What offset are you using on asi 533mc pro

[Craig a]

As the title states, I’m confused as to why the offset is set at 70 for all presets in native driver, does anyone use a different offset ? 

[PeterCPC]

I have been using 50. No particular reason 😄

[geeklee]

I just used the native offset (from ASCOM driver) when I had this camera. One less thing to think about. Plenty of people tweaking this a bit though. 

[bottletopburly]

 I asked on astro bin , Gain 100 10 offset for best dynamic range, in the booklet that comes with camera  there are three settings in the zwo driver , but 10 seems to be best setting for dynamic range and noise .

[geeklee]

1 hour ago, bottletopburly said:

 I asked on astro bin , Gain 100 10 offset for best dynamic range, in the booklet that comes with camera  there are three settings in the zwo driver , but 10 seems to be best setting for dynamic range and noise .

While wringing every last drop out of our equipment is to be admired, I feel it should come with a warning that when you deviate on these settings you should be careful with all your calibration files.  Being careful to ensure they match these settings and also that every time you take light frames in whatever application you use, that the camera is set the same every time and nothing has reverted to a default value (for example).

I only say this as not everyone is experienced in AP when they get an astro camera.

From what I've read on Astrobin and elsewhere, the offset tweak is just a small increase in dynamic range and you'd have to ask at what point you'd notice that in your images (for yourself you might of course!  For me, I doubt it )

Edited August 16, 2021 by geeklee

[MartinB]

5 minutes ago, geeklee said:

While wringing every last drop out of our equipment is to be admired, I feel it should come with a warning that when you deviate on these settings you should be careful with all your calibration files.  Being careful to ensure they match these settings and also that every time you take light frames in whatever application you use, that the camera is set the same every time and nothing has reverted to a default value (for example).

From what I've read on Astrobin and elsewhere, the offset tweak is just a small increase in dynamic range and you'd have to ask at what point you'd notice that in your images (for yourself you might of course!  For me, I doubt it )

There is a great deal of wisdom is this response!!

[Craig a]

Thanks for reply’s from you all, I think I will just stick to the default value of 70, there must be a reason zwo set 70 for all presets gain values 

Edited August 16, 2021 by Craig a

[geeklee]

1 minute ago, Craig a said:

Thanks for reply’s from you all, I think I will just stick to the default

It's a good place to start @Craig a and you know you can tweak values based on advice above in the future if you want to.  Main thing is getting going and being comfortable with the camera and its operation.  

[Craig a]

I’ve just read an interesting thread over on CN, that darks are not recommended for the 533 also no need to go higher than 15 offset, as no one has any idea why zwo decided on such a high offset, now I’m really confused 😂

[bottletopburly]

13 minutes ago, Craig a said:

I’ve just read an interesting thread over on CN, that darks are not recommended for the 533 also no need to go higher than 15 offset, as no one has any idea why zwo decided on such a high offset, now I’m really confused 😂

I’ve just done some data with darks , I will try without , which seem fine with 

[Craig a]

1 hour ago, bottletopburly said:

I’ve just done some data with darks , I will try without , which seem fine with 

Apparently from what I’ve read the 533 sensor has no fixed pattern noise so darks are not needed to get rid of it and hot pixels are gone with dithering and sigma rejection, also using darks reduces SNR, I’m not an expert but just quoting what I’ve been reading, also flat darks are not needed either just bias subtracted flats is fine with the 533, 

hopefully someone with abit more knowledge than me can set me straight on what I’ve read 

Edited September 1, 2021 by Craig a

[Craig a]

Still don’t know why zwo set the default offset to 70 though when I’ve seen quite a few people using offsets ranging from 10-25 🤔

[geeklee]

13 hours ago, Craig a said:

now I’m really confused 😂

 

11 hours ago, Craig a said:

when I’ve seen quite a few people using offsets ranging from 10-25 🤔

 

11 hours ago, Craig a said:

hopefully someone with abit more knowledge than me can set me straight on what I’ve read 

There's no need to be confused, just use the defaults to get started  .  I'm fairly sure the last thing you'll be thinking about or noticing is what that offset was set to.  I'm guessing ZWO were just playing it safe, knowing that the value they set still provides ample dynamic range - perhaps they'll change it at a later date, but the camera has been out for 18months+ already...

I used darks with mine and dark flats instead of bias and it all calibrated fine alongside my flats.  I would recommend dithering.

On the face of it, I don't think there's anything to set straight - there's just people doing different things with the camera that all work.

Maybe we all need some clear skies so we can get out and use our technology rather than worry about it 😅

Edited September 2, 2021 by geeklee

[Adam J]

On 01/09/2021 at 20:48, Craig a said:

Still don’t know why zwo set the default offset to 70 though when I’ve seen quite a few people using offsets ranging from 10-25 🤔

Because it's optimal independent of gain setting so even at gain zero it's fine. Also it's such a minimal impact on dynamic range in most cases that it makes no meaningful difference. Hence it's a good default and advanced users can do what they want to do.