Gerr

Hi Xiga, I'm glad you can vouch for the RC6 - that really helps. My head is starting to hurt trying to understand the science involved in the image sampling process!! But the explanations are very useful for deciding my next camera and telescope upgrade - ££ depending!! Thanks, Gerr.

Good points Vlaiv. My RMS error improves to about 0.6" RMS when I guide with the ED80 refractor. With the Newt being like a big sail it always is difficult to manage and guide accurately in anything more than a force 2 wind. The 6" Ritchey-Chretiens design reflector is lighter (approx 5kgs) and much shorter in length (391mm), so less of a handful for the HEQ5. This set-up should allow for longer guided exposures to off-set the higher f ratio (which converts to 6.75 with field reducer) so as you suggest a possible solution for me and my conundrum! I will give this some serious thought. Many thanks for your very knowledgeable input and guidance - much appreciated. Gerr

Wow, thanks for the informative reply. Those are some really useful equations for arc second / pixel ("/pix) resolution image capability. PHD guiding stats I tend to achieve for RA RMS are less than 2" and with Polar alignment error less than 5". I am worried about the scope you suggested as being slow (f 9). Won't this mean I have to take longer exposures? Gerr.

I use a Canon 650D: Sensor type CMOS Sensor size 22.3 × 14.9 mm (APS-C format) Maximum resolution 5184 × 3456 (18.0 effective megapixels) I am unfamiliar with what a good working resolution is? As a layman in this area - any image that does not appear pixelated. I am able to zoom up on images taken with my set-up but this is limited by noise and pixelation / definition. I'm not very good with the science of this I'm afraid. I know that longer focal lengths allow for smaller targets to be seen as larger objects in the telescopes field of view but at a cost of less light gathering capability (slower scopes \ reduced f stop number) I think?? Ger.

Thanks for the replies - I am intrigued by Vlaiv's suggestion - StellaLyra 6" F/9 M-CRF Ritchey-Chrétien Telescope. Could be a solution. Maybe using a 2xBarlow lens on a smaller reflector is another thing worth considering? Gerr.

I'm looking for advice on the astrophotography of small nebula and galaxies. I currently use a SWED80 refractor for large DSO's / Nebulas (e.g. North America Nebula, M42, Andromeda, Horsehead and flame nebulas etc) and a SW200P reflector for smaller targets (e.g. planetary nebula, sunflower and whirlpool galaxies, wizard and pacman nebulas etc). The mount I use is a HEQ5 Pro (Rowan belt) and the trouble with that is it's payload limit. The SW200p reflector with guiding camera makes this set-up a struggle for imaging in anything more than a slight breeze!! The SW200p is a great scope (the first one I got) but since I've moved into astrophotography I find it very cumbersome. I use a DSLR at the moment for image capture. Can anyone suggest a replacement scope where the HEQ5 is not overburdened and yet can still image small targets like the sunflower galaxy? Would the SWED120 Refractor be suitable??? Gerr.

I was lucky and bought my ED80 second hand from this forum and it came with a SW Field Flattener. My ED80 'speeds' up to f/ 6.37 with this!! Unfortunately these are expensive new (just like most things in this hobby). However; I connect all my stuff through EQMOD / ASCOM / EQDIR cable to Astro Photography Tool (APT). This software is brilliant and you can control your whole imaging session with it. It works seamlessly with guiding camera (PHD2), HEQ5 mount control, camera functions and sky charts (Cartes du Ciel - is best). It basically converts your telescope and mount into a stand alone and remotely controlled set-up. APT is free (you do have option to pay 18 euros for full fancy version) and so are all the other applications. You do need a laptop and connecting cables (especially EQDir to mount). I have not looked back since. Gerr.

Hi Dafydd, I am up the Donkey in Holyhead and use a HEQ5 Pro and have an ED80 Refractor. Your set-up is similar to mine and it is a great combo for wide field targets such as the North America Nebula and also big galaxies like Andromeda. Bright targets like M42 you can achieve unguided but most of my imaging is in the order of minutes (usually 3 or 4) to achieve good results. Consider a SW EvoGuide 50ED Refractor scope and ZWO AS1120mm Mini guide camera combo (see FLO site) as a solution for guiding long exposure astrophotography. I do find I can get dew forming on the lens of the scope (even though I store equipment in a cold garage before use). I have made cardboard dew shields as a cheap solution to this. I also use light pollution filters to reduce light gradients in my images and a field flattener to eliminate lens field distortion. Gerr.

Hi Owzat, Welcome to astrophotography!!! So many things effect this hobby as we all continue to learn. Main things are signal to noise ratio - more subs will improve this. Cooled cameras seem to have very little inherent noise. Use of flats, bias and dark frames (or dither after each exposure). Perfect focusing and PHD guiding for longer subs (Bahtinov mask and guide camera). Use filters to reduce light pollution (or image in Bortle 2/3 skies). Image on moonless nights and when your object is close to the zenith (less atmospheric effect). Become an expert in astroprocessing techniques where you can learn about 'background extraction' and further noise reduction and image sharpening processes. Optimise your equipment for the DSO you want to image. Know your equipment limits or buy more expensive stuff (can help). This hobby can be very expensive, frustrating and so dependent on the weather. But when it comes together you'll be amazed by what you can achieve!! Good Luck, Gerr M42 and Running Man Nebula

Hi Anser, In Anglesey (North Wales) I have had about 6 good nights since October. A perfect night where there is no wind, no moon and no clouds I have yet to experience!!!. I mainly do astrophotography though and have been doing this for over a year now. Love my hobby and am fascinated by DSO's but very much an intermittent interest!! Gerr.

Last night allowed for a few hours imaging but in somewhat non-ideal conditions (nearly a full moon - 90% waxing and high clouds streaming by). While waiting for Orion's sword to clear my rooftop I had a look at the little dumbbell (Messier 76) - a planetary nebula in the constellation of Perseus. Would my 8" reflector be any good in imaging this small target? It was not easy and I'll let you decide!! 30xLights of 2minute duration - ISO 1600. 20xBias and 20xFlats. Dithering used instead of Darks. Optolong L-enhance filter and Canon 650D. When the horsehead and flame appeared I was plagued by more clouds but still this looked like the only opportunity for astrophotography for a while so I persisted with image acquisition as long as I could (till 21:45 hrs). Over half my lights had to be discarded and an early finish to my imaging session. Horsehead and Flame: 28 Lights only (56mins total acquisition). Same settings as Little Dumbbell above. CC's welcome. Images are JPEG's.