One solution for that can be a focusing rail. They usually allow micro adjustments with more tolerance in the "focus" knob.IF you can have the fine motor control to make the minute adjustments to focus the subject.
http://www.bhphotovideo.com/bnh/cont...G&Q=&A=details
http://www.adorama.com/mcfrs1.html
As with all things camera they can be expensive but used ones are usually easy to find.
Last edited by SMB2; 04-17-2015 at 07:59 AM.
Stan
SIMPLY DISCUS IS AN OXYMORON
This lens has a push pull as well as a twist for focus. the push pull changes magnification and is easily knocked out of adjustment.
I know what you are saying about a rail
I also know that on a tripod this lens would be easier, but when I do flowers or fish I like the freedom to be able to move around my subject. Most of what I do is hand held.
God is the artist, he merely allows me to see and capture his work . http://davesphotography7055.zenfolio.com/ coupon code: angelfish
some of my work accepted by Pentax (the camera bodies I use): http://www.pentaxphotogallery.com/artists/davidgray