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2x Teleconverter

Thu Feb 13, 2003 2:56 pm

I have two question about 2x teleconverter the screw in type for my minolta dimage 7i.

How will the teleconverter affect light and picture quality

and Can I stack two together and how will stacking affect light and picture quality.

Canon 50D user; 100-400 MM L IS 10-22 MM, 60MM Macro
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RE: 2x Teleconverter

Thu Feb 13, 2003 4:50 pm

A friend of mine has bought a teleconverter for his D-100 lens. Bad idea, the autofocus didn't work well, and the pictures were blurry and with low quality. That's what I know - haven't used one myself yet Big grin
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RE: 2x Teleconverter

Thu Feb 13, 2003 6:10 pm

Ahh but there's Teleconvertors and there's teleconvertors....

I have a cheapo Jessops 2x convertor for my Nikon SLR and yes the pictures are pretty poor. I suspect if I'd paid the several hundred pounds extra for a genuine Nikon teleconvertor the results would have been significantly better.

On the other hand, these are teleconvertors that sit between the camera body and the lens, whereas on the Digicams (i.e. non SLR) these teleconvertors sit on the front of the lens. Will that have an impact I wonder?

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Flightlineimages DOT Com Photographer & Web Editor. RR Turbines Specialist
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RE: 2x Teleconverter

Fri Feb 14, 2003 6:10 am

Indeed there are 2 types of teleconverters. The SLR type is between camera and lens. They have drawbacks such as light loss as loss of sharpness. The type you put in front of your camera will have the same effect. The light loss will be harder to guage because there is no interface with the camera to tell the old versus new maximum aperture. You could know by setting Av to a determined value and see where your shutter speed sits before and after mounting the converter (pointing at the same light source throughout). The amount of sharpness lost varies with the quality of the teleconverter- but it will -never- be sharper than the naked lens! My experience with the AF with the front mount TC's shows that the AF is a little worse but I cannot quantify it for you at all.

Hope that helps a little.
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RE: 2x Teleconverter

Fri Feb 14, 2003 6:22 am

Well I use both types of tele-converters depending on the camera I am using.

I use a 2x auxillary lens, and also a fisheye and wide auxillary lenses on my Nikon CoolPix 950 and have had no problems at all. All three have had shots accepted here on

I also use a 2x on my SLR Nikon and again no problem. However there is a two-stop loss of light with the converter in place. It should be noted that if your prime lens is only a f:4.5 or so or a slow variable aperature lens, then the quality will suffer somewhat and the autofocus will most likely have problems due to the lower light levels reaching the AF sensors. My prime telephotos are all f:2.8 lenses so they work well, including autofocus with the extenders. This includes the 80-200mm f:2.8 and the 300mm f:2.8 lenses.

Perhaps why the quality stays good is that they are all Nikon converters and lenses. (no spam please) Big grin

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RE: 2x Teleconverter

Thu Feb 20, 2003 3:40 am

I've had a problem using TC's on my 7i. The lens shows up in the picture! I zoom out all the way but I cant get rid of it all.  Angry Has anything like this happened to you?

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RE: 2x Teleconverter

Thu Feb 20, 2003 5:52 am

Steve - I'm sure Nikon convertors work just fine in their own way - but can you stack 'em like Canon's? Sorry, couldn't resist  Smile

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Colin K. Work, Pixstel
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RE: 2x Teleconverter

Sat Feb 22, 2003 12:42 am


That's the sort of photo I aspire to producing.... Once again, nice work Colin!

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