teleconverter lens compatibility

[daniwoodman1]

I have a T2i with EF-S 55mm-250mm lens f/4.0-5.6 IS STM-EF-S and I am considering purchasing a Sigma 2X teleconverter with Canon mount to increase my telephoto. Will this Sigma converter work with my lens? Thanks for your valuable input.

 

[kanewolf]

It should. Your largest F-stop will be reduced (1 or 2, it has been a long time since I used a teleconverter). The quality of your images will also be impacted. They will usually have less sharpness than the lens only. Your camera body may focus slowly.
Teleconverters are a cheap way to get longer lenses but they do have down sides.

 

[bjornl]

A 2x teleconvertor will work badly if it works at all. A 2x TC cuts your light by a lot. Your t2i does not AF well above f/5.6. A 2x TC will drop you to F/11.
So you will be looking at dim images plus you are putting more pixels in the center portion of a low-end lens. You will have very low contrast. Your appearant resolution will be very low.

Bottom line, you will have very poor quality images and have to manually focus to get them.