Sony ICX-841 (used in SX-841C, ATIK490EX cameras) thoughts?

[rogerg]

Hi all,

I'm comparing one-shot-colour cameras to determine what the best camera would be for my purposes (that being, a short tube refractor: Megrez 90 ~590mm focal length, large undistorted field).

My comparison of 7 chips used by various camera manufactures currently has me leaning towards the Sony ICX-841 chip which is used in the ATIK 490EX and Starlight Xpress SX-814C cameras.

My reasons for shortlisting this chip are:

Reasonable size and resolution at 9.1MP
Reasonably well matched pixel size at 3.69 resulting in ~1.2 arcsec/pixel
Reportedly good QE compared to other OSC chips


Of the cameras, the SX-814C appears the best with ~40 delta cooling as compared to ~25 delta cooling and perhaps slightly lower read noise.

Cameras aside and considering the chip only .....

I note that the ICX-814 has relatively small Full Well Depth of 18,000. This is even lower than the generally considered to be low Kodak 8300 chip at 25,500. I'm not entirely clear what practical difference this will make, can anyone elaborate? As I understand it, the pixel may fill up more quickly but if anti-blooming is effective this still wouldn't result in blooming. The result then would be reduced dynamic range. Am I right?

Does anyone have either of these cameras to show examples or comment on their effectiveness?

Starlight Xpress SX-814C
ATIK 490EX


Thanks,
Roger.

[PRejto]

I don't know if this is really correct but it does seem that some refractors might have a blue issue with the Sony chips given their higher sensitivity in violet/UV. You might want to see if other users of your particular scope are having an issue with the Sony chip.

Peter

[Shiraz]

In view of Peter's problems with a high end triplet, maybe the 814 is not the best bet with a fairly fast doublet - particularly an OSC version of the 814. As Peter says, problem seems to be that the Sony chips are very sensitive to violet, so if your scope produces a violet halo, it will be visible as blue. The small pixels of the 814 simply don't give aberrations anywhere to hide (they are about 1/6 the size of the Kodak 9 micron ones).

Otherwise, the Sony chips are excellent, with very high QE and good overload characteristics. The well depth issue is a bit of a non-issue - if you take short subs (and you can because of the low read noise), you can get just as good (or better) dynamic range compared to other chips. Cooling is also no big deal - provided you can get them down to 0C or below, dark current is not really an issue.

If you want to use the WO scope with a Sony chip, get a mono version and do NB - should be a killer combo with no CA issues.

[rogerg]

Thank's both for your replies. That is not a factor I was aware of at all, very interesting and dissapointing. My Megrez 90 doesn't currently show any violet fringing but it is only a doublet and I wouldn't want to tempt fate, spend $3,000 and have it wasted. I do wonder if a violet reduction filter would help? but obviously that would cut sensitivity.

I am specifically interested in single-shot-colour for this scenario so won't be considering a mono chip, rather looking at alternative OSC chips.

Thanks :thumbsup:

[LewisM]

I had no blue/violet issues with my Takahashi FSQ-85EDX and the FLI ML8300 OSC.

[rogerg]

I suppose that matches the observations here in that the 8300 is a Kodak chip not a Sony. I was hoping to get a more suitable OSC than the 8300 for my situation.

[rogerg]

I realised I made a critical typo in the subject of this thread. The chip should read ICX-814C (was ICX-841C).

I still haven't been able to find anyone who is actually using the ICX-814C chip, available in cameras such as:

ATIK 490EX
Starlight Xpress Trius SX-814C


If anyone has example images or direct experience with such a chip I'd appreciate being pointed in the direction of examples.

Thanks!