Venus

[N1]

My first auccessful attempt at recording cloud detail on Venus (i.e. where I'm actually confident it's not artefacts I'm seeing), yet it was just an afterthought during a visual observing session this afternoon with the old untracked 8" dob. With the weather closing in, there was no time to set up anything else, so this was done with a guide cam, manually tracked. Still a far cry from what we've been seeing on here recently but I'm happy with the result of this impromptu imaging "session"

Good practice for processing better data later on too

8" GSO dob with TMB1.8x ED barlow, ASI120MM, Venus U and Pro Planet IR742. Side observation: The TMB ED barlow passes significantly more UV signal and has significantly less scatter and internal reflections in the UV than the GSO ED barlow, which I realised today is essentially useless for this task.

[multiweb]

Nice. You clearly did get cloud patterns in the UV. :thumbsup: Hard yakka with a 8" and shortish FL. Good point about the barlow. Never thought about it. I'll have to read up on mine see if ut has any kind UV/IR block coatings. That would be a bummer. :( Probably why it's best to use a long FL native system with a large aperture and no glass in the light path if possible.

[N1]

Thanks Marc, I think your barlow definitely works better than my GSO going by 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 able to compare both cams at prime focus though, and found that with the AR window in place, required exposure times increased about 4-fold (!).

[multiweb]

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. :question:

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.