 Judy vanHaaster |
Want to purchase a teleconverter lens. I have a Nikon AF 70-300 mm 4.5-5.6 zoom lens and would like to purchase a teleconverter lens to go with it. I am using a NIkon D70 digital camera. Please help me make an informed choice.
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robert G. Fately |
Judy, I can recommend two brands to you - Nikon's own TCs (which are, of course, pricey) and Kenko Pro. Now, Kenko offers two versions of TCs, the 'normal" version and their so-called Pro version (which is about twice the price) - get the Pro version - the difference is noticeable. In all cases, these TCs will allow you to use the auto-focus and VR features of the lens you use. Now, TCs come in various powers - 1.4x, 2x and 3x are the most common. They also reduce the light getting through to the CCD - by 1 stop, 2 stops or 3 stops, respectively. So, with your 70-300 on the 1.4TC at 300MM, you will effectively be using a 420MM f8 lens. That is, 300 x 1.4 is 420, and f8 is one stop slower than f5.6. Likewise, the 2X TC on the lens makes it a 600MM f11. So far, so good? Bear in mind that you will need to use some kind of support at these focal lengths to avoid motion blur, unless you shoot at very fast shutter speeds. The rule of thumb for the slowest shutter speed you should use hand held on your camera is 1/(focal lentgh x1.5). That is, without the TC, if you have the lens set to 300MM the slowest shutter speed you should handhold is 1/500th second (close to 1/450th). With that 3X TC, you'd have an effective 900MM f16 lens, and would need to shoot at least 1/1500th of a second (more likely 1/2000th) at minimum. Of course, f16 is pretty slow, so you could only do that on a very bright day perhaps setting the ISO to 800 or something. Otherwise, you would want a tripod or some other sturdy support (beanbag, whatever). Anyway, only you can decide what level of power you wawnt - or maybe you will want 2 TCs (I have the 1.4x and the 3x, but I also have fast lenses). At least Ihope this helps you to understand what's involved.
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Judy vanHaaster |
Thankyou Bob That really helps alot, I am really a very beginner photographer, but my sister and I will be traveling through Banff and Jasper in Sept. and would like to have something to extend the focal length of my 70-300 zoom. I also have a Nikon AF 35-70mm 2.8 lens, so I guess I could use the teleconverter on this lens also. It is a much faster lens. I hope one day to get a much faster 300mm lens one day but for now this will have to do. Again thankyou for reponding so quickly.
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Christopher A. Vedros |
Judy, Keep in mind that the autofocus on most cameras will not work if the max aperture of your lens is smaller than f/5.6. So, if you use a teleconverter on the 70-300 mm 4.5-5.6, you will probably need to use manual focus. I know this is the case with Canon, I think it is the same with Nikon. Chris
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robert G. Fately |
Yes, Judy - Chris makes a good point - auto-focus requires a certain minimal amount of light to work (the camera senses contrast, and needs enough light to do it). So with a slow lens, autofocus just don't work. The 300MM f5.6 puts enough light through in most situations to auto-focus, but at f8 (with the TC) it probably won't be able to focus by itself unless your outdoors at noontime (well, any time it's relatively bright out). A lot has to do with the scene as well - but you'll see how it goes. As for putting iton the 35-70 - yes this ecomes a faster (and heavier) 100MM f4 lens, but frankly, when your zoom is back at the 100MM area it's aready f4.5, which is not terribly differnt. So the TC on the 35-70 is probably not worth doing.
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Judy vanHaaster |
Thankyou Chris and Bob, you have been a great help. One more question. Bob you suggested Kenko TC's, there is several available on ebay, this is what they are called, please tell me if it an appropriate match. Kenko Conversion Lens Teleplus Pro 300 DG 2X for Nikon AF-S & AF-D lenses. My lens is an AF without the S or D.
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Robyn Gwilt |
Hi all - I know you're mainly talking Nikon, but Chris what about on the Canon 70-200 F2.8 L IS USM? I heard that one works with the autofocus. Is this correct? What will my minimum Fstop become then, R5.6? Thanks
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Christopher A. Vedros |
Yes, Robyn, that's correct. Your minimum f stop would be 5.6 and your autofocus would work. I have quite a few pictures in my gallery taken with the Sigma 70-200mm f/2.8 with a 2x teleconverter. Chris
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Robyn Gwilt |
Thanks Chris
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robert G. Fately |
Judy, the Kenko Pro 300 is he one I am suggesting above - their Pro series is the premium version. You can check B&H photo (www.bhphotovideo.com) to see pretty good prices for these TCs so you have something to compare eBay with (I often see eBay purchases made at prices higher than what you can get regularly)
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