Jane C

I use an 11" XLT with a 0.63x focal reducer, both from Celestron, and I mainly photograph galaxies, using a camera with an APS-C sized chip (a cooled ZWO ASI2600MC). My experience is that the stars are good and round all over the image. For me the irritants are as follows. I need to re-collimate every night, which burns up time, a precious asset in the cloudy climate of South Wales, where I am unlikely to experience a fully cloud-free night. I probably also need to do this after a meridian flip. Because of light pollution I lose a lot of the image space on the chip to reflected rings. Therefore the Edge HD would have advantages if I didn't have to keep re-collimating and if I could send the reflections to places off the chip by using a higher magnification. Holding focus is a puzzle to me. The FWHM I achieve often worsens during a long exposure, but it almost equally often improves. I put that down to seeing, which is rarely great in the UK, but that's a guess.

Hi: I'm starting to see adverts for a new generation of very black paints based on carbon nanotube technology. (Before any clever person says anything, yes I have been living under a rock.) My scope and peripheral tubes do suffer a bit from internal reflections, which are easily picked up when I photograph galaxies. (I won't embarrass the manufacturers by naming names.) Has anyone had a go with these paints? If so, what problems did you encounter? Thanks, Jane.

I use live stacking, not for the final image, but because it prevents clogging up disk space with frames the live stacking rejects. The usual reason for this is passing cloud. You also get some warning if you are getting nowhere before you invest time . For example, if the sky transparency gradually drops, which it often does in South Wales, without it being immediately obvious to the unaided eye, you know it's time to pack up and get some sleep.

Very interesting & congratulations. I tried it with my new Optolong Venus filter and a colour camera. Not a roaring success but I didn’t get far before cloud arrived. Weirdly the image came out in red & yellow. I also found that I needed 1/15 sec exposure with a C11 SCT. I’ll try again with a mono camera

Hi: I have been using SharpCap for planetary imaging ever since I changed computers and found that K3CCD had stopped issuing licence keys, which must have been five years ago or so. Now I have branched out into galaxy imaging, and find that SharpCap can do everything I want. Indeed it can do a whole bunch of stuff I have not yet tried. I see no reason to change. Here's a couple of recent examples of galaxies. (They are only jpegs, to keep the file size reasonable, so they aren't as good as the 16-bit images.) M31 got 4.3 hours over two nights, and M66 got 2.55 hours over one partly cloudy night. The images were then processed in PixInsight.

I already have Bob's Knobs, but thanks for the thought. 🙂

Hi: I'm able to collimate my C11 just fine. I use the GoldFocus system with the supplied Tri-Bahtinov mask. The frustration is that it doesn't stay collimated. I'm wondering why this is. I have various thoughts. I should perhaps mention that the telescope is fixed in an observatory building. 1. It's a differential cooling issue. We have had some hot weather lately in Wales. (Cooling is well known to affect focus, so why not collimation?) 2. Something is loose somewhere. I don't think it is the secondary mirror: I make sure all three Bob's knobs feel a bit tight. What else could be loose? If the primary is loose, how do I fix it? 3. Something totally else. Any suggestions welcome. Thanks in advance, Jane.

Amen! 🙃

I have the same camera. For planets I use: SharpCap for capture, Autostakkert for stacking, Registax for wavelets & gamma. Shoot your frames as a .ser file and don't use the full frame size (you can reduce it in SharpCap) or your .ser files will be as big as the planet you are trying to image 🙃 .

On the subject of focusing by looking at images on your screen, I would also add that varifocals make an annoying problem worse. There is only a very small "sweet spot" of sharp focus for any distance. If you look at a slight angle, you can't see well enough to focus. (I'm stuck with glasses because I have a ~3 dioptre cylindrical correction, but very little spherical correction, so a contact lens won't orient in my eye. Apparently if I were also very short sighted, it would be possible to orient one, but I'm not.)

I can think of very little to say about focusing that is printable, but a lot that would get me banned from this forum in an instant for un-ladylike language 🤣. I wonder what you think about focusing and collimating on a nearby star with Bahtinov and Tri-Bahtinov masks respectively, then slewing to the planet?

I agree with MarkRadice. I use a flip mirror. As it happens, I use the one from Baader Planetarium. I keep a 40mm eyepiece in it by default. But I also have a good quality, long eye relief 20mm eyepiece with cross-hairs. Finally, I control my equatorial mount with Celestron's own software, CPWI, from a PC. I had to rebuild my database of stars in its "model" of the sky after a PC crash, but I now have about two dozen stars in it (and I have learnt how to back it up). That's generally accurate enough that I don't need the finder scope unless I do something silly and knock the scope or hit the wrong slew button. As the planets ply their orbits and move, I keep adding nearby stars to the "model". Doing this works MUCH better than using the GOTO on the handset. 🙂 Jane.

"This boils down to how you do your planetary imaging. I guess the most common method is to take a video and stack the individual frames. I've just ordered an ASI224MC for planetary imaging, the reason being my ASI2600MC puts out file sizes in excess of 50Mb per sub (or each frame in the case of lucky imaging). The new camera will also manage 150 fps compared to 3.5 on the 2600. (or around 17 with your 294. Graeme" Hi Graeme, I get a very fast fps rate with my ASI294. ZWO claims 170 fps. I think that I have seen better than that when I cut the image size down to 320 x 240, but I'm sure they have to be careful with their marketing claims. The one of the new range that caught my eye was the ASI585MC, but I see that part of the penalty is that the max claimed frame rate drops to 46.9. That's only 27% of the speed of the ASI294MC. I suppose that this makes sense given the relative size of the chips. I wonder how fast the newer camera is when you cut the image size down? Jane. 🙂

There are some quite nice results from these cameras on the ZWO Facebook page https://www.facebook.com/groups/zwoasiusers. I'm an incurable devil's advocate I'm afraid. I'd be interested to hear people's views on why I'd need a separate planetary camera when I have a good ZWO deep sky camera. (I should declare that I own a ZWO ASI290MC planetary camera and a ZWO ASI294MC Pro deep sky camera.) Thank you. 🙂

Hi: If all other things were equal, is native 16-bit a significant advantage over 14-bit images converted to 16-bit images? Thanks, Jane.

My fixes to the problems. 1. Use Loctite 243, the grease-tolerant version, to affix the long threaded stud. 2. Affix two 1/2-inch -13tpi stainless steel nuts, and use big wrenches to screw them very tightly into one another. The stud is stainless, so I wanted to avoid mixing materials to deter galvanic corrosion. Two nuts tightened into one another tend not to come undone.

This product is so close to being an excellent product, but someone was half asleep when designing it. So I am now going to have to spend time & money sorting it out. 1. The main thread, a 1/2 inch UNC thread (13 turns per inch) is attached to the Vixen clamp via a small screw. But how do you tighten this screw without gripping the main thread so hard you are likely to damage it? There's nothing else to grip. 2. The handle to turn the thread on the clamp is too short, so that it bumps into the counterweight. That's a simple design oversight. It only needs to be about half an inch (12.7mm) longer. This means you can't screw the weight down tight. 3. Finally, there is nothing to stop the counterweight gradually unscrewing over time and falling off. It's heavy enough to hurt and do damage. Problems 1 & 3 could be easily fixed with an internal thread like at the other end, into which you place a screw with a big flat head with a knurled rim like the one shown. The weights would then not fall off so easily, and you could react the torque needed to tighten the screw at the base. Dear ADM, you can have my ideas to upgrade your product free of charge.

Thanks everyone. Debayering worked. 🙂

And yes I know it's out of focus. The original attachment shows that I am using SharpCap Version=3.2.6480.0. 🙂 Regards, Jane.

I’ve just bought a ZWO ASI294MC Pro Camera. With the settings shown in the attachment, my png images came out in black and white, not colour. Can anyone see what I’ve done wrong, please? I know it's a colour camera because the images on my computer screen were in colour. Thank you 🙂 M13_00003.Info.txt

Well, I've fitted the new O-ring. This afternoon in the sweltering heat I aligned the finder on a mountain-top antenna two miles away. Just now I fine-tuned the alignment on Arcturus. Let's hope that's the end of that little saga.

My new O-rings have arrived. When I examined the old one, I found several straight cracks in it, all perpendicular to the circumferential direction. The straightness of the cracks is a classic sign of fatigue damage, due to cyclic loading. In principle this could be worsened by ozone damage, though I don't think there'd be a source of confined ozone in my draughty observatory. (I don't fix the draughts to stop mould forming on the plywood walls.) I suspect that the cause is daily thermal cycling. I never imagined that there would be a lot of thermal cycling but evidently there is. The other place where I am critically reliant on stretched rubber belts is in the transmission from the motors to the RA and Dec drives on my CGX mount. Perhaps I should also lay in spare rubber drive belts for those. 🤔

Thank you all for your suggestions.

Mystery solved. All I had to do was look at my finder. 🙃 The O-ring holding the finder at the objective end has snapped. It's a 60mm x 50mm x 5 size. I have ordered a pack of five from Amazon Prime for £3.99. They arrive on Tuesday. I'm still a bit tempted to get a Telrad. I had one on my old 8" Newtonian. That finder and I got along just fine.

It’s a straight-through finder.