alphan
Well-known member
Found this on another site. http://www.owlastronomy.com/specials.htm half way down the page.Would this be regarded as zoom or prime? Any good for birding with Paul's Fujinon TC ? Only 260mm long!!!!
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Fancy a 500mm f3.25 ED (1 Viewer)
- Thread starter alphan
- Start date
Paul Corfield
Well-known member
This would be a prime but it looks like you can just use one lens for the 300mm scope or both lenses to make the 500mm scope. Not bad for the price, might be a bit heavy with all that glass though.
Paul.
Paul.
Musoman
PETE - Nikon/Sony Shooter
I would think at under 300mm long for the entire length of the scope, weight might not be too much of an issue. I'd imagine the foot plate to mount the tube would have to be very near the front of the tube, though. Hanging a camera and focus tube on that beast wouldnt bring the balance point to the centre of the tube
With the maximum 500mm setup, + 2x TC , 1000mm at f6.5 seems real nice, as long as you could accurately build the tube and set the glass at the critical points. I suspect this might be too much to take on for the average birder like me.
And they dont sell out of the USA, by the looks of things
With the maximum 500mm setup, + 2x TC , 1000mm at f6.5 seems real nice, as long as you could accurately build the tube and set the glass at the critical points. I suspect this might be too much to take on for the average birder like me.
And they dont sell out of the USA, by the looks of things
Paul Corfield
Well-known member
All the weight in the scope is in the glass and focuser so I was just thinking how far you can carry it before tiring. Owl Astronomy will ship all over the world, they ask you to email them first for a quote for shipping outside of the US.
Paul.
Paul.
Musoman
PETE - Nikon/Sony Shooter
What do you think a 150 aperture scope would weigh, allowing for the very short tube ( 50% shorter than our scopes ) ? Mind you, i guess the tubes themselves are not that weighty.
I have gone up 50% in aperture with my current scope over my old 80ED, and the penalty in weight was a measly 1lb.
Hmm... i forgot that the glass in that link is a triplet, plus a corrector lens
I have gone up 50% in aperture with my current scope over my old 80ED, and the penalty in weight was a measly 1lb.
Hmm... i forgot that the glass in that link is a triplet, plus a corrector lens
tjd
Tom
I`m sure that such a short focal length front element was designed to always include the second element in train to reduce abberations and to achieve the perfect image. Therefore larger element is not likely to produce a good image on its own.The second (negative ? ) will of course extend the focus point, like a basic telephoto lens, but it looks like the combined focal length will still need a barlow/extender to produce the higher magnifications.
alphan
Well-known member
I am not too worried about making a good tube , the final weight or shipping. I am only concerned about the quality of the optics, triplet + corrector lens + TC with macro tube to get 4 X.... 2000mm at f13 and still shorter than the 80ED.
The tube itself will not weight more than 500g, but the glasses should weight up to 7-8kg. Like Paul said, how long can you lug it around? Not too much of a problem if you can park nearby ....
The tube itself will not weight more than 500g, but the glasses should weight up to 7-8kg. Like Paul said, how long can you lug it around? Not too much of a problem if you can park nearby ....
