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02-17-2008, 04:29 PM   #1
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Super telephoto Lens

Has anyone used these super telephoto Lens I see on ebay. The brands are,Opteka, Phoenix, Kenko 420-1600mm or 650mm-1300mm. Or is it better to use a 2X Teleconverter with say a 70mm-300mm or a 18mm-250mm zoom lens. These super Telephoto lens are selling for under 300.00 us.

02-17-2008, 05:09 PM   #2
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I know they seem tempting,
But if you do side my side comparisons you'll find that a good quality prime of a modest focal length (even a 50mm) will look better when It's resized (cropped) to the equivalent of a longer focal length cheap lens.
I had a sigma 600f8 Mirror lens to test for a week, and while it was decent for sharpness... the depth of field was amazingly thin.
Still if you want a long lens at a reasonable price the older sigma mirror lenses are not a bad choice, and you can usually find one at a local photoshop or on E-bay in the 100dollar range.
I prefer local, because they will usually give you a 1 week evaluation period on used lens.
02-17-2008, 05:34 PM   #3
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QuoteOriginally posted by tommya Quote
Has anyone used these super telephoto Lens I see on ebay. The brands are,Opteka, Phoenix, Kenko 420-1600mm or 650mm-1300mm. Or is it better to use a 2X Teleconverter with say a 70mm-300mm or a 18mm-250mm zoom lens. These super Telephoto lens are selling for under 300.00 us.
neither solution is good.

the super tele is very slow, althoug people have had some good shots

Many of the tele zooms have a maximum apature of f6.3, which is too slow for a teleconverter to work and maintain autofocus.

if you want length, you need to start with a 70- 200mmF2.8, or faster equivelent. Perhaps a 300 F4 or 400F5.6

This means a 77mm filter diameter or bigger, The bigma is effectively 1/5 stop faster with it'w 86mm front end.

You will find nothing is cheap, to get length and speed. You may also wish to look ouot for a 500nn F8 mirror tele. I have seen a couple of them lately.
02-18-2008, 04:48 AM   #4
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Tommya, to the apt remarks by Levi and Lowell, I'll just add that those slow "super telephotos" will be just about impossible to focus accurately, either with auto-focus or manual focus, at most times that yield good light for photography. You might have some luck at noon within a couple of weeks of the summer solstice!

You'll need to use a really stiff tripod with a really solid head, too, and don't forget to use mirror lock-up and a remote release/self-timer with those long, cheap lenses. Why? Because the vibration of a shutter press or mirror slap will be hugely magnified. By the way, do you see any tripod mount on those cheapos? No? A dead giveaway; just look at the expensive brands of long focal length lenses and you'll see tripod feet to better balance the numerous, heavy lens elements needed to get modern image quality with really long focal lengths. While you're at it, look at what those expensive brands costs for longer zooms or even just prime lenses in the 400-to-600mm range. You don't get "super" quality long glass without spending some meaningful money.

Hey, I don't mean to poke fun at anyone's hopes for a screamin' deal; it's just that I hope you won't spend $300 on a lens that will most likely disappoint you. A better strategy is to save up two or three times that amount and shop for a decent, fast telephoto prime or zoom and a well-matched teleconverter.

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