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Poor QHY repair service; this is a slow boat to China

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#26 Hobby Astronomer

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Posted 14 February 2020 - 03:25 PM

I am not taking the side of QHY, but I needed some assistance with my QHY11 cooler. They charged me only about $60 for everything including the shipping. Camera has worked great since. Took about 8 weeks.

 

It is an interesting experience to work with them. 

 

HA



#27 maxmir

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Posted 16 February 2020 - 08:16 AM

I purchased my QHY128C two years ago. I never really got past plugging it in and testing operation.

This fall I tried again. It could not produce an image.

It was repaired in China after two months. Now it downloads images fine. I found another problem as I started using the camera.

 

I first noted that  the image center was offset by about 1000 pixel in X and 500Y. The sensor appears centered using a ruler in the camera .

The QHY128C comes with an adjustable front end piece with three screws

that allows for some lateral adjustment. However, a 1000 pixels exceeded the range. I have a lathe and removed 2mm from the adjustable front piece.

I am was now able to center a star and rotate the camera in the focuser without lateral shift. Offsetting the sensor took 2-3 mm.

I could not understand why the image was so far off center.

 

Next I did a plate solve ( this is where the plot thickens )

I measured 1.21 arcsec per pixel and FOV 2.03 x 1.37 degrees with TheSkyX's image link plate solution.

The scope in an AP130 f6. I verified that the scope has a FL of close to the specified 780mm focal length using a ruler.
                                                         

The predicted FOV should be about 2.64 x 1.76 degrees at 1.58 arcsec per pixel.  This is using  a 780mm FL scope and a 128C camera specified with 6036 x 4028 pixels  @ 5.97u.

The plate solution at  a FOV 2.03 x 1.37 and 1.21 arcsec per pixel suggests that scope has 1020mm  FL. This is most decidedly not true. 

 

I have determine that the camera likely has much smaller pixels ( about 4.7-5.0u) and is not using all the pixels on the sensor.

I am keeping in mind the fact that active imaging area is substantial offset.

I don't know if it is possible to install a 367C sensor and configure to readout a sub-frame using firmware.

The 367C has 4.88u. This would fit the measured offset and plate solution.

 

Kind of sucks too. I want the FOV.

 

What do you think?

 

 

 

Max



#28 maxmir

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Posted 16 February 2020 - 08:17 AM

Started another thread.

 

https://www.cloudyni...sed-up-qhy128c/



#29 cccha

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Posted 17 February 2020 - 12:03 AM

This needs to be confirmed. It should not be a deviation of the mechanical center, because 1000 pixels are very large and account for 1/4 of the whole in the vertical direction. This deviation can be seen intuitively. Can you intuitively see that the chip has a large deviation?




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