Atik 383L+ Mono First Tests

[Euan]

Well the wait is finally over, my first mono CCD arrived today

So far I'm really impressed by the build quality and software support. Being only a QHY user so far, I've been used to trawling the internet for drivers and software, and more often than not pulling my hair out. The 383 came with a CD with the drivers on, and a single software install from the Atik site gave me Capture, Atik's own image acquisition software, and all the plugins needed.

The set point cooling is really impressive, at an ambient temperature of 19 degrees, it was able to get to -20 in a few minutes.

The first thing I've been looking at is the controversial 1.25" filter issue. At lot of people with be buying this camera in the hope of saving a fortune in filters, by sticking with 1.25" rather than 2". To give it a good go, I have a T-Thread to 1.25" adaptor that can sit directly on top of the CCD, here I'm using a 1.25" Astronomik 6nm Ha Filter:

My scope is an F5 refractor, with a TRF-2008 reducer fitted at 57mm from the CCD. Here is a flat frame from it. The slight offset in the light is probably as there is a slight movement in the 1.25" adaptor mount and it's not 100% square.

For comparison here is a flat frame from my last CCD, the QHY8. This is with the same setup but with 2" filters

I'm not sure yet whether or not I'm happy with this level of signal loss. The next thing to do is to try a flat frame with a 2" filter and compare them

Cue the clouds and rain!!

[Euan]

Well, I've just taken the same flat frame but without the 1.25" filter, so it now has the full light from the optics with no obstructions

The result is really encouraging, it looks like I'm getting the light loss from the optics rather than the filter

Although I can't figure out how the bigger chip QHY8 had less loss overall

[Eddie]

Hmmm, that's an interesting comparison. The flat does look a little disappointing though. It would seem to me that the optical window is not quite large enough to work at f5 and still fully illuminate the 8300 chip.

1. Either this or the vignetting could be caused by the constraints of the shutter; as the chip appears to be set some way back from the shutter.

2. How long were your exposures for your flats? I have heard of regular illumination problems with short exposure lengths when taking flats (ie under 2 seconds) with full frame sensors.

HTH,

Eddie

[Euan]

Hi Eddie,

The Atik flats are 3 seconds

The QHY8 ones were probably about 0.1 - 0.2 secs

[Eddie]

Hi Euan,

Have you thought about taking a flat without the TRF? It may be that the optical window / shutter can not operate at faster f ratios because of sharp light cone that the optics would produce.

HTH,

Eddie

[BlueAstra]

What software does the contours?

[Euan]

What software does the contours?

It's CCD Inspector, it can perform a flat frame analysis

Welcome to CCDWare - CCDInspector

Eddie, here is a version without the TRF. I've tried exposures up to 6 secs but I get the same figures from 3 upwards

This makes the scope F6.25

[BlueAstra]

There's something a bit odd about the QHY flat in the second image. Its just visual, but the 6% line looks almost black and the centre looks much brighter than the first atik image, so visually the QHY gradiant from centre to the 6% line looks much steeper than the gradiant to the same point in the atik image. Are you sure the calibration is correct in the QHY image?

I think the Atik chip size is smaller than the QHY, so if its in the same focal plane I would expect a slightly more uniform image unless the Atik aperture infront of the chip is smaller than the QHY.

[Euan]

There's something a bit odd about the QHY flat in the second image. Its just visual, but the 6% line looks almost black and the centre looks much brighter than the first atik image, so visually the QHY gradiant from centre to the 6% line looks much steeper than the gradiant to the same point in the atik image. Are you sure the calibration is correct in the QHY image?

I think the Atik chip size is smaller than the QHY, so if its in the same focal plane I would expect a slightly more uniform image unless the Atik aperture infront of the chip is smaller than the QHY.

I think that's just now CCD inspector does the stretch, from the blackest point to the whitest regardless of the different in level

I don't understand the QHY flat either, I tried loads of flats I've taken over the past year and they are all the same

Does it make any difference that one is an interlaced and the other is a full frame CCD?

[NickH]

Ever considered an issue with the 8300 chip itself :-)

(walks away...)

[Euan]

Ever considered an issue with the 8300 chip itself :-)

(walks away...)

Troublemaker!!

What were your flats like for your test shots? Do you have any you could send me for comparison?

[NickH]

Almost identical to yours...will see if I kept them (archive on DVD's)...but they were very similar. Also the "darks" I got were never truly dark, initially put that down to the shutter on the 383 (in the review).. things I am hearing on other 8300 cams is making me think about that though...

Threading a filter directly onto the camera for me is just not an option...and I doubt for anyone seriously imaging

Your flats do look very similar to mine with 1.25" filters though..and I tried all sorts of positioning tweaks with the Atik EFW1, on a TMB at F6.2 and got the same every time pretty much (give or take). Loads of light bleed when doing darks too, even with the shutter closed.