Quote:
Originally Posted by N1
Thanks Marc, I think your barlow definitely works better than my GSO with those great results you've been getting. I was looking at fused silica negative achromats to make my own but now I think I'll have a play with the TMB's spacing to get more amplification out of it first. That might be all that's needed, especially on the RC. The dob's infocus probably won't allow much of that. It's also why I wasn't able to use my de-windowed regular ASI120MM with the barlow. I was however able to compare both cams at prime focus, and found that with the AR window in place, required exposure times increased about 4-fold (!).
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I had two cheap GSO barlows when I first started. A 1.5x 2" and a 3x 1"1/4. I was looking into Televues at the time and they were in the $300 a pop. I needed an assortment and thought too expensive. Then Peter Ward one day posted some deepsky shot he did on the keyhole in Ha with a Baader FFC and that blew my socks off. It was ~$800 at the time. I think it's in excess of $1k now. Still double the price of my telescope back then. But I thought that's likely the one and only barlow I'd ever need. x3 to x8 all in one. Some advanced planetary imagers swear by the Televues though.
Regarding chromatic aberrations I noticed also that my 462MC when debayered shows offset channels which is why I was getting fringing. Not necessarily the glass's fault so I'm looking into that too. I only noticed it yesterday playing with PIPP and splitting the OSC channels.
I haven't checked the window on my camera as well but because they're not cooled anyway can't hurt to try without. I've just received the ADC today in the mail so I'll have another go at Venus and Mercury as soon as those pesky clouds blow over.