03-05-2013, 01:22 PM
Quote:...... How bad is the focus shift in "normal" use? And how bad is the focus shift in macro use? And does it occur over the entire focal range?
.... oops sorry Bc i've only now read your last line, and i can't seem to be able to edit this extra answer into my last post to include the quote above, so another answer -
.... well i checked the first lens more thoroughly than i have so far with this one, but this one does look to be very much the same -
so the focus shift for lens#1 on my 7D appeared to be a 0 micro-focus correction at 50-70mm from f/4-f/8 and then from 50-24mm the correction required for best focus increased to a setting of +8 m-f correction at 24mm & f/4 - it appeared to require (at 24-50mm & f/8) an m-f correction of 0 (no doubt the extra depth at f/8 helps) - this current lens might vary that range from -1 to +7 but you can see for yourself by looking at the movement of focus on the sand in my gallery shots, the white board being the focus point, the shots id indicate the mm(24 or 70), the f# (4 or 8) and the plus or minus m-f, the shots are 100% crops which you can make full size - this smugmug gallery is at - <a class="bbc_url" href="http://www.smugmug.com/gallery/28208048_CvkBjw#!i=2385876358&k=K76g6wC" title="External link">http://www.smugmug.c...76358&k=K76g6wC</a>
- i haven't done 50mm again yet because: (1) no time, (2) weather and (3) i'm bored with all this, but i will and will update any difference from lens#1, just looking at it i expect not (but that's not very scientific and precise is it)
re. macro: i always focus manually and at 70-80mm should require no micro-focus correction anyway, but f/4 is a tad soft
.... anyhow for me all this is insane, so as i have said already enough of these silly lens games for me, no more, sorry
.... edit (8 march) ...
ok for what it's worth, here now my 7D micro-focus settings for this thing that appear to find auto-focus -
- taking f/8 as the constant zero point -
at 70mm: f/5.6 = 0, f/4 = 0
at 50mm: f/5.6 = 0, f/4 = = +3
at 35mm: f/5.6 = 0(close enough as i have only 3 quick picks via the C knob), f/4 = +6
at 24mm: f/5.6 = +3, f/4 = +6
definitely an Av lens, definitely a lens tragic