Is it okay if the center spot isn’t a doughnut?

[Dan20]

I am new to telescopes and read that collimating is very important. My telescope didn’t  have a centerspot and is it okay if the centerspot I put isn’t a doughnut but a big green dot instead.

 

[saac]

Dan so long as it allows you to identify he centre of the mirror I'm guessing it will not matter. Most folk use one of the sticky hole reinforcements you use on punched paper to put into a ring binder.

Jim 

[JamesF]

Anything will do.  Not everyone uses a circle.  As Jim says, the important thing is to be able to identify the centre of the mirror.

James

[Cornelius Varley]

The centre of spot needs to be clear so that the laser beam can be reflected back to the collimator.

[Ricochet]

Ideally, the centre spot would have a hole in the middle which will make aligning the centre mark with the shadow of your collimation cap easier. However, as you have already put the dot on your mirror I would be inclined to leave it in place as removing it is the operation where you are most likely to scratch the mirror (even if it his behind the secondary shadow). 

[wookie1965]

I used a paper reinforcement ring on my 8" when I cleaned it as been told the one on may wash off worked brilliantly.

[Dan20]

It’s  okay now, I have replaced it with a doughnut and I also get to clean my mirror. I thought that a dot will be enough but I just ordered a laser collimator so I had to change it. YouTube really helps

Edited July 2, 2019 by Dan20