Tilt on a G3, should I worry?

[Datalord]

My problems with the dream camera of a g3-16200 has no end in sight. Perhaps.

After getting my mount back from repairs, it seemed to be working fine, so I was looking forward to some prime pictures. Unfortunately, I have a problem I can't resolve. It looks like there is tilt in the sensor, if I'm diagnosing it correctly. Can someone with knowledge have a peek at these images? One is from normal position, the other is where I rotated the camera 90 degrees to eliminate the scope as cause.

L_Ha_2018-09-24_01-52-10_Bin1x1_1200s__-30C.fit

L_Ha_2018-09-25_00-53-14_Bin1x1_1200s__-30C.fit

[vlaiv]

I think something is loose in your optical chain, not sure what, but if you just rotated ota (or camera with rotator) between these two images and tilt was only issue - you would not get astigmatism in second image.

First image shows tilt - only one corner is in focus (well almost good focus, just a bit missing to be in perfect focus), while other parts of the image show defocus from tilt - stronger as you move away from the corner, but stars seem more or less concentric in their defocus.

Second image on the other hand, has no place of good focus, and while one corner exhibits concentric defocused stars, other 2 corners show sagittal astigmatism and the last one coma as dominant. If it were only sensor tilt, I would expect very similar type of aberrations in second image only rotated.

g3-16200 is very heavy camera, what scope are you using it on? What is the focuser like? Can it cope with that much weight?

[Datalord]

I guess I have to learn some more to understand these different kinds of problems, but I'm relieved it doesn't look like a camera issue. Thank you! 

I did think about the weight as a potential issue. It's on my WO71, which I've been using to test the system before my CFF 12" arrives. The new scope should definitely be able to handle it. 

[Skipper Billy]

This what CCD Inspector shows.

This would suggest that the tilt / looseness is in the optical train rather than a camera issue I think as you can see in the third and fourth images that the problem moves 90º whereas if the problem was with the camera it wouldn't move.

If you need future images running through CCDI just PM me for my email address.

 

 

 

[Big Jim Slade]

I tired my G3 on my WO ZS72 whilst I was waiting for my Esprit to arrive and got similar results. As vliav says, weight is the thing here, everything needs bolting together very tightly, compression rings won't cut it.

[Datalord]

29 minutes ago, Big Jim Slade said:

I tired my G3 on my WO ZS72 whilst I was waiting for my Esprit to arrive and got similar results. As vliav says, weight is the thing here, everything needs bolting together very tightly, compression rings won't cut it.

yeah, I have reconciled myself to that, so I can have peace until the new scope arrives.

[AngryDonkey]

I've had a similar problem with the WO Star71 II and in my case it was the camera angle rotator that caused the issue. I think it's poorly made (certainly compared to the Takahashi one I have) with just the one narrow screw which is quite difficult to tighten properly. It seems to be fine now for me if I really give it some welly but I am still considering removing it to be on the safe side.