Kenko Teleplus 1.5X TC + 70-300 = Good, Bad or Ugly?

[Lightstream]

I made the mistake of going down to my camera dealer and shooting the Bigma the other day and now I have a BAD case of lust for more reach! Of course I am aware the Bigma + 20D is around 5.5 pounds and I greatly suspect that I will not be as fond of the lens once I have walked a couple of miles on foot with it.

So I was thinking of adding a 1.5X Kenko TC to my faithful 70-300 IS USM zoom. The lens + TC combo would then clock in at 750gm, which is substantially lighter than the Bigma's 1880gm. I lose one stop (actually just 2/3rd of a stop compared to the Bigma) making it a 450mm f/8 lens, but I have IS to help combat handshake. No, this combo will not be used much for stopping action because I sacrifice too much in the way of AF performance and light using the TC, but I figured it would be nice to have for all those days where I need more reach, and there are quite a few of those days too.

I've read Bob Atkins' comments (http://www.bobatkins.com/photography/tutorials/tc3.html) on TCs, but I suspect he made a typo error - throughout the article, he refers to the 75-300, but the section where he tests it is entitled the 70-300. There is a whole world of difference between the two (I've shot both).

Someone also did testing with a 5D, 70-300 and 1.4X TC, and the results came out superb. It's supposed to be here: http://www.pbase.com/vciinc/tests but the images seem to have changed since I last visited.

Anyway.. any comments on my idea before I get tempted to run down tomorrow and buy the 1.5X Kenko? :)

[Jack W.]

I bought the Tamron 1.4 for my wife to use on her 100-400L.
Tried it on the 70-300IS (the new, non-DO one). Made the lens hunt like crazy and sound like a machine gun. Others have reported the same.

Jack

[Lightstream]

Thanks, perhaps micro-USM doesn't interoperate so well with teleconverters, perhaps because they can't slow down the focus drive enough (TCons usually do), which may cause the stop-start effect you've mentioned.

I'll wander on down to my reseller today and try it first before I buy it. Will report back on my findings.

[Nice Glass]

I'm always curious when people complain about slow focusing when using teleconverters. Do people really dislike manual focusing that much?

[RichardtheSane]

I'm always curious when people complain about slow focusing when using teleconverters. Do people really dislike manual focusing that much?
Basically, yes.
Manual focus is a damn sight less enjoyable than it used to me.
Small viewfinders. Poor MF rings. The low end lenses are terrible for manual focussing and by the time you move to qulity glass you are much less likely to even tryit let alone enjoy it.

[Lightstream]

OK... just got back from the dealer. He actually tried to talk me into trying a 2X TC and I did so just to humor him. He mentioned it could AF.... man I should have wagered some $$ with him that it would not ;)

I ended up trying a Kenko Teleplus 300 converter, not the 1.5X Teleplus SHQ I planned. The Teleplus 300 is supposed to be better quality. Not tremendously impressed with it apart from how shiny the mount ring is, IMHO. More costly, too. The Teleplus 300 also does lie about the maximum aperture, so the camera did attempt to AF on the 1.4X one.

With the 1.4X, AF works only at the short end. At the long end the 'machine gun' stop-start stutter is very noticeable and quite unnerving. I've heard of lenses suffering damage from being used in this way on a long term basis, and while I have no 100% conclusive proof, I DO have a marked reluctance to actually become the proof myself by trying it. So that means I go back to MF.

MF is not too bad, the 20D viewfinder really helps a lot. The "AF Confirmation" squares (I call them dots - still used to my 350D) do not light consistently with the TC, however. AF only works in the brightest of light. It would have been really nice to get consistent AF but I think it is not going to happen.