Observing Session 28-29th Dec '08

I have actually. I got a 0.6A Daystar filter recently with a 75mm ERF.

Oh, cool! You running that on your WO? Did you get one of the tilting ones or an oven-heated version?

We'll have to do a re-run of our comparison test once the sun gets a bit higher....

-- Jeff.

Jeff,
I got the T-Scanner - the tilting version. I have used it on the SCT so far so as to avoid a barlow/powermate. I made a cell to attach the filter off-axis onto the SCT from a sheet of aluminium I picked up in B&Q. However, I just got a 4x powermate so now I can start thinking about using it on the W0 80mm scope. It would be good to do a comparison alright. One thing I still need though is a long focal length 1.25" eyepiece to reduce the magnification and increase the FOV. At the mo I use a 26mm Polssl and a little 0.5x focal reducer which screws onto the eyepiece.
Michael.

Dave_Lillis wrote:

A good session there Michael,
How much of the field of view diameter does M51 take up with the 31mm?

The 31mm gives a FOV 34.7' and a magnification of 142x. For comparison, on your 20", you would get FOV of 1.01 degrees and a magnification of 81x - a significant difference due to the difference in focal length.

Michael.