double magnification filter mount?

xAGENTxMULDERx · Mar 8, 2013

my dad was telling me on an old camera he had a double magnification filter for his lenses that made his 70-200 a 140-400 and so on with his other lenses, i cant seem to find these for my nikon d3000 and its lenses, any help here would be appreciated

bratkinson · Mar 8, 2013

Back in my film days, I, too, had a 2X 'extender' that converted my 100-200 to 200-400. I think it was a Vivitar, as I recall, and I bought it at the same time as I bought the 100-200, also a Vivitar. The extender then, as now, mounts between the camera and the lens and had the correct mounting hardware to mate with both. 3rd party manufacturers make their lenses in a variety of mounts to broaden their market. Other than a couple of "let's see what it'll do" type of tests, I didn't use the 2x much. I did, however, get some good shots of small snow slides on Mt Ranier near Seattle on a 95 degree day using the 100-200 with the 2X. I don't think I ever used it again after that. The 100-200 didn't see much use either.

These days, most extenders are either 1.4x or 2.0x and still mount between the lens and the camera, providing the proper mount and electrical connections as well. The better ones cost several hundred dollars each. There are also a number of never-heard-of-them manufacturers that market cheap, screw-on 'telephoto extenders' or whatever they choose to call them that are complete junk. Typically, they are less than $40. These screw into the filter threads and don't work very well, producing an image that is far from being sharp. I tried one, thinking, what the heck?' The real lens couldn't focus in AF mode, so I focused manually. The results were blurry, and while removing the 'telephoto extender', the whole thing fell apart! So, don't waste your money on that trash.

tirediron · Mar 8, 2013

Nikon Tele-converters. As mentioned above, the type that screw onto filter threads are junk and NOT worth the money. It's also worth noting that if you double the focal length with a TC with a 2x, you will lose two stops off your maximum aperture, so your 70-300 f5.6 will become a 140-600 f11!

xAGENTxMULDERx · Mar 8, 2013

wow, thanks for the information! i found this

Tamron 1 4X AF Teleconverter for Nikon 725211147039 | eBay

tirediron · Mar 8, 2013

Certainly not up to the quality of the Nikon, but at that price, worth a chance.

SCraig · Mar 8, 2013

Keep in mind that nothing is free. In many cases, and optics is one of them, this means more than just the monetary cost.

The most common teleconverters are 1.4x, 1.7x, and 2,0x. They multiply the focal length of a lens by 1.4, 1.7, and 2.0 respectively however the cost is normally three-fold:

1. As has been mentioned they cost a lot of light. The cost in f-stops is equal to the increase in focal length, or 1.4 stops, 1.7 stops, and 2.0 stops.

2. Image quality is normally degraded because of the additional optical elements the TC adds to the lens. Sometimes it isn't dramatic and is acceptable, however with cheap TC's it can be horrendous. I have a 2x TC that is so horribly bad I won't even give it away. On the other hand I have a 1.4x TC that works very well and gets used quite a bit.

3. Some DSLRs will not autofocus when the maximum aperture is less than f/5.6. On the other hand, some will. My D7000 will autofocus with my 150-500 f/5.0-6.3 lens and a 1.4TC as long as there is good light. F/5.0 + 1.4 stops is about f/8.