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Old 09-07-2015, 11:44 AM
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JD2439975 (Justin)
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Atik 320e or 420??

Hi all,

I've been tossing up between the Atik 320/420 and with Andrews 10% off sale now seems as good a time as any.
Both cameras have the same chip and same price with only minor differences...

320 advantages - lower read noise, 3e compared to 4e and an st4 port for autoguiding.

420 advantages - higher QE, 65% compared to 45% and 5C extra ∆T.

One discrepancy I found was read noise, Andrews and Atik site(internet archive wayback machine for 320) state 3e and 4e for the 320 and 420 respectively, while Atiks pdf manuals state 4e and 5e? Either way the 320 wins.

I'd be using the camera mostly for photometry and grating spectroscopy so the lower read noise/higher dynamic range of the 320 is a big plus, lower QE can be compensated by longer exposures and as I'm no longer in that sweatbox Darwin do I really need that extra 5C?
Still a little voice says newer tech is better tech...damn!

Anyone care to share their thoughts, which one would you get?

Justin.
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  #2  
Old 09-07-2015, 05:44 PM
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lazjen (Chris)
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Summer temps can hit high 20s to 30+ at night. Would the extra 5 degrees off help then?

And with our crappy weather would it be easier or better to take shorter exposures and possibly more of them?
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Old 09-07-2015, 09:42 PM
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codemonkey (Lee)
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Given that the sensor in the 420 is 44% more sensitive and there's theoretically at most 33% more read noise, seems your SNR and thus dynamic range would be better with the 420. The other question is how often are you shooting such that you'd actually be read noise limited? You should be aiming to avoid that anyway.
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Old 10-07-2015, 02:03 PM
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JD2439975 (Justin)
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Thanks for your inputs Chris and Lee , you got me thinking and while researching I found what might be the clincher...the 320 does not have set point cooling so no calibrated darks/dark libraries.
Looks like the 420 wins this race, cheers guys.

Justin.
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Old 11-07-2015, 04:12 PM
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Slawomir (Suavi)
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Hi Justin,

What about Atik 414? It has larger pixels ( deeper wells ) and having a similar read noise as 420 it will have greater dynamic range. Cooling is the same as in 420.
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Old 12-07-2015, 12:44 PM
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JD2439975 (Justin)
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Hello Slawomir,

The 414 has a lot going for it but I'm concerned about pixel scale with my scopes, 1.1 and 2.2 arcsecs/pixel for the 10" and ED80 respectively.
I haven't had a chance to test it but seeing conditions here are visually way better than Darwin, stars are tight little points instead of extended near nebulous objects.
From what I've read for photometry I should be aiming for oversampling by 2-3 times the seeing...borderline for the 10" and the ED80 would need defocusing for sure.

If my FL was closer to 1500-2000mm the 414 would be well in the race, thanks for the post.

Justin.
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Old 12-07-2015, 01:11 PM
glend (Glen)
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Justin, I am going through the same exercise right now, thinking about trying out CCD imaging, and given that Andrews has 10% off I am going to need to make a decision one way or another soon. Your research has been useful thanks.

Last edited by glend; 12-07-2015 at 01:34 PM.
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Old 12-07-2015, 04:10 PM
SpaceNoob (Chris)
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1.1" and 2.2" are fairly ideal in most instances.... Don't get too caught up on it unless you're heavily under-sampling or oversampling. I would get whatever the biggest sensor that fits within your budget.
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Old 12-07-2015, 04:24 PM
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Hi Justin,

I am currently imaging at 1.33 arcseconds per pixel - although it is purely to create hopefully pretty images, I do not think that in South Queensland you would benefit from a much smaller image scale. I believe that imaging scale of 1.1 arcseconds per pixel is probably about maximum, and on the good nights too.
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Old 13-07-2015, 01:13 AM
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JD2439975 (Justin)
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Hi guys,
If I was only doing pretty pictures with it I'd be happy enough with that pixel scale but for photometry not spreading a star over sufficient pixels can lead to erratic results, or so I've read anyway.
The larger chip/FOV and deeper wells of the 414 I like, the lower resolution not so much and the extra $450 would get me a V and half a B filter...damn those things are expensive! Only 1.25" ones at that.

420 still winning,

Justin.
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