are teleconverters any good?

[kiffy]

hi folks, while looking on ebay ive seen teleconverters for sale. i dont know anything about them so wondered are they any good? whats the pros and cons of using one and would you buy one?

thanks
steve

[amk1977]

The benefit of having a teleconverter is that you can increase the focal length of the lens its attached to by the amount of the teleconverter lens. For example, a 70-200mm lens will become a 98-280mm lens with a 1.4x converter.

The only drawbacks with using them is that it reduces the amount of light hitting the sensor, thereby making the lens "slower". They also will cause a drop in IQ to some degree. This will vary by the quality of the optics within them.

My Dad has a 1.4x Nikon TC fitted to his Nikkor 70-200mm f/2.8 VR. It works very well. If I had the money and more importantly the lense that it would work on, then I would buy one. The Nikon TC lenses only work with the pro grade glass with internal focussing. Always best to check compatability before purchasing.

[OldBoy]

Agree with amk1977. I use both the 1.4 and 2x Nikon converters with great results. I have also used a 1.4 Sigma converter with my Sigma 50-500mm F4-6.3 but in manual mode only. To get the best from them you need lenses of F4 or less, and in some cases the AF will only work if you have a Pro or semi-pro camera. If the converters you seen on ebay are made by anyone else except you camera/lens maker then forget them unless made by Kenco, as they are usually rubbish and give you bad results. A 1.4 converter will cost you one stop, a 1.7 converter 1.5 stops and a 2x two stops.

[kiffy]

i love the idea of screwing on a simple lens that will double my lenses power, the one i was looking at was one that ive seen go second hand on ebay but have found new for £101, its the kenko teleplus mc-7 which i found here - http://www.microglobe.co.uk/catalog/...-for-canon-eos

my only lens at the moment that are under F4 are my tamron 90mm and the canon 50mm that i have coming in the enxt day or two. my two telephoto lens are both over F4, so maybe its not worth me spending another hundred quid right now

[AndrewKulin]

I am in agreement as well all that was stated above.

You will lose 1 or 2 f-stops depending which "magnification" you go with, you will likely experience slower auto-focus speed since less light is getting through to the camera, and as depending on the level of camera you have you may not be able to autofocus - my Canon 40D is stated to be auto-focusable to f/5.6 so I can use a 1.4 TC with an f/4 lens (--> f/5.6), pro models (1D's) apparently can auto-focus to f/8, so an f/4 lens could be used with a 2x TC (--> f/8).

The TC will/may also lead to some image quality degradation, more so with stronger tele-converters (e.g. 2.0 vs. 1.4)

Most important piece of advice I can give you before you purchase a TC is to confirm it will work with your lenses.

I have a Canon 1.4 TC Mk. II (Mk. III is now their current version), and its ser manual specifically lists the Canon lenses it will work with - these are all "L" series glass (pro-level/expensive) but not all their L-series lenses work with it so having L-series glass is not a guarantee.

In Canon's case the manuals (that I have at least) with their lenses will either indicate:

- the lens cannot be used with the tele-extender (listed as a note below the specifications table towards the end of the manual); or,
- if it can be used with the tele-extender, there is a separate section in the manual specific to tele-extenders.

Hope this helps

[OldBoy]

Originally Posted by kiffy

i love the idea of screwing on a simple lens that will double my lenses power, the one i was looking at was one that ive seen go second hand on ebay but have found new for £101, its the kenko teleplus mc-7 which i found here - http://www.microglobe.co.uk/catalog/...-for-canon-eos

my only lens at the moment that are under F4 are my tamron 90mm and the canon 50mm that i have coming in the enxt day or two. my two telephoto lens are both over F4, so maybe its not worth me spending another hundred quid right now

Yes, this Kenko will work with your camera. Not worth using with 50mm but would be OK with the Tamron 90mm macro. I use Nikon's 1.4 and 2x converters with my Nikon 105mm F2.8 VR macro, but be aware that it can hunt if you lose the focus. I've use both to photograph Dragonflies in the air.

[amk1977]

Originally Posted by OldBoy

Yes, this Kenko will work with your camera. Not worth using with 50mm but would be OK with the Tamron 90mm macro. I use Nikon's 1.4 and 2x converters with my Nikon 105mm F2.8 VR macro, but be aware that it can hunt if you lose the focus. I've use both to photograph Dragonflies in the air.

Personally, I wouldn't bother with a TC for the SP90. In my experience the Tamron SP90 is a real hunter and the auto focus can just go wandering off on its own, relatively willy-nilly. Stick a TC lens on the back of it to diminish the light even futher and you might as well just leave the lense cap on lol.

That and the fact that the AF on the SP90 is painfully slow, especially compared to the Nikkor105mm f/2.8. Now that is a beast of a lens, one which I covert from my dad's kit bag, along with his 70-200mm VR lol.

My advice would be to use the SP90 for macro work and posed portraits. If you want more magnification for macro work, get the Kenko extension tubes at around £135. You lose autofocus with them but still keep the metering information. Macro work is best performed in MF anyway.

[Matthew Forrest]

I just recently bought a kenko 2x mc7 teleconverter it wasn't expensive,sometimes autofocus works and sometimes it doesn't,works fine on manual focus,I use it on a canon 400d I don't know if its a compatibility issue or not,but yeah its handy to have in the bag!

[OldBoy]

Very seldom use manual focus on macro shots or a tripod either. Mostly handheld and using auto-focus.

[amk1977]

Originally Posted by OldBoy

Very seldom use manual focus on macro shots or a tripod either. Mostly handheld and using auto-focus.

LOL with the Nikkor 105mm VR, I'm not surprised. Try it with the SP90 and see if you don't march back indoors and get the tripod out!