I was looking at the Schneider digital center filter list - nice idea but very pricey - and only for Schneider wide angles.
Has anyone played with making their own digital center filter for use in Photoshop? At first glance it doesn't seem to be such a difficult thing to do but first glances are often (always???) deceiving.
Simply take a photograph of a perfectly evenly lit surface (at the magnification ratio you want to photograph at), scan, spot, invert and blur it, and use that as a exposure overlay...
In the Lens Corrections section of ACR, the Lens Vignetting settings should do the trick. I use ACR 4.6 so there may new tools to play with.
Nick
Last edited by Collas; 18-Jan-2012 at 04:35.
Yes, that's exactly what I was thinking - but I wonder if it really is that easy.
I guess what bothers me aout it it that I can't help thinking that any correction after the fact would have to reduce the dynamic range of the photograph whereas a true center filter would not. Thoughts???
Right - modern negative film tends to have more range than most output media, so it might not matter in many cases. But if you are after squeezing as much out of a image as possible, it might be wiser to combine some "wrong" centre filter with a correction of its over- or undershoot in postprocessing rather than to attempt to do it all in the post.Originally Posted by Jim Andrada
That could actually be a better Schneider product than a all digital centre filter. A standardized centre filter along with a digital correction filter that matches it to each lens could be considerably cheaper than individualized filters. (Schneider engineers: If you read this and build it, you owe me a freebie!)
" A standardized centre filter "
And how would you propose that a "standard" one be made when current Rodenstock center filters range in size from 58 to 86mm diameter screw-in and some, like the 67mm ones, are available in two different center densities whose choice of use depends on the coverage of the lenses. 75 4.5 and 90mm 6.8 require a center with a 1.5x correction and the 35, 45 and 55mm 4.5 lenses require a center density of 2.5x.
You might want to read this about the newest type of center filter design:
http://www.rodenstock-photo.com/medi...Engl_10184.pdf
Well,if you're scanning and printing digitally you'd really only have to "Dodge and Burn" once in PS - although each time you print you might WANT to dodge and burn differently because each time you might feel a little differently about the print.
I guess my disinclination to buy a center filter arises from a) having more than one size lens and b) really not using the extreme wide angles tremendously often. Often enough to have the lens, of course, but still a small percentage of my usage.
If I were doing a high percentage of work with the superwides, no doubt about it, I'd have the filter(s), particularly if I were using extensive rise/fall etc where I'd be working further into the corners and offset from the center of the frame.
And I might actually convince myself to get one - I'd like to have them, just a bit cost averse at the moment.
By the way, thanks Bob - The link you provided was very interesting.
By the way, do they do these absorptive glass filters for obsolete lenses too?
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