383 hot pixels..

[Coco]

Hi

It might be me having a 314L+ that was hot pixel free and noiseless (nearly) but can you 383 owners cast an eye on the fits file and tell me is this normal ..

http://www.spdautomotive.co.uk/astro/DARKS_082.fit

.

[PortableAstronomer]

Looks similar to dark frames I would get when I borrowed a 383 a few months ago, and that was while owning an Atik 314 and QHY8 which both had Sony super-had CCDs.

I found the 383 definately more noisy than the Sonys, handed that back, but since then also I sold the 314 (which I now regret).

I was also finding the smaller pixels in the KAF-8300 chip made images noticeably dimmer than the 314L, but it was great as a 2x2 binning camera (although still more noise).

The biggest surprise in comparing the "sensitivity to noise" ratio, for me, was not going from the 314 to a one-shot-colour (QHY8), it was actually going from the 314 to a 383 (mono).

Ironically the camera I've been doing most narrowband imaging with, is the QHY8 one-shot-colour (although that's more because the APS-C size format fits my 190MN scope very well)

I think with the 383 you have to ensure you take sufficient number of dark frames and stack lots of lights to really combat the noise. People do get great results with the 383. But I bet a lot of people don't realise what goodies they're throwiing away when they go from a Sony Super-HAD CCD to a Kodak.

[Coco]

OK, thanks , thought more could contribute, thanks Olly also for the tech support

Am waiting for ATIK to get back to me about sending it in for a summer service, shutter check,desiccant replacement, clean, its been 4 days no reply, perhaps they only want to sell new cameras..

[Deneb]

Guy, I take it your camera is the pre 2011 models...

Nadeem.

[Coco]

Guy, I take it your camera is the pre 2011 models...

Nadeem.

Yes it was bought June 2010 by a member on here, everything works fine, am just not used to so many hot pixels, in Maxim they do diminish and am sure 100% they will be cancelled out in a stack, just the broken ST4 lead and weather has stopped me testing it.

[shaunster]

You got one then... good luck with it

[Freddie]

I too have had no reply from Atik for close to a week now. Have they gone on summer holiday or something !!??

[Coco]

I too have had no reply from Atik for close to a week now. Have they gone on summer holiday or something !!??

If they have they should say so on auto reply via email??

Bit annoying..

[Deneb]

I had a reply from Vince next day after I sent Atik an email, but that was for something different...

Nadeem.

[FLO]

I have sent them a link to this thread on your behalves.

Atik are used to operating through dealers and have been restructuring (to enable more models to be held here in the UK) this month so they are probably distracted.

HTH,

Steve

[Coco]

I have sent them a link to this thread on your behalves.

Atik are used to operating through dealers and have been restructuring (to enable more models to be held here in the UK) this month so they are probably distracted.

HTH,

Steve

Thanks Steve..

Vince has been in touch.... Glad I bought an Atik

Superb service...

.

[opticalpath]

Guy, the Kodak sensors just show a lot more thermal noise then the Sony super-HAD; we just got spoiled by those super-clean Sony darks!

With my Atk-16HR, I hardly bother with dark frames - just map the hot pixels and replace them in processing. But with my QSI583, dark subtraction is essential. It's not really a problem though IMO, just an extra discipline. Once calibrated, the images are very clean.

What temperature did you set the cooler at for the dark frame you posted? I could see in the FITS header info that it was a 120 sec exposure, but could not see a set temp. If you want one to compare to, here is a link to a 120 second dark I took with my QSI583 at -20C:

http://universalconstant.com/dark(-20)_120sec.fit

Adrian

[Rob_Jn]

These were measured in AIP 4WIN and compared to my master dark taken at -20C and 5min.

Image Statistics for [1] DARKS_082.fit:

Image Type: Greyscale

Image Width: 3362

Image Height: 2537

Data Bytes: 34117576

Minimum: 272.0

Maximum: 65535.0

Mean: 437.32

Median: 423.41

Std Dev: 275.909

Skew: 104.6253

Ignore: 10.0%

Camera Type: Unknown

Pixel Width: 6.45

Pixel Height: 6.45

Original image: C:\Documents and Settings\Rob\Desktop\DARKS_082.fit

= 'Rotate 180'

Image Statistics for [3] 383L_Dark_1x1_5min_x37.fit:

Image Type: Greyscale

Image Width: 3362

Image Height: 2537

Data Bytes: 34117576

Minimum: 287.054

Maximum: 52259.8

Mean: 330.787

Median: 329.672

Std Dev: 59.1343

Skew: 470.776

Ignore: 10.0%

Original image: C:\Documents and Settings\Rob\My Documents\CCD\Masters\383L_Dark_1x1_5min_x37.fit

Average of 37 dark frames

Depending on the temp you took it at your dark of 120s has higher values than mine.

Rob.

[Coco]

Guy, the Kodak sensors just show a lot more thermal noise then the Sony super-HAD; we just got spoiled by those super-clean Sony darks!

With my Atk-16HR, I hardly bother with dark frames - just map the hot pixels and replace them in processing. But with my QSI583, dark subtraction is essential. It's not really a problem though IMO, just an extra discipline. Once calibrated, the images are very clean.

What temperature did you set the cooler at for the dark frame you posted? I could see in the FITS header info that it was a 120 sec exposure, but could not see a set temp. If you want one to compare to, here is a link to a 120 second dark I took with my QSI583 at -20C:

http://universalconstant.com/dark(-20)_120sec.fit

Adrian

I have to say it looks the same .. and thank you for the link

As you say we are spoiled with the little Sony chip

Mine is just approaching its first year, it going in to ATIK for a service, I think thats a good idea during this time of the year, maybe a shutter check and desiccant re fil, sensor clean, although it doesnt seem to need any the above..

A service is a touch base with the manufacturer.. new engine oil and filter etc....

.

[Deneb]

Good thing about the 383, you can push up the set cooling to -40c, once the darks are subtracted as Adrian mentioned the image is quite clean. It's got this neat option in artemis to do darks, you just check the dark box & the 383 shutter closes... but I usually cap the scope as well. Where people have mentioned the Kodak chips are noisy, they are still very acceptable noise levels, especially when you compare the noise levels to a similiar sized chip like a DSLR Sensor even it being less sensitive then a ccd chip.

Nadeem.

[ollypenrice]

While a service won't do any harm I have to say that my Atik 4000s hammer away like crazy in extremes of temperature and neither has had any attention. Influenced by Rob I now do deeper stacks of darks than I did and the hot pixels (I use a hot pixel filter in AstroArt for stacking) still just disappear. I really don't think you are going to have a problem, Guy.

It's a good chip and would suit a long FL scope in binned mode. I'd love to use that chip for camera lens imaging at short FL unbinned, too.

Olly