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Old 26-09-2017, 08:08 PM
brisen (Brian)
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Qhy23 ccd

I am currently looking at upgrading to an Espirit 100 ED triplet to allow for some wider field AP and considering upgrading to a QHY 23 mono camera to give an effective image scale of 1.38 arcsecs/pixel.

Just wondering if anyone here might have experience with this combination before I pull the trigger and spend enough for 6 months of cloud cover to appear.

Brian
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Old 26-09-2017, 10:28 PM
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billdan (Bill)
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Dr Qiu from QHY suggests the QHY22 is better than the QHY23 for DSO's

http://qhyccd.com/bbs/index.php?PHPS...5&topic=6035.0

Cheers
Bill
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Old 27-09-2017, 06:32 AM
brisen (Brian)
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Thanks Bill, and the QHY 22 is about a grand cheaper as well.

Brian
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Old 27-09-2017, 07:24 AM
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Atmos (Colin)
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I suppose it all depends on the resolution that you’re after. They both have the same size chip, QHY22 has 4.54 micron pixels while the QHY23 has 3.69 microns. They both have about 75% QE and I believe the QHY23 May have a fraction lower read noise.

The main question you need to ask is:
Do I want an image scale of 1.38 or 1.7?
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Old 27-09-2017, 08:09 AM
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A hard question really. Both are appealing cameras.
I used a Starlight Express Trius 694 for a few years. In my case it was on a CDK17 scope and also on a AP Riccardi Honders 305 F3.8 1160mm focal length.

So in one sense not a match made in heaven although it worked well on the Honders not as well on the CDK.

My SX Trius was an OK camera. I used to get weird little bumps in the stars at 1 o'clock and I always assumed some sort of guiding issue.

After I sold it the new owner checked with SX about it and he was advised it was blooming and SX sent a firmware update that fixed it. Wow, worth asking these questions of the camera maker.

I also sometimes had issues with fixed pattern noise. The camera worked best with simply biases. I used flats sometimes as well but vignetting was minimal with such a small sensor.

Fixed pattern noise though looked like the micro lenses. I don't know if others have had that issue with an SX Trius but I did. Usually just a bias and I didn't have that problem but occasionally as with usual calibration things don't always go to plan.

So I would prefer personally a QSI690 with the built in filter wheel and OAG. They seem to get the most out of the sensors they use. Also all in one camera bodies are the way to go as they seem to give the best autoguiding. You don't see images using QSI WSG8 cameras with wonky stars.

As to the 9mp sensor versus the 6.3mp sensor that is not as easy a choice.
Theoretically the 9mp sensor is better suited to your 100mm scope. 1.38 arc secs per pixel is a bit past the recommended 1 arc sec/pixel that Roland Christen of AP fame advises for those with average seeing of about 3-4 arc secs.
Suavi on this site has shown how awesome his 690 is with a small refractor. Gorgeous tight stars and great detail. Both will work well. The main difference I see is the 9mp has quite small wells. So does the 6.3mp though at just under 20,000 electrons which is pretty low. The 9mp is something like 12-15K electrons which is tiny. Perhaps not an issue for narrowband imaging but throw some bright stars into the image and you may get some ugly looking stars.

A counter solution is to use shorter exposures.

I must say though at 550mm focal length arc secs/pixel seems to be far less of an issue than say 3 metre focal length.

FSQ 106 images over the years are often at 3arc secs/pixel or more and look fabulous.

Still I would be inclined to go the 9mp sensor. The 695 sensor though is a safe bet as many have used it and shown it to be a winner.

The high QE of both of these especially in narrowband make them particularly suitable for narrowband imaging. Too bad Sony is not making anymore CCDs as a full frame Super HAD sensor would have really been something.

Greg.
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Old 27-09-2017, 09:48 AM
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I use a ZWO ASI1600 mono with my Esprit 100 and the combo, at 1.41”/pixel, seems to make the most of the seeing, as it is in SE QLD

You can always dither with a sufficient number of subs.

Given the low read noise of the Sony sensors the shallow wells aren’t such a big issue as you can take shorter exposures and still conquer the read noise, but like Greg says, expect stars such as Alnitak to have a ball if they’re in the shot.
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Old 05-10-2017, 09:39 PM
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Quote:
Originally Posted by Camelopardalis View Post
I use a ZWO ASI1600 mono with my Esprit 100 and the combo, at 1.41Ē/pixel, seems to make the most of the seeing, as it is in SE QLD

You can always dither with a sufficient number of subs.

Given the low read noise of the Sony sensors the shallow wells arenít such a big issue as you can take shorter exposures and still conquer the read noise, but like Greg says, expect stars such as Alnitak to have a ball if theyíre in the shot.

Its early days but it seems these types of cameras are likely to take over within a few years.

Now if only Sony would release its 36mp or 42.4 backside illuminated full frame sensors from the A7r and A7R2 (the 36mp one is also used in the Nikon D800, D810 and the Pentax K1). That would be something.

The 42mp backside illuminated sensor is still the highest rated sensor in digital cameras and at higher ISO has something like .3 electron read noise - crazy numbers.
QE is up around 65-70% despite a Bayer matrix, imagine what the mono version would have - 90%+.

Greg.
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Old 05-10-2017, 10:47 PM
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From what I’ve read, Sony keeps its best camera sensors to itself before it offers them out to others that wish to use them, such as Nikon and Fujifilm. No doubt this extends to others wishing to buy a batch of them.

The 36MP sensor previously seen in the Nikon D810 is in the hands of ZWO/QHY now, so it seems it’s just a matter of time (and money).

Of course, all of Sony’s larger sensors are OSC...

The 178/183 with tiny 2.4 micron pixels and BSI reportedly have QE ~83%, albeit with a gargantuan read noise (<2e) by comparison.
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Old 06-10-2017, 03:17 PM
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From what Iíve read, Sony keeps its best camera sensors to itself before it offers them out to others that wish to use them, such as Nikon and Fujifilm. No doubt this extends to others wishing to buy a batch of them.

The 36MP sensor previously seen in the Nikon D810 is in the hands of ZWO/QHY now, so it seems itís just a matter of time (and money).

Of course, all of Sonyís larger sensors are OSC...

The 178/183 with tiny 2.4 micron pixels and BSI reportedly have QE ~83%, albeit with a gargantuan read noise (<2e) by comparison.
Yes the OSC version of the 36mp sensor is available. I meant though the mono version which would be a special run I suppose as it has microlenses.

<2 electrons is of course amazingly low read noise and way lower than any CCD camera of which a good one is 6 and an average one about 12.

Greg.
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Old 06-10-2017, 05:45 PM
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QHY are currently beta testing their QHY367M which is a mono version of the D810. They’ve having to remove the Bayer themselves but it could make for an excellent sensor if it all works well.

Sadly there are virtually no telescopes around that have the optical correction to deal with 4.88 micron pixels 22mm off axis. The FSQ130 is about the only one that comes to mind.
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Old 06-10-2017, 05:52 PM
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If it’s BSI there’s a chance the QE doesn’t take too much of a hit.

No scopes that can handle it Colin? Maybe it’s better keeping it OSC
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Old 06-10-2017, 06:33 PM
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Quote:
Originally Posted by Atmos View Post

Sadly there are virtually no telescopes around that have the optical correction to deal with 4.88 micron pixels 22mm off axis. The FSQ130 is about the only one that comes to mind.
And also find room for an OAG prism to pick up stars outside the imaging circle.
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Old 06-10-2017, 07:18 PM
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I’ve used a D810 on my refractor on a couple of occasions and the correction at the edge of field is very good but not perfect. Going from OSC to mono makes it appear a bit worse.

I’ve noticed this with using my D7200 and QHY163 on the same lens (Sigma Art 85mm F/1.4). The D7200 @F/2.8 looked better than the QHY163 @F/3.2. The QHY163 has slightly smaller pixels at 3.8 vs 3.91 microns but it is also a smaller chip being a Micro 4/3 as opposed to an APS-C.

One of the reasons that the KAF-16803 is “easy” to correct for is the 9 micron pixels. Any telescope that shows even almost round stars with a KAF-16803 will show a reasonable amount of distortion with a QHY367M.
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Old 06-10-2017, 07:40 PM
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Quote:
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Iíve used a D810 on my refractor on a couple of occasions and the correction at the edge of field is very good but not perfect. Going from OSC to mono makes it appear a bit worse.

Iíve noticed this with using my D7200 and QHY163 on the same lens (Sigma Art 85mm F/1.4). The D7200 @F/2.8 looked better than the QHY163 @F/3.2. The QHY163 has slightly smaller pixels at 3.8 vs 3.91 microns but it is also a smaller chip being a Micro 4/3 as opposed to an APS-C.

One of the reasons that the KAF-16803 is ďeasyĒ to correct for is the 9 micron pixels. Any telescope that shows even almost round stars with a KAF-16803 will show a reasonable amount of distortion with a QHY367M.
I used to own a sony A7r which uses the same sensor as the QHY367C (there is no M as far as I can see).

One of the features for that sensor was it had microlenses at the side of the sensor sloped to the pixel so it allowed more light in the sides and corners to reach the pixel. That was mainly because the mirrorless format is quite short and so A7 series cameras were suffering from colour casts in the sides of the images on wide angle lenses. I wonder if that is an issue with a telescope system which has a flattener. It may work against you, it may not.

Greg.
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