Well I now have my ATIK 383L+ Mono CCD Camera, I have to wait a few weeks for the StarlightExpress 36mm Filterwheel and Baader Filters, there's a 4-6 week delay on the filters.

Whilst I am waiting for these, I thought I would start building my Dark and BIAS libraries, so I thought I would post on here what I used and how easy it was

1. The drivers that came with the camera were not at the level high enough to perform BIAS frames. I discovered this when I was getting an Error that the driver could not perform this. So after some research, I went onto Atik's website, downloaded the latest software and drivers and then I could perform my BIAS frames

2. Ease of use, the Set Point control software to control the cooling is a doddle, tell it what temperature you want the camera cooled to, and leave it alone, so I have mine set to -25 Degrees C, I chose this temperature because I looked at the averaging temperatures per month, and the highest would be 15 Degrees C, and whilst the camera will cool to -30 from +15, the max delta reported in the documentation is -40Degrees C Delta. So I opted to do all my BIAS and Darks at -25 Degrees C, this means one set of darks per exposure time, replaced every six months

3. Cooling system, the camera gets down from +14 to -25 within 2 or three minutes so imaging sessions could start very quickly.

4. I chose Maxim DL to acquire the darks and BIAS, simply because I could not find anywhere within any other of my applications to be able to do BIAS frames which was a little annoying.

5. Noise Level - The noise from the cooling system is well within what I would regard as acceptable, unlike my Cooled DSLR which when the fan speed was on the highest speed could be heard and was annoying (Hence why I fitted a fan regulator to it), but the Atik 383L+ Fan is extremely quiet in comparison

6. Build Quality - Well I made the right decission, the camera itself it of excellent build quality and there was a couple of reasons why I went for the Atik version with the Kodak 8300 chip over others, the main reason was the lower readout noise compared to QHY, SX, SBIG etc. It was slightly more expensive than the QHY9M, but well worth the extra.

7. I have not had to change the Gain or Offset settings for the camera whatsoever, nor have I found any settings to change these, it looks Optimal, the Minimum BIAS frame offset seen is 260, which between 100 and 1000 is perfectly acceptable. The gain level on the normall lit room on a 10 second exposure does not completely fill up the well capacity, and the result was 65529 which is below the maximum so there's no change required there also

So far I have performed all of my BIAS frames in 1x1, 2x2 and 3x3 Binned modes and my 5Min 1x1 and 2x2 are completed also, one thing I did notice that the Standard Deviation in my dark frames between 600S and 900S exposure times is exactly the same, indicating that the "Hot Pixels" are not differing between the exposure times.

I am extremely happy so far with my purchase, and once I have the filterwheel and filters I can't wait to put the camera to the test fully!!!!

If you are going to regulate the temperature of the CCD, as long as the temperature of your darks matches the temperature of your lights, BIAS frames are not required.

The Gain is set at the chip level (within the amplifier I think) - so you won;t be able to change it anyhow.

I'm not sure about offset - I do know that you can set a "pedestal" value in MaximDL.

Have a look at this thread for a discussion on CCD characterisation. Its easy enough (if you know how) and a worthy project. And best of all, can be done indoors when its cloudy...


www.irishastronomy.org/index.php?option=...itstart=20&Itemid=40

Looking forward to seeing your images.

From what I understand BIAS frames are required because of the "Value" of the pixel when the current is applied without exposure, this is why it is done at 0.00 exposure time. these "BIAS" frames get deducted from the Darks and Flats during porcessing, which is why nebulosity has selectable options for Darks, Flats and BIAS.

There's a good youtube video that explains it by John Blackwell



All my BIAS masters are completed now anyway

Simon

Simon - take a look at this:

www.cyanogen.com/help/maximdl/Bias_Frame_Calibration.htm

If you subtract the BIAS and your DARK from your image, you are effectively subtracting the BIAS twice - because the DARK already contains the BIAS.

Your master BIAS frames may still come in useful for your flats - if you haven't taken FLAT-DARKS.

Welcome to the world of CCD's...

And that like states:

"Ideally, the other types of calibration frames (dark and flat-field) should themselves be bias frame calibrated. MaxIm DL does this automatically when bias frame files are selected"

So in essence the Darks should also have the BIAS deducted, or am I reading that incorrectly?

"It should be mentioned that bias is also included in dark frames. As such, it actually is possible to perform accurate calibration without using bias frames. That said, you should always use bias frames if either of the following are true:

1. You are using exposure scaling to match dark frames to light frames

2. You are using flat-field frames but are not using matching dark frames ("flat-darks")"

If all your images (lights, light-darks, flats, flat-darks) are taken at the same temperature and exposure duration(easy with a temp controlled CCD and software) then no, BIAS frames are not required. I've never used them at all.

Darks already contain the BIAS.

See the bottom of this page re BIAS frames:

starizona.com/acb/ccd/advimcal.aspx

Hi- I know the weather has been awful but was just wondering how you were getting on with the camera? Would like an Irish perspective on it as have read countless reviews from guys in places like Arizona etc. whos skies are hardly comparable to ours!

I'm leaning towards the 460ex colour. I know I'll take a hit on quality over mono but I'm concerned I'll never finish an LRGB given our skies. If I only managed 20x5min subs before the clouds rolled in at least I'd have some data to work with if they were colour as opposed to just 20x5 green subs for example. If weather was no issue obviously I'd be going mono, I would really love to try some NB at some stage so would be very interested to know how the mono is working out for you. Thanks

Very nice, Simon! Congratulations. Weather really has been awful lately

stang wrote:

Hi- I know the weather has been awful but was just wondering how you were getting on with the camera? Would like an Irish perspective on it as have read countless reviews from guys in places like Arizona etc. whos skies are hardly comparable to ours!

I'm leaning towards the 460ex colour. I know I'll take a hit on quality over mono but I'm concerned I'll never finish an LRGB given our skies. If I only managed 20x5min subs before the clouds rolled in at least I'd have some data to work with if they were colour as opposed to just 20x5 green subs for example. If weather was no issue obviously I'd be going mono, I would really love to try some NB at some stage so would be very interested to know how the mono is working out for you. Thanks

Haven't done anything with it yet except build my darks library, I am still waiting for the Baader 36mm unmounted filters, my supplier has my filter wheel ready, just waiting for the filters.

I plan to image using MaximDL, it has a filter wheel controller, where you specify for example:

Position 1: Luminance
Position 2: Red
Position 3: Green
Position 4: Blue
Position 5: HA
Position 6: OIII
Position 7: SII

So when I image, I can tell Maxim to do it sequentially, so if I want 25 exposures of RGB, it will do them as RGBRGBRGBRGBRGBRGB....and so on

So at least I will have some data to work with too

wbean wrote:

Very nice, Simon! Congratulations. Weather really has been awful lately

Weather isn't bothering me at the moment as I cannot image anyway due to lack of filters...lol

CarlightExpress wrote:

So when I image, I can tell Maxim to do it sequentially, so if I want 25 exposures of RGB, it will do them as RGBRGBRGBRGBRGBRGB....and so on

So at least I will have some data to work with too

That's interesting, never thought of that as a possibility...Let's say the night only allows us 21x5 min subs, is the generally consensus that 7xR, 7xG & 7xB would give a better image than 21in colour?

stang wrote:

That's interesting, never thought of that as a possibility...Let's say the night only allows us 21x5 min subs, is the generally consensus that 7xR, 7xG & 7xB would give a better image than 21in colour?

You would be correct, with an OSC, you still have the Bayer Matrix which means there's more green pixels than red and blue, plus there's a better resolution from a Mono than an OSC. Don't get me wrong, I've seen some fantastic images with OSC cameras, Mono cameras aren't for everyone. Plus I plan on doing narrowband / hubble colours also