Exactly which Kenko 1.4X or 1.5X TC doesn't prevent autofocus with XXD bodies?

I am confused about the characteristics of the various Kenko 1.4X teleconvertors, of which I believe there are at least three ....

I already have a Kenko 1.4X Teleplus Pro 300 DG (model name taken from the box) which works very well with my Canon 70-200mm f/4. Autofocus is retained and IQ is quite good.

I just acquired a Canon 100-400mm f/4.5-5.6. The Kenko gives adequate (for my purposes) IQ with this lens also, but kills autofocus on both my 40D and 50D. I understand this occurs because the Kenko communicates to the camera that the effective aperture of the lens has dropped below f/5.6.

My understanding is that Kenko markets (or used to market) a different model teleconvertor of approximately 1.4X or 1.5X magnification and does not stop the cameras from autofocusing with lens of aperture less than f/5.6.

I know about the taping trick I could use with my current teleconvertor, but, to be honest, I would rather buy another teleconvertor that did not require taping especially for the 100-400mm, if autofocus could be retained and the level of IQ did not appreciately suffer as compared to my existing Kenko model.

Would an owner (or someone in the know) let me know which exact model Kenko teleconvertor I should get for my 100-400mm (and where to get it, if possible).

Thanks!!

Maxdave

I'm afraid I don't understand why you want to spend money on another (inferior) teleconverter rather than just using a bit of tape? It's not that the camera is supposed to AF with the cheap teleconverter, just that it doesn't know not to (the same as when using tape on the Pro version).

If you want a good TC (like your Kenko Pro), then you will have to tape the three pins. Just go ahead and do it.

I use a Tamron 1.4X C-AF1 MC4 which doesn't report and gives great results Only has 8 pins.
BH price $129

I had a Kenko 1.5x teleplus SHQ which didn't report. It was pretty crap compared to the new ones though.

The cheap teleconvertors generally do NOT report their presence, but the optics are inferior!

The good teleconvertors DO report their presence, but the optics are superior! The 'solution' is simply to tape the pins so their presence is not reported to the body; that will allow the body to TRY to focus even with f/8 lens, but that does NOT mean that the lens will SUCCEED in achieving focus...and you could burn out an AF motor from it trying and trying and trying!!!

1.5x convertors are all 'the cheap ones'. Some 1.4x convertors are cheap, some are good quality.

https://photography-on-the.net ….php?p=287408&p​ostcount=4

Thank you all for your information and opinions.

Maxdave

You don't tape all the pins.

If you're looking at it facing your on the body, it'll be the first three pins on the left.

Theres absolutely no downside to taping the pins. It's extremely quick and easy to do and if for any reason it ever needs to be removed, then that equally is a simple 30 second job.

I suppose Canon had to create the artificial AF/no AF point somewhere, otherwise AF motors could in theory be overworked, but I've not noticed my 100-400 working particularly hard or long to achieve focus since taping the pins but before I taped them it just point blank refused to play ball.

My experience is completely different. Neither my "white" Tamron, nor my Kenco are reliable, nor fast, on my 100-400L on any body I own. They both hunt unpredictably for focus

I've made plastic washers, one of which isolates the converter from the camera, one of which isolates the "magic pins" and I often completely disconnect the converter for use with a couple of old manual lenses I have.

I actually don't know why I don't just sell 'em.