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ZWO ASI 6200 MM PRO initial impressions

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#1 andysea

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Posted 17 November 2019 - 02:37 PM

Last week I was given the unique opportunity to test the new ZWO ASi 6200 MM PRO camera.

 

Please understand that I am in no way affiliated with ZWO and I am not paid for this review and these are just my initial findings.

Also I'm not a professional reviewer so please bear with me.

 

This camera uses the latest 61.2 MP Sony imx455 sensor.

This is an initial review with a description of the camera and accessories along with first impression and some test frames.

I received the camera last week and unfortunately the weather has been bad. Now I’m on a two-week trip in Europe and I won’t be able to actually use the camera under the stars until the first week of December.

The setup came with the camera, the 5x2” filter wheel and a new OAG.

 

Fit and finish and assembly:

The camera feels very compact and light, like a beefed up ASi1600. It is the usual ZWO red anodized finish .
It attaches to the filter wheel with four screws that are accessible through the carousel itself. You will need an open filter spot for that so either it needs to be done before the filters are installed, or you will need to remove one of the filters.

 

Connections:

The camera has a 17.5mm backfocus from the front plate and the front connection is M54x1 female threads. In addition to that there are four tapped holes to attach the filter wheel through machine screws.

The filter wheel also has M54 female threads on both faces.

The OAG looks and feels very solid and it has a fine focus mechanism for the guide camera. The clear aperture is about 63mm and it has an M63x1 female threaded connection on the camera side.

I really like how the components assemble together with machine screws instead of threaded connections. This assures that the pick off prism is at the top of the sensor, thus minimizing potential shadowing.

I was able to quickly figure out a connection to one of my scopes (Sharpstar 150mm f2,8) using m48 threads. This however will produce some vignetting. I suspect that one will end up with a bunch of custom adapters for the various scopes.

I still need to figure out a way to connect it to the FSQ 106 which will be the primary test scope.

 

Cooling and power:

The cooling seems to be very solid. My room temperature was around 21c and the camera was able to rapidly reach the temperature of -5c  and maintain it with the cooler at ~55/60%. The power consumption in this state is about 1.5a which is excellent.

If I wanted to lower the temperature to -10c then the cooler usage went up to about 80~85%

At 100% the power draw hovers around 2a.

Cooling much lower than -5c may not be necessary given the very low dark current.

 

I have attached a few unpacking photos and the following posts will have the links to the calibration frames.

 

I will be happy to answer any questions or specific requests.

I'm sorry that I won't be available to run any further tests or imaging runs until two weeks from now.

 

 

 

 

Attached Thumbnails

  • IMG_4811.jpeg
  • IMG_4814.jpeg
  • IMG_4815.jpeg

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#2 andysea

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Posted 17 November 2019 - 02:37 PM

This is another photo showing the connection between the filter wheel and the camera.

Attached Thumbnails

  • IMG_4825.jpeg


#3 andysea

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Posted 17 November 2019 - 02:41 PM

Below are the calibration frame links:

 

Gain 100 bin 1x1 temp -5c

 

https://www.dropbox....1t131pwtza?dl=0

 

Gain 000 bin 1x1 temp -5c

 

https://www.dropbox....LIzM2uFdqa?dl=0

 

I also tested the camera binned 2x2. For that I had to use the Ascom driver as the Native driver kept giving me an error when binning 2x2

Below Ascom driver gain 56 bin 2x2 temp -5c

 

https://www.dropbox....HEUxV0iBIa?dl=0


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#4 vehnae

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Posted 17 November 2019 - 02:44 PM

Interesting! Is it possible to attach the camera without the tilt plate using the provided screw holes?

 

  ++ Jari



#5 andysea

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Posted 17 November 2019 - 03:08 PM

Jari

That is not possible right out of the box. Here is a photo of the front of the camera with the tilt plate removed. I guess if you could machine four countersunk screws holes in the filter wheel plate, that match the pattern of the holes for the tilt plate, you can bypass the tilt plate.

Attached Thumbnails

  • IMG_4827.jpeg


#6 carballada

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Posted 17 November 2019 - 03:21 PM

Maybe could be possible to machine the tilt mechanism (pull screws) on the filter wheel itself.

In both cases you don’t have access to tilt when the camera is running ...

#7 ezwheels

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Posted 17 November 2019 - 03:37 PM

I like the idea to, if necessary, drill the filter wheel plate to allow for this super short back spacing configuration. I think ZWO could easily do this and give back 11mm... but then the distance from the prism to the main camera may be getting to be a bit shorter than you can bring the OAG camera in. They will not be parfocal. 



#8 andysea

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Posted 17 November 2019 - 03:45 PM

I forgot to post the back focus distances:

 

- Camera 17.5mm

- FW 20mm 

- OAG 15.5mm. However ZWO says the final version will be 17.5mm.

 

 

I like the idea to, if necessary, drill the filter wheel plate to allow for this super short back spacing configuration. I think ZWO could easily do this and give back 11mm... but then the distance from the prism to the main camera may be getting to be a bit shorter than you can bring the OAG camera in. They will not be parfocal. 

 

I think that the OAG may still work. There is a lot of range in the fine focuser and you have the option to either use a threaded connection to a standard m42 thread or to use a small guide camera that slides  in the guide port like an 1 1/4" eyepiece. That would allow extra adjustment range.


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#9 carballada

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Posted 17 November 2019 - 03:47 PM

I forgot to post the back focus distances:

- Camera 17.5mm
- FW 20mm
- OAG 15.5mm. However ZWO says the final version will be 17.5mm.



I think that the OAG may still work. There is a lot of range in the fine focuser and you have the option to either use a threaded connection to a standard m42 thread or to use a small guide camera that slides in the guide port like an 1 1/4" eyepiece. That would allow extra adjustment range.


That’s a good news, thank you for sharing all this pictures and info!!! :)

#10 andysea

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Posted 17 November 2019 - 04:04 PM

That’s a good news, thank you for sharing all this pictures and info!!! smile.gif

 

You're welcome!

Since I have a few more hours before I board my flight here are more pics of the OAG.

 

The pickoff prism is 11mm square and can be adjusted up and down.

Attached Thumbnails

  • IMG_4828.jpeg
  • IMG_4830.jpeg

Edited by andysea, 17 November 2019 - 04:06 PM.


#11 MapleEve

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Posted 17 November 2019 - 04:18 PM

I would like to follow up in this thread as the first tester result is published into local community:

 

1.jpg

gain 0 offset 900 since the ADC is 16bit

 

2.jpg

 

and a 900s dark in -10c



#12 andysea

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Posted 17 November 2019 - 04:25 PM

That's pretty much in line with the data that I shared at gain zero.

I can't remember what offset I used, I think it was 40 or 50. Is offset 900 really necessary?

The dynamic range at gain zero is impressive, as well as the full depth.

 

I would like to follow up in this thread as the first tester result is published into local community:

 

attachicon.gif 1.jpg

gain 0 offset 900 since the ADC is 16bit

 

attachicon.gif 2.jpg

 

and a 900s dark in -10c

 

Attached Thumbnails

  • Gain zero.JPG


#13 MapleEve

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Posted 17 November 2019 - 04:38 PM

That's pretty much in line with the data that I shared at gain zero.

I can't remember what offset I used, I think it was 40 or 50. Is offset 900 really necessary?

The dynamic range at gain zero is impressive, as well as the full depth.

The offset is a way to avoid the dark bands signals which is below zero I think.

 

That was how I asked him about the high offset thing. https://www.cloudyni...info/?p=9751613

 

And since the local test model is passed to another tester with TAK E130 and all new Antlia 3.5nm NB filter, I think another test result will be out soon.


Edited by MapleEve, 17 November 2019 - 04:41 PM.


#14 andysea

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Posted 17 November 2019 - 04:58 PM

Yes I’m clear about the need for offset. I just wonder if 900 is necessary.

#15 rockstarbill

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Posted 17 November 2019 - 05:02 PM

The 2x2 bin performance of that camera is exceptional. 


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#16 Coconuts

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Posted 18 November 2019 - 08:15 AM

Andy:  Super helpful, thanks!  It was also great to see the view with the tilt plate removed.  I have an odd, tight space goal: to adapt Sigma's new 14-24mm F2.8 DG DN Art, L mount camera lens (Flange Focal Depth = 20.0 mm) to this camera.  I posted about that lens, here:

https://www.cloudyni...trophotography/

The same would apply for any future Sigma Art L mount lenses.

 

I contacted ZWO to see if the tilt plate could be removed:

"Is the front attachment plate of your upcoming ASI6200 removable and so capable of being modified, or does it include perhaps the optical window and maybe hermetic sealing, such that this is not advised?  Will a dimensioned drawing for that plate be made available, if not now, nearer the launch?  Thank you."

 

They replied: "Apparently, if you only remove the front plate of 6200, it's meaningless on the back focus, and the optical window is just below it.  Dimensioned drawing is not available now or the near future. This camera will be ready around end of this year".

 

So that was good news, and your removal of the tilt plate demonstrates this.  In a camera lens, the FFD is defined by the flat flange surface, and the bayonet mount extends behind that.  I haven't yet measured this for an L mount lens.  On Canon EF mounts, the bayonet mount extends 3.86 mm past the flange, but the AF electrical contacts extend this to 7.86 mm.

 

So my questions would be:

  • How thick is the tilt plate?
  • Is the nominal 17.5 mm back focal length measured from the front of the tilt plate?
  • Is that with its tilt push crews backed out (ie, the tilt plate hard against the camera body)?
  • Lastly, do they provide a dimensional diagram (side view) that shows the distance from the black metal behind the tilt plate to the sensor?

Thanks again!  Your answers might be valuable to others with different tight space conflicts.

 

All the best,

 

Kevin



#17 bortle2

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Posted 18 November 2019 - 08:44 AM

In a camera lens, the FFD is defined by the flat flange surface, and the bayonet mount extends behind that.  I haven't yet measured this for an L mount lens.  On Canon EF mounts, the bayonet mount extends 3.86 mm past the flange, but the AF electrical contacts extend this to 7.86 mm.

How far a lens can extend into the mount is part of the mount specification. For instance, Canon EF and EF-S mounts are virtually identical and differ only in how much protrusion they allow; EF-S allows for more, so if an EF-S lens could be mounted (luckily, it can't) on a FF DSLR camera, the mirror could hit the back of the lens.

 

Leica L mount is kinda/sorta open, so I think that information can be found somewhere, although my quick search returned nothing -- it's an often overlooked part of the mount specs. If you're only interested in that 14-24/2.8, you might as well just measure it... But if you're going to adopt other L lenses, I suggest that you consult the specs.



#18 Coconuts

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Posted 18 November 2019 - 11:49 AM

I just found a dimensional drawing for ZWO's existing ASI071 camera (below).  It is 5.5 mm thick.  Also, it confirms that ZWO does measure the back focal distance of 17.5 mm from the front of the tilt plate.  IF the tilt plate for the ASI6200 is the same thickness as that of the ASI071 (which seems likely), then that, plus the delta between the L mount Flange Focal Distance (20.0 mm) and the ZWO BFD of 17.5 mm, gets me to 8.0 mm.  That should just make it.  Sigma will be releasing a series of high-end ART lenses for their co-adopted L mount (originally a Leica mount standard, now also shared by Panasonic), which is longer than those otherwise identical lenses that they will release for the Sony E mount (FFD of 18.0 mm).  Those would be unlikely to fit, although I lack dimensional info for the Sony E mount bayonet and AF contacts protrusion. 

 

But being able to mount all future Sigma, Leica, and Panasonic L mount camera lenses to the ASI6200 would to my mind be awesome.

 

I once personally machined an adapter to the Pentax 67 medium format bayonet.  It was challenging, but I succeeded.  If need be, I can do it again.

 

asi071pro-Mechanical-Drawing.jpg

 

All the best,

 

Kevin



#19 andysea

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Posted 18 November 2019 - 11:58 AM

I will measure the tilt plate thickness once I am beck home, but Kevin is most likely correct.

#20 chadrian84

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Posted 18 November 2019 - 12:37 PM

ZWO should have used M63 threads on both sides of the OAG and the OTA side of the EFW. The current configuration is only free of vignetting down to f/5.

 

Fastest f-ratio for no vignetting = Distance of opening from sensor / (Diameter of opening - Diagonal of sensor)

 

5 = 37.5 / (50.5 - 43)      M54 is around a 50.5mm opening.and the sensor diagonal is around 43mm.

 

If the tilt-adjuster can be removed vignetting will begin around f/3.5


Edited by chadrian84, 18 November 2019 - 12:53 PM.


#21 Coconuts

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Posted 18 November 2019 - 01:00 PM

With the demonstrated ability to remove the tilt plate, and replace it with a custom machined part, all sorts of options open up.  The ASI6200's "real" BFD appears to actually be only 12.0 mm.

 

All the best,

 

Kevin



#22 chadrian84

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Posted 18 November 2019 - 01:06 PM

Why make users get a custom machined part and have to forgo the tilt-plate?  There's almost no extra cost for ZWO to produce the items with larger openings.  

 

Basic design goals currently being missed:

- Maximize diameter of openings that could lead to vignetting

- Connection options for users who don't want to use the tilt-plate

- A tilt-plate that can be adjusted while connected (i.e. adjustment screws on the outside)


Edited by chadrian84, 18 November 2019 - 01:30 PM.

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#23 motab

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Posted 18 November 2019 - 02:22 PM

Why make users get a custom machined part and have to forgo the tilt-plate?  There's almost no extra cost for ZWO to produce the items with larger openings.  

 

Basic design goals currently being missed:

- Maximize diameter of openings that could lead to vignetting

- Connection options for users who don't want to use the tilt-plate

- A tilt-plate that can be adjusted while connected (i.e. adjustment screws on the outside)

+1 to this. 17.5mm is a lot of backfocus to eat up for no good reason and that's all at M54. I would prefer the sensor right up against the filter wheel in order for 50mm round filters to not vignette and have the OTA side of the filter wheel connect to the rest of the optical train with a far larger thread. In my case, I already have a 3.5" tilting unit and quite tight constraints on spacing so an inaccessible tilt-plate on the camera does me no good. Moreover, adjusting tilt at f/3.6 without the camera being connected seems like a waste of time.

 

ZWO have indicated a shipping date in January but my vote is to create a short-backfocus version like QHY are intending to produce without the tilt-plate with an M54 thread.


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#24 Coconuts

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Posted 18 November 2019 - 02:46 PM

In their reply to me, ZWO explicitly said that they will not be making customized versions of the tilt plate.  So that is on us.  But at that point, many things become possible, including tip/tilt adjustments that use two orthogonal adjustments aligned with the sensor axes, and which can be accessed while the camera is mounted.  And the ability to use Leica/Sigma/Panasonic L mount lenses.  And filter wheels that screw directly to the camera.  Etc. 

 

Get thee to a Bridgeport!

 

All the best,

 

Kevin


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#25 lucam

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Posted 18 November 2019 - 05:01 PM

Thanks for sharing, Andy. I look forward to hearing more about your experience with this camera. 

 

M63 opening in the front cover of the filter wheel wouldn't help with vignetting unless the filters are at least 50x50mm square. The round 50mm filters about 15mm out from the front of the camera would still vignette around f/4.5. The weight, moment arm, and bulk of a filter wheel with 7 50x50mm square filters should not be underestimated. 




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