wide using a sharp modellers knife and cut into equal lengths to suit.                                      

I find the underneath of a bread board good for cutting on because the wood grain is very fine

and gives a very precise cut.
 

 

 

This picture shows a close-up of my Bimam condenser with the strips stuck over my original, temporary  pencil markings, this is where the tweezers are handy for critical alignment.

The objective details were made using a simple spreadsheet with the alignment as close as possible with regard to the vertical marks.

 

And finally, the finished product..........
 
 

This picture shows the condenser in situ, racked down. 

Also shown is my home made extension arm for the condenser made out of black tubing because the original isn't long enough!

This is a push fit made from Tandy heat shrink tubing with an inner core made from a cotton bud plastic tube!

 

Now I've also started using my Nikon Coolpix camera with my scope I find the above modifications very useful in saving time especially with eyepiece adapters fitted to the Nikon and indeed for visual microscopy it can also be quite useful.

All comments to the author Ian Walker are welcomed.

Footnote: Some makers' condensers already have numbered/graduated iris diaphragm settings, so a table of settings could be kept next to the scope for reference as to what iris setting was required.


 

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