Starlight Xpress TRIUS SX-814 - User Temperature Control?

[Gib007]

Hello everyone, I'm thinking about upgrading my CCD camera and the Starlight Xpress TRIUS SX-814 is looking very tempting. I want this particular CCD sensor and like the price of this camera over QSI's 690. It also have -40°C temperature delta, like QSI's, whereas ATIK's is -25°C for the 490EX. My question is though, with the Starlight Xpress TRIUS SX-814, can the user physically set the temperature like with ATIK cameras (e.g. my 383L+)? I love the idea of being able to set a specific temperature, mainly for capturing darks at home the next day. 

Not having this feature would really put me off, to be honest. Thanks!

[ChrisLX200]

The noise is so low on these Sony chips you don't really need to go with very low temperatures. A -40 delta is a waste of time in the UK, I 've standardised on 0deg and I'm quite happy with the noise level.

ChrisH

[ChrisLX200]

Ah, just noticed you're in Gibraltar. Still, noise will still not be an issue for you.

ChrisH

[Gib007]

Hehe, bit warmer here, yeah. Summer nights are about 20°C outdoors. Winter, can be as low as 8°C but very rarely lower (like armageddon rare).

[Gib007]

So you think perhaps ATIK 490EX would suffice with its -25 delta?

[ChrisLX200]

So you think perhaps ATIK 490EX would suffice with its -25 delta?

I would say yes. Someone wrote a professional assessment of this camera, its low noise properties, and performance at various temperatures. I read it with interest but unfortunately did not bookmark it, but in summary the noise was so low it was barely worth taking any darks at all. The tester was someone assessing the camera for a scientific application not for astro imaging, and he had the equipment and expertise to provide a valid opinion.

ChrisH

[Gib007]

That's really good to hear. I love ATIK cameras, personally. I just have to find a viable price and buyer for my 383L+... Can't afford a new camera without first shifting this one, hehe.

[dmahon]

Yes, you can set the temperature on SXVR cameras (but not the older SXVF series). I set mine to -10 permanently).

The USB hub on the Trius will nicely run the SX filterwheel and a lodestar on an OAG.

[Gib007]

Thank you for confirming that. I'm still between deciding on which, ATIK 490EX or Starlight Xpress Trius SX-814. I'm a big fan of ATIK so it's pushing me in that direction but I like the cooling system of the Trius. Not too bothered by the USB hub though as I'd only put the Lodestar on it, but I guess it's handy!

What do you guys think? ATIK 490EX or Starlight Xpress Trius SX-814? Thanks!

[Stephen]

Thank you for confirming that. I'm still between deciding on which, ATIK 490EX or Starlight Xpress Trius SX-814. I'm a big fan of ATIK so it's pushing me in that direction but I like the cooling system of the Trius. Not too bothered by the USB hub though as I'd only put the Lodestar on it, but I guess it's handy!

What do you guys think? ATIK 490EX or Starlight Xpress Trius SX-814? Thanks!

Atik, purely for the fact it's got 4.5mm less back focus than the SX and that could matter

[Gib007]

That's a good point! My 383L+ is 17.5mm though so I already have the extra 4mm over the 490EX! Just wondering now about the 460EX / 490EX...

Here's an analysis: 

Telescope: Borg 77EDII F4.6 (367mm focal length as measured)

ATIK 460EX = 2.55 arcseconds/pixel

ATIK 490EX = 2.07 arcseconds/pixel

Telescope: Altair Astro 8" RC F5.4 (1089mm focal length as measured)

ATIK 460EX = 0.86 arcseconds/pixel

ATIK 490EX = 0.70 arcseconds/pixel

Gibraltar seems to have an average seeing of 1.25 to 1.5 arcseconds (sometimes 2 arcseconds) as far as weather forecast seems to be throughout the year. What are your thoughts? I'm a bit puzzled about the talk of exposure times. I always felt as though the telescope focal ratio led to that alone but it seems to me that perhaps the pixel size may also play said role in saturation speed. I don't want to shoot myself in the foot with extra-long exposures just because of the smaller pixels on the 490EX, unless the difference is very minor. 

[dmahon]

What's the backfocus of an atik setup with filterwheel and OAG compared to an SX setup with filterwheel and OAG? Mine (SX) is approx 58.5mm, which is near enough the 56 required to work with my focal reducer.

[Stephen]

What's the backfocus of an atik setup with filterwheel and OAG compared to an SX setup with filterwheel and OAG? Mine (SX) is approx 58.5mm, which is near enough the 56 required to work with my focal reducer.

Can't remember the exact numbers but if you mix and match (Atik camera, SX FW/OAG) then you get the magic 55mm

[thanders]

Here's an analysis: 

Telescope: Borg 77EDII F4.6 (367mm focal length as measured)

ATIK 460EX = 2.55 arcseconds/pixel

ATIK 490EX = 2.07 arcseconds/pixel

Telescope: Altair Astro 8" RC F5.4 (1089mm focal length as measured)

ATIK 460EX = 0.86 arcseconds/pixel

ATIK 490EX = 0.70 arcseconds/pixel

Gibraltar seems to have an average seeing of 1.25 to 1.5 arcseconds (sometimes 2 arcseconds) as far as weather forecast seems to be throughout the year. What are your thoughts? I'm a bit puzzled about the talk of exposure times. I always felt as though the telescope focal ratio led to that alone but it seems to me that perhaps the pixel size may also play said role in saturation speed. I don't want to shoot myself in the foot with extra-long exposures just because of the smaller pixels on the 490EX, unless the difference is very minor. 

According to theory you need 2 samples not to lose resolution. So ATIK 490EX = 0.70 arc seconds/pixel will do the job.

/Thomas

[Gib007]

Just worried about the exposure times if the pixels are so small. Ratio of square of pixel sizes between my 383L+ at 5.4 micrometres and the 490EX at 3.69 micrometres seems to indicate 383L+ is potentially 214% faster...

[Gib007]

Just a quick update, that I decided to keep my ATIK 383L+ after all. The reasoning as follows:

1. The choices were down to the 460EX (ICX694) or 490EX (ICX814). I was more keen on the 490EX because the sensor has more pixels, which are also smaller (yielding more resolution in arcseconds/pixel). If however you use the peak quantum efficiency of either camera plus my 383L+ (KAF8300), along with a reference star that outputs a certain number of photons and encompasses a certain number of pixels on each sensor, it seems that the 460EX needs exposures about 4% longer than the 383L+ for the same signal in terms of photons absorbed. The 490EX however needs 45% longer exposures. This renders the choice down to the 460EX for me. 

2. The 460EX has a pixel size very comparable to that of the 383L+, meaning that I don't get AS MUCH of a resolution improvement over the 383L+. The only benefit would be in noise, which to me isn't a big deal with the 383L+ because of cooling (keep in mind the temperature delta for the 383L+ is -40°C), stacking, calibrating and post-processing in PixInsight. 

3. Where the 460EX drops in value for me is the FOV achieved, which is significantly smaller than my 383L+'s FOV. The larger FOV of the 383L+ will mean that to me, the smallest imperfections due to resolution will be less visible and on top of that, I require less frames for a desired mosaic image than with the 460EX. 

The above negates the need for me to upgrade my camera as the 460EX is the best option and even that doesn't provide THAT much of a benefit to me over the 383L+ I have already. Selling the 383L+ would also mean a loss over what I originally paid, added to the extra cost of the 460EX would mean an expense of around £600 to £800. That's too much for some noise reduction that I already achieve with my methods and for a smaller FOV that will annoy me in the long-run!

So yeah, thank you all for your replies. I will keep my 383L+ for the time being. I will re-think the whole idea of upgrading my CCD camera in the future, perhaps when new sensors are out.