Does my SCT require collimating?

[WingnutR32 (Sam)]

Hi all,

After my hair pulling session last Friday night, I didn't end up heading back out on the weekend to give it another go.

I did however get a quick snap of something I am unsure about from Friday night.

Whether I am using an eyepiece or prime focus with a camera, I notice the attached image when looking at an out of focus star.

Is it just out of collimation?

Cheers
Sam

[g__day (Matthew)]

That just doesn't look right to me - out of collimation gives you an ellipse shape with the dark central void not correctly centred, not flattened.

Maybe download the trial version of CCD Inspector and e-mail the author your piccy for a comment. On the CCDWare forums

[RB (Andrew)]

I agree, it looks more like severe pinched optics, but even for that it's too severe.

[asimov (John)]

It's nothing like anything I've ever seen, that's for sure..Obstruction of some kind..??

[multiweb (Marc)]

Looks like your collimation is ok but something is obstructing the light path. My guess flexible dew shield or something hanging off the secondary cell or inside the baffle tube. Flocking?

[Allan_L (Allan)]

I had something a little like that on my CPC1100.
It turned out to be the dew shield, as Marc suggested.
Just needed a little re-aligning and all good again.
but it did not look quite that severe.

[WingnutR32 (Sam)]

Hmmm it very much could be my dew shield. Honestly didn't cross my mind but now you guys mention it...

I will take another test shot with the dew shield removed and report back.

Good to know my collimation is pretty good.

[RB (Andrew)]

Well that would explain it.
Keep us posted.