R100 + Sigms 17-70mm f 2.8 - 4 DC.

[Chako]

I went back for more critter shots, but this time, decided to try out the newish (for me) Sigma 17-70mm lens that came with the Canon Elan 7NE. I did notice a few times when the lens would not autofocus when demanded, mostly when the lens was towards the 70mm side of things. I always got the lens to work after a little zooming out and in. I wonder if the Sigma isn't 100% compatible with the camera and or the RF  to EF lens adaptor. I will soon use the lens on one of my other Canon EF bodies to see if I can replicate the error.

IMG_0502A by Chako, on Flickr

70 mm x 1.6 crop factor = 112 mm max. A far cry from the Bigma's 500 mm x 1.6 crop factor = 800 mm. For critter shots, 70 mm is on the short side.
IMG_0508A by Chako, on Flickr

Some will come right close provided the right incentives.
IMG_0515A by Chako, on Flickr

This guy decided to run just as I was taking the photograph.
IMG_0521A by Chako, on Flickr

IMG_0529A by Chako, on Flickr

IMG_0536A by Chako, on Flickr

IMG_0538A by Chako, on Flickr

IMG_0543A by Chako, on Flickr

[Farmer X]

The shot of the mallard is fantastic!

[Barry Rowland]

  and the green plants really stand out.  Well done Chako!  I'm enjoying your photography posts a lot!

[Chako]

Thanks. The lens works fine on my Canon 50D, so that means an issue with the R100 with Canon RF to EF lens adaptor.

[Vidar]

I assume Canon lenses work with the adapter? Sigma might have had to reverse engineer the command and communication protocols, and some miniscule thing went amiss somewhere. (Maybe something not even in use at the time the lens was made as EF lenses came before the RF standard?) Crazy guessing here I have a few Sigma lenses that work perfectly with EF cameras - even third party EF cameras.

The mallard popped well

[Chako]

Absolutely correct. That lens works on all of my DSLRs. It kind of works most of the time on the R100. I just won't use it on the R100. All my Canon lenses (those that I have trird) work on the R100. Thankfully my Sigma 50-500 mm lens works.