Lens extenders

[Colin O'Regan]

I'd like some opinions on lens extenders please. Is one range better than the other? i.e. 1.6 or 2.0. It would seem to me that an automatic choice would be the x2.0 but that doesn't seem to be the case. What am I missing?

Colin

[Shutterman]

Colin,

When you say extenders, do you mean teleconverters??

[Geoff F]

As you mention 1.6 and 2.0, Colin, I assume we are talking about lens converters (magnifiers) as opposed to extension tubes (no glass) which are used mainly for macro work.

The simple answer is what you will be missing, possibly, is quality; particularly with the x2 converter.

But in reality, the situation is a lot more complex and everything depends on the lens in question. All converters degrade your image to some extent, simply because you are adding extra glass. However, with a top grade lens you will probably find little loss of quality with a 1.4x converter and may well find a x2 is still acceptable in good light.

The other possible problem is loss of autofocus, particularly with the x2 converters, but all of this is variable depending on the camera and lens.

So if you can give some more details about your equipment and the make of converter which you are considering somebody will be able to give specific advice.

[Shutterman]

Geoff,

Aren't the 2x converters larger too? That has to be taken into consideration if you're mobile too, but i'm not sure if there that much bigger to be an issue.

[kevinbythebeach]

You also need to have an idea what lens you want to use one on...certain converters are not
compatable with certain lenses ,,atleast in the canon line up...

[Colin Southern]

Canon have 1.4x and 2.0x teleconverters. The first will cost you 1 stop, the 2nd 2 stops.

With any teleconverter there is - in theory - a loss of image quality, but in practice there's a lot more to it. Image quality using a 1.4x converter is just fine and with a 2.0x converter it's fine too, but sharpening is far more critical. A 70-200/2.8L with 2.0x teleconverter - stopped down 2 stops has the same IQ as a 100-400/4.5-5.6L (or thereabouts).

The big thing to watch is that the normal lens max aperture plus the F-stop loss from the teleconverter down't take you belot F5.6 for entry level / prosumer class cameras (or F8 for 1D series camera) (Canon) or you lose AF.

We had a thread on this a while back in which I gave an example.

Hope this helps!

[Colin O'Regan]

Of course I meant teleconverters, my apologies.
I was pondering "why" and paying no attention to what I was typing.
Surely that explains the mysterious 1.6x teleconverter right?

Thanks for the input. I need to find the "subject search" button.
Thanks for the link Colin S.

Colin