#1  
Old 22-09-2007, 06:55 PM
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bkm2304 (Richard Brown)
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which is bestter?

Helo all,

I am getting into doing some wide field pics and want to know which would be better strategy. I have a EQ mount and Nikon D40 body. I want to do images of say 2 -3 degrees should I get a lens like;

1 a 70-300mm F4-5.6 APO DG Macro AF Lens

2. a 650 - 1300mm tele zoom F8-16

3. a 500mm zoom mirror lens at F8

Your wisdom would be appreciated!

Richard
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  #2  
Old 22-09-2007, 09:01 PM
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citivolus (Ric)
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While I can't really comment on the quality of #1, #2 and #3 are likely to be equally bad build quality and difficult to use. I have not heard good things about either of those lenses, but maybe I have not asked the right people.

Oh wait, I used to have #1 in a Sigma. I guess I can comment! This is a very soft lens, and it tends to creep if pointed up. In other words, set it to 300mm, and 5 seconds later it will be at 70mm. This isn't very optimal. You could probably get around it by wrapping the lens somehow, but it would be difficult as it would restrict focusing. You can see why it creeps if you look at the attachment - its length changes substantially when zooming.

Unfortunately I don't have any good suggestions for similarly priced lenses for Nikon. Hopefully someone else will have some suggestions.

Regards,
Eric
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Old 22-09-2007, 09:50 PM
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There was a discussion a week or two ago about the 500mm mirror lens here

Is there a particular reason you want a zoom lens? A prime lens would most likely be sharper and provide a better image. For the prices you are looking at you could get an Orion ED80 and WO 0.8X FR which would give you 2˚ 08' X 3˚ with a D70 or you could get an FS60-C Tak with a slightly larger FOV
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Old 22-09-2007, 09:54 PM
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bkm2304 (Richard Brown)
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Thanks, Eric. What do you suggest for under say $500?

Richard
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Old 22-09-2007, 09:59 PM
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bkm2304 (Richard Brown)
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Quote:
Originally Posted by [1ponders] View Post
There was a discussion a week or two ago about the 500mm mirror lens here

Is there a particular reason you want a zoom lens? A prime lens would most likely be sharper and provide a better image. For the prices you are looking at you could get an Orion ED80 and WO 0.8X FR which would give you 2˚ 08' X 3˚ with a D70 or you could get an FS60-C Tak with a slightly larger FOV
Hi Paul. No zoom needed. I just want to do star fields and long exposures. Just looking at a thrifty option. I hadn't considered buying a refr... refraaacc.... refractor - there I said It! But it is worth a look.

Thanks

Richard
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Old 22-09-2007, 11:13 PM
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Be careful, you might like it

I'm wrapped in the ED80 with the William Optics Focal Reducer. For the combined cost I really dont believe you could get a better setup. Any of the variety of ED80s for under $600 and the WO FR for $259 and you will have a cracker of a setup at f/6. Even just the ED80 on it's own at f/7 is hard to beat.

While I haven't tried it the ZenithStar 66 f/6.1 Petzval ($400) has a good rep and with the WO 0.8X giving f4.8 would be a top little widefield scope. Plus it comes with a 10:1 focuser
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Old 23-09-2007, 12:28 AM
Benny L (Ben)
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if you can, you should keep away from those push-pull type zoom lenses.. as was mentioned before they move during the exposure. great if you have a replica captain's chair and like staring at the picture going "maximum warp... engage!"

i feel that the 650-1300 lens would be next to useless because all those lenses i have seen or delt with have been absolute crap.

out of the 3 i would reccomend the 500mm f8 mirror lens.

Sigma has a 600mm f8 for about $650
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Old 23-09-2007, 12:39 PM
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Hmm... Thanks, Paul, Benny.

I'll have a look at the ED option.

Richard
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Old 23-09-2007, 02:24 PM
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You can't go wrong with the ED80 option, but, as your focal length gets longer so does the need for accurate, polar aligned tracking. (wedge if you're going to piggyback on the LX)
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