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QHY8L workflow?

mindburner

By mindburner
in Discussions - Cameras

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mindburner

mindburner

Posted
Posted

Hi all

I have just taken the plunge and ordered a QHY8L OSC as an upgrade to the venerable canon 1100d.

My normal workflow goes something like:

CANON 1100d

CAPTURE

focus

take a load of 3 min subs

when finished, shoot same number darks at same temp

shoot 25 or so bias shots at 1/4000 sec

shoot 25 or so flats in AVmode against a laptop screen.

PROCESSING

Convert all images from CR2 to TIF (my old version of Neb hates the CR2 raws)

take BIAS away from FLATS in Nebulosity

subtract DARKS, FLATS from SUBS

normalise, stack and tweak

jobs a good un, sometimes :grin:

QHY8L CCD

CAPTURE

With the QHY8L I take it I can use the supplied software or get something like Maxim DL.

set offset & gain

focus etc similar to DSLR program

PROCESSING

Make up a dark library

Shoot BIAS frames - not sure on how to do this

can I make up a bias subtracted flat library too? ( as long as camera doesn't move in between) These have to be 4 seconds long? Achieve this with paper/t shirts in front of scope

Subtract Darks & Flats

Stack the resulting images

Debayer the stacked image

Stretch and tweak

Advantages seem to be the use of a darks library, lower noise in images

Disadvantages possible learning curve in processing

i.e. getting long enough flats

Does this sound like it's roughly right? Sorry for the questions but I just want to get ahead of the game before the camera arrives. I guess I am hope someone else has been through this change form DSLR to their first CCD and has got some good experiences:)

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A320Flyer

A320Flyer

Posted
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I have had the QHY8L for about 4 months now and I cant rate it highly enough. Its sensitivity and colour capture are excellent. I too upgraded from a Canon DSLR. I didnt find the need to alter my workflow much as both cameras are OSC. Like you, I too thought the Flats, and hence the Dark Flats (Bias) frames would need to be at least 4 sec long as thats what the published info seems to suggest. Through useage, I have found that simple Bias (zero secs) work best with normal Flats. However, I felt that Flats with a max edu of around 25,000 actually over-corrected he vignetting. I experimented with different exposures and found that a max edu of around 12,000 actually produced the best result after calibration.

Trust this helps

Bill

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Mav359

Mav359

Posted
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Ive had one for about two months now and i too love it, not a massive amount of usage due to the weather but still very pleased.

DARKS are temp dependant & because you can set a consistant temp of the CCD I have produced a DARK library using the camera, i use Nebulosity 3 which displays the actuall temp of the CCD (Craig Stark confirmed this to me) so i have a DARK library made up of 1,2,3,5,8,10,12,15,20,25,30mins all at -20c. 19:40mins total

I have also created a Master BIAS file (these can be re-used) only takes a few mins but why do it twice.

That just leaves me my SUBS & FLATS to gather during the session, Bill is right about experimenting with your FLATS but do your calibration as it will differ depending on your scope and your light source. My average is 23,000 which means a .675ms exposure seems to work well for me.

It comes with EZCap is not for me but it does work as i said i use Nebulosity 3 for all my pre-processing (Capture, Clibration,Normalizing & De-bayering, Stacking, Aligning) then do my processing in photoshop.

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sloz1664

sloz1664

Posted
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Hi Mindburner

I have the QHY8 Pro and as with the QHY8L if shooting at around -20 C you don't need dark files. The chip generates minimal noise.

Just Bias subtract your Flats. As Earl states your camera takes what is in simple terms a double image and with Bias frames being taken at a "zero Exposure"

the camera requires a time lag to piece the two images together. Just set a 5 sec pause btween exposures to overcome this.

And yes EZcap does give the edu readings for the image. Average is what you require. Check out the EZcap tutorial in Astronomyshed.

Hi Bill

That's interesting. I came to a similar conclusion & I generate my Flats at around 15000 edu.

Cheers

Steve

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Auntystatic

Auntystatic

Posted
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This post is very interesting to see how people have their different settings and advice, I've been after a QHY8 for a while, with ads on here and ABS, the only taker I've had is from the usa, I could buy a new L model or save more for the pro model or wait for the QHY22, decisions decisions. :confused:

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mindburner

mindburner

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many thanks to everyone. There's some great information distilled into one section. Like yourself Auntystatic, I nearly bought several CCD cameras on more than one occasion. One day it was 314L OSC, then mono, Then QHY8 basic, then pro the QHY9, then just stick with the DSLR. Overall the 8L seems to offer so much for the money. Lots of positives and little negatives.

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ollypenrice

ollypenrice

Posted
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Does anyone know the debayer settings for astroart using a qhy8l ?

Thanks Mike

Sent from my Nexus 7 using Tapatalk

For OSC I just took a daytime picture and tried the offset variations till I got a sensible colour. It doesn't take long.

You'll need to debayer your flats. I used to do this in AsroArt 5 using a shift of 0.5 pixel on each axis. Different stacking programmes do this differently, though.

I also agree about keeping the ADU down on flats.

Olly

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