#1  
Old 22-09-2019, 06:06 PM
Xeteth (David)
Registered User

Xeteth is online now
 
Join Date: Jul 2019
Location: Melbourne, Australia
Posts: 122
QHY9 Advice - Right for me?

I'm looking to buy a QHY9 Mono to upgrade from my Canon 650D. The Canon isn't in great condition and I'm really struggling to get decent images with it.

I considered the ZWO ASI1600 Mono but I have the means to step up to the QHY9 CCD. I'm looking for advice as to whether this would be right for me. I know going from color to mono is a jump, but I'm actually excited to be able to shoot narrowband etc using filters.

My scope is an Explore Scientific ED102 FCD100 and mount is the EQ6-R Pro. I believe this camera would be ideal in terms of over/undersampling based on the research I've done. Is there anything else I should consider?

Also - this will be a second hand purchase, can anyone give advice as to what I should watch for or be wary of in terms of getting a lemon.

Any advice would be much appreciated, thanks!
Reply With Quote
  #2  
Old 22-09-2019, 06:31 PM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 13,705
I would try and identify why your current camera does not produce results....you need to know what you lack before you proceed.
The camera you are thinking about is probably ok and if it is or is not will be part of your journey
Alex
Reply With Quote
  #3  
Old 22-09-2019, 06:41 PM
Ukastronomer (Jeremy)
Feel free to edit my imag

Ukastronomer is offline
 
Join Date: Jan 2019
Location: Llandysul, WALES, UK
Posts: 1,381
Quote:
Originally Posted by xelasnave View Post
I would try and identify why your current camera does not produce results....you need to know what you lack before you proceed.
The camera you are thinking about is probably ok and if it is or is not will be part of your journey
Alex
100%

As a photographer I rarely ever change my gear, before my new cameras four years ago I had my last one ten years, I knew all it was capable of, I could use it blindfold, same with my four year old D4s and D810 and lenses.

So many times I hear people say, the camera I bought last year does not give me the photos I want shall I change it, when in fact it is the person (NO disrespect to the original poster here) that is responsible. One it was said (again NO disrespect) a poor workman always blames his tools.

When I get a new piece of gear I can spend w e e k s learning to use it to my satisfaction.

I have seen the most amazing astro images from a £200 camera and real crap from £1000 ones and it is not the camera !!!!

It is like saying you can't take any good images with a Dobsonian telescope you must have the best EQ mounts, will there are people on dob forums shooting images that will blow people away who would disagree.


... and people with £100 cameras


...
Reply With Quote
  #4  
Old 22-09-2019, 06:49 PM
Ukastronomer (Jeremy)
Feel free to edit my imag

Ukastronomer is offline
 
Join Date: Jan 2019
Location: Llandysul, WALES, UK
Posts: 1,381
Eg

samples not mine
Attached Thumbnails
Click for full-size image (yyy.jpg)
182.7 KB31 views
Click for full-size image (yyyy.jpg)
76.5 KB25 views
Reply With Quote
  #5  
Old 22-09-2019, 08:01 PM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 4,974
Considering you’ve done some research, what leads you to believe that a QHY9 is a step up from an ASI1600?
Reply With Quote
  #6  
Old 22-09-2019, 08:51 PM
Ukastronomer (Jeremy)
Feel free to edit my imag

Ukastronomer is offline
 
Join Date: Jan 2019
Location: Llandysul, WALES, UK
Posts: 1,381
Quote:
Originally Posted by Camelopardalis View Post
Considering youíve done some research, what leads you to believe that a QHY9 is a step up from an ASI1600?
Good question after all IT isn't a £200 camera itself
Reply With Quote
  #7  
Old 22-09-2019, 09:14 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 6,864
It’s a difficult one, there are pros and cons to both sensors.
ASI1600
- Higher QE means it’s more sensitive BUT also means you’ll get more purple halos around stars.
- Higher resolution (16mp vs 9mp) but the smaller pixels means it stresses the optics more.
- Lower read noise is just a benefit as it means shorter exposure times, especially for narrowband.
- Both have a micro lens diffraction pattern BUT the QHY9 is a LOT nicer than the ASI1600.
- Same size sensor
- Much faster download times. The ASI1600 is around 2s while the QHY9 is around 8s.

Depending on the colour correction of your refractor the QHY9 could give better LRGB images.
Reply With Quote
  #8  
Old 22-09-2019, 09:39 PM
Ukastronomer (Jeremy)
Feel free to edit my imag

Ukastronomer is offline
 
Join Date: Jan 2019
Location: Llandysul, WALES, UK
Posts: 1,381
Surely as with everything just buying a different camera/car/bike does not make you a better photographer/driver/cyclist !

Last edited by Ukastronomer; 28-09-2019 at 12:57 AM.
Reply With Quote
  #9  
Old 27-09-2019, 01:01 PM
Xeteth (David)
Registered User

Xeteth is online now
 
Join Date: Jul 2019
Location: Melbourne, Australia
Posts: 122
Sorry it's taken me a while to get back to my post, been a really busy week with uni.

Quote:
Originally Posted by xelasnave View Post
I would try and identify why your current camera does not produce results....you need to know what you lack before you proceed.
The camera you are thinking about is probably ok and if it is or is not will be part of your journey
Alex
I completely agree with this, however there are a number of issues with the Canon I'm using that I feel are hindering me, these are:
- There is a large number of dead pixels
- The noise on this camera seems particularly bad, for what reason I don't know, but I've tested two other cameras (borrowed from friends) that have nowhere near the level of noise.
- No cooling sucks
- Not being able to pick up HA etc. (I really want to get into filters)

Obviously there are draw backs of DSLR's over CCD/CMOS cameras for AP, so I'm not expecting phenomenal results. The noise one is the main problem, I know this is tackled with an improved SNR which I try to do (bloody clouds in Melb lately ).

Quote:
Originally Posted by Camelopardalis View Post
Considering youíve done some research, what leads you to believe that a QHY9 is a step up from an ASI1600?
I'll be honest here, finding research on which is 'better' is hard. However, the QHY9 uses the KAF8300 chip which from everything I've read is a well tried and tested chip that produces great results. It is able to cool to a lower temp and has a built in filter wheel. Lastly, I was told by an astrophotographer I met with years of experience that the QHY9 was a much better product, however he didn't really elaborate on reasons so this isn't much.

Quote:
Originally Posted by Atmos View Post
Itís a difficult one, there are pros and cons to both sensors.
ASI1600
- Higher QE means itís more sensitive BUT also means youíll get more purple halos around stars.
- Higher resolution (16mp vs 9mp) but the smaller pixels means it stresses the optics more.
- Lower read noise is just a benefit as it means shorter exposure times, especially for narrowband.
- Both have a micro lens diffraction pattern BUT the QHY9 is a LOT nicer than the ASI1600.
- Same size sensor
- Much faster download times. The ASI1600 is around 2s while the QHY9 is around 8s.

Depending on the colour correction of your refractor the QHY9 could give better LRGB images.
This is the kind of stuff I guess I'm still trying to learn and wrap my head around. For reference my refractor is a triplet apo FCD100 series. Could you elaborate on what a few of these mean (perhaps point me in the direction of where I can learn this stuff), QE, resolution and stressing the optics, etc. I think I should wrap my head around these things before making a purchase. Why do you say the QHY9 could give better LRGB images?

Thanks all for the replies!
Reply With Quote
  #10  
Old 27-09-2019, 06:10 PM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 4,974
Quote:
Originally Posted by Xeteth View Post
I'll be honest here, finding research on which is 'better' is hard. However, the QHY9 uses the KAF8300 chip which from everything I've read is a well tried and tested chip that produces great results. It is able to cool to a lower temp and has a built in filter wheel. Lastly, I was told by an astrophotographer I met with years of experience that the QHY9 was a much better product, however he didn't really elaborate on reasons so this isn't much.
You need to determine what better means to you before you can compare. There is no “one chip to rule them all”, they all suit different scopes differently and have different quirks and costs.

For example, you mention noise. There are a number of different sources of noise. Two of the most common are read noise and thermal noise. If you compare those contributions, you will see that the KAF8300 performs quite poorly in those respects compared with more recent CMOS sensors. And deeper cooling is only beneficial if there are substantial benefits from doing so. Some manufacturers state the thermal noise in electrons per second at a specific temperature. Before dismissing any options based on some off-the-cuff advice with no basis, you should run these types of calculations for yourself to find out

You might find that some modern DSLRs/mirrorless cameras perform very competently now, although hard numbers are difficult to find.

QE is quantum efficiency. It is the proportion of photons received that generate electrons that are subsequently measured as signal. Higher QE is always better.

If you’re finding blue halos from your scope, check the cut-off of your UV/IR-cut filter.If you’re not using one, you might want to try one out. With a mono sensor, you can always refocus if the focal point of blue is different from the rest.
Reply With Quote
  #11  
Old 27-09-2019, 08:07 PM
RobF's Avatar
RobF (Rob)
Mostly harmless...

RobF is offline
 
Join Date: Jul 2008
Location: Brisbane, Australia
Posts: 5,563
I moved from a standard Canon 450D to a QHY9 years ago (2010) and its been a great camera. The DSLR was good on bright objects, but on more diffuse objects in summer (e.g. Rosette) it was a real struggle to pull out faint H2 structure.

Either camera would be an exciting improvement. The QHY9 8300 chip will give more noise, but that can be managed with proper bias/darks/flats.

I've got no CMOS chip experience sorry.
Reply With Quote
  #12  
Old 27-09-2019, 11:29 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 6,864
Quote:
Originally Posted by Xeteth View Post
This is the kind of stuff I guess I'm still trying to learn and wrap my head around. For reference my refractor is a triplet apo FCD100 series. Could you elaborate on what a few of these mean (perhaps point me in the direction of where I can learn this stuff), QE, resolution and stressing the optics, etc. I think I should wrap my head around these things before making a purchase. Why do you say the QHY9 could give better LRGB images?
A has been mentioned, QE is quantum efficiency. This refers to the theoretical amount of photos that make it to the sensor that are actually detected. The KAF8300 is around 56% peak while the ASI1600 peaks at ~65% from memory. The ASI1600 also has a higher peak into the UV (~2x) than the QHY9. This means that the less corrected your refractor is into the UV then more bloated stars will become in the blue channel.

This then moves into pixel sizes and how the ASI1600 with its smaller pixels stress' optics more. Let's just say that your refractor creates star sizes of 7 microns in red, 6 in green and 10 in blue. With the QHY9 (5.4 micron pixels) all of the stars will be contained within less than 2 pixels. As you move into the deeper blue (towards UV, where the spot sizes are more likely to reach 15 microns), the QHY9 becomes very insensitive so there is not much detectable bloat; stars are their true colours.

With the ASI1600 (3.8 micron pixels) the red and green are both below 2 pixels BUT the blue is at 2.6 pixels. It has a considerably higher QE towards the deep blue so there may even be a fainter blue halo reaching out to 3-3.5 pixels.
This means that you could have the centre 2 pixels being correct star colour but then a blue halo surrounding any non-dim star.

For narrowband none of this matters as you're only imaging a VERY thin slice of the spectrum. I've also just been picking random numbers purely for illustrative purposes. You're refractor, although not entirely cheap, is on the lower end of the triplet imaging refractors so it is built to a price point. Excellent value but it can have its limitations. Most of the halos and what I've been discussing can be processed out but my point in all of this is that if you're planning on LRGB images you will near certainly get better star colours out of the QHY9 than ASI1600. If you plan on doing narrowband then the ASI1600 is a definite winner over the QHY9 due to the higher QE and MUCH lower read noise.
Reply With Quote
  #13  
Old 28-09-2019, 09:53 AM
RobF's Avatar
RobF (Rob)
Mostly harmless...

RobF is offline
 
Join Date: Jul 2008
Location: Brisbane, Australia
Posts: 5,563
I meant to give some practical examples last night.

Here is 1hr of the Rosette in summary, 8" Newt, 450D, middle of summer, from surburban skies. If you look at the full picture the nebula detail is only just coming up out of significant sensor noise.
https://photos.app.goo.gl/7nhXpZ4MAWCXTH1h6

2nd pic is 1hr of Ha data from QHY9.
https://photos.app.goo.gl/Em4GcmTR8gR57Fq98

CMOS cameras with their high QE will likely show a greater improvement again.
Reply With Quote
  #14  
Old 28-09-2019, 10:51 AM
casstony
Registered User

casstony is offline
 
Join Date: Feb 2006
Location: Warragul, Vic
Posts: 4,482
Quote:
Originally Posted by Xeteth View Post
The noise one is the main problem,
If you have the time and commitment to learn then the cooled mono cameras will give the best results; otherwise you can still do quite well with a much less noisy dslr.

I started with the 600D (almost identical to the 650D) which was very noisy. I now use the Nikon D5600 which is fine for most of the year in our southern climate.

The Helix was taken recently after I modified my d5600, 15x7 minutes. The Rosette image was taken last year before I modified my camera - I'm looking forward to imaging it again with the extra Ha signal and a few more processing skills.

On those rare nights when I'm tired and the things just won't work because I've done something wrong it's nice to have less complicated gear.
Attached Thumbnails
Click for full-size image (Helix030819_DBE.jpg60%.jpg)
175.8 KB15 views
Click for full-size image (rosette last 5%.jpg)
184.9 KB16 views
Reply With Quote
  #15  
Old 28-09-2019, 06:17 PM
Xeteth (David)
Registered User

Xeteth is online now
 
Join Date: Jul 2019
Location: Melbourne, Australia
Posts: 122
Wow there is a lot to digest here. Thanks all for your replies and info, it's much appreciated!

Quote:
Originally Posted by Camelopardalis View Post
You need to determine what better means to you before you can compare. There is no ďone chip to rule them allĒ, they all suit different scopes differently and have different quirks and costs.

For example, you mention noise. There are a number of different sources of noise. Two of the most common are read noise and thermal noise. If you compare those contributions, you will see that the KAF8300 performs quite poorly in those respects compared with more recent CMOS sensors.

QE is quantum efficiency. It is the proportion of photons received that generate electrons that are subsequently measured as signal. Higher QE is always better.
I had mainly been focusing on thermal noise being the issue and had not really considered readout noise. I will definitely look into this now!

QE seems rather simple to understand... the QHY9 has a peak QE of 56%, would this likely mean I'd run into issues?

Quote:
Originally Posted by RobF View Post
I moved from a standard Canon 450D to a QHY9 years ago (2010) and its been a great camera. The DSLR was good on bright objects, but on more diffuse objects in summer (e.g. Rosette) it was a real struggle to pull out faint H2 structure.

Either camera would be an exciting improvement. The QHY9 8300 chip will give more noise, but that can be managed with proper bias/darks/flats.
I don't mind having to acquire a larger number of images to stack out any noise and am almost at the point where I'm confident with what I'm doing with darks/bias/flats, so it's great to hear that those issues can be overcome. Love the HA image you linked, pretty damn impressive!

Quote:
Originally Posted by Atmos View Post
This then moves into pixel sizes and how the ASI1600 with its smaller pixels stress' optics more. Let's just say that your refractor creates star sizes of 7 microns in red, 6 in green and 10 in blue. With the QHY9 (5.4 micron pixels) all of the stars will be contained within less than 2 pixels. As you move into the deeper blue (towards UV, where the spot sizes are more likely to reach 15 microns), the QHY9 becomes very insensitive so there is not much detectable bloat; stars are their true colours.

With the ASI1600 (3.8 micron pixels) the red and green are both below 2 pixels BUT the blue is at 2.6 pixels. It has a considerably higher QE towards the deep blue so there may even be a fainter blue halo reaching out to 3-3.5 pixels.
This means that you could have the centre 2 pixels being correct star colour but then a blue halo surrounding any non-dim star.

For narrowband none of this matters as you're only imaging a VERY thin slice of the spectrum. I've also just been picking random numbers purely for illustrative purposes. You're refractor, although not entirely cheap, is on the lower end of the triplet imaging refractors so it is built to a price point. Excellent value but it can have its limitations. Most of the halos and what I've been discussing can be processed out but my point in all of this is that if you're planning on LRGB images you will near certainly get better star colours out of the QHY9 than ASI1600. If you plan on doing narrowband then the ASI1600 is a definite winner over the QHY9 due to the higher QE and MUCH lower read noise.
Thanks for this write-up, certainly shed light on it all! One question - can the lower QE of the QHY9 (as compared to the ASI1600) be overcome simply by stacking more subs? Or will I still lose out?



Quote:
Originally Posted by casstony View Post
If you have the time and commitment to learn then the cooled mono cameras will give the best results; otherwise you can still do quite well with a much less noisy dslr.

I started with the 600D (almost identical to the 650D) which was very noisy. I now use the Nikon D5600 which is fine for most of the year in our southern climate.

The Helix was taken recently after I modified my d5600, 15x7 minutes. The Rosette image was taken last year before I modified my camera - I'm looking forward to imaging it again with the extra Ha signal and a few more processing skills.

On those rare nights when I'm tired and the things just won't work because I've done something wrong it's nice to have less complicated gear.
I'll certainly be keeping the 650D, it has it's perks for sure! Especially on those brighter targets. Love the rosette there, would be really interesting to see what you come up with given extra Ha signal.


Despite all this advice I am still somewhat unsure on how to proceed. I have the option of purchasing a QHY9 for about $2-2.5k at the moment. It seems like a great camera, but with the higher readout noise and lower QE than some of the CMOS cameras (namely the ASI1600) I am a bit concerned I'm not making the right purchase; which makes me think of getting the 1600 instead...

Given the two options, which would you guys likely choose?
Reply With Quote
  #16  
Old 29-09-2019, 01:26 AM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Hinchinbrook
Posts: 19,654
I can't comment on the ASI1600 but I've used a mono QHY9 for a number of years. It has a good well depth and very good cooling all year round so would recommend without any hesitation.
Reply With Quote
  #17  
Old 30-09-2019, 08:22 PM
AstroFeral (Steve)
Registered User

AstroFeral is offline
 
Join Date: Jun 2019
Location: Au
Posts: 3
It would be helpful to see some examples of the results your not happy with, those with experience will be able to provide feedback and identify potential issues if any providing more information on which to make an informed decision. Unless you have already decided a new camera is the only solution. This one step not done could save you a couple of grand in the short to long term.
Cheers!
Reply With Quote
  #18  
Old 01-10-2019, 05:28 AM
SteveInNZ
Registered User

SteveInNZ is offline
 
Join Date: May 2008
Location: Auckland, NZ
Posts: 229
I have a QHY9 and ASI1600. I haven't used the QHY9 much and the ZWO is the colour version but I have another mono camera.
The QHY9 has some advantages (well depth and pixel size) but only by a small amount for most applications. On the down side, it has higher read noise so from a practical viewpoint, you'd want to have longer exposures with it than the ASI. Not a big deal but a difference.
The QHY9 has a custom power supply while the ASI is powered from a single 12V lead and that does restrict your cabling options. The QHY9 has a mechanical shutter which the ASI doesn't. I find this to be quite a big advantage of the ASI because you can use a bright star/planet/moon to find focus with very short exposures. I use it with a barlow for solar system and then swap that out for a reducer for DSO. The QHY9 is purely DSO. If you had an unchanging setup, that wouldn't be such a big deal as you'd be close to focus anyway.

I don't think that either would be a bad choice. Overall, I'd describe the ASI as being more convenient.

You should do a search in the Ad section to check on the going rate for a QHY9. Unless that includes filters, that price does seem a bit high.

I'd also echo what others have said in regards to diagnosing your DSLR results.



Steve.
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 07:43 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Advertisement
Limpet Controller
Advertisement
Testar
Advertisement
NexDome Observatories
Advertisement
Bintel
Advertisement
Astronomy and Electronics Centre
Advertisement