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01-13-2008, 11:05 AM   #16
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QuoteOriginally posted by mysterick Quote
Would the 1.4x and/or the 2.0x work well with the SMCP 18-250?
the answer is really neither. to get your light meter to work right you need close to f.5.6 effective lens speed or a really bright day.

You start putting extenders on a lens that is that slow to start with and you lose f stops and things go downhill from there.

If you want to use an extender buy the longest fastest prime you can afford. Pentax will be
releasing a 300 mm f/4 prime soon (they've talked about it for a year) and you can get older pentax primes on ebay. Sigma's and the like are also around.

If money is not an object the Pentax 600mm f/4 which is offered for around $8000 is a good choice. With an extender you can push it will over 1000mm with decent optical results, but the fact remains that the prize winning bird photos are taken by photographers who
found a way to 'get the camera closer'.

01-13-2008, 07:54 PM   #17
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I'm glad to see hinckc using a telescope for birds. I've used my Stellarvue (also 480mm f6) for something a bit larger than a Chickadee, Bald Eagles on a nest 1/2 mile away on the opposite shore of the Connecticut River. Each February I try to improve, my best so far is pretty awful (you can tell they are eagles...).

This year I'm torn between a Barlow on the scope (960mm f12) or a Sigma manual zoom with doubler (420mm f11.2). I'm thinking the scope is pushing the limits of magnification and maybe a lens would be a sharper choice. I'll try them both out on a radio tower about 1/2 mile from home and see which looks better.

At that distance movement is not a problem, besides the Eagles often pose on the side of the nest. A telescope at closer range would not be agile enough to catch a bird in flight. I once used my Big Kit lens (DA 50-200mm) to shoot Seagulls soaring 15-20 feet overhead hand held full auto with spot focus. Worked like a champ, few shots were blurred. I think that is why my wife, who has been a manual lens user for 25 years, bought her first auto lenses, the same KIT lens pair I have (which are my only auto lenses).
01-13-2008, 10:26 PM   #18
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This has kinda been hijacked to a discussion on using telescopes instead of a telephoto lens. Allow me to continue the hijacking! For a LOT of information on how to use telescopes / spotting scopes, I'd suggest checking out BirdForum - The Net's Largest Birding Community, Dedicated To Wild Birds , go to the forums section, then about 3/4's of the way down is "Andy Bright's Digiscoping Forum". All sorts of info. 'Digi=digital' 'scoping=telescope or spotting scope' therefore digiscoping is the combining of the two.
01-14-2008, 08:23 AM   #19
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QuoteOriginally posted by ChipB Quote
This has kinda been hijacked to a discussion on using telescopes instead of a telephoto lens. Allow me to continue the hijacking! For a LOT of information on how to use telescopes / spotting scopes, I'd suggest checking out BirdForum - The Net's Largest Birding Community, Dedicated To Wild Birds , go to the forums section, then about 3/4's of the way down is "Andy Bright's Digiscoping Forum". All sorts of info. 'Digi=digital' 'scoping=telescope or spotting scope' therefore digiscoping is the combining of the two.
I have used both long telephotos and telescopes, basically the problem I have with my telescope (celestron C90) is that at 1000mm and the crop factor of a DSLR the real issues are tripod vibration and fast focusing. The C90 has many turns to focus, and really is a stationary lens for birds that pose. I think I now have the vibration issue solved with a Monfretto long lens support (an adjustable arm between one tripod leg and the camera, with the telescope supported by the ball head on the tripod.)

For birds that won't pose. I prefer a good fast lens, as indicated in my previous posts either the sigma 70-200f2.8 with a TC or my pentax 300 f4 with the 1.7x AF TC. it is not only the autofocus of these combinations that helps (but that is part of it) but also that I have control of depth of field with the apature ring, and can stop the lens down, this also helps with objects that move because you never know exactly your focus point, and with a fixed apature lens like a mirror, you have to be very precise. These combinations are usually supported by a monopod

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