First shots with ASI533MC-Pro : M33 and Horsehead, 28.11.2022

[cloudnine]

I'm quite pleased with how they turned out. I haven't done any processing yet to combine subs and remove darks ... I currently don't have the software to hand. But thought I'd share two unprocessed subs of 600 seconds each. I haven't even turned the horse head round. Soz if this offends.

 

Set-up: Autoguided EQ6, Esprit 120 + Field Flattener, IR-cut filter, ASI533MC-Pro cooled camera, ASIAIR controller

Settings: exposure 600s, gain 360 (max, edited from 300 given new evidence since originally posting), sensor temperature -10degC.

😊

 

Edited November 30, 2022 by cloudnine
Corrected gain value

[AstroMuni]

18 hours ago, cloudnine said:

But thought I'd share two unprocessed subs of 600 seconds each.

For just 600s that IS awesome !

Using my guided 130pds with ASI533mc pro + UV/IR filter on HEQ5 pro mount, after taking around 1.5hrs worth (60s subs at 240 gain, -10deg) from a Bortle 6 garden, all I managed to get was this. So whats your secret recipe please 🙂

Edited November 30, 2022 by AstroMuni

[cloudnine]

There’s the question! Is there a secret recipe? 

According to Clear Outside app, my sky is bortle 4, which I assume is a bit better. But I would guess, and it is only a guess, that a single 600s exposure will lift the low-surface-brightness galaxy well above the noise floor of the camera compared to 60s. Whilst I was imaging I sent a mate updates by taking photos of my iPad screen ASIAIR app. I attach two here, the first is 300s, the second is 600s. I’ve marked in red the ‘auto’ adjustment limits for on-screen viewing. The actual scale is off-camera, soz.

As you can see, the upper ‘limit’ is about 50% full saturation for the 600s exposure, and maybe 25% for the 300s. That’s the only thing I can think of. Not sure if 120mm (f/7) refractor gathers the same light as your 130pds (f/5).

Does this make sense?

I also attach my horsey iPad screen showing the saturation scale for a 600s exposure. Looks like my gain was set to 360 for the evening, not 300 as previously suggested.

[cloudnine]

4 hours ago, AstroMuni said:

For just 600s that IS awesome !

Using my guided 130pds with ASI533mc pro + UV/IR filter on HEQ5 pro mount, after taking around 1.5hrs worth (60s subs at 240 gain, -10deg) from a Bortle 6 garden, all I managed to get was this. So whats your secret recipe please 🙂

Your image is really nice. Nought wrong with that. Have you increased saturation on the colours a little?

[AstroMuni]

11 hours ago, cloudnine said:

Your image is really nice. Nought wrong with that. Have you increased saturation on the colours a little?

So the recipe seems to be a mix of Bortle 4, higher gain and exposure. I will have a try with higher gain & exposure to see what I get.

The 130/f5 should in theory get more photons as compared to a 120/f7 all else being equal.

[geeklee]

27 minutes ago, AstroMuni said:

higher gain and exposure.

For longer integration deep sky imaging, I'm not sure I'd agree with some of this thread.

When you increase gain you reduce the full well, couple this with increasing exposure and you will also clip more pixels.  This is evident in all images above.

Modern CMOS cameras have exceptionally low read noise at unity gain - the 533MC especially is already only ~1.5e at Gain 100 (unity). 

Typically I'd see higher gain for EAA where really short exposures are being used to live stack.  Alternatively perhaps with an OSC narrowband filter.

The full well at gain 300 is under 2000, 360 maybe 800, unity gain 100 is ~18,000.

Saying all that, for single shots to show off or test, then anything works if it works for you 😊  To be fair, if you're happy then that's also all that matters.  

Edited December 1, 2022 by geeklee

[iantaylor2uk]

I tend to use high gain (200 on my ZWO 071) with an L-Enhance filter (and with this filter I would usually use 2 or 3 minute exposures).  

If I'm just using a UV/IR filter I will often use 90 (unity gain on the camera) and 30 or 60 second. 

Agree with the above comment though, in general if you increase the camera gain it would make more sense to decrease the exposure time, or at least check nothing in the image is saturating.  

[cloudnine]

Thanks for the kind comments, and thoughts. I’m happy with the natural look, even if some stars are blown out. It was my first time taking long exposures so when I liked what I saw on screen I just went for it. I think the lack of amp glow allows one to push the limits.
 

I reckon brighter nebula would burn out much more quickly. More objects to image, any recommendations?

[windjammer]

I am amazed that horsehead is an unprocessed singe exposure!  I love the image scale - no mucking about. There is a lot left even in that single shot to bring out.  With a stack  it would be remarkable.