Review: Orion Sky View Pro 100mm ED EQ Telescope - Page 2

avandonk · #21 17-03-2006, 04:32 PM

Quote:

Originally Posted by Striker

just a shame it's F9.

Bring it in at F6 and I will think about it.

I have just bought one from Bintel and I am going to shorten the tube by 100mm so I can attain focus with my new experimental focal reducer. It will behave as a 576mm F5.76. The trick with FR's is to start with very good optics. I would not do this with a ridiculously expensive APO. Ok when this works I will.

Bert

janoskiss (Steve H) · #22 17-03-2006, 04:42 PM

Geez Bert, you're game. Taking a hacksaw to a brand new $1200 scope!

Hammerman · #23 18-03-2006, 05:32 AM

Sorry guys, I guess I was trying to defend myself a bit. Just didn't want you guys thinking "This bloke don't have a clue as to what he's talking about!" or "What does he know? He's from the United States."

Nothing wrong with a good, healthy bit of a debate. I have to get used to the differences in language here. We all speak English, but there is a difference in wordplay between Australia and the United States. Got to admit, I love your sense of humor here on the forum.... think I'll fit right in.

Oh, and Bert? You are one brave man cutting into that scope!

However a hacksaw is going to be slow cutting. Want to borrow my chain saw?

avandonk · #24 18-03-2006, 07:53 AM

Hi all managed to get a few shots off between the clouds. This is a sixty second exposure ISO800 with the scope as it came. The image is Beta Crux and the Jewel Box. No filter but used a Hutech FR/FF with the thick ring installed to flatten the field. Obviously used the Canon 5D. Focus could have been better but the clouds did not give me much time.

There are also a couple of crops to show detail. All pictures from unprocessed JPG. I think this scope performs very well no CA etc. Before I cut the tube will take more pictures with another focuser with 50mm clear aperture as the focuser that comes with it has a 44mm baffles which vignettes on a full frame camera.

Bert

[1ponders] (Paul) · #25 18-03-2006, 11:35 AM

(Off topic - Nice colour on that carbon star Bert

)

OT - Is there any talk of bringing the 100 out in a shorter focal length or is one all ready available, so us less brave souls don't have to do what Bert is doing?

Starkler (Geoff) · #26 18-03-2006, 12:35 PM

Paul the 100mm has to have a longer f ratio than the 80ed to maintain colour correction. To make it shorter would make it more of an achromat.

The focal ratio required to be colour free is a function of the aperture.

[1ponders] (Paul) · #27 18-03-2006, 12:59 PM

Quote:

Originally Posted by Starkler

Paul the 100mm has to have a longer f ratio than the 80ed to maintain colour correction. To make it shorter would make it more of an achromat.

The focal ratio required to be colour free is a function of the aperture.

There are shorter f ratio apo and "semi" apos around (Ziess 100 f/6.4, Vixen 108 f/5.4). Or is it because the Orion is a doublet and the others are triplets?