Do multi coated filters compensate for single coated lenses?

Discussion in 'Large Format Cameras and Accessories' started by Early Riser, Feb 22, 2008.

  1. Early Riser

    Early Riser Subscriber

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    As the title implies does the use of a multi coated filter compensate at all for the lower contrast of single coated lenses? ordinarily I would test this, and at some point I will, but right now the weather does not allow.
     
  2. 23mjm

    23mjm Member

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    I would say NO-----because the internals elements still produce the reflections that cause the loss of contrast.
     
  3. Early Riser

    Early Riser Subscriber

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    I was thinking it might help because it might cut down on stray light entering the lens which then bounces around hither and thither.
     
  4. 23mjm

    23mjm Member

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    I think a good lens hood would be a better way of achieving this!!! Personally I love lens hoods!!
     
  5. Harrigan

    Harrigan Member

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    No they do not.
     
  6. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    No. After all, most internal flare is not caused by stray light, but by light reflected from the subject, so anything you put in front of the lens increases flare, less so if it is multicoated.
     
  7. Early Riser

    Early Riser Subscriber

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    I know that there is flare even between lens groups and lens elements that have air surfaces, however even with a lens shade that is masked to the exact proportion of the image, and is at the borders of the image, there is still a certain amount of off axis light entering the lens. Wouldn't an MC filter cut down some of this light, and therefore reduce some of the flare?
     
  8. Larry.Manuel

    Larry.Manuel Member

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    Multi-coating allows greater light transmission.

    Uncoated and single-coated lenses suffer from more "veiling glare" than do multi-coated lenses. This glare acts as a veil, obscuring low-contrast details. Other posters have explained exactly what causes this - light ricocheting between various elements - and even inside the glass lens elements themselves. A single-element lens thus benefits from multicoating, too.

    If the lens is multi-coated, more of the light goes right on through - to the film. Thus, there is less light reflecting and refracting back and forth between various air-to-glass surfaces. Even cemented glass surfaces will create some [but very little] of this stray - or uncontrolled - light, bouncing around.

    Multicoating a filter accomplishes two things: {one} more light goes through to the next glass surface, and eventually to the film. {two} because there is less light lost at the surfaces, there is less light bouncing back and forth between the front and back of the filter's glass surfaces. Eventually, this bouncing light exits the glass, and it doesn't go in the same direction as the light that originated from the subject. Thus, it "veils" the image on the film by landing where this light should not be.

    A multicoated filter will perform better than a less-well coated filter. No filter will reduce the veiling glare inherent in the lens. Also, every multicoated filter will introduce more veiling glare than using no filter.

    In old movies [and photos] you will see huge reflections off eyeglass lenses. Often the person's eyes are not visible at all. There were no coatings then. Now, eyeglass lenses are nearly invisible as very little light reflects off the front, or back surfaces.

    In the film "Good Night and Good Luck", I suspect the eyeglass lenses were purposely uncoated, to give that "period" look.

    Multicoating allows about 99.5% transmission at each air-to-glass surface. Uncoated glass transmits about 96%.
     
    Last edited by a moderator: Feb 22, 2008
  9. Early Riser

    Early Riser Subscriber

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    Thanks for the comments. I was hoping that there might be some means of upping the image contrast of a recently purchased single coated lens. I didn't think the use of a MC filter would be a solution but as I never tested for this I was hoping that it could be.
     
  10. PhotoJim

    PhotoJim Member

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    Unfortunately, the only way to increase image contrast is through development or film choice.

    Low contrast can work to your advantage occasionally. Shadow detail can often be better with poorly coated, or uncoated, lenses because the reflections effectively prefog the film. I've seen some example photographs where a much punchier multicoated lens had minimal shadow detail in a specific scene but an uncoated lens showed significant detail. It was interesting.
     
  11. Trevor Crone

    Trevor Crone Member

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    Embrace your single coated lens, for has Jim wrote it will help with shadow detail. Uncoated lenses used judiciously are capable of wonderful luminosity. A good friend who had some wonderful Leica lenses would often favour the single/uncoated versions for this very reason.
     
  12. Ian Grant

    Ian Grant Subscriber

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    Not strictly true you can help enormously by using a good tight lens hood, the difference can be quite surprising.

    While you're not actually increasing the optical contrast of the lens you are stopping extraneous light from entering the system cutting internal flare, to a minimum. Ideally a rectangular shaped hood, rather than the circular.

    Ian
     
  13. MattKing

    MattKing Subscriber

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    It seems to me that there may be some benefit if the filter filters out a component of the light that includes a lot of flare.

    I know that sounds confusing, but if I can provide a possible example:

    If the ambient light is quite yellow, and the lens is likely to flare in the yellow part of the spectrum, a blue filter would block a portion of the spectrum, including that yellow portion of the light that contributes so much to the flare.

    Does this make sense?

    Matt
     
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  15. panastasia

    panastasia Member

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    I'm in favor of multicoated lenses for brightly lit subjects, like sunny landscapes. I sometimes use a single coated 65mm f/8 Super Angulon and can see fuzzy highlights (flair) in my prints. Not so with my multicoated 150mm f/5.6 Symmar S.

    If this observation relates to differences in "luminosity" between one lens and another, I'd rather not have unintentional flair. For intentional fuzzy specular highlights in glass, or metallic objects, it can be a benefit, though.
     
  16. 23mjm

    23mjm Member

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    He said in his second post that he wants to cut down on stray light---a hood is the best way to cut down on stray light!!!
     
  17. Trevor Crone

    Trevor Crone Member

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    Like most the majority of my photography is with modern MC lenses. However I do have a couple of oldies that are single or uncoated and I do occasionally use these on overcast days to achieve a soft, quite luminous, almost 'orthochromatic' look. Bearing in mind that I only shot b/w. I also achieve a similar 'look' when using my MC lenses by again shooting on overcast days, over exposing and cutting back the film development. I've then got the flexibility to expand or contract the tonality even further at the printing stage.
     
  18. panastasia

    panastasia Member

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    Trevor,

    Overcast days were never a problem for me - my single coated lens is a gem!

    I only shoot B&W now and your methods are similar to mine, but I usually don't underdevelop for lower contrast scenes - in order to maintain luminosity in the print - maybe we're both looking at different aspects of tonality, or contrast range (mid tone manipulation, that is). It sounds like your MC lenses give you more contrast than you desire sometimes. By "orthochromatic look", I assume your talking about cloudless skies.

    Regards,
    Paul
     
  19. Trevor Crone

    Trevor Crone Member

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    Hi Paul,

    White skies or very pale grey (in the print) and 'open' detailed shadow areas.

    I do find modern lenses can at times be a little too contrasty for my tastes.

    I just adore overcast days and there's plenty of opportunity for them here in the UK:smile:

    Regards,
    Trevor.
     
  20. Harrigan

    Harrigan Member

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    Yes of course a lens hood is but ER already knows that. My comment was based on his question about mc filters not a response to yours about a lens hood. However I'm happy to provide a beating post for you if that outburst made you feel better. :smile:
     
  21. matti

    matti Member

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    A single coated lens blocks out a specific wave lenght, right? Then to filter out other light might give more contrast.
    /matti
     
  22. panastasia

    panastasia Member

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    I believe it's more about reducing flair caused by reflecting surfaces and allowing more transmitted light to reach the film.

    About how different wavelengths are affected, I'm not sure, that's a little beyond my understanding; too theoretical for me. I think the ultraviolet part of the spectrum is where control is most needed.
     
  23. matti

    matti Member

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    I ment "blocks out reflections of a specific wave lenth. Not transmits. Sorry.
    /matti
     
  24. walter23

    walter23 Member

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    I doubt it; a coated filter works by reducing the ability of the glass to reflect light. It transmits more light directly through, so in effect, it's more invisible than an uncoated element. Hence it's almost like having nothing in front of the lens, except for whatever effect the filter is supposed to have.

    Uncoated glass surfaces result in a lot of internal reflections. Take an uncoated lens and look at it under a lightbulb; you'll see lots of little reflected copies of the lightbulb inside. This is what causes your loss of contrast. Putting a multicoated filter over the front isn't going to make any difference, the image of the lightbulb is still going to bounce around inside the lens once it's efficiently been transmitted through the multicoated filter.

    Stray light from out of frame can be blocked by a hood; the multicoated filter has no effect on this.
     
  25. Early Riser

    Early Riser Subscriber

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    I did some quick additional film tests, taken on 2 different days but very similar lighting conditions, i.e. same type of day, same POV and subject, and both days were very clear, completely cloudless days. There was a big difference in reflected light as day 2 was after a substantial snow, filling shadows somewhat but also adding to the potential for external flare. Tmax100 film. The different locations refer to a highlight/shadow area and a highlight/midrange area

    MC lens no filter: day1
    location A/B 1.19 .12 density difference 1.07
    location C/D 1.23 .54 density difference .72

    single coated lens, no filter day 1
    location A/B 1.10 .21 Density difference .89
    location C/D 1.08 .50 density difference .58


    MC lens with MC yellow filter, day 2
    location A/B 1.06 .33 Density difference .73
    Location C/D 1.10 .79 density difference .31

    single coated lens with MC yellow filter day 2
    Location A/B 1.18 .41 density difference .77
    Location C/D 1.25 .90 density difference .35

    While this was a quick test of a landscape scene and not fixed gray test targets so there can be many variables that are unaccounted for. You can see that the differences between the MC lens and the single coated lens became much smaller when used with an MC yellow filter. I am not certain if this is due to the altering of the color spectrum by the yellow filter or the MC qualities of the filter. I will need to test this with a non colored MC filter and using gray test targets to get more accurate results.
     
    Last edited by a moderator: Feb 24, 2008
  26. David H. Bebbington

    David H. Bebbington Inactive

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    A multi-coated filter will lose less light at the filter, but that's all. In other words, using an uncoated or single-coated lens with a multi-coated filter will mean performance just a little closer to that of the lens with no filter. compared with the same lens and a single-coated filter. There's no way a filter can improve lens performance, only impair it less!