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View Full Version : Are Kenko tubes wort it?



zacker
08-02-2006, 07:52 AM
Thinking of getting a set, are they worth it and also, do they mess up Aperture and AF any?
Thanks!

Orgnoi1
08-02-2006, 08:02 AM
They are definately worth it... even in using a dedicated macro lens I still use a 12mm Kenko tube... Trish uses Kenko tubes religiously on all her macro shots as she doesnt have a macro lens.

convergent
08-02-2006, 09:30 AM
To answer his aperture question, I believe since there are no elements (its just a hollow tube) then there is very little effect on aperture... however you probably have a little light fall off, right?

Orgnoi1
08-02-2006, 09:53 AM
Opps sorry about that... no there is no glass so you dont affect aperatures at all... and actually light loss is minimal... the only thing you have to be careful of is if you stack tubes you run the risk of losing AF... which really isnt needed anyways since most of the time you should be shooting Macro in manual focus...

zacker
08-02-2006, 10:05 AM
now what exactly do they do? just allow you to focus closer? or do they actually extend the reach of the macro lens? I mean, if I want to get really close to something, can i do that at a farther distance than i can now with my 100MM macro?

Orgnoi1
08-02-2006, 10:12 AM
They allow you to get closer but also by allowing for a longer focal plane they enhance the ratio of the lens... so by using the 100/2.8 Macro lens at 1:1 you may get close to 2:1 ratio out of it...

convergent
08-02-2006, 10:13 AM
Longer focal lengths let you get "farther" from the subject and achieve the same magnification. Extension tubes have no glass in them and their only purpose is to move the lens farther away from the sensor/film. By doing this, it allows you to get closer to the subject, and thus get a bigger magnification factor.

zacker
08-02-2006, 10:16 AM
so i cant get any more reach then? Ok.. got it.. its going to just let me focus closer to the subject. Hmmmm.

convergent
08-02-2006, 11:01 AM
Yep, closer focus equals greater magnification.

zacker
08-02-2006, 01:56 PM
cool... thats what I thought it ment.
Thanks Mike!