100mm f/2.8L with a diopter?

[RussRoc]

Is there a down side to putting a +4 diopter on the front of a 100mm f/2.8L, to cut down on the minimum focal distance? ???

 

[Loswr]

Reduced IQ from the diopter. You may be better off cropping...

 

[AprilForever]

Try extension tubing...

 

[brad-man]

Try extension tubing...

+1 I use a 25mm tube with excellent results.

 

[TommyLee]

as said above 12mm and 25mm tubes... work great

 

[Dick]

Extensions work well indeed, but may require additional light that can end up ruining everything. I can't think of a more effective way to ruin macro shots than using a ring flash. Be ready to miss some shots too, when interesting objects appear 1 meter away.