Originally Posted by
rdenney
One thing I would like to add: The farther the opening of the hood is from the lens, the sharper the cutoff of extraneous light because the less out of focus it will be. Short lenses may need hoods that are quite large on the front to be long enough and still not intrude into the picture.
And another thing: The opening on the hood has to move with respect to camera movements. Thus, a compendium shade that is adjustable only in length will be a compromise when significant movements are used. Related to this is that a shade with a rectangular opening will be more effective than a shade with a round opening, assuming both are adjusted to just avoid vignetting.
Flare that can be improve by shading traces to several causes. One is when the main light source is shining on the front of the glass. That will cause visible internal reflections in many lenses, and also overall veiling flare. When that light source is part of the subject, that flare is unavoidable and part of the picture. But when it is outside the frame, we want the rim-lighting effect and not the flare. Much of this sort of flare can be alleviated by just holding a hand or dark slide between the light source and the lens to shade it.
A second cause is non-subject light bouncing around inside the camera. Bellows minimize the effect of this, but don't eliminate it. It would take all sorts of tight internal baffling to really eliminate it, but that would inhibit all the other things a view camera must do. Tight shading on the front is like adding some of those baffles outside the camera.
One of the really strong features of my Sinar is its many paths to effective shading. At the extreme, one can extend the rail, add a multipurpose standard, stretch a bellows between it and a holder affixed to the lens standard, with an adjustable mask on the front of the multipurpose standard. The bellows can be stretched out along the subject axis to obtain the deepest possible shading, and the mask can further reduce it down to the rectangular format. This was intended for the studio, of course.
But they also make a straight rod and a pair of clips that allow a standard bellows to be affixed to the lens standard and adjusted for length. This alone provides as much protection as any lens-mounted shade, and has the advantage of being fairly large so that even with short lenses the shade can be deeper. Sinar also makes a rod with a ball joint in the middle so that the clip-on shade can be aimed without having to nail the front of the shade to the rail in a new spot. Both of these are quite practical for field use--I use them routinely in the field.
Lee probably makes as good a lens-mounted shade as there is. I also use a Hasselblad lens-mounted compendium shade for some of my medium format stuff, but its adjustment rail may project back too far to make it practical for adapting to view camera lenses--it may run into the board with short lenses.
Even a screw-in rubber shade is better than nothing, especially if you get one that is too long and trim the rubber to just avoid vignetting. I would favor a bigger shade for a larger filter ring on a step-up ring--it will be larger and deeper for the target focal length.
Rick "sometimes wondering why people argue about the difference in contrast between multicoated lenses and then use them without shades" Denney
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