speed after extenders...

Say I add a 1.4 or 2.0 extender onto the 85 1.8 or 100 2.0.....what would the max F Stop be?
Also, is it possible to add extenders to these lenses????

Thanks in advance

WildWolf,
Look around the info is right in front of you
-=FAQ=- Teleconverter/T-Con FAQ

I know John BUT that says u can't use a tc with the 85 OR the 100 is this true????

WildWolf wrote in post #2103471
I know John BUT that says u can't use a tc with the 85 OR the 100 is this true????

That page doesn't lie about that.

From Canon USA...
http://www.usa.canon.c​om …tegoryid=154&mo​delid=7462

why can't u use with the 85 1.8 or 100 2.0? what is the rational? Thanks

From the FAQ Linked above;


It is important to understand that the use of a teleconverter is subject to a number of conditions, including the following.

1: T-cons can not be used with all lenses. Only the lenses listed in the charts will physically "fit" the T-cons. If it's not listed. It won't "FIT". The reason they will not "fit" is because the front element of the Canon T-cons protrude forward into a recess found only on specific telelphoto lenses, for a true matched optic that works only with these telephoto lenses. Other lenses do nat have the space behind there rear elements to allow this protrusion to fit into.

2: T-cons will decrease the effective aperture of any lens to which it is attached.

3: In many cases, the increased f/stop will result in a loss of Autofocus.
In some cases, the use of a T-con will result in use of only the center AF point for autofocus.

4. Additionally, EF Extenders reduce lens drive speed. The EF 1.4x or 1.4x II reduces lens drive speed by approximately 50~67% depending on the lens in use.
The EF 2x or 2x II reduces lens drive speed by up to approximately 75%.
This speed reduction gives the AF system more time to detect focus. This can be helpful since the depth of focus is reduced with the longer effective focal length and the chance of defocus increases. However, the reduced tracking speed and smaller maximum apertures caused by the use of Extenders can be a disadvantage with fast moving subjects, particularly in low light.

5. T-cons WILL degrade the final image quality f the lens in use.
(the degree to which this is perceptible varies depnding on the lens with which it is used)

thank you!!!!!!!!

Anyone know if the Canon 1.4x works on the Tamron 200-500? This review sort of confused me.

http://photo.net/equip​ment/tamron/200_500_Di​/

Sounds like from this review the 1.4x works, but the Tamron 1.4x worked better? If this is the case, how well does the 1.4x Tamron current model work? What about the Tamron 2x? The Tamron teleconverters are very cheap so I figured it doesn't hurt to ask. Does the Tamron teleconverter work on any EF lenses?

Interesting results, buit not too surprising really.
The Canon 1.4x and 2x as mentioned have a prtruing front elelment, and are designed to work with specific lenses that can accept this protrusion.

That the Tamron will let the 1.4x fit is the surpirse (even if it won;t fit unless the lens is zoomed out) but the fact that the Tamron is NOT designed to make the best of the Canon's optical design is no surprise.

It's best to think of T-cons as "the best match" not as "who's is better"
Anywya, Tamron 200-500mm owners can be happy that a 1.4x will cost them about $75.00 as opposed to $270.00 !!!!

CyberDyneSystems wrote in post #2104513
Interesting results, buit not too surprising really.
The Canon 1.4x and 2x as mentioned have a prtruing front elelment, and are designed to work with specific lenses that can accept this protrusion.

That the Tamron will let the 1.4x fit is the surpirse (even if it won;t fit unless the lens is zoomed out) but the fact that the Tamron is NOT designed to make the best of the Canon's optical design is no surprise.

It's best to think of T-cons as "the best match" not as "who's is better"
Anywya, Tamron 200-500mm owners can be happy that a 1.4x will cost them about $75.00 as opposed to $270.00 !!!!

So I'm wondering. If I pick that lens up, I supose picking up a Tamron 1.4x converter (I would think 2x would be overkill on a lens with such a focal length and not the widest aperture), would be a good idea. I am going to get a 70-200 F4 and probably a Canon 1.4x for that, but if the Tamron is so cheap I don't see much of a harm in picking one up.

BTW Cyberdyne, I supose the cheap converter makes up for the fact your going to spend the $ on those huge 86mm expensive filters.