On Wed, Mar 21, 2012 at 12:52 AM, Anthony Farr <[email protected]> wrote: > On 21 March 2012 13:00, Mark C <[email protected]> wrote: >> The second biggest challenge was getting the image exactly registered with >> the film plane - no perspective tilts. > > Put at mirror on the copy plane. When the lens's reflection is in the > centre of the viewfinder then you've got perfectly parallel image and > focal planes. Re-position the artwork (without altering its tilt) to > centre up the framing, but don't move the camera again for this setup. > Batch the paintings into similar sized groups to minimize the number > of setup changes you'll need. > > Works with low textural relief can be treated as simple copies using > equal lights from each side, or from each corner if the work is larger > than 50cm a side. If the work has high textural relief then light it > as a 3D object, but watch out for falloff of illumination, because the > light will be predominantly one-sided. One trick is to feather the > light so that the bright centre of the beam is directed to the further > edge, while the nearer edge to the light gets the dimmer boundary of > the illumination circle. Half of the light will be wasted, so be > careful that it doesn't reflect back into the copy area. Use barn > doors if you can. With care and luck the light spread will be even. > And, importantly, ensure that the light appears to come from "above", > i.e. the dominant light should come from the top edge of the artwork, > even if you've laid it down or have it hanging/standing sideways. > > regards, Anthony > > "Of what use is lens and light > to those who lack in mind and sight" > (Anon)
Great idea about the mirror; I must try that. That light from "above" thing is important too. The image looks very odd if you don't keep that in mind. I've been Photoshop-cheating. I put artwork on the floor, position the tripod and camera as square as I can, but not fussing over it. Take the shot into Ps, level it, set the crop lines so they just touch the art edges on all four sides, crop, select-all, open the edit-transform-skew tool and carefully drag each corner in turn until the art edges line up with the image edges. It's best to work in full-screen mode so you can see a grey out-of-image area around the image. That squares up the image perfectly leaving no visible crud. If the camera was way out of square with the artwork this process would distort the aspect ratio from parallax distortion, but if you're close to square already the distortion is negligible. And I always apply a horizontal or vertical exposure gradient of 1/2 or 2/3 stop across the entire image to correct for light fall-off. That's easiest to do in Lightroom. -- -bmw -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
