ASI1600 Pro - Exposure times

[Imme (Jon)]

You know when you've got your gear running great.....
You know all the settings to use and basically every exposure you take ends up looking good.......

We've all been there right......and then we decide to upgrade and it all goes to pieces!

I've gone from an ASI1600 OSC to an ASI1600 Pro using ZWO filters. I'm testing exposure times and using the ASI sub exposure tables on here as a guide however it appears these are just for Luminance filters (the exposure time stated in the table is pretty close to exactly what works for me).

But what about the RBG filter exposure times? Due to the reduced amount of light getting through to the sensor how much longer should the exposures be? Or will the same length work?

Any info on what you are doing with your setup would be great.

PS - I am running a F6.9 scope in an area with pretty dark skies. 150 seconds luminance exposure is giving me fairly good results.

I'm a little lost on these colored filters to be honest

[glend (Glen)]

Ray's charts offer exposure guidance based upon a particular set of f ratios. I Don't recall that f6,9 was specifically listed. Perhaps you should be using his guidance on ADU number, typically determined by a dark area on the lower left side.

[Imme (Jon)]

I understand that. I’ve ‘guesstimated’ exposure time based on the f6 and f7 values and crosschecked the ADU value......that’s all good, luminance is fine.

What I am specifically after is what difference people have in their luminance and coloured filter exposures that works for them, as in actual seconds per exposure per filter. E.g. - If Joe Blow does 150 second exposures for luminance. How many seconds does he then do on RGB filters per exposure.

I guess I’m looking at the exposure length ratio per exposure - lum v RGB

Make sense?

[ericwbenson (Eric)]

Hi Jon,


RGB exposures are usually about three times longer since the spectral banspass is one-third of the Lum. However you can play with this alot and still be ok. (I use equal exposure lengths for L and RGB since calibration is way more convenient! Plus my standard sub length for L is 30 min...)



To be exact it's a lot more complicated since the QE of the chip varies and the sky background brightness also varies across the different wavelengths. And even more complicated the sky background can change for different locations (light pollution type) and times of year (airglow variations).


Best,
EB

[Imme (Jon)]

Thanks Eric, just what I was looking for.
Took a punt tonight and am capturing RGB twice the length of Lum so will see how that goes (not home at the moment so not sure how it’s going!).
If it’s clear tomorrow I’ll try for triple the time if double doesn’t work out for me.

[xelasnave]

Exposure time for me is determined by how long I can track before the stars look eggy and gain determined by how high I can go without a white out ..combinations determined by how many subs are on hand.
I look forward to the day it is regulated by Rays excellent chart.
Alex