Atik 460ex issue

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Atik 460ex issue

Postby Keith Graham » Tue Feb 13, 2018 11:03 pm

Hi,

I recently purchased an Atik 460ex camera to replace my ST8Xme. In creating a master cosme file in ISIS I was quite surprised at my results and perhaps I am misinterpreting exactly what the cosme file is telling me. The table below shows a comparison of threshold values vs number of pixels above each threshold value. I was quite surprised to see the high number of hot pixels for the 460ex when compared with those values for the 314L at the same temperature, exposure length and binning. I use the 2x2 binning with the 460 since I use it with the LhireIII that works best with 9u pixels as in the ST8.

As is quite apparent, the ST8 has many more hot pixels above the given threshold levels except for 5000 and 10000. That is to be understood considering that the ST8 is known to be quite noisy. However the massive differential at 600 second exposures between the 314 and 460 is very confusing. Note that with 10 second exposures the differential is very close (except at the threshold of 500). So why such at difference at 600 second exposures?

The 460 has been lauded as being such a quiet camera, so can someone please shed some light as to why is there such a differential between the 460 and the 314 at the 600 sec. exposure /500 threshold level? The 460 camera appears to be quite noisy compared to the 314? Is this normal? I am wondering if there might be some defect in the 460.

Thanks,

Keith Graham


Pixel Counts
Camera 460ex 314L 460ex 460ex 314L314L ST8
Bin 1 Bin 1 Bin 2 Bin 2 Bin 2 Bin 1 Bin 1
Exp Temp 0 0 0 0 0 0 0
Exp Time 10 10 10 600 600 600 600

Threshold Value
500 135 79 338 13530 219 372 60981
1000 36 42 56 6131 182 316 32605
1500 22 30 29 604 169 293 5427
2500 15 22 19 399 154 272 1565
5000 9 13 11 308 128 229 391
10000 5 5 5 196 66 135 159
Keith Graham
 
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Re: Atik 460ex issue

Postby Keith Graham » Wed Feb 14, 2018 12:02 am

I see that the table on this message did not line up. I am trying to scan and attach a file, but my scanner is now giving me fits. More to come.
Keith Graham
 
Posts: 125
Joined: Thu Sep 29, 2011 6:20 pm

Re: Atik 460ex issue

Postby Andrew Smith » Wed Feb 14, 2018 12:06 pm

Hi Keith, have a look at the topic "Warm Pixels" viewtopic.php?f=8&t=1919 different camera same chip (I think)

Regards Andrew
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Re: Atik 460ex issue

Postby Keith Graham » Wed Feb 14, 2018 1:15 pm

Thanks a bunch, Andrew. Looking at all of the graphs, the results appear to be very similar to what I found.

I was puzzled at these results because I have seen posts from other Atik (314 and 460) users claiming their images are so clean that they do not use darks because their images are very clean without them. I have been a bit skeptical of not using darks, but the results shown here indicate to me it is still best (and perhaps even necessary) to do dark subtraction.

Cheers,

Keith
Keith Graham
 
Posts: 125
Joined: Thu Sep 29, 2011 6:20 pm


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