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Old Aug 25, 2006, 11:01 PM   #1
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I see 3x telephoto and wide angle Tele-Conversion Lenses
l
enses are cheap. Why dont a lot of people use them?

How does their quality compare to real lenses?
If I get a Canon rebel XT($750) or Nikon D50($700) w/kit, and attach
a 3x Tele-Conversion lens to it, instead of buying a lens, I'd get
165mm. Which is more than the Olympus Evolt-500 w/150mm lens kit($700).
If I get a 200mm lens, and use the 3x with it, why bother buying a 600mm?
Likewise, why not use a 3x wide angle Tele-Conversion lens instead of buying
a real one?




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Old Aug 25, 2006, 11:30 PM   #2
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Could you post a link to exactly what you are refering to?
Are you talking about something that mounts in front of the kit lens, or something that goes between the lens and the camera?

I have a different responce depending on which you mean.

Eric
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Old Aug 26, 2006, 12:34 AM   #3
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I'm not sure you can get 3x teles for slrs, at least not good ones.
2x teleconverters are popular, but they have several drawbacks.
First, to double your focal length while keeping the aperture the same size only 1/4 the amount of light is now hitting the lens. You have lost 2 stops. With a cheap, slow lens the auto-focus will not now work as the lens is now too dark. With a fast lens, well, you now have a slow lens.
Second, more glass for the light to go through (and it has to be bent and then straightened out again too) means a loss of quality. Once again, this can make poor quality lenses unusable and reduces the quality of good ones.
Those huge white lenses you see pros carrying at sports events are big not just to get lots of 'zoom' (in fact many have less zoom than most point and shoots) but to make sure enough light gets into the lens to take decent pictures.
In photography, while size does matter, the width of your equipment is just as important as it's length.
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Old Aug 26, 2006, 2:44 PM   #4
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I agree with Jacks... I just wanted to add another downside to a teleconverter.
They magnify any flaws in the lens. So a bad lens will be even worse.

This is another reason why the big white canon lenses are so nice. The really top end ones are so good that you can add a teleconverter with basically no loss in optical quality. You have to pay through the nose for them, but you do get something for it.

Eric
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Old Aug 26, 2006, 4:38 PM   #5
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3X TELEPHOTO LENS FOR OLYMPUS E-500 E-1 EVOLT ZOOM LIST

I believe what romphotog was referring to was not a teleconverter, which fits in between the camera and lens, but a teleconversion lens, which screws onto the front of the existing lens (see above link). If you have a fixed-lens camera, these are your only option. For DSLR's however, they cannot match the quality of a lens made specifically for the camera. Consider what adding all that additional glass does to the possibility for distortion. That's why manufacturers (Nikon, Canon, Olympus) will make these for their fixed-lens products, but not DSLR's. For that option, you normally must seek out a third-party supplier.
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Old Aug 27, 2006, 11:26 AM   #6
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If that is what he was refering to, then products like that are of varying quality.
A few companies make front-mount lenses like that and you have to be careful. I don't know if that one is any good, but I'm always a bit scare do them. I went to a web site of one company and they made a 2.5x and a... 4x or something. What shocked me was how bad their "sample" pictures were for the 4x. So bad I would never have considered it.

So they can be good... or not. I would look for someone who has it and see what they think... and even better get them to post an example image with it.

Eric
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Old Sep 2, 2006, 12:42 AM   #7
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Hi,
I am nathan from India, just joined.
I hv purchased a Canon S1IS. Since canon has stopped making teleconversion lens for this model, I am looking for an alternative set of lens / adapter. Can somebody advise on a 2x or 3x tele conversion lens.
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Old Sep 2, 2006, 5:43 AM   #8
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Umm, well there are no worthwhile x3 lens for digicams and maybe one average x2.2 tcon that is usable.

You could try an Olympus TCON17 1.7x or Raynox DCR 2020PRO 2.2X though the 2020 pro was mentioned as being a poor match for the Canon S2 so I doubt it would be any better with the older S1.

As far as I know you will need to buy a tube adapter for the camera before add on lenses can be used, so factor that in as well. I think you can get either 52mm or 55mm tubes.

http://www.lensmateonline.com/have various adapters etc and details on tcons and wcons that fit the Canon S series.




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Old Sep 3, 2006, 3:46 AM   #9
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romphotog wrote:
Quote:
I see 3x telephoto and wide angle Tele-Conversion Lenses
l
enses are cheap. Why dont a lot of people use them?

How does their quality compare to real lenses?
If I get a Canon rebel XT($750) or Nikon D50($700) w/kit, and attach
a 3x Tele-Conversion lens to it, instead of buying a lens, I'd get
165mm. Which is more than the Olympus Evolt-500 w/150mm lens kit($700).
If I get a 200mm lens, and use the 3x with it, why bother buying a 600mm?
Likewise, why not use a 3x wide angle Tele-Conversion lens instead of buying
a real one?


You will be sorry about this decision. There are a number of reason. First, there are no good 3X teleconverters and all good ones (e.g., Nikon TC-E3ED) are of small to very small thread types (e.g., 28mm) that cannot be used on any SLR/DSLR lenses. Second, even though you can find 3X converters on eBay and elsewhere, its image quality is below average or very poor. As a result, you will have CA almost everywhere and it is soft to soft edge and/or corner performance. Third, since virtually all kit lenses have large diameter front glass in order to gather more light for the corners, it is very likely you will see vignetting at the longest end of your kit lens.

Consequently, it may be better to buy a cheaper long zoom such as Sigma's 70-300 than a teleconverter.



CK

http://www.cs.mtu.edu/~shene/DigiCam

Nikon Coolpix 950/990/995/2500/4500/5700, Panasonic FZ-10/FZ-30, and Canon A95 User Guides


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Old Sep 7, 2006, 12:52 PM   #10
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Thanks for the advise, really, but I am looking for something stronger for birding. Maybe the initial choice of camera was wrung, but being a newcomer, I was told the 10x of Canon S1 would be ample range. Can I try some of the larger telephoto or mirror lenses. I saw an 8x crystalvue lens that supposedly fits an S1 with adapter available for $ 169. should I try that.
Alternately give me a camera telephoto lens combination that I may buy, keeping in mind that I am a student. not much money to splurge.
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