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Received my QHY268M

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#51 BenKolt

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Posted 30 January 2021 - 12:02 AM

Nico:

 

Thank you very much for the explanation about the back focus confusion.  I look forward to seeing more of what you can do with your new camera.

 

Ben



#52 2ghouls

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Posted 30 January 2021 - 03:09 AM

Indeed. I think we are all agreeing on the same thing and tripping on wording. The 17.5mm is with the added 5mm thick M54 threaded adapter (although I'll be very pleased if mine also comes with an M48 version as well!) and with that removed and just the non-removable body plate that has the bolt-on mount holes the BF is 12.5mm

Got you. There is a great variety of spacers with the bolt pattern included (several 1mm, 3mm, 5mm, and 10mm thick). There are no M54 threaded parts included in the box I was sent (I actually sort of wish there was, since I have a M54 filter drawer I prefer to the M48 one I am now using). There are a couple M48 threaded adapters (female threads) that also have the bolt pattern. See my first post for photos.



#53 2ghouls

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Posted 30 January 2021 - 03:22 AM

Ok, last post of the night. 

Here is a 10 minute sub, and ran the AbberationInspector script on it. Conditions were bad, but I think this still looks pretty good in terms of star shape from what I can see. I probably won't mess with tilt if it stays this good, as I'm not super fussy about getting corner stars perfect.

 

QHY268M, Antlia 3nm Ha filter, Stellarvue SVQ86

10 minutes, -20C, Gain 56, Offset 25

Bortle 9, Object at 23 degrees, Windy

rosette.jpg

abberation.jpg

 

FITS file: https://drive.google...fvL?usp=sharing


Edited by 2ghouls, 30 January 2021 - 01:27 PM.

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#54 ChrisWhite

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Posted 30 January 2021 - 06:40 AM

Thanks for sharing nico!

#55 ChrisWhite

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Posted 30 January 2021 - 05:20 PM

Data looks very clean.  Just like my IMX455 (as expected).  Looking forward to receiving mine.


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#56 dotmod

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Posted 31 January 2021 - 04:20 PM

Lots of useful information in this thread!

 

Some points are not really clear to me. I'd like to use the 268M with the Baader UFC System (Filter Charger) and the RASA 8". The limited backfocus of 29mm of the RASA with the UFC adapter (RASA thread 1,4mm + UFC Base 13mm + M54 Camera adapter 2mm) just leaves 12,6mm of backfocus.

 

I thought about threading it directly with the M54 adapter by Baader (https://www.baader-p...mera-sided.html) but it seems like the Base of the QHY268M is not female threaded. So I would need another adapter, is that right? Would it possible to switch the Base with a female threaded Base to directly connect the M54 adapter to the Camera?

 

I hope this makes sense and someone can clear things up smile.gif

 

- Yannick


Edited by dotmod, 31 January 2021 - 04:21 PM.


#57 2ghouls

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Posted 31 January 2021 - 08:14 PM

Lots of useful information in this thread!

 

Some points are not really clear to me. I'd like to use the 268M with the Baader UFC System (Filter Charger) and the RASA 8". The limited backfocus of 29mm of the RASA with the UFC adapter (RASA thread 1,4mm + UFC Base 13mm + M54 Camera adapter 2mm) just leaves 12,6mm of backfocus.

 

I thought about threading it directly with the M54 adapter by Baader (https://www.baader-p...mera-sided.html) but it seems like the Base of the QHY268M is not female threaded. So I would need another adapter, is that right? Would it possible to switch the Base with a female threaded Base to directly connect the M54 adapter to the Camera?

 

I hope this makes sense and someone can clear things up smile.gif

 

- Yannick

Hi Yannick, 

You are correct that the camera body itself is not M54 female threaded; it just has a smooth hole (dovetail) with a pattern of 6 threaded holes around for bolting stuff on with M3 threaded bolts. While it comes with a number of spacers, adapters and bolts, none would really work for your case out of the box. The only threaded adapters it comes with are two M48 female threaded adapters that are 5mm thick, this would put you at 17.5mm away from the sensor so that's a no-go. Even if that did work, you would want to get shorter M3 bolts as the one's it comes with are all too long to only attach the 5mm adapter to the front. They really designed this thinking one will be using it with a QHY filter wheel.

I think what you would need to do is remove the front plate on the camera which is 5.5mm thick / 90mm wide and replace it with a custom one from precise parts that works for your use case. The front plate is very similar to the one used on the QHY600 short back focal length edition, and you can see a schematic/pictures of it on this page: https://www.qhyccd.c...catid=30&id=317 Let me know if there is any more information you need. 

Cheers, Nico


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#58 aatdalton

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Posted 01 February 2021 - 01:43 PM

Nico, your image on AB looks amazing! Glad to see the hype for this camera holds up to reality.



#59 bokemon

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Posted 02 February 2021 - 05:46 AM

[stuff]

I have a QHY 163M camera, but the idea is similar.  If your camera is bolted to the filter wheel, don't bother trying to shim between the camera and filter wheel because you have to take the whole thing apart every time.  I shim in front of the filter wheel.  Since all you have to do now is loosen the 6 screws for the spacers, and slide the shims in underneath the spacer.  I used an assortment of brass shim stock from the hardware store and cut it into little U shaped pieces so I can slide it in where the screws are.  To ensure more repeatability, I only shim at two locations, the first and third screw location, because three points define a plane, etc.

To confirm tilt, I find a bright star and use a Bahtinov mask (at the same orientation each iteration)  Focus with the star at center, then move the star to the right, left, top, bottom of the image to check tilt.  This took many hours, but eventually I got it right.  There was 0.013" worth of shims piled under one of the spacers at the end.


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#60 Typhoon

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Posted 02 February 2021 - 07:38 AM

I have my camera QHY268M, but I have a doubt, which are the choices of PRESETS, GAIN and OFFSET to work properly with LRG and NB and which READMODE is the apropiate?

 

Thanks


Edited by Typhoon, 02 February 2021 - 10:58 AM.


#61 2ghouls

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Posted 02 February 2021 - 12:11 PM

I have my camera QHY268M, but I have a doubt, which are the choices of PRESETS, GAIN and OFFSET to work properly with LRG and NB and which READMODE is the apropiate?

 

Thanks

PRESET: ignore this. While there are DSO and Planetary presets in the driver, QHY did not seem to input sensical values in those presets. Feel free to use this feature to make your own presets though.

 

READMODE: For my style of imaging, I imagine I will probably only be using mode #1 (High Gain) and possibly mode #0 (Photographic DSO). My initial tests were all in High Gain (#1). See the charts on this page for how these different read modes affect read noise, full well cap., and dynamic range : https://www.qhyccd.c...=94&id=56&cut=1

 

GAIN: In High Gain read mode (#1), I plan to use gain 0 (or 56) for broadband and gain 56 for narrowband. I also want to test gain 26 in Photographic DSO read mode (#0), and gain 0 in ExtendFullWell2CMS read mode (#4). Note: just looking at the data from the charts linked above, I could see the argument for using Gain 56 in High Gain mode for everything as it has the lowest read noise and highest possible dynamic range. The only advantage to other modes/gains, would be the higher full well cap., but in practice, I'm not sure I ever need a large full well cap. with my style of imaging, but I'm keeping an open mind and will do some tests in the field.

 

OFFSET: You need to test this for yourself. The goal is to introduce enough of an offset that you have some separation from the left and are not clipping to black. My initial tests were at an offset of 25, but I might raise that to 30 or 40 with more testing, as I'm not convinced 25 was enough of an offset.


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#62 OhmEye

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Posted 02 February 2021 - 02:50 PM

I look forward to testing various modes and gains but from my research so far I agree with 2ghouls and I'm most looking forward to mode #1, gain 56, offset 25. That is looking ideal for my DSO work for best gain with lowest read noise and good dynamic range. I definitely recommend testing yourself with Sharpcap to empirically find for certain where the gain switches from LCG to HCG, that's 56 for this camera and where the read noise should be minimum in the HCG realm. Then it's just a matter of increasing offset until the left of the histogram is clearly not clipping at all yet not excessive and I expect that to be about 25. Regardless there is no need to guess when it's fairly simple to test and discover for sure.



#63 Sponge

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Posted 02 February 2021 - 04:00 PM

My initial tests with my 268M have shown that an offset of 10 is sufficient to prevent clipping for all frame types at both 0 and 56 gain in mode #1. I suppose this depends on the sensor but I don't imagine anything more than 25 would be necessary. The lowest value in any frame I've seen so far is ~30ADU. I appreciate that this is a little close to zero but I've taken full calibration libraries (300+ frames of Bias, Dark and Flat) with no clipped values.

 

I've attached some BasicCCDParameters screenshots from my tests.
 
Gain 0 Offset 10:

 

681462680_Gain0Offset10.png.82affbdca980

 

Gain 56 Offset 10:

 

1879016271_Gain56Offset10.png.f45b9437e5

 

Cheers



#64 Sponge

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Posted 03 February 2021 - 12:47 PM

As an outcome to the QE debate, QHY have done an absolute test and are posting the results tomorrow! https://www.facebook...078708155565780



#65 aatdalton

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Posted 03 February 2021 - 02:41 PM

I've got mine in hand as well. Ran SharpCap sensor analysis on it for Modes #0 and #1 if anyone would like to see the results. Spoiler - it's basically the same chart QHY published. tongue2.gif

Also glad to help answer any questions.



#66 xiga

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Posted 03 February 2021 - 09:00 PM

I might have a laptop that still has 2.9 installed. I could try to check later. I did these tests on whatever the latest version of SGP3 is.

 

Weight: 812 grams. Length: 107mm Width: 90mm

 

attachicon.gifweight.jpg

attachicon.giflength1.jpg

attachicon.gifwidth.jpg

Nico, were you able to find a laptop with SGP 2.9 on it to test? 



#67 2ghouls

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Posted 03 February 2021 - 10:56 PM

Nico, were you able to find a laptop with SGP 2.9 on it to test? 

It turns out the laptop I was thinking of has Windows 7, SGP 2.5.1.17. I installed the latest QHY driver package and the QHY268M seemed to work in this version of SGP without issue using the ASCOM driver. I was able to choose settings, ran the cooler down, and took a couple of darks. I am guessing you will have no issue with any version of SGP.

Cheers, Nico


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#68 Sponge

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Posted 04 February 2021 - 05:54 AM

And to put an end to the QE debate, QHY have published their curve.


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#69 OnTheArrow

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Posted 04 February 2021 - 09:32 AM

Ok, so 268M = 600M in APS-C format. That's nice)

#70 xiga

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Posted 04 February 2021 - 08:21 PM

It turns out the laptop I was thinking of has Windows 7, SGP 2.5.1.17. I installed the latest QHY driver package and the QHY268M seemed to work in this version of SGP without issue using the ASCOM driver. I was able to choose settings, ran the cooler down, and took a couple of darks. I am guessing you will have no issue with any version of SGP.

Cheers, Nico

Thanks so much Nico!

This is brilliant news, as it will save me 150 bucks upgrading SGP. I'm quite happy with my v2.9 for now.  

Expecting some funds to land in tomorrow morning. Assuming they do, i'll be putting my order in. smile.gif



#71 aatdalton

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Posted 04 February 2021 - 11:35 PM

I'll report in that the 268M is working great in NINA with the latest .dll package installed from QHY. There's one bug currently being worked out for the readout mode to be switchable by the sequencer but you can still manually change readout modes in the program. Hoping for some clear skies next week.


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#72 DaveB

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Posted 05 February 2021 - 12:22 AM

And to put an end to the QE debate, QHY have published their curve.

Wow, this is significantly different than the graph posted by ASI/ZWO for their variant, which they say is the test results of Sony: https://astronomy-im...ds/2600-QE图.jpg

 

The Red/Ha response shows a big drop-off on the ZWO graph (60% in Ha, 57% in SII). The QHY graph shows 75% and 73%, respectively.

 

Note that the QHY graph is a combination of experimentation and extrapolation.



#73 2ghouls

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Posted 05 February 2021 - 05:06 PM

I have my camera QHY268M, but I have a doubt, which are the choices of PRESETS, GAIN and OFFSET to work properly with LRG and NB and which READMODE is the apropiate?

 

Thanks

 

I've got mine in hand as well. Ran SharpCap sensor analysis on it for Modes #0 and #1 if anyone would like to see the results. Spoiler - it's basically the same chart QHY published. tongue2.gif

Also glad to help answer any questions.

Hello other 268M owners, Can you confirm that your 268M did NOT come with any M54 threaded adapters and that the only adapters with threads were M48? QHY has updated their website to indicate the camera should include M54 threaded adapters "*Standard Free Adapters and Interface

Both 268M/C can compat with M54 and M48 threads with free adapters provided." So I'm now wondering if it was just my box that was missing the M54 threaded adapters, or if QHY has got this wrong.


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#74 matthisk

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Posted 06 February 2021 - 03:48 PM

Here are some pics if you scroll down:

 

https://forum.astron...n.291742/page-2
 


Edited by matthisk, 06 February 2021 - 04:31 PM.


#75 OhmEye

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Posted 06 February 2021 - 04:09 PM

I notice that today HighPoint's price changed from the preorder special of $2099 to regular price $2399, still listed as backordered but I hope this means they received their first stock and will be shipping preorders soon (mine among them!)




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