alacant

My preference, first. It has more stars.

Hi I don't understand 'bar' in this context.

Don't know which telescope you have (all f4s are nice), but it will almost certainly need to be dismantled. Whilst it's apart, replace the springs with ones which are up to the task. 8", we use 1.6mm wire. 6", 1.4mm etc. Include passive springs over the locking screws leaving the latter loose.

If you have the primary fixed with silicone to prevent sideways and up and down motion, then no. This also has the advantage of the coillimation holding at all angles the telescope assumes during imaging. HTH

Ah, ok. I see it now. Same on kubuntu.

The theory may predict that dark frames are essential and although Siril's dark optimisation comes close, so far no algorithm we've found is capable of compensating for the artefacts dark frames introduce. That's what we found by trying it. Not only with a 5d, but most other DSLRs which have passed through our hands. Best to do a comparison and decide yourself. Summary: light, bias and flat frames. Dither between the former. Stack with a modern clipping algorithm. Cheers

Hi Lovely shot. Some nice detail emerging. A few bits of hands on advice... 5D iv noise? Bands? So lose the dark frames. Use flat and bias frames only. Add some dithered -say about 12 pixels- frames next time out. process the whole lot of them again without the dark frames and stack using a clipping algorithm. Most of the noise will be gone. Instead of DSS, try Siril. Lastly, add sheets of paper between light source and lens to adjust the exposure for the flat frames to at least 1 second and take them in a dark room. (Had a go at the stars. Maybe have a look at polar alignment?) Cheers and HTH

Yes. Anything near the mirror causes light spread. No theory i'm afraid, just hands on, but our conclusion after correcting several pds' is that it's best (and easier) to have nothing in the light path. Each sw is different though. Try it on yours, With and without, With and without... until you get fed up dismantling/collimating and re-aligning the thing, decide you can't see any difference anyway or drop the mirror cell in the dark, breaking the main mirror. Whichever comes first! Cheers

Hi We find that nothing in the way of the mirror works best.

Hi Yes but IMO, better to hold out for the 130. Cheers.

ST4 it is then. On camera only. There's an overview here. Good luck and HTH

Assuming the mount has a suitable port, just as you envisage, but with the addition of a mount to laptop cable. HTH

Hi If you want to stick with st4, we'd recommenend, in addition to the camera - mount connection... ...connection as an aux device between computer and mount. This will allow you to both re-use your calibration and add the ability to control telescope pointing from the computer too. Cheers and HTH

Fatter stars and diffraction spikes due to -presumably- the edge of the baffle introducing thousands of tiny intrusions, gaps and reflections of its own. But IIRC, there's little in it. We haven't had a 130 for a while, but every example we've seen behaves differently You'd have to test it yourself. If you have only one though, it's a pain. In the end, if you're satisfied with what you have, just leave it. Anything though, is better than the protruding focuser and the mirror clips;)

Maybe on older models. The 130 mirrors we've seen recently have had a bevel, so introducing fewer irregularities that an aperture mask. Easy to test without the clips and with/without the aperture mask of course. Cheers

+1 It prevents lateral mirror movement and in so doing represents the only way we've found to retain collimation during and between sessions. No need for mirror clips (and hence no aperture mask) either.

The z's flange to sensor is 16mm, so the adapter should put the m48 shoulder of the cc at a distance of 43mm from the flange on the camera. If you still want to keep the Baader t2, this type is the closest we found:

Hi Lovely shot. This is going to be a very nice 130. Baader cc? Before going further, perhaps best to tackle the astigmatism, which to a greater extent is helping keep the stars triangular in shape.. Unless you're accurately square and have exactly the correct sensor distance, there'll be astigmatism. The only way we've found with the Baader cc is to lose the -awful- m42 adapter and space it properly from the m48 shoulder. The best spacing is around 58mm to 59mm. The method is described here, but check carefully the spacing you need for the z50. If you've one of the old compression ring fittings with only 2 screws, you'll also need to drill and tap a third. However, due to the undercut on the cc -which causes tilt- it's best to just use the old ring with a third screw, as here. Push the camera assembly tight up against the collar as you tighten each screw a little at a time. HTH

Hi It depends which channel you choose, but if you can't live with it, it's easily corrected in software. Here's red, which is the worst, along with an attempt at correction. But hey, it's a nice shot. Get the colour sorted out and you're there. +1 @Chefgage's tilt suggestion. HTH

They never have for us;)

IMHO, neither. If you have only a standard camera, all you're going to achieve with filters is longer exposure times and false colour. All a filter does is remove light. It makes the camera less sensitive. Stick to galaxies, star fields and clusters and you'll get some nice shots Modern apps make the effects of any light pollution you may have easy to remove. HTH

There's a good method described here. Open source download here. HTH

Is this any use?

No. We try anything once or twice, but otherwise, we're strictly hands on. We do what works, not that which theory suggests should work. We gave up using any type of dark frame. It's just more to have to correct further down the line. This is just us with eos700ds. We'd recommend trying @lock042's suggestion. It works fine here. Cheers

Here is our test. These are the same portions of a fits of 5208x3476 from an eos700d. One with a master bias, the other with a constant median value.