Sigma 24-70mm EX lens on EOS R6 Mark II: Bad AF for video

[prigekhas]

so I have an R6 mkii and I bought a sigma ex 24-70mm 2.8 macro wanting to use it for video/photography. photos, everything seems to work fine, but on video, the autofocus just craps the bed

ive read there can be issues on the older lenses with the newer AF tech and software. Is that what’s happening? or is it possibly a lens issue?

[shadowsports]

Greetings,

in this case, I'm quite sure It's the age of the lens.  The ex version of this lens was released in 2004 (22yrs old). The motor technology and communication standards in older lenses are not capable of keeping up with the communication standards and speeds of mirrorless body's.  It's important to use a Canon brand adapter, but that won't matter if you're using a 20 plus year old lens.  I used a Sigma EF 24-70 f2.8 Art successfully adapted to my R5 C.  If you can't afford the RF version new, shop used or refurbished.  I don't recommend the Canon EF 24-70 since one, it doesn't have IS and two, it's prone to ribbon cable failure.  Only the Mark II is still under support.  Since your body has IBIS you will get some IS but if the ribbon cable goes it's going to be expensive.  Hopefully you can return the EX lens and purchase something newer.  

[ebiggs1]

"... I have an R6 mkii and I bought a sigma ex 24-70mm 2.8 macro ..."

I have never understood the logic of buying a top drawer camera then putting poor lenses on it. The lens is more important than the camera, always. I realize we all want to save money as most of us don't have a barrel full. However, it can be quite expensive to make a poor lens work and/or adapt to a new R series camera. And when you are done making it work, it still won't support all the features of the R6 Mk II.

If money is tight haunt the used market(s) and the refurb store. "I don't recommend the Canon EF 24-70 since one, it doesn't have IS and two, it's prone to ribbon cable failure." Yes it is something to know but far more ef 24-70mm f2.8L never see the flex cable issue then do. Mine never has and it is and has been used heavily ever since I bought it.

Bassically the Canon EF to RF adapter was made for folks that already own an inventory of EF lenses and now have purchased a new R series camera. It was not intended for folks to go out and buy EF lenses to use on their new R series.  Yes, I know people do it and that's OK but not the intention.

[SignifDigits]

An relatively inexpensive option that will work great for you is the Canon RF 24-105mm f/4 L IS USM.  That lens is very reasonable used and in very good condition.  Cheaper and lighter (less than half the weight and cost) would be the Canon RF 24-105 f/4-7.1 IS STM.   If you absolutely have to have f/2.8, then double your cash outlay and go for it on the 24-70, or learn to adapt to using a prime lens.

If your time has value to you at all I'd toss in the towel on the Sigma, but I hope you can prove me wrong and wish you all the best!