ASI585MC – Starting out in EAA

[Fir Chlis]

I’m sure this is a common story, but, after years of visual observation, I’ve recently dipped a toe into the waters of EAA – and what a difference! No more twisting and turning to look in the eyepiece of a Newtonian, no more freezing out in the dark, no more exhilaration at seeing a tiny fuzzy blob, but also no more of the amazing clarity of the Pleiades seen through a visual eyepiece, which I don’t think can be repeated on a computer screen.

With advice from FLO, I got my Skywatcher 200PDS/HEQ5Pro set up for automated control from a laptop, and bought an ASI585MC, as an affordable camera that should be suitable for EAA for DSOs. Now I can sit indoors in comfort, connected to the controller laptop via VNC, and I’ve been very happy with the results so far. It’s not astrophotography quality (which I don’t expect from EAA) but what I’m seeing now compared to visual observation is amazing.

I’m an avid reader of manuals, so I’ve gone through the Sharpcap manual and numerous YouTube videos, but it’s a steep learning curve, frustrated by the familiar problem of clouds night after night.

These are pictures from my first session (M81, M82, and M1), like a kid in a sweetshop, picking off as many Messiers as I could without really knowing what I was doing. All were at gain 252 (magic number for the 585MC), 8s exposure, no darks or flats. M1 has been cropped and enhanced using Registax, the others are as seen, saved from Live Stacking.

Next session had a very bright moon, and I was astounded at the detail in the image. Jupiter seemed blurry during live stacking, but after stacking the video file in Autostakkert and enhancing a bit in Registax, the result is OK. But with my setup I’m not sure if I will get any more detail, as Jupiter is very small in the FoV.

 

Third session, I tried for a comet, Pons-Brooks and I discovered the perils of not using darks, with a green line appearing at the left of the images from a hot pixel in some of the other objects from that night. I also tried the Brain function in Sharpcap, which proposed gain 300, but I found that this introduced a lot of noise.

Fourth session, I used the Brain function again, but rounded the proposed exposure to the nearest of 1, 2, 4, 8, 15 seconds – followed by capturing darks and flats, and this seemed to improve the image quality for some objects. These were all at gain 300 with exposures of 4 or 8 seconds. Bubble and Iris seem quite nice, but cocoon is rather grainy – I’m not sure why – maybe because it needed more stretch to make it visible.

So I’m pretty pleased so far with my new camera, but would be very happy with any thoughts on how to improve what I’m seeing.

Cheers

 

Geoff

Edited March 5 by Fir Chlis
Correcting text.

[Elp]

Some great results there.

If you're willing to learn it, the jump you've had from visual to EAA will be magnified if you start to employ AP capture and processing into your workflow. I mostly image because I can't really do visual due to LP, the detail you pick up doing AP just can't be matched, though I do remember the visual sessions more.

If you're sticking to EAA for now, increasing the total time per target will help. Using colour narrowband filters will help massively with emission nebulae but you'll have to increase the exposure time (or total time).

[Ratlet]

Amazing images mate.

[PeterC65]

Your setup is similar to mine. I also do EAA with an Explorer 200PDS and an IMX585 camera (the Player One Uranus-C in my case).

The images you posted are very good.

I use a gain of 400 all the time for DSOs (my camera has a LCG/HCG switching point of 210) and I've been using 15s exposures of late (I started initially with 4s). When I first started doing EAA I did some tests with gains from 0 to 600 in steps of 50, same object, same night, same exposure, same number of frames, and concluded that 400 gave the best images. 15s exposures are a bit less real time than 4s but I find that for the same total exposure time I get more detail with 15s subs.

The image does get better the more frames you capture but if you're doing EAA you won't want to stay on one target for more than 10 minutes unless it's something special. As I type this I'm capturing frames of the Eskimo Nebula which is looking good, hence the wait for frames.

I use no filter (for faint broadband objects), a UV / IR cut filter (for brighter objects when I want to see their colour), and an Optolong L-eNhance dual narrowish band filter (for emission nebulae). All three have their uses.

For observing the Moon and planets I'd recommend you try out the new planetary stacking feature in SharpCap. It is just as good as post processing captured frames I think, and gives you a close to real time experience.

Now back to the Eskimo Nebulae ...

 

[M40]

Great pictures and an amazing variety of images 👌

[Fir Chlis]

14 hours ago, Elp said:

Some great results there.

If you're willing to learn it, the jump you've had from visual to EAA will be magnified if you start to employ AP capture and processing into your workflow. I mostly image because I can't really do visual due to LP, the detail you pick up doing AP just can't be matched, though I do remember the visual sessions more.

If you're sticking to EAA for now, increasing the total time per target will help. Using colour narrowband filters will help massively with emission nebulae but you'll have to increase the exposure time (or total time).

Thank you. It's going to have to be EAA for the moment, as I only have the one camera and, as I understand it, I'd be needing guiding if I was going to try AP. And I like the immediacy of EAA - it's still new and exciting to see the detail in objects that used to be small fuzzy blobs.

But last night I did stack all my objects for 10 minutes (was about 5 minutes previously) and I think I'm seeing some improvement.

[Fir Chlis]

10 hours ago, PeterC65 said:

Your setup is similar to mine. I also do EAA with an Explorer 200PDS and an IMX585 camera (the Player One Uranus-C in my case).

 

 

Thank you. I'll have a try at testing the stepped changes in gain that you suggested - and maybe longer exposures.

I've not tried a filter yet - I do have an Astronomik UHC which I used to use for visual - so that's another thing to try out. I'm very fortunate to live under Bortle 1 skies.

As for Jupiter, I was using the Sharpcap planetary stacking, but the live results weren't brilliant (a bit blurry), so I tried a bit of enhancement afterwards. I'll need to try some of the wavelet sharpening in Sharpcap next time. Given that you have a similar set-up, I'd be interested if you have a best image of Jupiter - it might give me an idea of what I could achieve.

[Elp]

16 minutes ago, Fir Chlis said:

I'm very fortunate to live under Bortle 1 skies

You should be able to get some fantastic results then. You're already doing the AP thing I mentioned by stacking. After you have the images, calibrate your frames (if you're not doing it already as you can do it for EAA also by applying flats, darks etc), do a background extraction (to remove any LP gradients if you have any) and do some minor levels stretching and you'll see far far more details.

Total time is what will improve your captures the most.

[Elp]

FYI, I've just uploaded an example here showing the difference it can make between standard EAA and AP post processing (not a like for like comparison between the two images but it gives you an idea):

 

[PeterC65]

9 hours ago, Fir Chlis said:

I've not tried a filter yet - I do have an Astronomik UHC which I used to use for visual - so that's another thing to try out. I'm very fortunate to live under Bortle 1 skies.

I used to use the Astronomik UHC filter for EAA but it is designed for visual use and passes IR which is detected by the IMX585 as it is sensitive to IR. Because of this I switched to the L-eNhance which cuts IR and gives less washed out images with less fringing around the stars.

9 hours ago, Fir Chlis said:

As for Jupiter, I was using the Sharpcap planetary stacking, but the live results weren't brilliant (a bit blurry), so I tried a bit of enhancement afterwards. I'll need to try some of the wavelet sharpening in Sharpcap next time. Given that you have a similar set-up, I'd be interested if you have a best image of Jupiter - it might give me an idea of what I could achieve.

I don't have many snapshots of Jupiter using the new SharpCap planetary stacking tool as it hasn't been around for long and while I like observing the planets, they need a different EAA setup which isn't so good for DSO (Explorer 200 with x2.4 Barlow to give F12 rather than the F5 which is what I use for DSO). You will need to use the sharpening and image adjustments to get a good image, but that's no different to AP. I find that 80% of Fine sharpening on its own (no denoise, no wavelets) does a good job, with auto adjust of the brightness / colour and a bit of manual uplift on the saturation (to 2.000).

Here's an example using the Explorer 200 and x2.4 Barlow ...

 

I've recently been using dark and flat frames for EAA and for me the jury is still out. The SharpCap hot pixel removal and sigma clipping when stacking do almost as good a job as dark frames I think, and without messing up the position of the peak in the histogram. Flats seem to be useful when you are using high magnification and would otherwise see dust bunny's. But both take a while to capture I find, and that adds to an already lengthy setup time for EAA. These days I think of visual as my grab and go setup!

 

[Fir Chlis]

14 hours ago, PeterC65 said:

I used to use the Astronomik UHC filter for EAA but it is designed for visual use and passes IR which is detected by the IMX585 as it is sensitive to IR. Because of this I switched to the L-eNhance which cuts IR and gives less washed out images with less fringing around the stars.

Thanks for the Jupiter photo - useful to see that it doesn't have masses more detail than the one I managed the other night. At least I now suspect that with my set-up, I'm not going to be getting much more detail.

I started to test different gains with the same exposure, but images became saturated very quickly with the higher gains and, with wind gusts, the imaging wasn't too sharp. At 15 seconds I was getting star trails - maybe gusts, maybe limitations of my gear.

I'll have to try the UHC sometime but, after a bit of reading, I'm unclear whether filters are going to give me much a Bortle 1 area.

And I failed to see Pons-Brooks, because (as I realized this morning) I was entering JNOW coordinates into Sharpcap, not J2000.

This was the best from a not terribly good night - C7.

Edited March 7 by Fir Chlis

[Jonathan_Shields]

Very nice. I have that camera but I use a 6 inch goto dob (so alt-az) so I am limited to 8 seconds tops. You will really get the best out of the camera with 8 inches and being able to take longer frames.

If the crappy weather abates I am going to try both flats and darks on a good night. I tried them last time but the high clouds rendered the night a waste of time in the end.

I have been using gain 350 but I am thinking of trying 252 to reduce noise a bit.

[Fir Chlis]

@Jonathan_Shields I need to experiment with gain settings on the 585MC, but the SharpCap brain function is consistently suggesting 300 as the best gain settling for me. After a few sessions without them, I started using darks, and I’m sure they have helped, especially when trying higher gain settings.

[PeterC65]

45 minutes ago, Fir Chlis said:

@Jonathan_Shields I need to experiment with gain settings on the 585MC, but the SharpCap brain function is consistently suggesting 300 as the best gain settling for me. After a few sessions without them, I started using darks, and I’m sure they have helped, especially when trying higher gain settings.

I find that the SharpCap brain function suggests settings that are more appropriate for AP than for EAA, and for an EQ rather than AZ mount.