got my nice new second hand st2000xm - how can i determine the position of the filter

[h0ughy]

well i received the st2000xm yesterday, but being a newbie with this mono thing how does one determine the number order of the filters?

[gregbradley]

Turn it on and connect to the computer and shine a torch down to see which colour filter is current and set it in the filter wheel dialogue box in your software. Have the software select the next or a colour filter and see what colour it actually is and enter it in your software.

Greg.

[h0ughy]

ok thats so obvious i didnt think - but no knowing what "colour" the filter is - well deceiving , the red filter is blue in colour ;)

[JohnH]

Hi - looks like you have the CFW8 there - if yes then the position is detected by the IR sensor beam being broken by the little white tabs. There are two by the #1 filter position. Resetting the power will cause the FW to go to that posn. And yes it looks like you have interference type filters thus red looks blue etc - ie red filter accepts red but looks blue from the scope side (will look red from the camera side).http://www.olympusmicro.com/primer/java/filters/interference/interferencejavafigure1.jpg

[h0ughy]

thanks john - didnt realise it worked that way:thumbsup:
and thanks for the tip on the 1 position - does it go clockwise or anticlockwise for the positions?

[Dennis]

Hi Dave

Here are a couple of screen captures from my PowerPoint set up file for the CFW9, they may help.

Cheers

Dennis

[h0ughy]

thanks Dennis - i take it the cfw9 is only slightly different to the cfw8

[Dennis]

Hi Dave

Page from CFW9 Manual on left, page from CFW8A Manual on Right.:)

Cheers

Dennis

[naskies]

If you're not totally sure, the easiest way to confirm is by taking pictures. Assuming you have L R G B Ha, take a picture of the night sky with the same settings across all the filters.

The L filter will be brighter (higher mean ADU) than all the other filters. You may need to tweak exposures so that they don't saturate the chip (i.e. bunched up against the far right of the histogram).

Likewise, Ha will be the dimmest of the remaining four filters.

To work out the colours, you can just point them at bright, well-known objects such as the Triffid Nebula. The red channel will show the red part of the nebula most prominently/brightly, and the blue channel will show the blue area most prominently. The last filter is therefore green.

You can also work out the colours if you have a (saturated) red torch - just compare the exposures and see which one is the brightest, etc.