Taping contacts

[Black5]

I'm sure I have seen that by taping some contacts on a Canon lens you can 'fool' it into autofocusing when using a convertor.

Is this right?
It's a mate who wants to use a x1.4 with his 100-400mm 'L' on a 1D mkII - if this matters?

[beano500]

This is crying out for something to be said about .... well you know



But before it descends....



*bump*


...and I am curious to know how taping up contacts would help? Are you meaning that it doesn't try and autofocus and you go into full maual overide? Why would you need to tape up contacts, rather than switch the camera to manual focus?

"Intrigued" of Intriguesville

[joust]

From a random BBS said:

What is the tape trick? I know that it entails taping over some contacts, but which ones, and is there any risk to the camera/lens? With the converter in hand: looking at the end of the converter that attaches to the lens rotate it so the contacts are at the top the leftmost 3 contacts are the ones to tape over for reference, the rightmost 3 contacts are on a raised area What you end up with is that the converter basically becomes invisible to the camera. The camera still receives most info from the lens and therefore the EXIF will have the focal length of the lens alone (without the extender's multiplication factor). It also means that the camera will not realize that the stuff hanging off the front is worse than the f/5.6 cutoff point for autofocus. But, unless you are shooting in very good light at high contrast subjects, you will usually get a lot of seeking and frequently it simply will not focus. But it does work! As far as damage to the camera/lens/converter - no chance that I know of unless perhaps there are some nasty chemicals in the tape you use to cover the contacts.

But, some people have said

A random person on a BBS said:

The tape trick generally isn't worth bothering with in my opinion, as like Jim said, it will seek/hunt A LOT and even when it does auto focus it will be slow as dirt. To give you an example of slow...and this should really put this in perspective: The Canon 1dMkII Autofocuses with anything to f/8 or less. With my 400mm f/5.6L and a 1.4x TC giving me 560mm@f/8, the MkII autofocuses without taping..it was so incredibly sluggish and slow that I never bothered with trying to autofocus with that combination again, because it was a waste of time and an exercise in frustration. The MkII is the fastest focusing camera in Canons lineup...given that...you can imagine why I recommend against even bothering with trying to tape pins to fool a 10D into autofocusing at f/8 or what not. Secondly, I wouldn't even use a TC with the 100-400 which has sharpness problems to begin with. Adding a teleconverter to it just wouldn't produce very many quality images in my opinion. I'm generally dissatisfied with images from my 70-200 f/2.8L USM (which is the sharpest zoom lens in Canons lineup) when I add a teleconverter.

>> Edited by joust on Friday 2nd December 10:25

[Black5]

Ta, that's what I was after.

[monkeyhanger]

1 series bodies will autofocus to f8 with a convertor fitted.

By my dodgy maths, with a 1.4x fitted the 100-400L will work fine on a 1DMk2 or 1DsMk2

The 100-400 needs decent light at the best of times though..

Tell him to put the tape away.

>> Edited by monkeyhanger on Friday 2nd December 19:25