Africa Wild

Wed Sep 28, 2011

I have a 550D with a 70 - 300 lense. Is it worthwhile getting a 2x extender (converter)?

two disadvantages of using a converter are

you lose light and your autofocus does not work....

WTS...wat the smurf, :D does a converter do??

a converter is fitted between the lens and the body

and it increases the zoom capacity of the lens by 1.6x or 2x

depending on which converter you have.......

wow ok cool thanks.

does it cause pixelation or have clarity issues?

You do have light loss to the same factor as the converter.

A 1.5 converter will result in a 1.5 stop loss of light.

If you use a 2x converter you lose two stops. If your correct exposure would have been f11 without the concerter it will now be f5.6 with the converter.

1 stop of light is 1/2 as much light if less or twice as much light if more. To understand that in simple terms if all other settings are the same the camera will take twice as long to take a picture with 1 stop less light and 1/2 the time to take the picture with 1 stop more light assuming equal exposure. Not sure about a 1.5x convertor but Canon's 1.4x reduces light to the camera by 1 stop and their 2x convertor by 2 stops.

Tele-convertors are not a good idea with entry level zoom lenses (Canon's are normally not even compatible) due to the loss of auto focus ability and reduction in image quality.

Try this one http://www.dryreading.com/camera/

Here you can change settings and see what the result will be. Give it a bash, it helps!

Hi Guys something else I see that was not mentioned or I missed is that a 1.4 or 2x converter only works with a f stop of 4.5 or lower. If it's higher than 4.5 the auto focus wont work and you will have to manual focus. Just be aware of this and check.

Reading through the photographic section of another forum last night a forumite asked how a teleconvertor would affect the image quality of his lens ..a Nikkor 70-300 f4.5 - 5.6 zoom. The Nikon 'expert' then gave a whole lot of advice no doubt well meaning but what the advice he should have given is that a none of the 3 Nikon convertors even fits this lens and cant as a result even be used..Poor Vinkie you should ask for decent advice on this site first..hope your trip to Kruger wasnt spoiled and you didnt waste your money