Peter,
I used my Canon 600D for 4 years in 6” and 8” newts in Sydney Bortle 8 heavy light pollution and South Coast NSW Bortle 3/4 nice dark skies
My ISO setting was predominately ISO800 which provides the best dynamic range at the lowest read noise ( which is high anyway being a DSLR , the drawback with using a DSLR that damn noise )
Sub exposure lengths vary due to the quality of sky conditions, moon phase , light pollution levels etc...
Unfortunately not one shoe fits all
In Sydney Bortle 8 , I never used a NB filter ( and should have ) but generally used the following sub exposures -
No Moon
Emission Nebula 90 sec to 120 sec
Planetary Nebula 120 sec
Galaxies 90 sec
Globular Clusters 60 sec
During Moon
Emission Nebula 90 sec
Planetary Nebula 90 sec
Galaxies 90 sec
Globular Clusters 60 sec
On the South Cost NSW Bortle 3/4 I used the following -
No Moon
Emission Nebula 120 sec to 300 sec
Planetary Nebula 120 sec to 300 sec
Galaxies 120 sec to 300 sec
Globular Clusters 60 sec to 90 sec
Note: I only used 5min subs on nights of good seeing
During Moon
Emission Nebula 120 sec
Planetary Nebula 120 sec
Galaxies 90 sec to 120 sec
Globular Clusters 60 sec to 90 sec
The Cats Paw is a very challenging object for a DSLR as it’s not a very bright object , I certainly didn’t attempt it with my DSLR. There’s a risk with DSLRs running longer subs as you introduce more noise not more detail into your images and we are all trying to get a better SNR
Good Sky conditions will allow you to push longer subs and capture a bit more quality detail but a DSLR is a DSLR
When I jumped from my old 600D to my current ZWOASI2600MC it like trading in a 64 Holden to an E class Merc , absolutely chalk and cheese in performance
My recommendation for the Cats Paw is to keep your 600D at ISO800 and maybe increase to 150 sec subs but capture at least 3 to 4 hours worth of data with darks etc.. I presume your in fairly darks skies ??
Hope the above is helpful
PS I still use my 600D for dabbling in lunar and planetary imaging during planetary season ( July to September)
Best
Martin
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