Jeff Ford , Mar 21, 2010; 02:44 p.m.
Need a very low distortion lens for copying artwork. Originals are generally A4 or A3, some smaller, some bigger.
Currently using a 100mm macro Sigma and the distortion is becoming very tiresome
Can anyone recommend an 85(ish) lens that will return square and true results?
thanks
Robert Hooper 
, Mar 21, 2010; 03:11 p.m.
I purchased a Sigma 105mm f2.8 D Macro lens several years ago in order to photograph flat art with my Nikon F4 and the lens performed flawlessly, without any distortion. Are you sure you are perfectly centered, and perpendicular to the art work? It takes some time to set things up properly. I had the wall marked out, 45 degree lighting angles lines taped to the floor and a 20' perpendicular tape line from the wall for the position of my studio stand. I used to have a corner of my studio permanently set up to shoot flat art otherwise each assignment becomes very labor intensive. I also used sheets of Polaroid material over my strobes and lens to eliminate reflections especially from thick brush strokes.
Jeff Ford , Mar 21, 2010; 03:47 p.m.
Yes, absolutely plumb, squared, centred. Its a pin cushion effect, not tapering.
Hans Janssen , Mar 21, 2010; 03:48 p.m.
Try a trial of DxO 6, that has characteristiecs in it for correction of distortion of a lot of lens/camera combinations, even a fish eye comes out straight(not wanted).
Mike Earussi , Mar 21, 2010; 04:54 p.m.
Robert Hooper , Mar 21, 2010; 05:19 p.m.
I think you have a bad copy of the lens, Tony. Pin cushion effect is non existent in my lens. Is it under warranty?
Rodeo Joe 
, Mar 21, 2010; 05:42 p.m.
Focal length shouldn't really matter for flat artwork. How about an old MF 55mm f/2.8 or f/3.5 Micro-Nikkor. Dirt cheap, pin sharp and negligible distortion. Also computed for optimum performance at 10:1, which is almost ideal for A4 to 35mm.
Most modern "macro" lens designs utilise front-group or internal focusing - not a good idea for low distortion at all focus settings.
Jeff Ford , Mar 21, 2010; 05:45 p.m.
Rodeo Joe , Mar 21, 2010; 05:48 p.m.
BTW, square and perpendicular setup is fairly painless if you use the technique of auto-collimation. Set a small mirror flat in the centre of the copyboard and line up the reflection of the lens with itself, dead centre in the viewfinder.
Matthew Currie , Mar 21, 2010; 06:21 p.m.
If you can't find a 55 macro, another possibility might be a 50/f2, considered at one time to be one of the better lenses in terms of linear distortion. You could put it on an extension tube if you need to get closer.
