Page 3 of 6 FirstFirst 12345 ... LastLast
Results 21 to 30 of 54

Thread: Lens hoods advice

  1. #21
    Joanna Carter's Avatar
    Join Date
    Oct 2006
    Location
    Plestin-les-Grèves, France
    Posts
    992

    Re: Lens hoods advice

    Quote Originally Posted by Bob Salomon - HP Marketing View Post
    That is why some manufacturers include or offer cropping masks for the front of the shade so you don't need to have a bellows equal in length to the camera bellows.
    Indeed. Having seen the Sinar setup, they are obviously interested in getting the very best out of the camera, providing for being able to use bellows as a compendium shade and providing adjustable cropping blades for the front of those bellows.

    For GPS benefit, I will reiterate that, without going to the extent of the Sinar system, the Lee hoods are a reasonable compromise, but there have been times when I wished I had a "compromise" compendium with adjustable masking as well.

    When using a field camera, there always tend to be compromises, like weight versus rigidity; the length of a compendium is another.

    In this LF world, sometimes we have to forego "technical perfection" in favour of being able to carry the camera bag without injury.
    Joanna Carter
    Grandes Images

    UKLFPG

  2. #22
    Joanna Carter's Avatar
    Join Date
    Oct 2006
    Location
    Plestin-les-Grèves, France
    Posts
    992

    Re: Lens hoods advice

    Quote Originally Posted by GPS View Post
    Or the other way round - why - when a half size film format mask put at a half focal length distance does not eliminate all the extraneous light - the mask in the film format size put at the full focal length distance suddenly does (according to you) eliminate all the stray light? What doesn’t give?
    Geometry, geometry...
    Inernal reflections, internal reflections…

    The more ridges in the shade, the more chance of eliminating them.
    Joanna Carter
    Grandes Images

    UKLFPG

  3. #23
    Moderator
    Join Date
    Apr 2009
    Location
    Northern Virginia
    Posts
    5,324

    Re: Lens hoods advice

    Here's what I heard Joanna say, for those avoiding the debate: Any hood is demonstrably better than no hood, a compendium hood is better than a screw-in hood, a hood adjusted for the focal length is demonstrably better than a hood that is too short, a hood for a long lens may need a mask to avoid having to be impractically long, and that the hoods that are practical for use on a field camera will be a compromise on what is possible.

    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

  4. #24

    Join Date
    Jun 2005
    Posts
    2,480

    Re: Lens hoods advice

    Quote Originally Posted by Joanna Carter View Post
    ...
    For GPS benefit, I will reiterate that, without going to the extent of the Sinar system, the Lee hoods are a reasonable compromise, but there have been times when I wished I had a "compromise" compendium with adjustable masking as well.

    ....
    Here at least we agree. Indeed, any lens shade (inclusive Sinar one) is a compromise. Stray light can never be completely eliminated, even with lens shades twice the focal length (make it trice, if you prefer).
    There are lens shades that are better than anything on the market today. But those are manufactured specifically for the optical characteristic of the individual lenses used on a specific film format - the very same reasons for which they are not marketed by any firm.

  5. #25

    Join Date
    Sep 1998
    Location
    GA
    Posts
    12,878

    Re: Lens hoods advice

    Quote Originally Posted by GPS View Post
    Or the other way round - why - when a half size film format mask put at a half focal length distance does not eliminate all the extraneous light - the mask in the film format size put at the full focal length distance suddenly does (according to you) eliminate all the stray light? What doesn’t give?
    Geometry, geometry...
    Maybe it would, but that is not what the manufacturers have done. They have chosen to add the masks to the front of the compendium and have been doing so for decades. If you have invented a better way then go for it. But I am familiar with Linhof, Wista and Sinar systems and they all put the cropping masks in front of the compendium. Maybe they tested other placements and found them lacking? For instance, it is very easy to stand behind the camera, look through the gg and adjust the masks while checking to make sure that they do not vignette.
    It would be a royal pita to try to do that with masks at a different position.

  6. #26

    Join Date
    Jun 2005
    Posts
    2,480

    Re: Lens hoods advice

    Quote Originally Posted by Joanna Carter View Post
    Inernal reflections, internal reflections…

    The more ridges in the shade, the more chance of eliminating them.
    Forget about internal reflections - bellows shaped flock paper is more than enough to eliminate them, especially with longer lens shades. And - if you were tempted to make a lens shade with the "appropriate" mask not at half a focal distance but right at the lens rim -wouldn't you eliminate those internal reflections? Yes, you would - but the lens shade would be very pitiful from an optical point of view. Geometry, geometry...

  7. #27

    Join Date
    Jun 2005
    Posts
    2,480

    Re: Lens hoods advice

    Quote Originally Posted by Bob Salomon - HP Marketing View Post
    Maybe it would, but that is not what the manufacturers have done. They have chosen to add the masks to the front of the compendium and have been doing so for decades. If you have invented a better way then go for it.
    ...
    Maybe won't do here. If the lens shade at half a distance had the same optical effect the manufactures would go for it like crazies - a smaller lens shade with the same effect would be only an advantage.
    The reason why they go for longer shades is - well, a geometrical one. The shading effect is better. Unfortunately, never 100%. Never. Even with a Sinar lens shade.

  8. #28

    Join Date
    Sep 1998
    Location
    GA
    Posts
    12,878

    Re: Lens hoods advice

    Quote Originally Posted by GPS View Post
    Maybe won't do here. If the lens shade at half a distance had the same optical effect the manufactures would go for it like crazies - a smaller lens shade with the same effect would be only an advantage.
    The reason why they go for longer shades is - well, a geometrical one. The shading effect is better. Unfortunately, never 100%. Never. Even with a Sinar lens shade.
    The basic Linhof and Wista compendiums are short ones, that is why they have the mask option. Either as an add-on accessory or as part of the compendium itself.

  9. #29

    Join Date
    Jun 2005
    Posts
    2,480

    Re: Lens hoods advice

    Quote Originally Posted by rdenney View Post
    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
    Rick,
    the sharpness of the hood mask doesn't play any role on its optical effect (is minimal) and is not the reason why shades are made longer. The cutting function at its edge is the same.
    Right you're - Sinar solution is for the studio, Lee also for the field. But nobody contests that.
    For lenses used in a field the total majority of them can use - with an excellent optical effect - shades between 60-150mm long (depending on the focal length in use) provided they are made for the specific lens/film format combination. There is the devil's detail. Movements make a mess of practical lens shades but that is comprehensible. Geometry, geometry.

  10. #30

    Join Date
    Jun 2005
    Posts
    2,480

    Re: Lens hoods advice

    Quote Originally Posted by Bob Salomon - HP Marketing View Post
    The basic Linhof and Wista compendiums are short ones, that is why they have the mask option. Either as an add-on accessory or as part of the compendium itself.
    Even the Sinar compendium lens shade cannot fully eliminate all the stray light. All lens shades are a compromise. A very good one, good or a bad one.

Similar Threads

  1. Advice for long lens rental for Yosemite
    By An Infinite Journey in forum Lenses & Lens Accessories
    Replies: 48
    Last Post: 1-Feb-2010, 11:04
  2. Lens design & glass types
    By IanG in forum Lenses & Lens Accessories
    Replies: 21
    Last Post: 31-Mar-2009, 17:20
  3. Large Format Lens Hoods?
    By Michael Kadillak in forum Gear
    Replies: 15
    Last Post: 19-Mar-2001, 01:33

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •