skywatcher 150pds central obstruction size

[username]

Does anyone know the size of the central obstruction of the 150pds please?

I can't seem to find a value after trawling the net. I'm thinking it should be bigger than the 150p CO due to the moved mirror but none of the suppliers have it listed and I haven't found any thing on the forums.

Thanks in advance

[Stargazer_00]

Ignore the middle product, their website is screwy and wont compare 2 products only 3....

http://www.skywatche...7=199&x=38&y=19

http://www.skywatcher.com/swtinc/product.php?id=199&class1=1&class2=104

Their site doesnt even list it, so id guess no ones does :/

[username]

It's infuriating that they don't list it. I saw a post from a couple of years back that quoted 29% from another source but that would make it smaller than the 150p which i thought improbable as the primary was closer to the secondary for back focus with cameras.

[Stargazer_00]

email OVL, they might give you a direct measurement.

http://www.opticalvision.co.uk/

[username]

They say on their site that they don't accept technical queries from joe public.

I'll email Teleskop Service as they have had the majority of my astro money so don't feel weird asking them. I suppose it depends if they know off hand/have an open box example to check though.

I'll report back in case people are searching for the same thing in future...

[Mr Q]

Username - I have read several works on this issue and they all agree that any obstruction over 30% starts to effect image quality and light gathering power. These comparisons were against a refracter (no obstruction) with all else being the same. Since most (if not all) reflector designs try to keep costs of manufacturing to a minimun, chances are very good that most any reflector will have an obstruction of under 30% that of the primary mirror.

[username]

teleskop service got back to me (very promptly) and its 50mm.

@mr q which seems to agree with what your saying. Its 33% like an sct or my mak. well above 30% was what I was worried about. The 150p co is a bit smaller.

@ star gazing thanks for help

I've negotiated a new scope with the gf with the agreement that its the last toy for some time. I'm visual atm but wanted to get an all rounder with imaging later on and the 150pds keeps appearing on the list.