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Old 07-10-2018, 04:58 PM
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Atmos (Colin)
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Quality comparisons between manufacturers

I was really unsure as to how to title this thread but I'll stick with what I have at the moment.
When it comes to cameras, FLI is considered to be the gold standard. Take the KAF-16200 sensor for example. The ML16 typically gets about 6e- read noise but it is 10-12e- with every other manufacturer. I used to have a QHY22 (ICX694) that had a read noise of 4.5e- but the ML694 was around 2.5e-. FLI does this with faster downloads, deeper cooling and a price tag that goes with the quality.

What about filter wheels and other connections though? Is there the same difference in quality here?

I have a QHYCFW2-M that works well, sometimes it gets a little lost over USB but doesn't have any issues running over serial. The ZWO filter wheels generally aren't large but you don't hear much if any in the way of bad reports about them. My QHYCFW uses M54 threads so it'll work with everything but the largest of chips (they do have bigger filter wheels though) and doesn't suffer from any flex but then again it doesn't have a heavy FLI camera on it.

I have a Nikon adapter for the filter wheel that so far seems to be working well, are components like this better from some other manufactures?

QHY has brought out their next generation of filter wheel but I have also long coveted one of the 8 position SBIG filter wheels or upgrading to a FLI filter wheel with a larger sensor (FLI doesn't have any 36mm unmounted filter wheels I don't think). There is a fair difference in camera quality so I am curious as to whether that moves onto the simpler mechanical side of equipment.

Last edited by Atmos; 07-10-2018 at 05:29 PM.
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Old 07-10-2018, 08:54 PM
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SX all the way for me - every imaging camera and guidecam I have is SX, as is my filterwheel. Not a single complaint, and the customer service from Terry is absolutely positively PHENOMENAL!

Never used a CMOS camera (except for a DSLR ), and I am VERY thankful for the CMOS revolution as it has brought the cost of CCD's second hand WAAAAAAAAAAAAAAAAY down I don't mind snatching those "archaic" CCD's up
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Old 07-10-2018, 08:56 PM
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Camera read noise is important when comparing the same sensor from different manufacturers. My QHY22 was a brilliant camera but the ML694 is better and it has the cost to go with it. I simply used the example of read noise because FLI routinely does it better with THE SAME SENSOR.

The CMOS sensors aren’t quite there yet, not the mono ones anyway. I know I’ll have to part with my QHY163M as the microlens diffraction is a real issue with the RH200. On my Sky Rover it only happens on the bright bright stars but on the RH200 with the steepness of the light cone (F/3), I get it on even medium brightness stars in RGB.

If you take the ASI1600/QHY163M our you’re left with the QHY183M which I am thinking about getting for galaxy work but it certainly isn’t a wide field sensor; small sensor size. All of the larger CMOS chips out there are OSC. The CMOS Revolution is still quite some time away.
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Old 07-10-2018, 08:57 PM
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Quote:
Originally Posted by Atmos View Post
Camera read noise is important when comparing the same sensor from different manufacturers. My QHY22 was a brilliant camera but the ML694 is better and it has the cost to go with it. I simply used the example of read noise because FLI routinely does it better with THE SAME SENSOR.
Glen removed his post Colin, so it seems like you are talking to yourself
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Old 07-10-2018, 09:00 PM
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I sometimes like to remind myself that I am shooting occasionally pretty pictures just for the fun of it, from a backyard in a coastal tropical location, so there is little point in stretching my limited budget and getting scientific grade equipment normally purchased by institutions with deep pockets for professionals, since such equipment wouldn't be utilised to its full potential by me anyway due to a lack of time, location (not being high in the deep dark mountains) and perhaps my limited skills as well. So some equipment compromises, such as noise in the data or an occasional tweak are fine with me.

And yes, there are mechanical differences in simple things such as adapters, with good quality ones ensuring precise orthogonality, not flexing at some angles and not causing internal reflections. A cheap thin extension I used to have once upon a time was, to my surprise, flexing a fair bit. I suspect cheaper filter wheels can leak some light, and more likely won't keep the FW at the right angle to the optical axis at all times, and perhaps won't return filters to the exactly same position each time. Whether it really matters is for everyone to decide for themselves.
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Old 07-10-2018, 09:05 PM
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Quote:
Originally Posted by LewisM View Post
Glen removed his post Colin, so it seems like you are talking to yourself

It was not there very long, and I reserve the right to remove anything after I see it in print (so to speak). It was removed because I thought it was important to take my contribution off to another thread with a wider look at where equipment and software are headed, specifically systems integration.
I did not want to hijack Colin's thread.
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Old 07-10-2018, 09:12 PM
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Quote:
Originally Posted by LewisM View Post
Glen removed his post Colin, so it seems like you are talking to yourself
I thought it must have been subliminal advertising

Colin:

There are a couple of components to read noise. One is on-chip and there's not much you can do about that except testing and discarding the worst samples (or getting the sensor vendor to do this for you.) The second component is generated in the off-chip amplifier and analog to digital converter. It is definitely possible to combine good quality components with clever design to make a difference here. You can also put effort into shielding the sensor from stray signals, keeping the power to the sensor free of noise, etc. It does seem that FLI do a good job of this and their cameras often have very good read noise characteristics for any given sensor.

Wrt overall quality, I've heard horror stories about cameras and accessories from all of the major vendors. I think you can be unlucky with any of them. Some would be worse than others but its hard to tell without something more statistically robust than a handful of ad hoc reports.

Cheers,
Rick.
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Old 07-10-2018, 09:36 PM
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All companies will have QC issues, the good companies make it as painless as possible to fix those issues And then there is OOUK who deny all knowledge

I’m not so much asking about quality control as much the General quality. It’s like comparing ZWO narrowband filters against those of Astrodon. ZWOs are significantly cheaper but with that come wth some quirks that you can let bother you or not.

QHY make a M54 to Nikon F Mount adapter which I think is quite reasonable. FLI make one for their CFWs. As Suavi points out, there may be design differences like better shielding or stiffer heavier materials.

The reason I brought up FLI cameras is that if you compare the PL16803 against that made from SBIG, QHY, SX (I think they do one) and Moravian. The FLI costs a lot more but you get 10-15C deeper cooling, faster download speeds, Argon purged chambers and better read noise (6-7 e- vs 10-12 e-). You pay extra but you do get that extra in performance. Same went for Astrodon narrowband filters, they cost more but generally have less scatters than the cheaper competitors.
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Old 07-10-2018, 10:11 PM
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I love the "best of threads"....

they are the best.
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Old 08-10-2018, 09:49 AM
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That's a big difference in read noise for the same sensor chip - 6-7 v 10-12e-. I wonder how much of that is related to how it is measured etc etc. We need a Canstar for astro gear.
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Old 08-10-2018, 07:29 PM
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Quote:
Originally Posted by ChrisV View Post
That's a big difference in read noise for the same sensor chip - 6-7 v 10-12e-. I wonder how much of that is related to how it is measured etc etc. We need a Canstar for astro gear.
It's pretty easy to measure and very useful to know. You can do it yourself with a couple of bias frames. There's no wriggle room for interpretation.

Cheers,
Rick.
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Old 09-10-2018, 10:09 AM
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I'm not sure what the QSI range of cameras will be like under Atik ownership but I have to say the QSI cameras I have owned are simply fantastic. They have been bullet proof in general. The seals alone have meant neither camera have ever had to be re-gassed. One camera is 9 years old, the other is 7 years old. I cannot say the same for the SBIG I have in my possession, though it is now significantly more capable of dealing with corrosion which is inherent from the design in my opinion (if you own an SBIG camera (red body) open up the camera back and look for corrosion on the boards). The QSI electronics also produce as clean an image as is possible for the cooling and sensor.

I did consider buying an FLI at one point in the last few years and would have if the price tag was not so prohibitive. Without doubt it is the gold standard in terms or build and quality control via reputation alone.
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Old 11-10-2018, 01:23 PM
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Quote:
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............dealing with corrosion which is inherent from the design in my opinion (if you own an SBIG camera (red body) open up the camera back and look for corrosion on the boards). ...................
I know you are not happy about your corrosion experience Paul, but attached is an image of my 5 year old STX16803....clean as.

That said, leaving a SBIG camera in an observatory, close the coast, 24/7 is not advised. SBIG specifically have never warranted against corrosion.
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