Useful focusing chart.

[hank]

Just bought a Sigma 28mm f1.8 ex DG APO Macro Lens.

The switching Arrangement from MF to AF was designed by a comittee ! Other than that, it's a great lens.
In reading about it, prior to purchase, I came up with lots of critique about front focusing/back focusing. I've read of these issues with other lenses before, it can be a bit daunting to a beginner.
After purchase, I downloaded a focusing chart from here ..........

http://www.k10dbook.com/AFCHART.pdf

The lens was spot on with my Canon 20D. However, with my 50D, I had to make a correction ( on the microadjustment ) of +20. fortunately, the 50D can register these adjustments.

I think the 'Front focusing/Back focusing, Good copy/Bad copy issues of lenses that get reported on various sites, don't take into account that there may be camera issues that ought to be taken into consideration as well.

Rant over !

H.

[PMG]

I don't think any of my lenses have focussing probs but thanks for this advice I've printed one out and will give it go just for curiosity - in fact that curious I will google adjustment charts and see if anything else comes up thats any different to this. I occasionally have out of focus pics but think its something I do rather than the camer - I can't see it producing pin sharp one min and blurred the next by itself!!!!

[darrenm]

will test this out and may need to adjust my camera to my 400mm lens now after using the 300mm for the last 6 or 7 outings. This morning i found the 400mm very soft but it may also be down to the light off out gain soon with the 300mm again

[The_Moaner]

After I was told my 400mm f5.6 was slightly front focusing I did a -1 addjustment and it looks lots better now. Thanks for checking it Gerry H, at the Leighton Moss Meet.

[Geoff F]

There are a number of similar charts but the problem with them is that although they may give you a basic idea, you do have to get the camera angle correct in order to achieve a meaningful result.