What am I doing wrong?

[Gralston92]

Hi all, first post so any help will be greatly appreciated. I recently bought a skywatcher 130pds (after the amazing reviews from almost everyone). I have a coma corrector and 600d dslr. Out trying to get started last night and could grab the moon n problem, yet when I moved to stars, focused with mask and raised exposure time it didn’t do much good. I have basically a single dot as a star. (also have a clip in LP filter) which makes me think I’m doing something wrong or missing the point. I went from 30 secs - 1:00 and still doesn’t seem to collect any more. Thing I’ve noticed is my aperture setting on camera says it can’t be set as there is no lens but I’m into the focuser on the scope?? I’ve attached a few photos to try and explain what I mean. Again, any help would be greatly appreciated.

[PeterCPC]

You are not going to see much with the exposure set to 1/320. Using something like BYEOS or APT (free) will make it so much easier and you can set the exposure to as much as you can get away with without trailing. Also that star is not in focus. Using Live View - centre a star then use + to zoom into the star and then adjust the focus until the star is as small as you can make it.

[Gralston92]

I’m not using any computer software just dslr and mount. But still thought surely it would collect more than that? I focused with a bahtinov when zoomed in.

[Shimrod]

11 minutes ago, Gralston92 said:

Hi all, first post so any help will be greatly appreciated. I recently bought a skywatcher 130pds (after the amazing reviews from almost everyone). I have a coma corrector and 600d dslr. Out trying to get started last night and could grab the moon n problem, yet when I moved to stars, focused with mask and raised exposure time it didn’t do much good. I have basically a single dot as a star. (also have a clip in LP filter) which makes me think I’m doing something wrong or missing the point. I went from 30 secs - 1:00 and still doesn’t seem to collect any more. Thing I’ve noticed is my aperture setting on camera says it can’t be set as there is no lens but I’m into the focuser on the scope?? I’ve attached a few photos to try and explain what I mean. Again, any help would be greatly appreciated.

 

 

In most cases a single photograph of a star is not going to show much more detail. If you have a view of the Orion Nebula (which is an easy target), then 30-60s will give you a reasonable amount of detail. Oher targets to consider would be the M51 or M31 galaxies, although I think M31 at the moment sets before sunset - or at least it will be very low on the horizon.

In terms of your camera, you should drop the ISO to 800 which is the recommended maximum for astro work - beyond that you introduce noise with no gain. As you have discovered, the moon is a nice, easy and bright target - short exposures of a fraction of a second are all that is needed to capture a nice level of detail. You might want to consider capturing a video of the moon and using something likel AutoStakkert to stack the resulting video. This is the same technique used for planets and caters for a 'wobbly' atmosphere, selecting only the best out of several thousand frames. Deep Sky Stacker (often referred to on here as DSS) is another free stacking tool that is used for deep sky objects like galaxies and nebula. For the Orion example above, you might try capturing and stacking 20 or 30 30second frames to bring out more detail. Some of the pictures on here can be made up of hours of image capture!

You cannot change the aperture on your camera - this is done in a camera lens using electronics to open or close a diaphragm to restrict the amount of light through a lens. None of these electronics exist in the telescope so the aperture is that of the telescope. You can make a manual aperture mask and place it over the front of the telescope to change aperture, but you generally want to capture as much light as possible.

[Shimrod]

14 minutes ago, Gralston92 said:

I’m not using any computer software just dslr and mount. But still thought surely it would collect more than that? I focused with a bahtinov when zoomed in.

Your second photo shows the star looking like a little doughnut which indicates that it is out of focus. When using the Bahtinov mask you need to get the spike right down the middle of the star. If you can connect even a small tablet to the camera you will find it much easier to do with a bigger screen than the one of the back of the camera (even when zoomed).

[Gralston92]

Thanks I’ll bare that in mind. I was only trying 30 sec photos and iso between 800-6400 but I thought I would have revealed a lot more than that. Could see more looking up myself that what the camera revealed which seemed odd to me. Try again then ha😴
 

Thanks again for your reply!

[Gralston92]

Shimrod that second photo is due to me moving when taking the photo on my phone this morning. I used the bahtinov and had it focused and locked in. Even at that I’ve attached one that’s got a decent focus and still hasn’t exposed that much?

[Shimrod]

39 minutes ago, Gralston92 said:

Shimrod that second photo is due to me moving when taking the photo on my phone this morning. I used the bahtinov and had it focused and locked in. Even at that I’ve attached one that’s got a decent focus and still hasn’t exposed that much?

With a star you might get a bit more colour but that is about all - for an 'interesting' photograph you want to be aiming at a deep sky object such as a galaxy or nebula. There is a table Messier targets that gives a relative ease of observation of Messier targets - pick the easiest target that is still visible for you and aim for that. If you look at Hubble images on the Nasa website, you will see that outside of the imaged object, stars are just pinpricks of light.

The second picture definitely shows a telescope that is out of focus. If you look at this image you will see what I mean - even with a bahtinov mask focus can be quite fiddly to get right as each touch of the focuser can send vibrations through the scope and you have to wait for it to settle.

 

Edited April 17, 2021 by Shimrod

[Gralston92]

No problem mate I’ll take a bit extra time trying with the mask. Thanks for your reply. Think it’ll just be a case of try again and again 😅just thought that even all that considered I should still have gathered more light in the pictures but not happened for me yet. 
 

Cheers again 👍🏼

[Shimrod]

1 hour ago, Gralston92 said:

No problem mate I’ll take a bit extra time trying with the mask. Thanks for your reply. Think it’ll just be a case of try again and again 😅just thought that even all that considered I should still have gathered more light in the pictures but not happened for me yet. 
 

Cheers again 👍🏼

If you fancy a bit of DIY you can make yourself a cheap, battery free focuser for around £10. It will help eliminate telescope shake and give you a finer focus control. DIY electric focuser