Silver Efex Lens Roll Off

[sanyasi]

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In Silver Efex, I have found that by combining the Fine Art preset and the Lens Roll Off setting under vignettes that I obtain nice contrast. Could someone explain what is happening with Lens Roll Off? I read a brief discussion that says it is a way to compensate for an imperfect lens by creating an inverse of something, but the feature in Silver Efex seems to be placed there for creative purposes.

 

Thanks for any enlightenment.

 

Jack Siegel

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[erudolph]

Jack, under the Finishing Adjustments > Vignette settings in the current version of Silver Efex, in the pulldown menu, I see some Lens Fall Off presets. They seem to be different degrees of vignetting.

[sanyasi]

Thanks. That is a feature I have been using. I am curious what the term means. I have been assuming that there is an analogue in the film world like dodging or burning. Whatever it is, I will continue to use it, but I was curious if the term/ technique has historical roots.

 

Jack Siegel

[250swb]

The lens fall off is to control the amount and shape of the vignette, going from a natural round shape (where the corners of the image are darkened) to a less realistic rectangular shape where all the edges are darkened. In fact I find the Vignette function more like the general edge burning you would do in the darkroom to hold the image in the frame by slightly darkening the edges. The idea is that slightly darkening the edge of the print area counterbalances the visual effect of the white border, which otherwise visually bleeds the edge tones and makes them appear lighter than they are. It seems to work better than the 'Burn Edges' function unless you simply want one or two edges burnt in.

 

Steve

[sanyasi]

First, my mistake: Lens falloff not roll off. Second, I agree, fall off works better than burning the edges in many cases (at least for me). I find falloff allows me emphasize the main subject, although sometimes the falloff also darkens the subject, which I then have to reverse using a control point.

 

Jack Siegel

[250swb]

I agree Jack that the default setting does darken the image a lot, but if you set the slider from 'circle' to ' rectangle', and then play with the 'size' and 'amount' sliders it does change the amount of vignetting (as a better way to do edge burning) into a very subtle and effective tool. But yes, it does need turning down from the default and then gradually bringing back up, if necessary.

 

Steve