Quick question for neuro and or anyone who has the my lens and can answer... I believe neuro said in some post somewhere back he has/had a 70-200 F4 IS... Has he or anyone else use this lens, with a step up ring to 77mm for a polarizer or whatever filter had any problems with the hood? I have that lens and the hood shoots out a little bit width wise which seems like it would accommodate it, however, it is a longer circular hood so adjusting lets say a polarizing filter with such a hood on would be cumbersome... any experience with this lens and filters or this lens and step up rings and filters and the hood? Any thoughts from those who have this lens would be welcomed. =)
I don't have the 70-200, but i have the 70-300L, and i'm guessing that the designs would be the same.
If the hood reverses to go over the body and shoots out wider straight away, it looks possible. actually, just looking at the TDP Compare Tool, the hood shoots out even wider sooner.
But you want to put a 77mm on a 67mm thread, so now i'm not so sure. if you've got the lens, first thing to try is whether you can get the 77mm filter to touch the lens without jamming on the hood (you can even do it with the hood and filter, without the lens). my 72mm filter goes all the way up the hood (doen't that sound dirty?) of the 70-300L, so i'm guessing it'll easily work with the stepring (which i must buy on ebay today, didn't get there yesterday).
my plan for a way of controlling it is with magnets. firstly, the hood is plastic, so it won't interfere. I've got a tiny (2*2*1mm) super-magnet (neodymium?) which i'll glue to the edge of the CPL (it won't stick if the cpl is brass/alu). I've got a bit bigger magnet for the outside, which will attract the smaller one inside and when i move the outer one the smaller one will drag the ring around with it. (i plan to add some kind of cloth covering or fluff to the magnet outside the hood so as to not scratch the hood).
whether this works will depend on if the magnets are strong enough to attract each other through the distance to outside the hood, and if i can glue the smaller magnet to the CPL without gluing it to its holder and stop it spinning around at all.
if it works (trying it as soon as i get my step ring delivered) i'll post photos.