cfpendock

Sometimes known as the Little Sombrero, this edge-on galaxy is rather small - around 5.5 x 2.3 arcmins. Really this effort should be described as work in progress, but with the appalling sky we have had so far this season, I thought I'd better process what I have anyway. In any case any further data would have to wait until next winter as it is now getting too low. Scope is CPC1100 Edge at 2800mm focal length, with Atik 4000 camera. Around one hour each of LRGB, five minute exposures. Chris

Hello Gav. I have just stumbled across this post and found it very interesting. Certainly some of your problems have been experienced by myself using my CPC1100 Edge which is pretty similar to your set up - albeit with less exotic filters.... I have found two things: 1. Most of my problems disappeared when I fitted a motorised focuser onto the visual back, so the mirror was effectively always locked in one position, focus being achieved by moving the camera assembly in or out rather than moving the mirror. Probably there are good optical reasons why this is not correct, but it works for me. 2. I have never been able to obtain the crispness of stars using the CPC rather than my Tak refractor - allowing for difference in focal length. The stars from the CPC always seem to have a certain "softness". Chris

And I especially like the big screen. But it does look a bit tidy... Chris

For the forum "Getting started with imaging", this is fantastic, with amazing star colours and a very nice looking and nicely framed image indeed. But in my view, perhaps the star colour is a tad over saturated? Chris

That is exceptionally nice. What scope / camera did you use? Chris

Pretty amazing for such a short imaging time. Chris

I may not be alone here. Living almost in the geographic centre of one of the more advanced countries in the world, the best we can manage is 2MB/sec (on a good day). To download 10 MB can take a very long time. For this reason it is rare that I am able to look at the full resolution of posted images. Chris

Well, I suppose it could. I am always very careful about getting the balance slightly off so I am generally guiding in only one direction, mostly because I suspect that with the weight of the C11 + bits then I am close to the weight limit for the mount. Otherwise I don't think that just bad guiding would lead to the shapes which you have. I presume collimation is OK? Not tilt I suppose? I use Fat-tail Richardson-Lucy deconvolution plugin for Maxim: https://vanderbei.princeton.edu/images/deconv/deconv_MaximDLnew.html . It needs a lot of experimenting to get right, but when it works, it works.... And I only use it very sparingly, and only on those bits of the image I think need it. It can sharpen up the stars nicely, without giving them hard edges, but as I said, it takes some time to get right. Chris

Just seen this, Gav. Nice one! I also like to use long focal lengths (my deforked CPC1100) to get shots of far away stuff. I also hit 0.55sec/pixel using my old Atik 4000, so I usually bin the subs. So I know it's not easy, especially to avoid the softness of the stars. And I have the benefit of using my EM200 mount which gives around 0.4 secs RMS. But I do use some very slight deconvolution (as NigeB suggested above) to try to tighten the stars. You say that the softness is not due to the scope. Well, looking very carefully at your full image, there seems to be a problem with some of your stars. They seem to be elongated, especially in the top left. This should not be due to tracking which should surely give round (but bigger) stars - especially given the relatively long sub times? Also there seems to be some colour mis-alignment on some of the stars, as well as some misshapen stars. Is the OAG well clear of the light path? I think that the long total time was well spent - you have remarkably little noise in the main galaxy, and I think that the image is very well processed. Chris

Oh yes. That's good. Chris

I have seen many really good images of this in narrowband using various palettes, but always I prefer just the Ha. Excellent result! Especially considering the moon. I think you have justified the Astrodon filter.... Chris

Yes, nice field of view. Chris

That is good. I am very tempted to get a reducer for my C11 but the price seems very high. None on the second hand market that I've seen. But this M51 certainly shows it's potential. Chris

That TEC combined with the Atik 460 certainly does the job. Not to mention the expertise of the operators and the processing of course.... Chris

I certainly find that re-focusing interferes with guiding, so usually turn off guiding during re-focussing. Otherwise I need at least 2 minutes for the guiding to settle back down. But I've never had a problem losing the guide star. I don't use SGP, I use MaxPilote, but I think it does much the same thing. Chris