ASIAIR Image Sizing Question

[gcooksley]

Hi, I might have a dumb question but I will ask it all the same. 

I am using a ASI533mc with an ASIAIR mini with a 750mm focal length dob telescope on an EQM35 mount. I use my phone to control and capture the images from the mount. Last night I captured M31 for the first time ever which I was very excited about. The images on my phone looked really good for my first time capturing it (I did 204x60s captures). When I connected my laptop to transfer the images over, it says the image size was 3008x3008 resolution but, i suppose I am wondering if this is what the image should like on my computer? I would have expected a bigger image to be honest. I will attach two screenshots from my laptop that shows what i am seeing. The first image is what my screen looks like when I first load up the FIT file (not the jpeg). The second image is what happens when i make the image size 1:1 and its pretty blurry and does not look good at all. 

Is this what I am supposed to be expecting? (maybe my expectations are too high?) Or potentially just error by me for not being in focused enough? Or maybe just another equipment thing. I do have a newer AP refractor telescope that I will be buying shortly so maybe the quality of the lens in my current telescope could be a reason? What do you guys think, I just am not sure what to expect quality wise for an image on my laptop and any feedback would be appreciated, I am trying to learn as I go in this hobby and it can be tough lol. 

[Elp]

The resolution is correct for that camera. The image is blurry because your focus is off, did you use the focus routine as it's the first item on the list on the asiair on the RHS menu options so should be done before anything else. Try to find a medium sized star (not a tiny one or a large one), click on it and the app will zoom in to that star, and focus until your FWHM is as low as you can get it. Focus then step back as any vibration or touching of the setup will affect the result, keep looking at the graph and FWHM numbers until it's approximately settled due to seeing conditions, and it's as practically low you can get it, you'll know if you're very close as the tiniest of stars will appear within the starfield.

The dob should give sharp views but an apo refractor will be sharper still and you can get lower FWHM values all things being equal. Longer focal length also affects the achievable FWHM so you have to focus to the best you can get it. You could always try a bahtinov mask to check focus on a bright star but I find the asiair focus routine so good it's not necessary.

 

[Elp]

Also if you're not using a UV/IR block filter or a luminence filter the stars will also be slightly larger due to IR but it's quite minor.

[gcooksley]

23 minutes ago, Elp said:

The resolution is correct for that camera. The image is blurry because your focus is off, did you use the focus routine as it's the first item on the list on the asiair on the RHS menu options so should be done before anything else. Try to find a medium sized star (not a tiny one or a large one), click on it and the app will zoom in to that star, and focus until your FWHM is as low as you can get it. Focus then step back as any vibration or touching of the setup will affect the result, keep looking at the graph and FWHM numbers until it's approximately settled due to seeing conditions, and it's as practically low you can get it, you'll know if you're very close as the tiniest of stars will appear within the starfield.

The dob should give sharp views but an apo refractor will be sharper still and you can get lower FWHM values all things being equal. Longer focal length also affects the achievable FWHM so you have to focus to the best you can get it. You could always try a bahtinov mask to check focus on a bright star but I find the asiair focus routine so good it's not necessary.

 

okay cool, thank you for responding! I have just been using the preview setting with around 5 second exposures to see if i was in decent focus or not. I will have to try that focus routine you mentioned instead

[Elp]

It okay to use preview, I still use it prior to starting a run as a final check. But the focus routine is real time so much easier to adjust focus.