don4l

Excellent! Hopefully the Siril team will produce a simple tutorial at some point. I think that the confusion arises because it looks like the "working directory" is where the source files must exist. If they used the term "Temporary directory" I think that it would be much clearer.

Sorry, I think that I left an important bit out. Have you clicked the "Convert" button on the "File Conversion" tab? This will make copies of all your images in the "working directory" and also a file that ends in ".seq". The ".seq" file should then appear in the selection list on the sequence tab. It all seems very counter intuitive at first, but once you process a couple of images, it becomes very quick to use.

That's a pity. I was hoping to find something that took up less back focus. To be honest, I am very happy with the results that I am getting at the moment. They are much better than I was expecting, and anything that I have managed before. I also have a much clearer view of the options. The helical focuser appears to be working far better than I expected. The Tal seems much easier to focus than my F5 refractor. I'm quite shocked by the difference.

Try this. Create a new directory in the directory where your images are. Call it "SirilTemp". Open Siril. It should display the "File Conversion" tab. Click the "Change Dir..." button and choose the (empty) directory that you created above. Type a suitable name (eg "M51") into the "Sequence name" box. Now use the "+" button to select the images that you want to process. They should all get listed in the "Source" box. You should now be ready to continue. When you are finished, you can move the final stacked image somewhere else and delete the rest of the files in "SirilTemp".

I've taken some photos, and noted the measurements. I'm posting this in case anybody finds it useful. I'v also discovered that I have at least 17mm spare backfocus, and I can get another 25mm at least!! The first photo shows all the bits labelled with their dimensions. The 7519 filter holder is just used as a spacer, so I can lose it if I want to add something else. I can also get a shorter 2" adapter, which could save at least 20mm. I also have another nosepiece for the camera which uses about 5mm less. The second photo shows all the bits screwed together ready for the camera. This setup reaches focus with a few mm either side. I'm going to investigate field flatteners to see if something exists which will fit. My big question concerns field curvature. I really don't know anything about this (apart from the elongated stars).

Thank you. To say that I am pleasantly surprised would be an understatement! I'm no expert, but these images are way beyond anything that I was expecting. I've got all sorts of plans for it.

I thought that might be the case. Can you remember if you managed to get close to focus with any of the flatteners? I've got at least 10mm spare at the moment. I'm fairly sure that I could conjure up another 10mm by getting a freind to use his lathe on the M57 to 2" adapter. I could get even more by using a shorter nosepiece on the camera. I will take some photos this evening which will make things clear. (I'm no longer worried about reducing the focal length. I seem to be getting along fine with 2000mm.)

I thought that I should update this in case there are any Tal200 owners wanting. I've had another couple of clear sessions over the last week. Things are going far, far better than I expected. My "wobbly" focuser does not seem to be a major problem at this stage. I guess that these things are not as critical at F10 as at F5! I now think that a field flattener would be a much more useful use of the limited backfocus. As far as I can tell, I have an 18mm circle that is fairly flat. Beyond this, things quickly deteriorate. My camera chip is 27 x 18mm, so there is quite a bit of data being cropped off. I've put some images below. I have added some Red and L (60m) to M82. I hope to get another couple of hours of Ha on this. It is already my best ever Galaxy image. I also took an hour of L on M51 and added it to an image that I took at 850mm FL. This has improved the image no end. It is also the first time that I have mixed data from different scopes. I had a look at supernova sn2019ein in NGC 5353. The attached image is 3 x 300s. at m14.2 it showed up clearly in a single shot. In fact, it would have been obvious in 60s subs. I've also had a go at imaging the "jet" in M87, which can be seen clearly in the last image.

A lovely image. I would never thought of trying something like this.

I was getting odd results with the platesolving. Sometimes I couldn't platesolve an image at all. Other times I would swap from Astrometry.Net to ASTAP, or visa versa to get it to work. Last night I started dark subtracting before solving and it kicked into life. Images that wouldn't solve at all suddenly solved in under 2 seconds. This probably depends on how noisy your camera is (mine has some real humdinger hot pixels).

An update... I needed to get a proper handle on the backfocus, so I had a go at reassembling my old helical focuser. I'm lucky that I did this, because I have about 16mm less than I thought (139mm Vs 155)! Everything is now connected up, and working much better than I expected. I've been practising on M82 with subs up to 10 minutes long. The attached image was collected over the last two nights. Unfortunately, I have to be up in the morning for work, so I have only got limited data so far. This image has no Red data, only Ha, G and B. It consists of 60m Ha, 35m Green and 25m Blue. The resulting colour is not great, but I'll add some red and maybe Lum when I get a chance. To say that I am chuffed would be an understatement! I can now take my time to decide what I need to do. I'd like to get a focuser that could have an autofocus, but I woud also like to fit a field flattener. I haven't seen any focuser that leaves enough space for anything else!

I was thinking of ordering one about this time last year. Unfortunately, Crawmach all seems to have gone very quiet.

Thank you for that. I hadn't realised that SCT focusers did not protrude into the OTA! When I posted my question, I wasn't very optimistic about getting anywhere. Now, it seems that I have some choices in front of me, The forecast says that it is going to be clear tonight, so I will see if I can connect up my old wobbly image train and get some accurate dimensions for backfocus. Ideally, I would like to get a field flattener into the system, and if I could reduce the F/L to about 1500mm, then I would be very happy indeed!

Your plan to spend the summer playing with the kit is the best thing that you could do. I got back into imaging this time last year. I spent the summer learning the equipment. This turned out to be the best decision that I could have taken. I agree with the comments about globular clusters. M53 and NGC5053 would make a good pair to practise on.

Have you measured the backfocus? I'm wondering if the F10 and F8.5 versions have the same backfocus. Mine is F10, and I have measured it (roughly) at 155mm from the rear plate. Another question ... do the drawtubes in SCT focusers retract back into the OTA?

Top marks -Thank you! That looks very promising.

Thank you both for your answers. An SCT adapter plate would be excellent. I'll have a Google, although I am not hopeful. I do have a plate with a female M57 (Borg/Hutech) thread. However, the only focuser that I can connect to this is a helical one that isn't quite able to take the weight of the camera (and I've managed to break it). I do have a 2" adapter that I can screw in, so if I could find a focuser that fitted into an existing 2" eyepiece holder, then I would be able to get going.

I've got a Tal200k that I would like to use for imaging. I think that I need to change the focuser. I'm really struggling to find a focuser that will fit on the back of the Tal. I used a Borg helical focuser in the past, but I don't think that it is strong enough for the weight of the camera etc. Has anybody else adapted a Tal for photography, and what did you use? The camera is an SBIG6303. I can easily put a 2" nosepiece on it, or I can get to M56 or M54 threads. The main problem is that most focusers have a drawtube that extends into the OTA when retracted. The hole in the back of the Tal is only about 40mm diameter. Any suggestions for a suitable field flattener, or focal reducer would be very much appreciated.

I Imaged all through last summer especially in H Alpha. I'll do the same again this year. The only thing that I found was that you have to be a bit more aware of haze, or thin cloud.

I've just moved to Indi in the last month. I've given up with Ekos/Kstars because they seemed too closely connected to the Indi server. The server and the "client" (Ekos) should be completely separate. This caused me some problems with software crashing. I've been using CCDCiel instead, and after a short learning curve, I am getting along brilliantly with it. For astrometry, I have both Astrometry.net and ASTAP. If you are having problems solving, then have a look at the FITS header in an image file to check that the focal length and pixel size are set correctly. I started with the Pi 3+. but quickly came to the conclusion that it couldn't move large files around quickly enough. I'm now using a refurbished Dell Laptop ( cost £230.00 from Dell) and it does the job perfectly. To start and stop the Indi server I use "IndiStarter" https://sourceforge.net/projects/indistarter/ There is also a simple client "Indigui" which allows clear control of the individual drivers. I think that IndiGui is included with Indistarter. I haven't managed to figure out the limits yet, but I did have a problem with the park position. The default position was pointing somewhere silly, which caused the mount to "crash" the ota into the tripod. To fix this I powered up the mount in its home position. I started Indi, and on the EQMOD driver I went to the Site Management tab. There (beside Park Options) I clicked "Current" and then "Write Data". This seems to have fixed it.

That's an excellent result!

Very enjoyable, professional, educational ....brilliant!

That looks perfect. I must say that once I had figured out the zooming bit I was very happy, but this will save new users some confusion. I'm currently moving to linux. Tonight, I tried CCDCiel with both ASTAP and a local Astronomy.net. Platesolves were *much* faster on ASTAP (with G17) - 1 second versus 28 seconds. I used two copies of the same image.

It shouldn't be in the centre of the eyepiece. I've attached a screenshot from Cartes du Ciel. The NCP is at the centre of the two circles. Polaris rotates around the NCP roughly every 24 hours. The circles represent the view through a 25mm eyepiece that has a 52 degree field. The smaller circle is with a 2000mm focal length scope, and the bigger circle is for 850mm. These circles will only be useful if your OTA is mounted parallel (orthoganal???) to the mount. You can loosen the clutches to rotate the mount to correct the "home" position, but I don't think that it would be worth it if you are setting up the tripod every session. However, if you do find that it is correct one night, then put a couple of pencil marks on.

Nice! I've tried to capture the jet and failed miserably. Well done.