help me convince myself i need this TC

If you want it just go buy it.

.. well ... i'd say yes,. but that lens is pretty new and I have no first hand info..

that said,. the two sets of TCs have so far proven to be 100% interchangeable from a physical stand point.

which two sets CDS?

.. the Sigma and the Canon's.. isn't that what we were discussing?

yes ur right. i umm was in an altered state of mind.

Hehe,

Ill probably pass anyway. I was thinking about it long and hard, and i probably dont need the extra length. Theres other things i can buy that i will use more probably. Im not up for spending nearly 300 dollars for the extra length. Ill probably buy a third party one in a few weeks.

Well, i just went ahead and bought it along with a nicer monopod with nice head that was recomended in this thread.

Also a nifty 50.. Cant wait, hope its here in time for my next football game.

You don't need an excuse to buy toys, you only need to justify tools.

I conducted tests of the 1.4x-II with the Canon 70-200 f/4, and I could see NO difference in photos with vs. without the TC at the same equivalent focal length (200mm in both cases) with the lens wide open. I published my finding to a group of photo friends who I have known a long time, and a number of them confirmed my findings. Other photographers sing praises for this pairing, too, on other forums!

This it´s an example of the 70-200 f/4 L + Kenko x1.4 TC Pro 300 DG taken four hours ago:

Byte size: ZERO | Content warning: NOT AN IMAGE

In my testing, I made a test target using different symbols and letters at increasing text sizes using Microsoft Word. Then I photographed with TC and without, and pixel peeped with Photoshop to see the smallest text and symbols which could be read in each image. I could see no difference in that test, somewhat analogous to optical test patterns which can be found. It would be interesting for you to perform similar measurements on test patterns and text, rather than real world images, as there is not a basis of truly comparing. The photo does look great, but we can't tell how much better or worse the TC affects the prime lens.

For what it's worth, I bought a Tamron 1.4X SP TC over the similar Nikon product for use with my D70s and 85/1.4 AF lens. Why? Because the Nikon TC does not allow AF and metering with the 85/1.4 AF lens I intended to use it with, though in fairness it will allow AF and metering for lenses it's designed for, including the 300/2.8 and other such lenses.

The Tamron has proven super sharp and ultra reliable.

My word of advice: make sure that the TC you intend to buy allows for AF and metering.

If you search the forums, you'll see that everyone agrees. You get out what you put in, meaning, if you attach a TC to a quality optics you should end up with good results. If you attach a TC to a crap piece of glass, don't expect miracles.

I currently own a modern Nikon digital system and there are hoards of loyal Nikon enthusiasts out there who will who mock anyone who so much as thinks about buying non-Nikon. Well, I needed a TC for greater reach and was about ready to buy the Nikon 1.4X TC when I learned that it would not allow for AF and TTL metering. That is when I looked into the Tamron SP 1.4X TC (discussed on many forums as one of the shrpest TCs available, regardless of brand). I've owned mine now for only a year, but so far I have not stopped being super impressed by its performance. Similarly, if you are considering the Canon product, you may want to check that it allows for AF and TTL exposure metering. If not, you won't be disappointed with the Tamron SP. (Tamron also makes a non-SP model which is significantly cheaper. But I didn't want to take a risk with sub-par product on my beloved Nikon optics such as the 85/1.4.)

Last, before you buy, do a little more research on the forums where they include reviews of actual owners. This was more useful to me than looking at the advertisements in the magazines and the net.

If you buy something other than the Canon TC, the paint color won't match the lens. That could cause all sorts of grief for you

I splurged for the Canon 1.4, and don't regret it.....

Quality: I have the Canon 1.4X-II and the Canon 70-200 f/4L. Absolutely no degradation shooting resolution test targets with the lens wide open!

Speed: Focus is just a tad slower than a bare lens, because Canon wants the focus to slow down a bit for improved accuracy, and the TC communicates the 1EV decrease in effective lens speed for the same reason. Some 3rd party TC communicate neither. Good, bad...for you to decide. In practice I don't really notice speed of focus slowdown much (I do notice my non-Canon lens focus being slower more than I really notice Canon lens + TC slowdown!)

Compatibilty: The Canon TC has elements which protrude FORWARD, so the mated lens has to have some relief at the rear for the elements to slide into and the lenses can mate. No relief in the lens, potential crash of lens to converter glass elements! Also, the Canon TC has an EF mount, so it cannot be used with EF-S mount lenses.