Trying the achieve a flat field with the IMX455 sensor (QHY600). Having a horrible time of it...

[SimonIRE]

Hi All, 

I am new to this forum (I am active on CN - I used to live in the US but I am back home in the UK now). 

I have recently moved from a QSI683-FSQ106 combo which is very forgiving to a QHY600-FSQ106 set up and I am having some difficulties. The summary is that, as perhaps I should have expected, my field does not appear to be as flat as I had hoped (as measured in CCD inspector). 

I just read this thread with great interest

 

I am having great difficulty taming the outer 30% of the image. The combination of small pixels and large sensor are proving to be a significant challenge. Added to this, I think I have some tilt. 

In the interest of having an easy life (particularly given that experimenting with equipment is very difficult when so few nights are clear), I am seriously considering downsizing to a smaller sensor. The next clear night I am going to try 2x2 binning and see if that helps. 

I am very interested to hear people's experiences with the IMX455 sensor, specifically in relation to achieving a flat field. Some of my colleagues have suggested that if visual inspection of the images looks good, then who cares but I am pretty sure I can see eggy stars in the corners. 

Thanks for reading, 

Best, 

Simon

 

 

 

[Ken82]

Trying to correct the field with a large sensor and small pixels isn’t an easy thing to do. 
 

I ended up getting the m68 ctu tilt adapter which works great. You’ll never get it perfect with such a large field of view and tiny pixels.

I think focusing is key as the CFZ at f5 is quite small so you’ll see the stars at the edge either have sagittal astigmatism or tangential astigmatism depending what side of focus you’re on. On Some software like Nina you can pick the CFZ to be around or near the edges which seems to work best. 

I’ve been lucky to see many raw images from the fsq 106 over the past year and for widefield with this sensor it’s probably the best I’ve seen apart from 2x scopes I’ve seen using the quadtcc astrophysics reducer. 
 

Ken