Help with Quattro Collimation

[SB (Chris)]

Hi everyone,
Have been trying to get good collimation with my Quattro 800 without great success. Today I'm trying a collimation cap.

Here is a photo looking through the cap apperture. Is this what I should be seeing? (the clips looks even around the primary and the centre circle of the primary mirror contains the image of the collimation cap aperture and is aligned with the centre of the spiders).

Prior to this I was using a collimated laser. The primary mirror circle and the collimation cap image was aligned but substantially offset from the centre of the spiders.

Many thanks

Chris.

[croweater (Richard)]

Originally Posted by SB

Hi everyone,
Have been trying to get good collimation with my Quattro 800 without great success. Today I'm trying a collimation cap.

Here is a photo looking through the cap apperture. Is this what I should be seeing? (the clips looks even around the primary and the centre circle of the primary mirror contains the image of the collimation cap aperture and is aligned with the centre of the spiders).

Prior to this I was using a collimated laser. The primary mirror circle and the collimation cap image was aligned but substantially offset from the centre of the spiders.

Many thanks

Chris.

Hi Chris. I cant see your picture that well on my phone but I think that is a normal offset collimation pattern that you see when collimated fast newt (the quattro is f4 ?). Have a look at "Astro babys guide to collimation-Newtonian telescope" on the net and at the bottom of the page she has a picture of this. Her guide to collimation is the best I know of. Hope this helps.
Cheers, Richard

[Stephane]

Hi Chris, your image looks good to me.

At f/4, I’ve noticed that by far the greatest error in collimation I get is not millimeter precision in mirror alignment, but rather getting the camera square in the focuser. To highlight this, you’ll notice that if you remove the laser collimator from the focuser and place it back in, the dot will likely no longer be in the center of the primary mirror. The trick is consistent screw tightening when securing your laser & camera in the focuser. I personally take the slack out of the screws and immediately stop as soon as I hit resistance, then tighten each screw incrementally, one at a time.

I cannot emphasize how much this technique has positively impacted my star shapes at f/4. Hopefully this might help you achieve your perfect collimation.

Regards,
Stephane

[SB (Chris)]

Hi Richard and Stephane
Thanks for your help. I’m certainly finding this a challenge. I’m just not getting consistency with F4. Perhaps an F5 scope would be easier? I have an upgraded focuser which holds the coma corrector and camera firmly. The primary mirror springs are fairly tight. I also noticed that the star shapes can vary with angle of the scope.

Chris.

[SB (Chris)]

Hi Richard and Stephane
I followed your suggestions for tuning the Quattro.

Here is an image of M83 - 80x 180 Seconds Camera ASI183MC pro. Stacked and processed in Affinity. It's an improvement from what I was getting before. The stars are marginally oval but I think that's something I can work on.

Chris.

[croweater (Richard)]

Hi Chris. That's an excellent M83. I like it. I had to zoom in before seeing any oval shape at all so your pretty close mate.
Cheers, Richard.