OSC CCD's and debayering - How different to a DSLR?

[swag72]

When I used my DSLR for AP, I took lights and flats and used to chuck them all into DSS and it used to spit me out a decent starting point. I have just acquired a OSC CCD and am aware of seeing some threads with OSC CCD's where the bayer matrix has shown - Can I just throw lights, flats and bias into DSS and get a workable image out in the same way as a DSLR? Or do I have to do things differently with a OSC CCD?

[martin_h]

You need to tell DSS what the CCD is(drop down list) or what the bayer pattern is for it

[steppenwolf]

Sara, I know you have MaximDL - why not use that to calibrate and de-Bayer your OSC images? I find that MaximDL gives you plenty of control and once set up it makes the task very automated.

The sequence in Maxim is:-

1. Produce Master Bias, Dark and Flat frames - this is very automated

2. Calibrate your raw images with the masters - automated

3. De-Bayer your images - automated easily using a simple macro

4. Stack your calibrated images - lots of options but there are some pretty sure-fire choices

5. Save as a 16bit TIF file

6. Image process in PhotoShop or similar

[ianaiken]

Hi Sara, it's already been answered by Steve, I just wanted to point out that you calibrate your lights before debayer. Your calibration frames should also not be debayered. I believe you set the correct bayer pattern in DSS and that's it, just throw the files in.

One point to note that if your having problems with your flats from the OSC you may have to shift the stacked master flat by 0.5 on both the X and Y axis for each colour channel, or something along those lines I can explain further when I'm on a PC with the software on (or someone else can add to this). I have to do this with my OSC otherwise my flats don't work correctly no matter which software I use. I know how to do this in PI and AA5. Olly and Harry have discussed this a few times on SGL and I believe it's referred to as the "shift magic" by some

Edit: Step up to the challenge and stack in PI, you'll have loads of fun!

[swag72]

Cheers guys - I'll look at Maxim for stacking if needs be, but I was planning on trying the new PI stacking script. Where do I put the Bayer pattern in DSS? I've not seen an option for that before - Is there some obscure menu I've not found?

[ollypenrice]

The Bayer pattern is also sometimes called the Offset. I haven't succeeded in stacking/calibrating in PI but Yves will be here fairly soon to explain in words of one syllable how to do it!!

I can confirm that I debayer flats by applying a 0.5 shift on both axes. Isn't this called a Boxcar Filter in Maxim for some reason?? Clear as mud to me, Holmes.

As you can see, Steve's sequence is the same as mine though I do it in AA5. (I got it from Harry. Cheers, 'Arry.)

Olly

[Stephen]

Raw/FITS Settings on the left hand side, then seleect the FITS tab.

My 314L+ OSC is offset 0,1 IIRC!

[steppenwolf]

Isn't this called a Boxcar Filter in Maxim for some reason??

Indeed it is but you try to find a reference to it anywhere else! The boxcar filter essentially 'slides' the data thus destroying the Bayer Matrix which is exactly what applying a 0.5 shift on both axes does. I love all this!!

[ollypenrice]

Indeed it is but you try to find a reference to it anywhere else! The boxcar filter essentially 'slides' the data thus destroying the Bayer Matrix which is exactly what applying a 0.5 shift on both axes does. I love all this!!

You do? Lawks, it drives me nuts but that's cos I'm thick!!

Boxcar filter? Who thought of that? Mind you, what would they call it in Pixinsight? Bi-directional pixeldisplacement integrator ... if they were feeling particularly taciturn that day.

Olly

[harry page]

Hi

Just for a change Pixinsight flats ( OSC type) are easy Pi automaticaly does all the work , just shove in the raws and it works like magic

Harry

[swag72]

Cheers Harry - I look forward to watching your vid and trying the new PI stacking routine if I ever get some data!! I know I could stack some old stuff to have a play, but once I've done one target to death, it never sees the light of day again!!

[ianaiken]

With my OSC (QHY8L) master flat I do have to use the PI Bi-directional pixeldisplacement integrator process otherwise it doesn't work so well. I tried throwing everything in and weird things were happening with the red channel.

[harry page]

Hi

My sxvf m25 seems to work fine so not quite sure what is going on with your camera as its the same chip as mine

Harry

[ianaiken]

Maybe it's the way it's been put together

I've read on the PI or QHY forum another having to do this with their flats too. I can get away with not doing it, but the result is much better when I shift it. Does your camera also have double exposure mode for shots less than 3.47s?

[harry page]

Hi

nothing fancy like that req with sx m25

Harry

[ianaiken]

Well you get what you pay for

[keithmrris]

I have just bought a QHY8L ccd, I usually use a Canon 450D astro modded DSLR. All I can say is with just one imaging session under my belt with the QHY8L I am absolutely blown away with the result. I will probably never use the 450D again.

In DSS you need to set the Debayering to "Generic GBRG" DON'T use the "QHY8" one.

I captured a very nice M81/M82 using a Baader Neodymium LP filter AND there was a full moon up and I can tell you I captured more detail in the dust lanes of M81 with 20 x 120s exposures with the QHY8L than I did a few months back with the modded DSLR shooting 30 x 180s exposures.

True a mono is upto 4 times more sensitive, but with the cloud cover we have been having this year the number of clear skies has limited how many DSOs you get the opportunity to image. I would rather take 30 + images at 120s with a OSC than 20+ 180s L and then 20+ 100s binned for Red then Green then Blue (depending on your target of course) with a mono camera. I just don't have the time (due to work and health issues) to spend an evening and only getting half the information needed then having to wait a couple of days (or weeks) to capture the other channels.

Keith

[Earl]

I have just bought a QHY8L ccd, I usually use a Canon 450D astro modded DSLR. All I can say is with just one imaging session under my belt with the QHY8L I am absolutely blown away with the result. I will probably never use the 450D again.

That was exaclty the same for me when i got my 8l, and then the same again when i got the 383.