alacant

The best is the original prescription GPU. A search avoiding the term 'TS' shows it available here. There's also a used one here. For the 130pds over aps-c we use 52mm cc to sensor. At focus, this needs 10mm removing from the inner focuser barrel to prevent its intrusion into the light cone. That's ap. I've never looked through a PDS, with or without cc. Cheers and HTH

... and more helpful to the beginner. The biggest concept I've had to come to terms with in ap is that for me at least, pragmatism is the only way forward. Example. When I first started, I wanted to know how to stop the focuser slipping on my ed80 and how to prevent stars looking like big blue blobs. I didn't want endless commentaries about pinions/crayford/chromatic this/ lateral that... Most disconcerting also was that the very guys who had recommended certain hardware (in the days when the only recommendation was an ed80 and a heq5) had never been anywhere near the stuff they were recommending, let alone have any notion of how to fix it. The software side was even worse. If you really are serious about getting online with ap material, perhaps hands on with what beginners use and ask is probably the only niche left in the already overcrowded ap influencer market. There are many examples on this very forum where seeing it done would be vastly superior to reading about it, but still nowhere near the level of understanding you could gain from simply going along to your local astro club and fixing your 80ed with someone who knows what they're doing. Cheers and good luck.

Hi 600d, so dither at least 10 pixels between frames and lose both dark and camera sourced bias. Instead, simply pre-process by subtracting the offset (2048) from both the flat and light frames before registration. Stack with one of the clipping algorithms. Siril makes these tasks easy. Working with the linear stack, crop the frame edges and extract the background before photometric colour calibration. That will clean the background and so go some way to avoid artefacts introduced by other software😉 Cheers and HTH

Hi Stick a yellow filter, available cheaply, before the sensor. A #8 will control the blue without removing it completely. A #12 or 495 long-pass will remove most of it. Former preferred. If you're looking for a software method, split to rgb, use deconvolution with stars+halo selected on b only, then recombine. Cheers and HTH

Hi Use one of these and one of these. That gets you connected. If you're ok with the images, that maybe all you need😉 HTH

Apart from the eos circuitry which introduces its own artefacts when combined with conventional dark frames, the impossibility of matching the varying temperature of your dark frames with your equally temperature variant light frames introduces more noise rather than help eliminate it. 700d? Same here, so simply enter: =2048 in the field where you would normally enter the location of your master bias file. ... about dark frames on a 700d? Really? I'd guess the authors had never been near a DSLR. In this game theory, whilst maybe interesting to some, is of little use to those wishing to retain what remains of their hair. Cheers and HTH

Hi Dark frames of any type on a DSLR are bad news. Forget. Don't use... etc. DSLRs employ sizeable offsets. To prevent the flat frames over-correcting, this should must be removed. Don't know what camera you have but on e.g. recent eos models this is easily achieved by simply subtracting a constant bias of 2048. Don't forget to do this for the light frames too. No need to shoot separate bias frames. No nonsense, open-source method for this? Siril. Cheers and HTH

Hi Lovely shot. You have captured detail right into the difficult bright bits. Beats anything I've seen over 60s. Cheers

Hi You don't mention how you deal with any offset, but your description is consistent with incorrect or absent bias subtraction. The easiest way is to deal with this is to simply subtract a constant value corresponding to the offset you used. The more laborious, applying dark flat frames. Cheers and HTH

Hi We use and recommend DSLRs. True, a few years ago, early models were insensitive and noisy but technology moves rapidly. They are rugged, affordable and above all most have a decent aps-c sized sensor. A dedicated camera this big is going to cost far more than a DSLR. The images they produce are easy to process and of more than acceptable quality. From experience, we do not recommend going used for camera. Which DSLR? You don't need a top of the range model as most of the daylight shooting wizardry therein will never be used. Any Eos model with the 18mp sensor works well when astro-modified. We use mainly 700d and 4000d. The 24mp models are also good but we had trouble with the earlier 750d models. AFAICT, all newer and subsequent models are fine. Anyway, HTH you decide.

Hi Stu, everyone As always, lovely detail from the fast reflector.. To get this really good, perhaps have a look at tilt, bottom left and something which resembles a distorted dew shield, top right. Any ideas? Should be easy to locate and put right. Cheers and HTH

More nebula-safe stars. Alas, there are -perhaps disqualifying- dark bits. l to r ngc869, ngc884 and ngc957 in Perseo. Thanks for looking. eos700d + asahi takumar 200: ~90min, ISO800: st 1.8.527

Another go. This time in the nebula-safe area of Perseo. NGC 1245 Thanks for looking. eos700d: 90 min ISO800: st 1.8.527

Hi everyone Nice to see so many stars. We spend €enormous to be able to take images thereof. Then obliterate them to death! Here is HD34452 and friends in between the -not easy to avoid- gas and dust of Auriga. Thanks for looking. eos700d + Bresser-150: 90 min, ISO800:: st 1.8.527

Hi You've probably hit the mount limit at the meridian. Set RA to a few minutes after. Cheers

Yes.

Imagine the mount head -only the mount- suspended in space with the RA axis pointing at the pole. It matters not how you keep it there. It doesn't need to be a tripod or support from underneath even. Whilst leveling the tripod does no harm, it's also unnecessary. The only time I can think when levelling may be useful is to have some sort of set-up reference if you tear down end of session. But then again, you're going to align anyway so .. Cheers.

If you're good at -e.g. eBay- auctions, there are good alternatives. The Zeiss and Takumar 135mm perform well. OK, you don't get f2 but hey, for around €50 they give very good results. Here's an example we took with the Zeiss. HTH

Hi I think it's fair to say that the 75-300 isn't perhaps the best lens Canon have produced. As the lens does not focus all colours at the same point, a focusing mask will not give the best focus. With the lens set to AF, decide on focal length and leave it there. Depress the shutter to focus centre frame on the moon. That will get you close to infinity. Back to MF. To refine it from there (difficult), centre a bright white star. In live view at x10, twist the focus so that the halo just disappears. Sirius is good. Depending upon where you are in the zoom range, the halo could be either blue or red. Your aim is to compromise between bloat and false colour. Tape the focus ring to prevent it drifting. That's the best we could do. You might want to consider a fixed lens. There are some good examples, e.g. 135mm and 200mm, available cheaply on auction sites. Cheers and HTH

Hi AFAIK, it isn't. It wasn't possible for our trial version at least. Cheers **EDIT. Recommendation: for ease of processing, upgrade to Siril.

If it's the carbon tube UNC, you should be fine.

Hi One way would be to swap to a f8 or slower Newtonian. I'd guess the examples you posted are from a faster ratio. To simplify the procedure, perhaps best to lose the concentre and use instead a Cheshire sight tube throughout. One with cross-hairs, even better. Remember that apart from reflection, the secondary has no optical properties. It's just a flat piece of glass. Get it somewhere close. Then leave it. By far the most important alignment is that of the primary. Be sure to read Telia's collimation myths and Seronik's no nonsense guide, both of whom outline the simplicity of a much misunderstood procedure. Cheers

If the issue persists, simply 'unband' the whole sequence before registering. Then stack using a decent clipping algorithm. Siril's sequential approach is the best we've found for both the above. Cheers and HTH

600d, so no dark frames. Of any sort. Simply calibrate using a constant bias of 2048. +1 for a 15 pixel dither between frames. HTH

Ah, ok. So all you need to do is add an 'aux mount' entry so that phd2 knows where the telescope is pointing.