Teleconverters, the good, and the bad.

[Mark1616]

You are not going to get great results as you will lose AF on everything apart from 70mm when you have f4 and also the Sigma TC's will not work with that lens due to their construction which has a lip stopping it fit to a lot of lenses. If you go to the Sigma site there is a list of lenses you can use them with.

I would not suggest using a TC with anything apart froma lens that is constant f4 or brighter.

[Cyberf828]

I like mine so far, I am a beginner so I don't see the difference I posted a pic in the Sony thread with my H5 and tele. I was taking pics in low light almost dusk and was told I need to have very good light for it to work if anybody is interested look here below. Like I said I am not very good.

http://forums.steves-digicams.com/fo...mp;forum_id=28

[TCav]

Anytime you add optical elements to a lens, you decrease the sharpness and increase the distortion. Sometimes by miniscule amounts, and sometimes by not so miniscule amounts.

(This is true of filters and close-up lenses as well as teleconverters, btw.)

If you can tolerate the decrease in optical performance in order to get the increased focal length, have fun.

[amazingthailand]

If you are talking about a picture taken with your H5 and a teleconverter, then you are not talking about the same item as we are.

The TC originally refered to is for an SLR camera and goes BETWEEN the camera body and the lens, it is not an addon to the front of the lens, as in your H5.

See here: http://en.wikipedia.org/wiki/Teleconverter

[Hayward]

My GENERALIZATION would be don't go over 1.4/5x (also 1 stop loss) TC's.....

If you do expect to pay a lot for something decent (maybe as much as the low cost zoom it only equals) and again 2x even the best will be a 2 stop loss of exposure.

PERSONALLY experience the Tamron 1.4x is a relatoive bargain good optic and only minimal 1 stop exposure loss.

Other thing would be 2x might be OK on a normal range (35-135mm) lens.... bt don't expect most inexpensive 2x TC's to do well on aq LONG lens, except maybe in very bright day light where both shutter and F/stop can be pretty high..


And not even sure I would EVER consider a 3x TC.... even the one that make really good expensive 2x's don't make 3x's (which are also 3 stop light loss)

[Cyberf828]

amazingthailand wrote:

If you are talking about a picture taken with your H5 and a teleconverter, then you are not talking about the same item as we are.

The TC originally refered to is for an SLR camera and goes BETWEEN the camera body and the lens, it is not an addon to the front of the lens, as in your H5.

See here: http://en.wikipedia.org/wiki/Teleconverter

Sorry thats what I get for being a beginner my apologies to all. I will learn about this stuff one of these days.

[eric s]

I just thought of something else.
The Canon TC's have a protruding front element that can physically *hit* the rear lens element in the lens. In some lenses, the last element is recessed, so the TC won't hit it. On other lenses (like the Canon 28-135) a Canon TC won't fit because the TC's front element will hit the lens' rear element.

I don't believe the Tamron TCs have this problem, but you should check before buying!

I don't know if the 70-300 can take a Canon TC or not. This is the compatability list I just got of www.canoneos.com:
EF 70-200 f/2.8L, 70-200 f/2.8L IS, 70-200 f/4.0L, and 100-400 f/4.5-5.6L IS

which *does not* include that lens. But maybe their web site it out-of-date.

Eric

[amazingthailand]

for Cyberf828: Your H5 comment gave you away. But no problem, we all come here to learn. So just keep on learning.

Cheers.

[PeterP]

Oups, really late to this thread.

The Sigma TC's are basically clones of the Canon TC's, they will both fit the same set of lenses they are matchedto.

And because of their designwill not fit the other lenses notintended to take a matched TC.