creative technique obviates expensive center-filter purchase

[Daniel Taylor]

I have been using my Schneider 72mm XL Super Angulon on my Linhof Technikardan w ith great success. I do not use the center-filter as the slight fall-off is not objectionable and is actually a welcomed characteristic in some of my work. my p rofessional colleagues however have been critical of my judgement, and within th eir own work require it. I had loaned my architectural photographer friend the 7 2mm XL which promoted lengthy discussions and his insistence that this lens need ed the expensive center-filter without question. it was not the expense, but the added workload of removing/attaching the filter and the associated losses that compelled me to look at this problem deeper. I scan all my 4x5 negatives, and si mply made an image of a evenly lit white/featureless backdrop. scanning this neg ative allows me to characterize the lens response and create a Photoshop gradien t mask used to normalize the response of the overlayed subject scan.

nothing new here, other than allowing solutions to surface from keeping an open and playful mind. in my case, a good cabernet sauvignon contributed profoundly.

[abiggs]

On a different tangent, do many people feel the need for a center filter on the Super Angulon XL 90mm? Or just the 'regular' 90mm?

[Paul Chaplo]

I strongly recommend the center filter for the 90mm SA XL. (Unless you have the Cabernet Sauvignon and Photoshop ) With enough of the proper vintage, you don't even need film...

[Armin Seeholzer]

Cheers Daniel

I`m working with a Nikon f4,5 75mm and a Schneider SA f8 90mm without any center-filter and I make some scans and some Ilfochromes and I`m happy and also my customer. If I have to shift to the limits of the lens than I use not the full frame from neg. or I work with hold back under the enlarger or what ever is needed it depends on neg. or pos. but I never take a center- filter!

[David A. Goldfarb]

Yes, it is easy to remove falloff with the center gradient tool in Photoshop if you're scanning, or by dodging the corners if you are in the darkroom, but be sure to compensate when exposing to make sure that you don't lose detail in the corners.

[Daniel Taylor]

the thrust behind my solution is to offer refinement and accuracy to normalizing the response. obviously, you can create a generic radial gradient layer that approximates the response that might suffice.

as for Dan Smith's response, his commentary is interesting though I believe flawed. his belief is that the 'right' way is the existing way and apparently the only way:

"If you have to go to the trouble to make corrections in Photoshop, why not do it right from the start? How much trouble is it to screw on a Center Filter?"

how much trouble is it to avoid the expense of the center-filter, leverage the light that is not lost to filter attenuation, take advantage of the decreased setup times allowed by not requiring the filter? screwing a filter on/off is not necessarily a burden, but then, neither are two mouse clicks to add the compensation layer. once again, I am arguing from the Photoshop realm, where we are scanning directly into our process environment.

I also want to point out that advances in our pursuits can certainly come from an open and playful mind. we can lock ourselves into existing ways of thought and convince ourselves that any deviation must be surely detrimental to our clients cause. this of course is not true at all.

the point of my comments on having a glass of wine, was only to represent thinking outside of our self-imposed limitations. Dan, and others can surely understand that you don't have to add another layer of glass with its associated problems, to compensate correctly. understanding math and physics can allow a better and more accurate solution, cabernet sauvignon influenced or not.

[dangal]

Folks, I have a 47mm F5.6 XL and I wouldn't bother taking photographs without the filter on, even with B & W! The fall-off is very profound to say the least. Also, I'm having enough trouble trying to minimise its distortions.

[Daniel Taylor]

> "What may be OK for you might be trashcan material for another photographer."

and though this might be true, I can easily transpose this and say "what may be OK for you, based on your old-world and Luddite- centric view, would be totally unacceptable and below the standards practiced and demanded by those imploying the refinements and increased accuracy afforded by the latest technological advancements."

the point is, that we think ... clearly and freely without prejudice and bias. we express our ideas without self-imposed boundaries or bullshit ideas of what is 'right' and immutable.

[Cesar Barreto]

Maybe it isn't too late to add some comments on center filters. First, they really become a pain if one needs some other filters, like usually happens in B&W. But, if contrast control acts in development, N+1 or above, the fall-of problem certainly gets worse. And it can be impossible to solve if the subject already shows some kind of middle hot-spot. Exposure doesn't change while using such filters, as the borders would be under-exposed anyway. So, as a conclusion, I'd would never say never about center filters. They can be quite handy sometimes. Thanks to all,

Cesar Barreto

[Daniel Taylor]

no one is arguing against center filters. they do introduce the potential contributions of distortion and flare. they also are expensive, which is hard to justify when the kids want a new 27" Sony Trinitron and you blow the family savings on a two-inch piece of glass for the same price. maybe you need the $400 to replace those old Firestone tires that tend to explode on your Ford Explorer.

or maybe .. you just keep forgetting to put the darn filter on, or found that you, once again, have left it in your other camera bag. it happens.

enjoy the moment ...