will this affect scope performance?

[tyler_jrb]

looking at my scope again and realised it is out of collimation slightly, bad weather and it gave me something to do. Upon taking the collimator out and looking at the secondary i noticed an imperfection allmost like a flat on one of the sides(at the bottom left spider vein in the picture), I dont think its supposed to be like this but then again it may be. Just wondering if anyone knew why its there and if it is supposed to be. Ive used it many times and when de-focusing on a star it is perfectly circular and there doesnt seem to be a flat edge on anything. Ive attached a picture for you to look at, i took it by taking a picture down the tube at the secondary. the flat part is at the bottom left.

Thanks everyone, tyler.b

[Steve Ward]

Hi ,

Panic not,

The secondary on my 200PDS is almost exactly the same , very small flat on one side .

It makes no difference as the mirrors are somewhat oversize , i.e. the cone of light from the primary does not fit to the edge of the secondary exactly.

I have seen a scope with a pretty big chunk out of the secondary that looked horrendous cosmetically but made no impact on the performance at all.

[tyler_jrb]

sigh of releif. Thanks steve. it was just annoying me slightly because I thought it may have had some affect on performance. Although using the scope has given me awsome views and is much better than my old one.Upon looking again i notice that the primarly doesn't fit fully in the secondary so as you say it is oversize.

Put my mind at rest, thanks again steve .

[sunshine185]

Hi Tyler, had the same on my 8" dob, on my new 10" dob I have the same on the top and bottom of the secondary. I panicked when I first noticed it but after reassurances from the good folks at sgl I just ignored it. Had some spectacular views in the 8", so it makes no difference at all. Breath a sigh of relief and enjoy your scope.

[Moonshane]

agreed it makes no difference. to reassure yourself, you'll be able to see the whole of the primary in the secondary at the focal point so this proves that the outer edges are 'spare'.

my secondary on my 6" f11 is not even perfectly oval. it matters not but had me scratching my head when I first collimated it.

[Steve Ward]

If the mirrors were sized exactly to fit the cone I think the forum would be full of collimation queries and nothing else........

[Spec-Chum]

Mines the same mate, I didn't think anything of it to be fair. Even less so now lol

[StuW]

Mine doesn't have a flat bit, but it does have a little imperfection in the silvering, it's bit like crystals growing?

Sent from my HTC One X using Tapatalk 2

[alan potts]

Years ago I chipped the edge of my reflectors secondry mirror and that didn't have any effect what so ever, well not that I could see.

Alan.

[MBJ]

my 200p secondary has a very small flat on one edge but never noticed it until i took it out to blacken the edges so i wouldnt worry.

[fatwoul]

A side effect of bad weather - besides the obvious lack of observing - is that it affords us time to fiddle with equipment and find things to worry about (usually unnecessarily!)