Celestron4

Here's a picture of M51 taken earlier in the year. It has roughly 2-3 hrs of exposure time (mostly in 3 and 5 minute exposures at ISO 1600). It also seems to look a little bit 'washed out'. Any ideas why?

Looks better! I will add more image time which I hope should make a difference. I have attached the .tiff file from DeepSkyStacker. I'm wondering whether it is only the way I'm processing the images or something else? Night 1 Stack .TIF

It’s quite possible that my processing is the issue. I use DeepSkyStacker and bring the stacked image into photoshop. There is just over an hour worth of image time in it at the moment which might also explain the ‘washed out’ appearance. I used 5 minute exposures at ISO 1600 of that helps. Most of the images were taken when the moon was below the horizon or setting so shouldn’t be the cause. Any other ideas?

I have class 4 Bortle skies according to the ClearOutside app. Would a broadband filter work with an unmodified DSLR? I know that using narrowband filters with an unmodified DSLR is not ideal and was wondering if broadband is the same.

My camera is unmodified. I am looking at one-shot colour CCDs at the moment if this helps.

I have a Celestron focal reducer, not sure if it acts as a coma reducer though. I’m looking at one-shot colour CCDs at the moment. Would a different camera help with the coma?

I have had a go at photographing NGC 281 (Pacman Nebula) and am starting to get some results from 16, 5 minute exposures. I have posted the processed image below. I use a Celestron Nexstar 6 Schmitt-Cassegrain telescope on a Celestron AVX mount. My imaging camera is currently a Canon EOS 1100D DSLR. I realise that more image time will bring the nebula out more clearly and I am aiming to get more images when I can. Is there anything else I can do to improve my image and is my camera going to limit what I can do?

I have had another go. I gave the polar drift alignment and Guide Assistant more time (roughly the worm period for my Celestron AVX mount (approx 400-500s, I think). I decided to have a go at photographing NGC 281 (Pacman Nebula), it doesn't show up as well as M51 but starting to show itself in s a stack of about 15, 5 minute exposures. The tracking in the centre of the image is much better but the issues now lien the outer edges. Is this something to do with my camera? I have attached a test image, the Guide Assistant readout and the log file, I hope they help! PHD2_GuideLog_2020-07-31_000005.txt

I use a Celestron AVX mount, forgot to mention that... Exposure times not an issue, just minor tweaks needed to minimise star trailing

I have a 6” Celestron Nexstar Evolution. Schmitt-Cassegrain at the moment. It’s worked quite well for what I have looked at so far (M51, M101, M42 etc). I still have some tweaking to do regarding the tracking (currently having issues with 5 minute or longer exposures) and can probably get more out of the DSLR but I realise that I might struggle with imaging some objects, nebulae in particular. I have mainly been focused on galaxies so far but Iam looking at taking some pictures of NGC 281 (Pacman Nebula) and will likely look at the Flame, Horsehead and Orion nebulae in the winter. I hope this helps!

I am looking at changing my imaging camera and have been looking at cooled one-shot colour CCD cameras in particular as they seem a logical step up from the Canon EOS 1100D DSLR I use at the moment. My budget would ideally be £1000 or less if possible. ZWO seems to be a name that comes up a lot and Altair Astro have some lower priced ones on their website that look to be good options. Can anyone give me some advice on which camera to go for please?

I am looking at getting a new astrophotography camera and was hoping for some advice. I currently use a Canon DSLR which has worked well with my 6" SCT (I use a focal reducer which brings it to F6.5, I think) so far but its limitations begin to show during warm nights during the summer and as I move towards more 5 minute exposures. What are my best options without having to spend too much? (preferably under the £1000 mark).

I have upgraded to an equatorial mount and was wondering whether I could use the go-to Alt/Az mount that came with the telescope (a Celestron Nexstar Evolution 6) for taking tracked exposures with a DSLR and telephoto lens. Would this work? If so what would I need to buy to attach the DSLR to the mount? I realise that it is not an ideal setup and am looking at the tracking mounts from skywatcher and iOptron but am wondering whether my old mount could work as a stop-gap.

I have used the Polar alignment feature in the past and it has got me quite close but I didn’t use it this time as the polar drift alignment tool on PHD2 required little adjustment (the required star position (red circle) was within the green square). I ran the Guide Assistant until the numbers for Right Ascension, declination. And polar alignment had settled as is stated in PHD2 when you run the tool.

The test image is not ideal. It was a very warm night (DSLR sensor temperature showing as 30 degrees on Astrophotography tool) and close to the Solstice so quite light and very noisy

Finally managed to have another go with PHD2 last week. I have attached the Guide Assistant readout and log file. along with another test image. The polar alignment seems to have been quite good and the mount was nudged north until the star visibly moved before calibration. I have also upped the guide speed to 0.8 and subsequently 0.9 but I still seem to be getting star trails with 5 minute exposures. Any ideas as to why? PHD2_GuideLog_2020-06-24_224627.txt

I used the manual guiding on PHD2 to move it northwards (basically held the north button) until I saw the star move. I will try using a faster guide rate see if that works!

Thank very much for your help so far! I have attached the data from a few nights ago. I used the manual guiding tool in PHD2 to nudge the mount north before calibrating which seemed to reduce some of the north movements. The log file shows 'guiding stopped 03.06.2020. My DSLR imaging camera died and caused both PHD2 and Astrophotography tool to crash and have only just managed to close them properly. PHD2_GuideLog_2020-05-30_121318.txt

Had another go. I have attached the new guide log and guide assistant page. I used the PHD2 polar alignment tool which seemed to help improve my alignment. I managed to get some just about usable images such as the one attached below. Moving in the right direction and getting closer! PHD2_GuideLog_2020-05-30_000728.txt

The polar alignment tool on the mount works quite well most of the time and have not had to move my alignment at all when I use the tool within PHD2. I will try using the tool in PHD2 rather than on the mount and see if this makes a difference.

I've had a look at the mount. The Backlash compensation seems to be set to 0 for both Dec positive and RA negative as you can see. I have also attached the settings showing RA and Dec Indexes and the Cone value if these help. I used the settings recommended by the Guiding Assistant on PHD2 which may have lowered my tracking rates. I leave them out tracking the object while it calibrates. Its seems to work fine for 3 minutes but problems occur at around 5 mins. I have the guide camera set to 2s exposures which seems to work. I will change the tracking rates to 0.90 on the hand controller see if that makes a difference.

Finally got a clear night. Set up the scope and AVX mount as before and connected to PHD2 using the on-camera connection. I ran the Guiding Assistant as you said and I have attached the results below. It shows that my polar alignment was slightly off even though I ran the polar alignment tool on the mount which usually gets me quite close. I have also attached one of my 3 test images (I take them in raw form but have converted it to .png for ease of upload) which should show the issue. Its close but not quite there. Any ideas? PHD2_GuideLog_2020-05-28_232456.txt

I have been using the on-camera connection. Is this part of the issue?

Just realised that the Guidelog shows every time I stopped and restarted the guiding. The goto system on my mount wasn’t being helpful (M101 was just outside my camera field of view and took some fiddling to get it right. My calibration was done in the area of the target. Is this best or should I be using a bright star near the pole?