I had a couple of questions about the full time DMF on the Sony 300mm 2.8. I’ve had this lens for a number of months now and it’s fantastic, but I have ran into some issues that the full time DMF helps with and also potentially causes. Sometimes if I’m trying to photograph a bird or other animal that’s obscured by grass or vegetation it will focus on the vegetation and have no idea that an animal is buried in there. Since the image is so zoomed in at 300 (or 420 with a 1.4 TC) and the plane of focus so narrow the animal will relegated to bokeh heaven and the autofocus system can’t even begin to know an animal is even there. Full time DMF is great for this as you can manually adjust focus closer to the animal and then let the autofocus do the rest. However there’s a couple issues with this I’ve found. The biggest one is that the focus ring is very responsive and it’s easy to move accidentally especially since I naturally rest my hand on the focus ring and it seems like the shape of the lens encourages that hand position. It wouldn’t be a problem if the DMF only worked while you weren’t half pressing the shutter button, but it continues to work even when you are actively auto focusing. I feel that I have to be super careful as I’m afraid of messing up focus by slightly nudging the focus ring while shooting.
Some questions:
1) do you use the full time DMF with this lens?
2) if you don’t use DMF how do you get around the issue of the lens getting “stuck” on something else entirely and not being able to see your subject cause it’s in bokeh land
3) is there a way to change the focus throw of the ring?
4) is there a way to change the full time DMF so that it only works when you’re not auto focusing? I.e it’s disabled when you’re half pressing the shutter button
5) what do you all use the function ring for?
1) Yes... I have it on 100% of the time
2) An alternative is to set DMF off and instead set a button to change to toggle AF/MF. I think there is an option to have a button just toggle it on/off OR a button that you hold in when you want MF (not 100% sure on that second way)
3) No
4) No
5) Preset focus distance recall
arbitrage wrote:
1) Yes... I have it on 100% of the time
2) An alternative is to set DMF off and instead set a button to change to toggle AF/MF. I think there is an option to have a button just toggle it on/off OR a button that you hold in when you want MF (not 100% sure on that second way)
3) No
4) No
5) Preset focus distance recall
Hey thanks for your reply! Do you ever have trouble with inadvertently hitting the focus ring? I like having the full time DMF on so my options are to move my hand position further forward off the ring or keep it where it is but be super duper cognizant of the risk of moving the ring
