Does anyone else have an STV ?

[montewilson]

Guys,
My STV is lonely. It thinks it is the only one in Australia. I keep trying to reassure it there must be others out there just like it but in truth I have never seen anyone here with what must be the best Autoguider/CCD/Live Video Astronomy camera ever made.

I have pointed out to my STV that there are plenty of ST4's in Australia but it gets rather snooty at the mention of the 4 which it regards as quite inferior and "sooooo last century".

Anyway if anyone else has one I would love to share thoughts on it. I have plenty of experience with it.

[nightsky]

G'Day Monte,
:welcome: I think we have met at Ilford,the name rings a bell,anyway any chance of writing a review on your STV,like the different between models and prices etc.and it's good side and bad side (if any) I for one would be very interested in a review and maybe your STV might not be alone for very long :P
Cheers
Arthur

[jase]

The SBIG STV was discontinued in March 2006. You can still pick them up reasonably cheap through Astromart.

The ST-402ME is the current successor. KAF-0402ME CCD makes a great autoguider - very sensitive. Not many players are using CMOS due to the lack of sensitivity. Certainly cheaper than CCD, but if performance is what you're after in an autoguider i.e guiding on faint stars, stay away from CMOS.

A new standalone autoguider by SBIG is anticipated in Sept-Oct 2007 timeframe. It is labled as the "Smart" guider and uses a KAI-340 CCD chip. More info can be gathered at http://www.sbig.com/aic2006/AIC2006.PPT

[nightsky]

G'Day Jase,
Thanks for that info m8,but I was just trying to get Monte to write a review as his camera seemed lonely :( and by writing a review he may have got another member to buy one and join him :P as for me I have a Meade 10" LX 200 GPS and the camera in question is not recommend for that type of scope.
Cheers
Arthur

[Ambermile]

I'm pretty sure you will find that the reason CMOS is a *bad thing* astro-wise is nothing to do with sensitivity but rather has a whole lot to do with noise.

Arthur

[jase]

Not wanting to change the purpose of this thread, but I disagree with your comment Arthur.

"each pixel on a CMOS sensor has several transistors located next to it, the light sensitivity of a CMOS chip tends to be lower. Many of the photons hitting the chip hit the transistors instead of the photodiode."
http://electronics.howstuffworks.com/question362.htm

This implies that you need longer exposure times to compensate for the lack of sensitivity, this in turn increases the noise (as you mentioned). Both noise and sensitivity can be controlled through cooling and pixel binning respectively.

[montewilson]

Guys - I´ll try to do a review of the STV soon. I spoke to to the Alan Holmes about the discontinuation of the STV and he said the problem was the screen availability. That killed it off. As they had to redesign the main board a few times to accomodate a different screen they decided it wasn't worth re-doing after the last screen became unavailable. I love mine and I'm hoping it will keep working for a long time.

Regards

Monte

[nightsky]

G'Day,
Good on yeh Monte :)

[Ambermile]

So then, what about the switching noise from "several transistors" next to each pixel? Not to mention the heat generated by having those on the chip as well? Add to that the significant increase in physical chip size and consequent increase in TEC size and current requirements? Pixel binning should also be an option, not a requirement surely?

arthur

[jase]

Yep, I see your point. This is the reason why Canon design and manufacture their own CMOS sensors. They use "amplifiers" that replace the transistors - advanced signal converters to make the pixels more sensitive. In addition to this they also have a noise frame subtraction circuit which is performed prior to final image output.

These two components significantly reduce noise. From a TEC and current requirements, CCD's are actually require more power and cooling than their CMOS cousins to perform well. I read somewhere that CMOS sensor uses 1/5th the power of a CCD chip.

Indeed pixel binning should be optional. Actually, I'm not aware of any CMOS sensors that allows you to bin. It maybe possible through modified camera firmware. If the camera could bin, sensitivity would increase and shorter exposures would result, thus reducing noise. I never said any of this was a requirement.

Quoted from the MaximDL manual;
"Important Note: Some cameras use a TC-237 guide sensor instead of the original TC-211 guide sensor. These sensors have much smaller pixels; it is strongly recommended to operate these sensors at 2x2 or 3x3 binning."

Based on these circumstances and your arcsec/pixel configuration would I deem binning a requirement for guiding purposes. Actually, having the STL11k with the TC-237 chip, I bin when guiding. I'm sure others do too.