any reviews for "Celestron 1000mm F 11" ?

opteron · Post by **opteron** » Thu May 31, 2007 2:17 am

saw it on auctions and planning to use it for my camera but need u guys' reviews about it first....

Post by **VinSnr** » Thu May 31, 2007 2:09 pm

I don't understand what scope is this. Sounds like a refractor...

Post by **Airconvent** » Thu May 31, 2007 9:22 pm

Scopes are normally quoted according to their aperture and focal ratio.
1000mm does not seem very realistic unless they are selling an observatory scope! If the guy meant the focal length, obviously this is not an informed seller.

Meng Lee · Post by **Meng Lee** » Thu May 31, 2007 9:37 pm

I guess in any case, try not to get scopes as "telephoto lenses" with big f-ratios, it lengthens the exposure. But for moon , then big f-ratios don't matter so much.

Canopus Lim · Post by **Canopus Lim** » Fri Jun 01, 2007 10:37 am

It is probably a 90mm f/11 achromat

opteron · Post by **opteron** » Sat Jun 02, 2007 12:18 am

hmm

the link is here. pls take a look.

http://cgi.ebay.com.sg/ws/eBayISAPI.dll ... :IT&ih=016

Meng Lee · Post by **Meng Lee** » Sat Jun 02, 2007 5:26 pm

Looks like Celestron C90. Avoid C90 and all its incarnations. My Mak 90 and ETX 90 (spotting scope version) has much better qualities.

Meng Lee · Post by **Meng Lee** » Sat Jun 02, 2007 8:16 pm

You can PM me if you want to try out my Mak 90. Its still available:

http://www.singastro.org/viewtopic.php? ... highlight=

kayheem · Post by **kayheem** » Sat Jun 02, 2007 10:26 pm

The C90 as in the ebay link is the older C90 which focuses by turning the barrel. This is not suitable for astro.

This newer one is more suitable IMHO:

http://www.celestron.com/c2/product.php?ProdID=203

Post by **Airconvent** » Sat Jun 02, 2007 11:24 pm

I see! Its actually the camera lens version. No wonder the guy referred to it as "mirror" lens. I have a Sigma one for my Pentax camera too. These ones are sold for photography and not specifically for astronomy.

The C90 is essentially the same as the astro version except it is provided with a t-adapter for attachment to an SLR camera.
BTW, the C90s are very compact but the central obstruction is bigger as compared with the ETX90, so contrast would not be as good. Overall, its a very portaball grab and go anyway but small aperture would not be rewarding here in Singapore.

cheers