## ZWO ASI533 MC Pro - Optimum Exposure Time ?

KEJ
Posts: 18
Joined: Mon Feb 24, 2020 7:37 pm

### ZWO ASI533 MC Pro - Optimum Exposure Time ?

Robin hi

May I ask you some more questions please regarding the ZWO ASI533MC Pro (Colour Astro Camera - Zero Amp Glow - Cooled Camera).

Back to the age old question of optimum exposure time, previously I had got to grips with ISO, but now moving on to Gain.

Attached Fig01 spec for ASI533 MC Pro.

So, I believe, I should always aim ideally for unity gain or greater, in this case 100 or 100>.

So am I correct in thinking, based on that, taking the 100 point on the bottom graph(info from also Fig02 for calculations),
my calculations should be:

For Gain 100. (1.5 log2 = 2.8)
20 X 2.8 x 2.8 /3.28 = 48 secs/exp

For Gain 350. (1.2 log2 = 2.3)
20 X 2.3 x 2.3 /3.28 = 32 secs/exp

Question 01
I should therefore aim for as many possibly exposures (if using Gain 100 ) of 48 secs and in theory, is it still correct to assume that :

60 x 48 sec/exposures are better than say 10 x 300 sec/exposure ?

Question 02
And may I pick your brains, Galaxies VS Nebula and exposure duration with gain.

Looking at the numbers above, strictly speaking, should I treat galaxies in the same way when taking pictures of Nebula & vice versa ?

Or do you find, cameras are more responsive for nebula with longer exposures or does that totally go against the above ?

Or is it just a case as in my example(if correct) Gain 350 is more sensitive, but 32 secs is optimal.

Therefore at Gain 350, 200 X 32 sec/exp should do nicely(or 20 x 5mins)!

_______________________________

Should we treat cooled astro cameras differently.

Hopefully thanks

Fig 01
Screenshot 2020-10-10 at 15.17.49.png (562.14 KiB) Viewed 517 times
Fig02
Screenshot A12020-10-10 at 16.05.30.png (232.38 KiB) Viewed 513 times

KEJ
Posts: 18
Joined: Mon Feb 24, 2020 7:37 pm

### Re: ZWO ASI533 MC Pro - Optimum Exposure Time ?

My Gut feeling is to stick a Gain of 100 and potentially just alter the duration of the exposures, depending on the target.

Ie:

Bright targets stick with 48 secs and many exposures.

Faint targets stick with 3 to 5 min exposures, many exposures.

But then its back to the optimum duration..........

Also whilst(me being new as well) I hear everyone mentioning to shoot at Unity and I am thinking therefore that should that always be my starting point Or with the brighter subjects, should I really be cutting that back to the lower numbers, Gain of 0 would it be that bad(haven't had chance to try yet).

Avocette
Posts: 16
Joined: Thu Nov 07, 2019 7:11 pm

### Re: ZWO ASI533 MC Pro - Optimum Exposure Time ?

Hi @KEJ - have you tried carrying out a sensor analysis on your 533? I measured mine and the unity gain measured 111.

KEJ
Posts: 18
Joined: Mon Feb 24, 2020 7:37 pm

### Re: ZWO ASI533 MC Pro - Optimum Exposure Time ?

Avocette wrote:
Sun Oct 11, 2020 7:34 pm
Hi @KEJ - have you tried carrying out a sensor analysis on your 533? I measured mine and the unity gain measured 111.
No, I haven't........thats interesting, not something I have tried.

Is it straight forward to test ?

Do you have a link or is it in the help docs for SharpCap ?

Cheers

Avocette
Posts: 16
Joined: Thu Nov 07, 2019 7:11 pm

### Re: ZWO ASI533 MC Pro - Optimum Exposure Time ?

Hope you’ve found the answer by now? I just followed the instructions in the manual!