10D, 100-400L, 1.4X?

[Roy NN7DX]

Does your 10D autofocus using the 100-400L/IS when you add a 1.4X teleconverter? In "normal" light? If it works, what TC are you using?

I asked this elsewhere and got information on the300D, D60 and 1D2 when used with a wide assortment of lenses. Others gave me information about how it would never work, an f8 combo on a "f5.6 body"... Only a few answered the question that I asked...

This combo seems to work for many, if I’m reading their postings right… I’d just like to get some idea about % of success/fail and an insight about which TC is used by those who have it working.

[Scottes]

The combo in question has never worked for me, using Canon 1.4TC.

I've heard of people "taping the contacts" and getting this to work. I've also heard of some of those folks getting the lens fixed due to burned out focusing motors.

[ssim]

I've heard that other manufacturers TC's will give you AF with the 100-400 but I've never witnessed it personally.

I find it odd that Canon would do this with one of their lenses and their teleconverter.

I do get AF with the 1.4 on my MKII but not with the 2.0. The 2.0 gives me AF on my 400 DO IS.

Some things are just plain weird.

[Scottes]

Some things are just plain weird.

Not really.

A 10D requires f/5.6 or larger to autofocus. A MkII requires f/8 or larger.

Your 100-400 is f/5.6 at 400mm, and with the 1.4x TC this becomes f/8. The MkII will AF but not the 10D.

Your 400 DO is f/4, but with a 2x TC becomes f/8 - which means that it will AF with the MkII but not the 10D.

The 400 DO with the 1.4 should AF on both bodies.

Taping the contacts stops the TC from informing the camera that it exists, so a 10D will try to AF the 100-400 w/1.4. Since the real aperture is now smaller than f/5.6 the 10D's sensors have a tougher time and resorts to more hunting - especially in low-light - which may be the cause of burned-out focusing motors.

[Roy NN7DX]

"Does your 10D autofocus using the 100-400L/IS when you add a 1.4X teleconverter?" My question above skips a key point, the 3 taped contacts or a TC that does not report to the lens (which is what reports the f setting to the camera)... I'll tape the contacts...

Thanks Scottes... I'm not worried about burn out as I'd never let the lens cycle without a focus lock...

[xuxu1]

"Does your 10D autofocus using the 100-400L/IS when you add a 1.4X teleconverter?" My question above skips a key point, the 3 taped contacts or a TC that does not report to the lens (which is what reports the f setting to the camera)... I'll tape the contacts...

Thanks Scottes... I'm not worried about burn out as I'd never let the lens cycle without a focus lock...

Roy, let me know what your experiences are! Maybe i´ll put a 1.4 TC on my shopping list too.

VY73 es 55
de ED
... _._

[JoeTampa]

Speaking of which, does anyone know what the min focus apeture is for the 20D? Might be another on the list of reasons to upgrade if my 100-400 becomes AF again with the 1.4... :)