ZWO ASI2600MM-Pro vs Cooled and Modded DSLR image quality

[MarsG76]

On 19/04/2021 at 01:19, rsarwar said:

if you are concerned, change your order to asi2600mc. it will work better with hyperstar anyway.

I won't be changing from mono.. but there is a change in the air.. apparently ZWO can't get sensors to make new cameras and now I'm told that the cameras wont be here until mid July... so my question is... how do you find the software and stability of the QHY268???  It's essentially the same camera, some say that it's buit better than ZWO.. but do you get freezes, corrupted downloads after exposures or general bugs with the system???

 

 

Edited April 24, 2021 by MarsG76

[rsarwar]

2 hours ago, MarsG76 said:

I won't be changing from mono.. but there is a change in the air.. apparently ZWO can't get sensors to make noe cameras and ow I'm told that the cameras wont be here until mid march... so my question is... how do you fond the software and stability of the QHY268???  It's essentially the same camera, some say that it's buit better than ZWO.. but do you get freezes, corrupted downloads after exposures or general bug with the system???

 

 

 

i use mine through a RPi, using their linux drivers -> indiserver -> kstar (remote desktop).

only had a couple of driver faults in the first week while taking dark. but ran fine on every session since getting it. i think i had about 7-8 session thus far with it,

[MarsG76]

OK I canceled my ZWO2600M order and got the QHY268M instead... and of course after 3 weeks of clear skies, it's not forecast to be cloudy for at least the next 5 nights.... I'll spend this time setting up the camera and drivers.. practice and than hopefully it'll be clear as the moon is approaching new moon phase for me to re-image NGC3603 for the "dedicated cooled mono astro camera vs cooled and full spectrum modded canon 40D DSLR showdown" comparison I was waiting to do,

[MarsG76]

Hi all,

I had some progress...  I have the QHY268M camera but didn't get the QHY filter wheel or OAG, just wanted to use my existing gear with it... the first hurdle I had was that my filter wheel is with a M42 type connector and the QHY come with adapter for M52 & M48.. so obviously I wasn't going to to be attaching those two together in their current form... so (as everything in my life(, time to mod it for a custom fit. 😄

I used one of the spacers as a template and drilled holes to combine the two units together.

 

When I put the kit together with the required spacing between the filterwheel and the OAG to reach par focal between the two sensors, I progressed to installing the software & drivers on my observatory PC.

Below is a first exposure test through my 7nm HAlpha filter (after a few test shots to get to know the operation of the camera through all bits of software)...

Both of these frames are taken through the same equipment (except for the cameras... derr) and both are single subs,  600 second long exposures. The Left image is the Cooled40D at 10C ISO1600 and the right is with the QHY268M at HGC mode at gain 56 cooled to -10C.

The only "processing" carried out was to convert the DSLR image to grayscale and match the histograph of the QHY raw to resemble the unstretched DSLR image out of the camera... reason for the stretch is that the DSLR does a in camera stretch before exporting the CR2 RAW.

 

Verdict so far is that obviously the QHY is considerably more sensitive... and this was only a quick and dirty comparison.... and already the QHY is winning... I think that stacking a number of subs will be very interesting to see and I'm very optimistic to it being considerably superior to the DSLR.

The software and drivers work very well, I had no crashes or freezes yet... APT works flawlessly with it as well as I was able to have the camera connected to both APT and QHYs EZCAP_QT program. I was imaging in APT and EZCAP was used to report the sensor chamber temperature, humidity and pressure to make sure that I'm not approaching danger of condensation...

It is worth noting that the temperature control was possible it both APT and EZCAP_QT with no software or driver clashing.

I had NO condensation issues and the dew point on the night was +14.4C, ambient temperature was 17C.

 

My connection was in USB2 speed so I had to use 4x4 binning while framing to speed up live preview for framing which was no problem.. but imaged in bin 1x1... My cables are too poor quality for a long USB3 transfer but the short supplied camera works great in USB3... tested on the bench...  just that it's too short to reach the telescope... something I will rectify when I'm cleaning the cabling in the observatory.

Takes about 3 seconds to transfer the full res bin 1x1 frame from the camera to the PC over USB2 speed. FOr imaging purposes this is no problem, just previewing is a bit delayed.

Am I happy with the purchase??? ABSOLUTELY...

 

I spent the rest of the night capturing 600 second HAlpha subs until the nebula became obscured by my home... ended up with 9 subs... I'll aim for 15 subs through each filter before generating calibration frames and combining the final image.

 

To be continued...

CS

 

 

 

[SteveNickolls]

This is all great news MarsG76 and I can't thank you enough for this work. I'm sure though you are enjoying it all, not to mention the new gear he he. Realy look forwards to seeing the results of stacking.

Interesting your mention of cables and binning. It had come to mind the comparable file sizes between the two cameras. Right now I can control dslr imaging from indoors using a 20m active USB 2.0 cable although the dslr is powered from a mains supply to dummy battery. I'll need to consider an ASiair Pro set up for the ASI2600MM.

Good luck, thanks and clear, dark skies.

Cheers,

Steve

[MarsG76]

44 minutes ago, SteveNickolls said:

Interesting your mention of cables and binning. It had come to mind the comparable file sizes between the two cameras. Right now I can control dslr imaging from indoors using a 20m active USB 2.0 cable although the dslr is powered from a mains supply to dummy battery.

Hi Steve,

The binning is just to cutdown the resolution to transfer the frame faster while previewing,,,, as far as the USB connection is concerned, the QHY has it's own power supply too, and data transfer across USB2.0 is no problem... I'm using a 5 meter usb2 cable without problems but the USB3 is a struggle... obviously USB 2 protocol is more versatile than USB 3.

I might need to get a active USB3 cable for the camera... but looking at the proce of those cables, I'd like to test it before buying.

 

[SteveNickolls]

Cheers on that MarsG76, all good to know.

Steve

[rsarwar]

On 04/05/2021 at 11:47, MarsG76 said:

Hi all,

I had some progress...  I have the QHY268M camera but didn't get the QHY filter wheel or OAG, just wanted to use my existing gear with it... the first hurdle I had was that my filter wheel is with a M42 type connector and the QHY come with adapter for M52 & M48.. so obviously I wasn't going to to be attaching those two together in their current form... so (as everything in my life(, time to mod it for a custom fit. 😄

 

 

errr, you could have bolted the M48 adaptor to the camera and then used a m48 to T2 ,  that way you would not have that gap between the edge of the filterwheel and the camera opening. or ruined a perfectly working equipment. at least that was my plan when i was looking at a asi 36 mm filter wheel, before finding a second hand 2 inch instead and going with that instead. With the 2 inch filter wheel from asi, i used their m54 to m48 adapter

It sounds so unreal, that i am not sure if i missed what you are trying to accomplish.

https://www.365astronomy.com/photography/photographic-adapters/m48-adapters/zwo-short-adapter-with-t2-female-thread-and-m48-male-thread-2-filter-thread-zero-effective-length

 

 

 

 

Edited May 7, 2021 by rsarwar

[rsarwar]

Quote

The only "processing" carried out was to convert the DSLR image to grayscale and match the histograph of the QHY raw to resemble the unstretched DSLR image out of the camera... reason for the stretch is that the DSLR does a in camera stretch before exporting the CR2 RAW.

can you please link a source to the DSLR stretching please. DSLRs are known to clip the blacks, but that is the opposite of a stretch. but you cannot do an arbitary stretch on one of the image and then compare them to each other. that is just minupulation of data to match your narrative of "brightness".

anyway, here is what i get from D7000 (25*600 sec) and QHY268M (25*300 sec on ha and 25*120 on rgb). i will let you decide which is which; both images drizzled by 2 and cropped by a factor of 3

 

 

 

 

 

 

 

Edited May 8, 2021 by rsarwar

[MarsG76]

1 hour ago, rsarwar said:

or ruined a perfectly working equipment. at least that was my plan

...nothing is ruined and like you said... that was "your" plan... so stick to it and I'll stick to my ideas. 

[MarsG76]

1 hour ago, rsarwar said:

i missed what you are trying to accomplish

I think you might have.

 

[rsarwar]

do explain then how it better to drill holes in a EFW to and leave a gap compared to a simple adaptor 

[MarsG76]

1 hour ago, rsarwar said:

 

 

 

Great pics... the top one is definitely an improvement... little bit yellow for my taste but looks gentle with subtle detail coming through, nothing that a color balance wouldn't fix... the overly blue one looks a little bit over cooked but great detail in there nonetheless. Well done.

 

 

[MarsG76]

3 minutes ago, rsarwar said:

do explain then how it better to drill holes in a EFW to and leave a gap compared to a simple adaptor 

Don't worry about it.

 

[rsarwar]

 

6 minutes ago, MarsG76 said:

Great pics... the top one is definitely an improvement... little bit yellow for my taste but looks gentle with subtle detail coming through, nothing that a color balance wouldn't fix... the overly blue one looks a little bit over cooked but great detail in there nonetheless. Well done.

 

 

its lacking because its missing details. however the first picture, from the D7000 was "brighter" despite the missing details.

not sure, but i hope you are going to confirm a source for "DSLR stretching". should be an interesting read. 

I am not worried - just amused mate

Edited May 8, 2021 by rsarwar

[MarsG76]

3 minutes ago, rsarwar said:

 

its lacking because its missing details. however the first picture, from the D7000 was "brighter".

not sure, but i hope you are going to confirm a source for "DSLR stretching". should be an interesting read. 

I am not worried - just amused mate

Mate? Geez... ok... 

Edited May 8, 2021 by MarsG76

[MarsG76]

5 minutes ago, rsarwar said:

going to confirm a source

OK, obviously someone does not know what a hobby is and wants to pretend to be a "scientist", with links and confirmations, and it's all good.. all to their own... this, to me, is a hobby nothing more and nothing less.. I'm having fun.. I'm very amused and happy to be having a bit of fun...

If I choose to drill a hole through, oh for example... the middle of the sensor just to see what will happen, I will.. and I don't need a link to confirm my reason to do it... if I make a mistake, it's my mistake... if I damage some gear than guess what.. it's replaceable... its only a thing... that you know.. keeps me amused...

 

I started this thread as a direct comparison between two cameras not a debate.

 

[rsarwar]

wow, someone does not like being contradicted. 

i dont need to pretent to be a scientist.

G'day mate

[MarsG76]

1 minute ago, rsarwar said:

wow, someone does not like being contradicted. 

i dont need to pretent to be a scientist.

G'day mate

"Contradicted"?? Um OK.... go else where.

 

[rsarwar]

3 minutes ago, MarsG76 said:

"Contradicted"?? Um OK.... go else where.

 

did not realize you own the forum and can make data up to fit your world view. 

 

contradict /kɒntrəˈdɪkt/ verb past tense: contradicted; past participle:  assert the opposite of a statement made by (someone).

[sharkmelley]

On 04/05/2021 at 11:47, MarsG76 said:

The only "processing" carried out was to convert the DSLR image to grayscale and match the histograph of the QHY raw to resemble the unstretched DSLR image out of the camera... reason for the stretch is that the DSLR does a in camera stretch before exporting the CR2 RAW.

I'm not sure what you mean.  The values in the CR2 RAW are linear unstretched values, just like the values in the QHY raw file are linear unstretched values.

Mark

[MarsG76]

4 hours ago, sharkmelley said:

I'm not sure what you mean.  The values in the CR2 RAW are linear unstretched values, just like the values in the QHY raw file are linear unstretched values.

Mark

Are you sure that the canon software doesn't apply a stretch to the totally raw data before exporting as CR2??? Because if that's the case, than I have a small (first world) problem... this would signify that the modded and cooled canon 40D is more sensitive than the QHY268M comparing on the same object, using the same filter, with same the same exposure time with gain settings as matched as well as I can see...

 

The QHY268M did have visibly more detail... so that's a plus...

I'm still experimenting between clouds and I'm sure that the QHY has (and will) to blow the 40D out of the field...

Edited May 9, 2021 by MarsG76

[sharkmelley]

7 hours ago, MarsG76 said:

Are you sure that the canon software doesn't apply a stretch to the totally raw data before exporting as CR2???

Yes, I'm absolutely certain that the CR2 file contains linear raw data.

Mark

[MarsG76]

4 hours ago, sharkmelley said:

Yes, I'm absolutely certain that the CR2 file contains linear raw data.

Mark

Than unstretched my cooled 40D is considerably more sensitive than the QHY... BUT clouds cleared away and I started exposing 900 second H-Alpha subs, and playing with and looking at the single subs, these subs definitely have more detail than the 40D HAlpha subs... sensor sensitivity might look worse (on the surface?) but the true 16bit greyscale allows for a substantial stretch and the extra detail captured is substantial.

 

[The Admiral]

Perhaps I'm being a bit dense here, but won't the output levels from either camera be influenced by their respective gains or ISO setting. How do you take that into consideration?

The CR2 raw can surely still be linear data, even if there has been a lot of gain applied from using a high ISO?

Ian