Meter through B&W Filters

Discussion in '35mm Cameras and Accessories' started by lhalcong, Feb 12, 2014.

  1. lhalcong

    lhalcong Member

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    Metering with a sekonik through B&W red or orange filter does not work , I have to meter without the filter and then use the compensating factor. Correct ?
     
  2. Tom1956

    Tom1956 Inactive

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    That is the best idea, as the spectral sensitivity of the meter cell is an unknown and probably not at all linear. Translation: possible color blindness leading to erroneous readings. You're following the safest idea.
     
  3. Jeff Kubach

    Jeff Kubach Member

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    That's what In do.

    Jeff
     
  4. RalphLambrecht

    RalphLambrecht Subscriber

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    In my experience ,the safest way to go is meter withoutfilter and apply the filter fsctor afterwards.meters have a different spectral sensitivity to eyes and/or film
    :confused:
     
  5. brian steinberger

    brian steinberger Member

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    I always have accurate exposures metering through color filters with my Pentax digital spot.
     
  6. Poisson Du Jour

    Poisson Du Jour Member

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    Look up the filter factor for both the red and the orange filters, individually.
    With the Sekonic, adjust the ISO2 button to give +3.0 (e.g. 8EV) for the red filter. Meter the scene with the Sekonic with the filter in place. At the conclusion of metering (e.g. averaging), press ISO2 for the factored exposure. Transfer to the camera. Bracket up (but not down) from the reading/ISO2 setting, and take notes.
    Same technique for using a polariser, though a couple of potential traps there. Another time. :smile:
     
  7. Bill Burk

    Bill Burk Subscriber

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    I think if you have a hand-held meter... Metering without the filter and then applying the manufacturer's filter factor is a good plan.

    Likewise, it's obvious when you put a red filter on the lens and the meter on the camera only sees one or two stops difference.... There's something wrong about metering through the filter. I've ended up with thin negatives exposed by red filter because I didn't notice it (years ago when I shot lots of black and white landscapes in 35mm on auto).

    So I was intrigued by the Gordon Hutchings filter factors, intended to be used after metering through the filter.

    If you look in Google Books for Using the View Camera By Steve Simmons, the free preview includes the page which explains the Gordon Hutchings filter factors.

    I haven't seen a lot of excitement regarding the Hutchings factors, and Doremus Scudder pointed out an apparent fallacy. The caption under the chart explains blue light in shadows are why you need additional exposure when metering through a deep red filter. Doremus pointed out that red light would curtail blue light to the meter, leading logically to the opposite conclusion, that a meter reading of blue shadows through a red filter will already recommend additional exposure.

    I have to believe Gordon Hutchings tested his factors, and so looked again. The practice described is to take meter readings of bright, mid-tone and shadow through the filter to determine exposure and developent... THEN add the Hutchings factor... If you base your exposure on three meter readings, the shadow reading isn't playing as much a role (Hutchings-style) in the overall exposure calculation... While shadows play a significantly greater role in exposure calculation when you base your exposure from a shadow reading and your development from a highlight reading (Zone System-style). So maybe the Hutchings factor works if you do your metering his way.

    One of my favorite thoughts about determining exposure, is that you can be eclectic and pick and choose pieces of technique that fits your way of working. But you should check that the pieces fit together well and do not correct for the same thing twice.
     
  8. Bill Burk

    Bill Burk Subscriber

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    I think you double-compensated here.
     
  9. Dr Croubie

    Dr Croubie Member

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    Actually, the real safest way to go is to hack the firmware/bayer filter of a digital camera to have exactly the same spectral response to your film in question, take test shots with the same lens and filter in place and look at the response curves. Or have a portable darkroom and develop your test-shots on site.

    But given that it's Black and White film then you'll have enough latitude that +/- 1 stop out from 'perfect' can easily be fixed when enlarging/scanning, so just meter without and take off the filter factor as everyone else does, it'll be near enough.
     
  10. R.Gould

    R.Gould Member

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    I I am using 400 film and filters I would set iso 200 for a yellow filter, 100 for an orange and 50 for red, and meter using those settings, works fine for me
     
  11. 250swb

    250swb Member

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    It couldn't be any more difficult than doing exactly that, or so I thought until I read this thread.

    Steve
     
  12. StoneNYC

    StoneNYC Subscriber

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    There was a simple formula on a similar thread recently, now I can't remember... Bill, was it...

    ASA / filter factor # = new EI?

    Like 100 ASA with yellow filter (factor 2) is 100/2= EI 50?

    So 100/red (5) = EI 20?

    Is that right?
     
  13. David Allen

    David Allen Member

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    I seem to be in the minority camp here as I always metered through filters (when doing landscape work - I rarely ever use filters today). However, this is using a Weston V meter which responds to colours very much like film. I have always found filter factors to be unreliable as they do not account for dominant colour of light or colours within the scene. For example, when metering dark shadows to determine ZoneIII there is often a lot of blue light and the exposure compensation is often more than 3 stops.

    I am aware that earlier in-camera meters had spectral sensitivity problems and do not know how your meter responds and how you meter.

    I would be interested in what other photographers approach is.

    Bests,

    David
    www.dsallen.de
     
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  15. Xmas

    Xmas Member

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    The problem is the spectral sensitivity of CdS cells and TTL metering - you need to know what you are doing.

    Taking the battery out of the OM1 is easier I might needle follow rather then push the button.

    The rest of us can work around non average sceanes any way we chose.
     
  16. pdeeh

    pdeeh Member

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    If you're finding photography straightforward then you're clearly doing it all wrong
     
  17. momus

    momus Member

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    "If you're finding photography straightforward then you're clearly doing it all wrong"

    I will assume this is satire, and funny satire at that. All you'll ever need to know on this subject is stated concisely and clearly by R. Gould (and thank you for that post). If you will just commit this to memory or jot it down somewhere, you can then adjust your in camera meter to agree w/ this, and extrapolate the different ISO films from the 400 base. But if you did that, then we couldn't argue about how many angels can dance on the head of a pin.
     
  18. Xmas

    Xmas Member

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    It probably was satire and quite risible, but true if you want shots 'like' Ansells, he employed a zone system and quaint developers...

    But R Gould post wont (always) work with a CdS meter camera with a meter cell behind the filter e.g. lots of the early range finders and almost all early SLR, It is important not to 'set up' beginners with a new film camera and a yellow filter. It is ok with a silicon cell behind the filter, camera except you don't adjust the ISO at all!

    If you don't understand that, please read momus' post again, If I use a filter I remove the battery from my 'post' cell metering cameras first... and use my Weston as RGould suggests, note YMMV

    Lots of our kids are moving from lomos to metal cameras and need basic training that does not occur in a DSLR course in college...

    Noel
     
  19. benjiboy

    benjiboy Subscriber

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    That's O.K, as long as you don't forget to reset the compensation factor when you remove or change the filter, I find it a better method with my Sekonic L358 to apply the filter factor after taking the meter reading easy, and you can't forget to reset the meter.
     
  20. pdeeh

    pdeeh Member

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    well, I wouldn't dignify it with the epithet 'satire' but, yes, to be clear, it was intended to be humorous.
     
  21. Sirius Glass

    Sirius Glass Subscriber

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    Same for me with Minolta and Nikon through the lens meters. According to others I must not have enough experience with this since I have been doing it this way since the 1970's.

    Silly me :whistling:
     
  22. Too old to care

    Too old to care Subscriber

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    This is what I do. My Leica M6 TTL cannot meter correctly through colored filters either, max correction with a red filter on the Leica is one f-stop, a yellow filter is less than 1/2 f-stop. So, set my ISO according to the settings above, meter w/o the filter, attach the filter and shoot away.

    Wayne
     
  23. Xmas

    Xmas Member

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    Hi Ben

    Your meter has silicon cells it should be reasonable through a filter, the early CdS cells are woeful in lots of conditions? Have you tried it?

    Noel
     
  24. Mr Bill

    Mr Bill Member

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    I'm in the camp of metering the subject directly, then apply the filter factor.

    An important point is where you get your filter factors from. I recently posted in a thread about filter factors for some sharp-cutting red filter (like Wratten 25). Someone was using factors supplied by the filter manufacturer, which I maintain is the wrong place to get them from - you should ideally get them from the film maker, and ideally for the light source you use.

    Since I went to the trouble of writing an explanation, I'm also going to paste it in here:

    Most of the time your exposure won't be so sensitive to filters - this is sort of a worst-case situation. The #25 red cuts sharply at about 600 nm (at 580 nm and lower virtually nothing comes through) so exposure only occurs from there on up. This means that there can be a big exposure difference between films with different amounts of red sensitivity, such as the two listed.

    If anyone is inclined to meter THRU the filter, they ought to consider how the meter would handle the difference between these two films: Tmax 100 vs Tech Pan.
     
  25. StoneNYC

    StoneNYC Subscriber

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    Or Acros100
     
  26. benjiboy

    benjiboy Subscriber

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    I know the spectral sensitivity of Silicon Blue cells is better than Cadmium Sulphide ones Noel, your'e quite right, but they are still not perfect or as good as photo electric meter cells it's just the method I tend to use myself that works for me.