What camera

[Trekrider]

I have a GSO RC8 and have been using a full spectrum modified EOS 600D and want to move on to a better camera.

The folks at the place I got the RC8 from recommend a ZWO ASI1600MM Pro with filter wheel which is in my price range.

I have been told independantly that I should be looking at a camera with at least a 6u pixel size (the ZWO is 3.8u) to match the RC8.

Having looked for larger pixel size sensors I can only find either full frame size or much smaller than I have now - The RC8 has a maximum sensor diameter of 30mm.

I'm also not clear on the performance difference between CMOS (like the ZWO) or CCD - it used to be that CCD was far superior to CMOS but is this still the case?

Thanks in advance for any suggestions.

[PKay]

Hi Barry

Since no one else has kicked in, maybe go with the advice from the folks that sold you the scope.
The ZWO cooled cameras (or another make) will give you a much better image.

[glend]

CMOS cameras, like the ASI1600 and its QHY clone, are ultra low read noise devices, this gives it a significant advantage over CCD cameras -which need much longer sub times to build signal to over-come read noise.

[raymo]

I haven't seen any of your results here, so I don't have any idea what image quality you are producing. Have you taken your 600D to its limit? With skill
and perseverance stunning images can be obtained with a DSLR.
Sarah Wager, one of the worlds most noted astrophotographers used a DSLR
early in her career, and produced images I would have been overjoyed to
have taken with any type of camera. If you want to move on to narrowband
imaging, that's a different matter.
raymo

[RickS]

With 3.8um pixels you'll get an image scale of 0.48 arcsec/pixel which is going to be significantly oversampled. You could bin x2 or use a reducer.

Cheers,
Rick.

[ChrisV]

Maybe you'll need a focal reducer. I don't know how experienced you are but a focal length of 1625mm sounds difficult to me.

[Trekrider]

Thanks Raymo, All of my images have that horrible multi-coloured background that I assume is at the noise level from the camera. I'm guessing cooling would help and I have made a cooler for the camera but that's extra weight on an already back heavy setup plus I don't feel the camera would stand up to the condensation too well. I recently discovered the Script for removing the banding that you get from the DSLR (Cannon script in Pixinsight) which helps with the banding but still leaves the multi-coloured background. See attached images.

Oh, and yes, I would like to be able to move on to narrowband imaging as well.

[Trekrider]

Thanks Rick, That's the point he was making, hence my question - rather than fix the oversampling find a camera that is actually correct for the scope.

[Trekrider]

Thanks Glen, That makes sense.

[Trekrider]

Thanks Peter

[Trekrider]

Almost complete newbie Chris :lol: hence I'm not sure I follow the comment on a focal reducer.

[raymo]

Hi Barry, the only cooling that works with a DSLR is a cold finger, which is
quite a pricey proposition unless you do it yourself.
What picture style is your camera set on, and in that style what is the sharpness set on? The higher the sharpness, the higher the noise will be, and vice versa. Set the sharpness to zero, and any sharpening needed can be done during post processing.
You can help matters very considerably by producing nebular and busy star field images during warmer months, and distinct objects with areas of fairly
blank sky during the coldest months; you will find hugely less noise with
ambient temps around 5 or 6 degrees or less.
raymo

[Trekrider]

Thanks Raymo, I only shoot in RAW so picture style has no effect on my images.

[PKay]

Hi Barry

What ever your doing, keep it up!

Those 3 images are really really good.

Personally, I don't mind some noise in the background space and sometimes, it can add to the image.

Not sure what processing software you use.
In PI: I always do the SCNR (remove green) and read (print!) what Rick has said in the thread below.

[ChrisV]

Just saying this because ithink the discussion should be about the scope and camera. Not just the camera. Especially given you are new to this.

Guiding at a long focal length (1625mm for RC8) is difficult . There will be alot of threads about this. And also some about using focal reducers - there's a recent thread about this with an RC8. Most people start below ~600mm then move up.


Maybe I'm barking up the wrong tree ?? Maybe someone more experienced could address this better than I have

[Trekrider]

Thanks Peter, you are too kind. I'm a bit of a perfectionist when it comes to photography and I see the great images people produce with really black backgrounds and that's what I want.

I use PI so will have a look at SCNR - my spiral galaxy shots do have a bit of a green tinge :)

[Trekrider]

I really appreciate the help Chris but this is about the camera as I'm not about to change the scope any time soon.

Guiding isn't an issue for me - I use PHD2 with the AS120MM on a 280mm guide scope and get perfect right angle plots in PHD2. I can guide all night long with no issues. Whilst experimenting I tried exposures as long as 15 minutes with no elongation of stars. I did get guiding sorted on the ED80 I had before this scope which I guess is what you mean :lol: OAG is another matter though - I have had it working but not consistently so keep going back to what I know works. I plan to try again when I get the new camera (what ever that is).

[blink138]

RC 0.75 reducer in classifieds at the mo?
pat

[gb44]

Have you tried dithering with the current camera setup? Moving the scope at least a star diameter every few shots would improve the issue of background artifacts...
Anybody doing this in PhD?

GlennB

[RickS]

Barry,

Using a reducer is a reasonable strategy but a larger pixel camera makes sense too. You could look at a camera with an ICX-694 sensor (0.58 arcsec/pixel - still a bit small but very good if you get the occasional night with exceptional seeing) or a KAF-8300 (0.69 arcsec/pixel.)

A good rule of thumb is that perfect sampling is when the seeing is about 3.5x the image scale. Oversampling is wasteful. Undersampling is fine if you're looking for a larger FOV and willing to trade off resolution to get it.

The ICX-694 has pretty low read noise. The KAF-8300 is a bit long in the tooth and has fairly high read noise, so you'll need to do longer subs to get the best out of it.

Cheers,
Rick.

[Trekrider]

Thanks for the reminder Glenn, I just put together a new imaging computer and didn't spot that dithering is off by default - now corrected that :)

[Trekrider]

Thanks again Rick, someone else mentioned the KAF-8300 to me but it looks like cameras based on those two chips are out of my league - more than the ASI1600 with filter wheel for just the camera :(