Trius SX694 Pro or SXVR H694

[pmlogg]

I'm trying to decide whether to buy a new Starlight Express Trius SX694 Pro or a used SXVR H694.

Do the benefits, particularly of the re-chargeable Argon Filled imaging chamber but also the revised electronics and built-in hub (fewer cables), make it worth the extra cost? 

I'd be particularly interested to hear any comments on fogging/frosting during imaging with the SXVR-H694.

Many thanks

[Adam J]

On 28/10/2020 at 11:03, pmlogg said:

I'm trying to decide whether to buy a new Starlight Express Trius SX694 Pro or a used SXVR H694.

Do the benefits, particularly of the re-chargeable Argon Filled imaging chamber but also the revised electronics and built-in hub (fewer cables), make it worth the extra cost? 

I'd be particularly interested to hear any comments on fogging/frosting during imaging with the SXVR-H694.

Many thanks

Personally if you can afford a new SX694 Pro then I have got to wonder why you would not wait for a mono APS-C CMOS sensor?  Or even go with the ASI294mm Pro? 

[newbie alert]

On 30/10/2020 at 13:37, Adam J said:

Personally if you can afford a new SX694 Pro then I have got to wonder why you would not wait for a mono APS-C CMOS sensor?  Or even go with the ASI294mm Pro? 

Maybe because he's looking at a ccd rather than a cmos...

[Adam J]

1 hour ago, newbie alert said:

Maybe because he's looking at a ccd rather than a cmos...

Kinda like some people still have a soft spot of Steam Trains over diesel / electric I guess.

I am not aware of any current advantage that the ICX694 would have over a Mono IMX571. Hence I was simply stating my opinion in the hopes of helping the OP.

In the end its a fantastic CCD sensor, I just would not buy a new one these days there are superior options for you cash. Second hand, why not.

Adam

Edited November 9, 2020 by Adam J

[newbie alert]

10 minutes ago, Adam J said:

Kinda like some people still have a soft spot of Steam Trains over diesel / electric I guess.

I am not aware of any current advantage that the ICX694 would have over a Mono IMX571. Hence I was simply stating my opinion in the hopes of helping the OP.

In the end its a fantastic CCD sensor, I just would not buy a new one these days there are superior options for you cash.

Adam

That a a matter of opinion, I'd rather have a prehistoric tried and tested  sony sensor , a true classic

As a answer to your comparison to the electric cars as they're on the cusp of new technology,  a customer of mine has a Teslar, probrably streets ahead of the other manufacturers electric car era.. but he says he wouldn't buy another, would rather go back to a normal tried and tested model, had more than enough of things going wrong with it, he says the garage has it far longer than him..New technology,  suppose it's the price you pay... great idea but not quite there yet..

[Adam J]

13 minutes ago, newbie alert said:

That a a matter of opinion, I'd rather have a prehistoric tried and tested  sony sensor , a true classic

As a answer to your comparison to the electric cars as they're on the cusp of new technology,  a customer of mine has a Teslar, probrably streets ahead of the other manufacturers electric car era.. but he says he wouldn't buy another, would rather go back to a normal tried and tested model, had more than enough of things going wrong with it, he says the garage has it far longer than him..New technology,  suppose it's the price you pay... great idea but not quite there yet..

They are both Sony sensors. One is just vastly more capable than the other. The ASI6200mm pro is the same technology and it's talking images on astrobin that a 8 year old CCD can only dream of. 

Edited November 9, 2020 by Adam J

[newbie alert]

3 hours ago, Adam J said:

They are both Sony sensors. One is just vastly more capable than the other. The ASI6200mm pro is the same technology and it's talking images on astrobin that a 8 year old CCD can only dream of. 

Now you're jumping to a 4k camera..

[Whirlwind]

3 hours ago, Adam J said:

They are both Sony sensors. One is just vastly more capable than the other. The ASI6200mm pro is the same technology and it's talking images on astrobin that a 8 year old CCD can only dream of. 

It's not as simple as this.  There are pro's and cons to each type of camera.  Professional observatories are still sticking with CCDs, the specialist companies are still manufacturing them etc.  Yes, they are fading in the consumer market but that is because of factors outside the amateur astronomer 'region of interest'.

CCDs still have much more stable bias and dark frames because of the way they read out.  So for photometry and spectroscopy they are still the go to choice.  The calibration hence tends to be easier and cleaner overall.  CCDs also tend to cool better.  On the other hand you need to expose longer so need better mount and guiding, whereas you can get away with shorter exposures with CMOS and stack lots - although 6200MM has individual images of around 120MB so processing also takes a lot longer and you need a hefty computer.  Binning pixels on CCDs can be done at the hardware level (whereas CMOS is restricted to the software level so the noise reduction is a lot lower).  QHY also claim that consumer grade sensors degrade over time (but might be hype to sell the industrial version).  On the other hand damage to CCDs from cosmic ray hits can result in bad columns (but which can be averaged out).  

So there is no right or wrong choice.  Both have strengths and weaknesses but they can also both take great pictures.

 

[Adam J]

3 hours ago, Whirlwind said:

It's not as simple as this.  There are pro's and cons to each type of camera.  Professional observatories are still sticking with CCDs, the specialist companies are still manufacturing them etc.  Yes, they are fading in the consumer market but that is because of factors outside the amateur astronomer 'region of interest'.

CCDs still have much more stable bias and dark frames because of the way they read out.  So for photometry and spectroscopy they are still the go to choice.  The calibration hence tends to be easier and cleaner overall.  CCDs also tend to cool better.  On the other hand you need to expose longer so need better mount and guiding, whereas you can get away with shorter exposures with CMOS and stack lots - although 6200MM has individual images of around 120MB so processing also takes a lot longer and you need a hefty computer.  Binning pixels on CCDs can be done at the hardware level (whereas CMOS is restricted to the software level so the noise reduction is a lot lower).  QHY also claim that consumer grade sensors degrade over time (but might be hype to sell the industrial version).  On the other hand damage to CCDs from cosmic ray hits can result in bad columns (but which can be averaged out).  

So there is no right or wrong choice.  Both have strengths and weaknesses but they can also both take great pictures.

 

Did not realise OP was doing photometry or spectroscopy.  That explains everything.

But lets face it you can do just fine with a CMOS in that respect too:

http://www.astrosurf.com/buil/atik_vs_zwo/

Also we are catigorically not discussing pro observatory equiptment here.

Personally I would go with (in comparison to upcoming ASI2600mm or even the 294 for that matter):

1) Higher QE

2) 3x the surface area (larger sensor)

3) Higher dynamic range

4) Faster read times

5) larger full well capacity

6) Less fragile (one cosmic ray hit will not take out an entire column).

7) No dark frames required (IMX571 yes I have a friend who just dithers it) its actually cleaner than the CCD we are talking about here (provably so if you make me)

8 ) No amp glow.

 

So ill ask you for the IMX571 vs ICX694:

You say calibration is cleaner, can you prove it?

You say dark frames are more consistant, can you prove it?

You say CCDs cool better...can you prove it?

 

I strongly suspect that some if not all of what you are saying (while true of older generation CMOS sensors) is no longer true of the latest generation sensors like the IMX571. 

Sony will cease development of CCD soon, thats a fact and its bacause there are no real advantages to the technology moving forward and they can offer superior sensor in CMOS format.

And for the record the performance advantage is so large that even accounting for SW bin 2x2 vs HW bin 2x2 you will still get better SNR from a modern CMOS sensor.

4 hours ago, newbie alert said:

Now you're jumping to a 4k camera..

No I am talking about an upcoming APS-C that has 26mp and is likely to cost about 2.2k and said "the same technology as the ASI6200mm pro", but you know that dont you?

 

In the last year the price of a new Trius SX694 pro has dropped from a peak of 2.3k to 1.8k. I could be wrong but I would guess its because they are not selling so well. Maybe trying to sell up current sensor stock while its still relevant. Its also possible that the sensor is being sold cheaper by sony...also indicating lower demand. All guesses but I cant think of any other explanations when CMOS cameras are increasing in price at a steady rate taking currency fluctuations into account.

 

Adam

Edited November 10, 2020 by Adam J

[newbie alert]

10 hours ago, Whirlwind said:

It's not as simple as this.  There are pro's and cons to each type of camera.  Professional observatories are still sticking with CCDs, the specialist companies are still manufacturing them etc.  Yes, they are fading in the consumer market but that is because of factors outside the amateur astronomer 'region of interest'.

CCDs still have much more stable bias and dark frames because of the way they read out.  So for photometry and spectroscopy they are still the go to choice.  The calibration hence tends to be easier and cleaner overall.  CCDs also tend to cool better.  On the other hand you need to expose longer so need better mount and guiding, whereas you can get away with shorter exposures with CMOS and stack lots - although 6200MM has individual images of around 120MB so processing also takes a lot longer and you need a hefty computer.  Binning pixels on CCDs can be done at the hardware level (whereas CMOS is restricted to the software level so the noise reduction is a lot lower).  QHY also claim that consumer grade sensors degrade over time (but might be hype to sell the industrial version).  On the other hand damage to CCDs from cosmic ray hits can result in bad columns (but which can be averaged out).  

So there is no right or wrong choice.  Both have strengths and weaknesses but they can also both take great pictures.

 

This is exactly how I see it, choose the camera type that suits you, not that suits someone else

[newbie alert]

15 hours ago, Adam J said:

18 hours ago, newbie alert said:

to a 4k camera..

No I am talking about an upcoming APS-C that has 26mp and is likely to cost about 2.2k and said "the same technology as the ASI6200mm pro", but you know that dont you?

Again, the op is looking for the differences between 2 camera's, I'm sure he's looking for answers from users that maybe have owned both so he can judge his purchase..

In  the meantime you're now adding further cmos camera's into the mix, inc a 4 grand 6200, then to justify your statement you add another camera that doesn't exist yet..

I use a 694sensor in my Atik, I don't use any calibration frames, I just dither.. lots of friends that use ccd also don't use calibration frames so I'm not on my own..

Make a note that I'm not slagging off cmos, it maybe the future , it's just atm ccd suits me far better but for now cmos isn't quite there yet, which maybe the way that the OP see it, hense why he maybe asking between 2 camera's which both have the 694 sensor

[Starflyer]

I'm a die hard CCD user, even twelve months ago I was wondering what all the interest in CMOS was and truly believed it was all marketing generated hype. CMOS = DSLR type sensors right? This is absolutely not the case any more.

After doing a lot of reading and research I believe that CMOS is now, not the future, the technology has matured to the point where it makes no sense to buy a new CCD camera.

I'm waiting for the ASI2600mm to be launched and then I'll be moving to CMOS.

Sure, everyone has the right to their own opinion and to buy what they want to.  If I was the OP I'd welcome advice like this, I know it's not what they asked but the advice is sound and the latest CMOS cameras have huge benefits over CCD.

That said there will be more and more CCDs coming onto the second hand market, grab yourself a secondhand bargain if CCD is what you want.

[Adam J]

32 minutes ago, newbie alert said:

Again, the op is looking for the differences between 2 camera's, I'm sure he's looking for answers from users that maybe have owned both so he can judge his purchase..

In  the meantime you're now adding further cmos camera's into the mix, inc a 4 grand 6200, then to justify your statement you add another camera that doesn't exist yet..

I use a 694sensor in my Atik, I don't use any calibration frames, I just dither.. lots of friends that use ccd also don't use calibration frames so I'm not on my own..

Make a note that I'm not slagging off cmos, it maybe the future , it's just atm ccd suits me far better but for now cmos isn't quite there yet, which maybe the way that the OP see it, hense why he maybe asking between 2 camera's which both have the 694 sensor

I find that most people have a fanatical attachment to the sensor / camera that they own. I try to avoid thinking like that. I currently own a ASI1600mm pro but with the new stuff coming out at the moment I would not recommend it to anyone. I would just be telling them to get the very best they can for their cash. In this case January 2021 is not long to wait for a next generation sensor in my opinion. I sold an ATIK 460ex mono that I got as part of a full setup I purchased for another item and bearly got £900 for it a year ago after two months on the board. If he really wants that sensor I would advise he gets a second hand one as there are many coming up on the market for good prices but for a 60% drop from new to used I would not advise buying a new one. 

[Starflyer]

1 minute ago, Adam J said:

I find that most people have a fanatical attachment to the sensor / camera that they own. I try to avoid thinking like that. I currently own a ASI1600mm pro but with the new stuff coming out at the moment I would not recommend it to anyone. I would just be telling them to get the very best they can for their cash. In this case January 2021 is not long to wait for a next generation sensor in my opinion. I sold an ATIK 460ex mono that I got as part of a full setup I purchased for another item and bearly got £900 for it a year ago after two months on the board. If he really wants that sensor I would advise he gets a second hand one as there are many coming up on the market for good prices but for a 60% drop from new to used I would not advise buying a new one. 

My 460EX will be up for sale in January 😉

I'm not expecting more than 50% of the new price for it even though it's pristine.

[Adam J]

17 minutes ago, Starflyer said:

I'm a die hard CCD user, even twelve months ago I was wondering what all the interest in CMOS was and truly believed it was all marketing generated hype. CMOS = DSLR type sensors right? This is absolutely not the case any more.

After doing a lot of reading and research I believe that CMOS is now, not the future, the technology has matured to the point where it makes no sense to buy a new CCD camera.

I'm waiting for the ASI2600mm to be launched and then I'll be moving to CMOS.

Sure, everyone has the right to their own opinion and to buy what they want to.  If I was the OP I'd welcome advice like this, I know it's not what they asked but the advice is sound and the latest CMOS cameras have huge benefits over CCD.

That said there will be more and more CCDs coming onto the second hand market, grab yourself a secondhand bargain if CCD is what you want.

Exactly I would be very dissatisfied if I paid 2k for a tiny CCD sensor and then the ASI2600mm pro came out a few months later and no one had told me about it. It has all the traditional advantages of CCD and CMOS in one package. 

And as you say of you really want a Sony CCD there are many to be had second hand at great prices. 

Edited November 10, 2020 by Adam J

[david_taurus83]

Ah lads! Don't make me change my mind again! 😄

[Craney]

3 hours ago, Starflyer said:

My 460EX will be up for sale in January 😉

I'm not expecting more than 50% of the new price for it even though it's pristine.

Keep me in the loop about that one...   

[Jonk]

3 hours ago, Starflyer said:

My 460EX will be up for sale in January 😉

Interesting..... give me a shout if it is 👍🏻

[Hallingskies]

Whilst I hesitate to give an opinion in case someone sneers at me for being a steam engine enthusiast or something like that, I would say that one thing in favour of both Starlight Xpress and Atik CCD products is their superb (and local) customer service - even for old or second hand equipment.

I have no experience of (say) ZWO, but they would have to be REALLY good to match SX on that front....  

[Whirlwind]

21 hours ago, Adam J said:

Personally I would go with (in comparison to upcoming ASI2600mm or even the 294 for that matter):

1) Higher QE

2) 3x the surface area (larger sensor)

3) Higher dynamic range

4) Faster read times

5) larger full well capacity

6) Less fragile (one cosmic ray hit will not take out an entire column).

7) No dark frames required (IMX571 yes I have a friend who just dithers it) its actually cleaner than the CCD we are talking about here (provably so if you make me)

8 ) No amp glow.

 

So ill ask you for the IMX571 vs ICX694:

You say calibration is cleaner, can you prove it?

You say dark frames are more consistant, can you prove it?

You say CCDs cool better...can you prove it?

 

Diffraction Limited have a good introduction on the pros and cons of each choice (it also saves me waffling on for ages more than I do below)

https://diffractionlimited.com/ccd-versus-cmos-better/

In terms of the points noted

1) Yes some of them have better higher QE.  This isn't intrinsically linked to CMOS or CCD as you can get very high sensitive CCD as well.  Considering a balanced comparison of front and back illuminated sensors from Sony they are pretty equivalent.  The disadvantage is that back illuminated CCDs never entered the consumer market.
2) To an extent though the 6200 is similarly priced to the 16200's or 11000's anyway.
3) To an extent, yes but this is due to CMOS being user configurable.  CCDs can reach these levels but they are generally configured at the factory to balance noise/gain/well depth etc. It is relatively straight forward to get higher dynamic range but you have to sacrifice something (and the same goes for CMOS, it is just the users choice here)
4) Definitely faster read times.  Rather than one column/row that everything is read through CMOS can read each column simultaneously (although that brings noise issues - see below)
5) Again this largely based on what the consumer choice on the settings.  CCDs can have just as much well depth (if not more), but those without anitblooming gates could easily reach 100,000+
6) This is a bit of an urban myth.  Although it can happen it tends to be that very few cosmic ray hits will complete saturate and destroy a pixel (although I have seen it with some space telescopes).  For most users it damages the pixel so that the sensor always see it as having a residual charge which then feeds down the column or row so it is warm/hot but not completely useless.  In comparison CMOS seems to more generally degrade over time (especially the consumer versions) but there seems to be little evidence of how long this might take and/or based on number of exposures.  However they haven't been used widely for a while but will be interesting to see how these assertions pan out.
7) Yes, dithering averages out noise characteristics but doesn't remove the noise.  A lot is made of low noise characteristics, but really it is the calibrated frames that is important, but I'll come to this in a minute.
😎 No amp glow is the same for both cameras really so doesn't really matter (realistically it will calibrate out but with some cost in additional noise)

In terms of the questions, I can't prove it here because the CCDs are to be set up remotely and CMOS at home so can't really give you a direct comparison.  However, from a statistical perspective and the structure we can say some things.  Firstly the CMOS reads out from along all columns.  The columns each have their own electronics and it is impossible to get every column set exactly the same.  As such you do get column artefacts within CMOS (some worse than others).  Dithering and averaging out does help but it is residual noise that can't be fully calibrated out because it isn't truly random.  In comparison a CCD output (generally) discharges through one set of electronics so the noise artefacts nearly represent true random noise and hence can be subtracted to obtain the 'real' signal.  In comparison although you can make a proxy random noise character of the CMOS there is still a residual 'real' signal in the data which adds an element of noise to the calibration.  In addition there are structures within a CMOS that can be seen to some extent in the flats (for example see 10 minutes in this video):-

CCD and CMOS calibration files

Again these can be largely calibrated out.  At a very basic level though you have multiple non-random signals within the data.  Each of these signals has a small error within it and these add overall.  Again if you refer to the above video at about 4:40 you will see a similar effect in relation to subtracting amp glow (for the avoidance of doubt this is shown to prove the principle, not a discussion about amp glow as more modern CMOS are controlling this).  However from a principle perspective the noise where the amp glow was is still higher than other locations.  This is not an example of poor correction but a natural consequence of subtracting a non random signal from itself and leaving a higher overall level of error.  As such the more 'real' signal sources you have the more errors you compound.  Ultimately there are more 'real' signals in a CMOS camera that you have to remove.  Hence although by pixel noise levels can be lower, the calibrated signal can be worse and to an extent also more dynamic which doesn't favour being able to detect the faintest of objects.  You can never be quite sure whether it is real or not.  In comparison a CCD might have to expose longer but you can be more sure that the faintest objects (by flux) are real because the calibration is cleaner.

Finally as to whether CCDs can be cooled further, yes they can.  I've regularly cooled CCDs with liquid nitrogen with no issues. CMOS are more sensitive because the electronics are in the individual pixels and generate a lot of heat within the pixels (though I'm not an electronics engineer so the exact issue is not my forte.

From a personal perspective having used both, my preference at the current time is CCD over CMOS.  It isn't just just the stability of the noise but also most are manufactured in China and don't currently wish to support what I think is a regime with questionable environmental, social and democratic approaches (which isn't open for discussion).  I also worry that if lifespan of CMOS is relatively short then it encourages a greater throw away society and I don't support that approach for the future of my niece and nephews. Nevertheless in 5 years it may be a different question.

 

 

 

[pmlogg]

Well that has unleashed a lot of very interesting discussion.  I did have two PM that did offer good advice on the SXVR-H64 and as I did have a used one in mind I bought it.  Still waiting for a good clear night to properly test it.

I had decided on that sensor some time back because I wanted to switch to an anti-blooming sensor. I was attracted to the relatively high QE, the compatibility with my 1200mm refractor and with the ability to stick with 1.25" filters.  I'd been able to upgrade my set of those so I'm not ready to move to larger diameter ones.  There were a lot of good reports of the sensor too.  I was attracted by the good prices for 2nd hand 460EX cameras but my existing setup was long, making space a bit awkward in my observatory.  With the Atik it would have been even longer whereas the squat layout of the SX would save me space.

I was attracted by the built-in hub on the newer Trius models but views on that are mixed. My current thought is to mimic that using a 12V  powered separate hub which I think I could fit onto my filter wheel.

Service was another consideration.  I'd already been in contact with Terry and have found him very responsive and helpful.

In the future I may well switch to CMOS but for now I'm going to have a go with the SXVR-H64.  I may even try the spectrography, noting the comments on that.

Many thanks for all the comments.