Ow. My brain hurts

Discussion in 'Exposure Discussion' started by mark, Nov 22, 2004.

  1. mark

    mark Member

    Messages:
    5,264
    Joined:
    Nov 13, 2003
    Reciprocity math sucks

    Here it goes.

    I want to take a photo in my son's room.

    He is adverse to bright lights so the room is not glowing. I measured the shadows and got an EV of two. I measured the highs and got an EV of 6.

    I've never shot anything with this long of an exposure. Using data I found hear(which looked okay to me when I applied it for a 60 second exposure) with efke pl100 a 60 second exposure should be upped to 3'15". Using the dial on my Luna Pro I measured the EV and got an exposure time of 15 minutes placing the shadows on zone 4. DOing the reciprocity math I would be exposing for an hour-ish.

    Now factor in a filter, yellow would increase the exposure 2/3 stop and bellows extension another full stop. If I decide to go orange then the exposure is upped 1 1/3 How the long will my exposure end up? For some reason I keep coming up with 3 hours. Can this be right?

    I tried brightening things up but the look was no where near what it was before I introduced new lights.

    Like I said my brain hurts
     
  2. rbarker

    rbarker Member

    Messages:
    2,222
    Joined:
    Oct 31, 2004
    Location:
    Rio Rancho,
    Shooter:
    Multi Format
    Yes, reciprocity in this context is more take than give. :wink:

    I would suggest, however, that there is probably no need to add a filter - unless you are wanting to adjust how the B&W film renders certain colored objects in the room. I'd shoot it straight.

    Your son should be at his desk, of course, and hold perfectly still for the hour (no breathing, now). :wink:
     
  3. Francesco

    Francesco Member

    Messages:
    1,020
    Joined:
    Sep 11, 2003
    Location:
    Düsseldorf,
    Shooter:
    8x10 Format
    I would shoot Efke PL100 rated 100, EV 2 to 6, f.32 at 15 mins, no filter or bellows factor added. About an hour with filter and bellows factor should do the trick. This might be a bit too dense for a negative destined to be enlarged. If this is the case then you could reduce it down to 30 mins and be okay.
     
  4. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

    Messages:
    17,946
    Joined:
    Sep 7, 2002
    Location:
    Honolulu, Ha
    Shooter:
    Large Format
    First off, you might consider a faster film or a film with better reciprocity characteristics like TMX or TMY. TMX is faster than Tri-X for long exposures, interestingly enough.

    In computing the exposure, you want to figure reciprocity last after basic exposure, filter factor, and bellows factor. See what that gives you.

    Why do you need the filtration? Usually you would use a yellow or orange filter for a landscape, and not so much indoors unless you are photographing some brightly colored objects that would appear the same in B&W and you want to get better separation between them. You might also use strong monochromatic filtration to reduce chromatic aberration with an old lens or the single cell of a convertible.
     
  5. mark

    mark Member

    Messages:
    5,264
    Joined:
    Nov 13, 2003
    My son is two and a half. He doesn't sit still for a portrait at 1/500. A really aggrevating little guy when it comes time to ship a new portrait off to the grand parents. He and his mom are out of town right now that is why I can actually take pictures in the house. If he was there, all photographic equipment would be in serious danger. Especially since he loves to look at the groud glass, push the button on my strobe that makes it fire, look in the wrong side of the lenses and measure the light in every nook and cranny when he sneaks off with the light meter when I am in the field.

    Everything I did to my dad's equipment. :D

    I am looking at a filter to seperate an orange hat from a yellow rain slicker. After that I am going to move to the toys.
     
  6. mark

    mark Member

    Messages:
    5,264
    Joined:
    Nov 13, 2003
    David

    I have Efke and Classic 200 that is it. Would the classic be a better choice?

    Francesco. Thanks. The next problem is development. WOuld I keep it normal. Usually I drop the development down by 20%. it made for a pretty good neg, except for the damn gouge I got while processing.
     
  7. Francesco

    Francesco Member

    Messages:
    1,020
    Joined:
    Sep 11, 2003
    Location:
    Düsseldorf,
    Shooter:
    8x10 Format
    With SBR 9 (EV 2 to 6) I would develop for about 65% of my normal time (i.e. dev time for scene of SBR 7) as long as the dev time is above 5 minutes.

    The extra stop of Classic 200 is not enough to warrant choosing it over Efke PL100, a much nicer film with superior reciprocity characteristics. If you really needed more speed, Classic 400 is a better choice.
     
  8. rbarker

    rbarker Member

    Messages:
    2,222
    Joined:
    Oct 31, 2004
    Location:
    Rio Rancho,
    Shooter:
    Multi Format
    Ah, OK. I think you will find that the yellow filter will lighten both the yellow slicker and the orange hat, as both contain yellow. It might lighten the slicker slightly more, however. So, you might try one shot straight, and one with the filter, to be able to compare the degree of separation.

    I've often thought that large patches of velcro and super-glue would work wonders when shooting kids, but it's tough to get the mothers to warm up to the idea. :wink:
     
  9. Aggie

    Aggie Member

    Messages:
    4,925
    Joined:
    Jan 1, 2003
    Location:
    So. Utah
    Shooter:
    Multi Format
    I just had this problem whe I was in Zion. We all were out at grafton, the ghost town, and I was doing interior shots of some walls. I was shooting fp4 rated at 65. I didn't do much in the way of mental gymnastics. my initial reading was at f11 I got 8 seconds. So I quadrupled it for 32 seconds. I gave it 20% more development when I processed the negs. I'll add one of the scans of my work prints in a few minutes. All turned out fine. I also forgot I had the yellow filter on the camera.

    The work print is actually lighter than what the room was lit. There were windows, but the fast work print I did, I didn't adjust. I just did a straight print with no buring or dodging.
     

    Attached Files:

  10. mark

    mark Member

    Messages:
    5,264
    Joined:
    Nov 13, 2003
    I'm a teacher and one day a couple of years ago I was out sick for a day and my substitute decided he could solve the problem with duct tape. I imagined dact taping these two particular students into their chairs on many occasions but he actually did it. He got fired and one of the mothers slapped him when they were in the principal's office.

    mothers don't look too kindly on that whole bondage issue.
     
  11. mark

    mark Member

    Messages:
    5,264
    Joined:
    Nov 13, 2003
    Neat shot aggie. It sure was nice of Bobby to scrawl how much he loved what's her name back in 1989, on the wall wasn't it.
     
  12. Alex Hawley

    Alex Hawley Member

    Messages:
    2,894
    Joined:
    Jul 17, 2003
    Location:
    Kansas, USA
    Shooter:
    Large Format
    I've never come up with an exposure greater than about 30 minutes, which included a bellows extension factor. Here's the sequence I use to calculate:
    1) Take exposure reading,
    2) Add filter factor,
    3) Add bellows factor,
    4) Calculate reciprocity and add to all the above.

    Try a few shots for experimentation before you try to get the real "keeper".
     
  13. tbm

    tbm Member

    Messages:
    365
    Joined:
    Jun 3, 2004
    Location:
    Southern Cal
    Shooter:
    35mm
    Re "He is adverse to bright lights", note that the correct word is "averse".
     
  14. Sponsored Ad
  15. arigram

    arigram Member

    Messages:
    5,474
    Joined:
    Sep 21, 2004
    Location:
    Crete, Greec
    Shooter:
    Medium Format
    I don't know if it will help, but I made this little card to help me out in the field. I laminated it just today. Here's a gift to every APUGer!
     
  16. doughowk

    doughowk Subscriber

    Messages:
    1,765
    Joined:
    Feb 11, 2003
    Location:
    Jacksonville
    Shooter:
    Multi Format
    I learned the hard way that Efke 100, as well as other old-fashion films, have severe reciprocity problems. Surprising to me is that Efke 25 doesn't, and may even be a good choice in low-light situations. For example, Efke 100 at 100 seconds requires an exposure of 20 minutes ; whereas Efke 25 only needs a 2/3 f-stop increase. Not sure about the math or science; but it does suggest that some so-called slow films may be more responsive to low light levels.
     
  17. mark

    mark Member

    Messages:
    5,264
    Joined:
    Nov 13, 2003
    Thank you for your more than helpful response to my situation.
     
  18. rogueish

    rogueish Member

    Messages:
    877
    Joined:
    Apr 30, 2004
    Location:
    3rd Rock
    Shooter:
    Multi Format
    Thanks! It's the little things like this that push this site (easily) over the top as the BEST! (and the people too) :smile:
     
  19. mark

    mark Member

    Messages:
    5,264
    Joined:
    Nov 13, 2003
    Hmmmm...What should I be looking for in the way of knowing if I have done things right? Will the negative be too thin or will it be dense as hell but flat?

    PL100 at 3'15" because of a sixty second initial reading with 20% less development time looked pretty good. Nice shadow detail and the highs were not blown out but were pretty thick.

    How did you arrive at the 100 seconds equals 20 minutes?

    I think I am getting more confused.
     
  20. mark

    mark Member

    Messages:
    5,264
    Joined:
    Nov 13, 2003
    Arigram-that's a great chart. I will make one up when I get this figured out. That way I don't have to do the head math again.

    I will be using yours when I get my hands on some of the film you have listed.
     
  21. doughowk

    doughowk Subscriber

    Messages:
    1,765
    Joined:
    Feb 11, 2003
    Location:
    Jacksonville
    Shooter:
    Multi Format
    I was given a chart by a friend for Efke 100 & found Andrew O'neil's times for Efke 25 on the web ( believe at LargeFormatPhotography.info ). Here's a link to a previous discussion on Efke reciprocity. Matt Miller's times of 60 sec -> 8 min 45 sec for Efke 100 shows comparable findings. My limited experience with low-light situations suggests that Efke 100 as well as J&C Pro 100 are very unreponsive whereas Efke 25 may be a good choice if you want sharp detail without the grain of faster films.
     
  22. Francesco

    Francesco Member

    Messages:
    1,020
    Joined:
    Sep 11, 2003
    Location:
    Düsseldorf,
    Shooter:
    8x10 Format
    I have a completely opposite experience re: Efke PL100. I have used it over the summer (about 70 sheets) to take nearly all my interior church scenes in my Places of Worship gallery on my site and on the contact printers gallery. I have exposed and developed Ekfke for scenes from EV 1, and with SBRs from 6 to 15 (N+1 to N-8). Almost all of my interior scenes will print very well on new G2 AZO. The ability to build local contrast very well without increasing overall contrast and density too much is the main reason it is my primary film.
     
  23. Donald Miller

    Donald Miller Member

    Messages:
    6,242
    Joined:
    Dec 21, 2002
    Shooter:
    Large Format
    I noticed that someone mentioned increasing development in a reciprocity situation. That should be clarified...

    The normal development compensation in reciprocity territory is to reduce development. The reason is that the reciprocity effect may not apply equally to all differing brightness values in a scene. In other words, if one has a situation in which the low values fall in the plus 1 second range but the highlights fall in the minus one second range then the highlights will not be exposed at the reciprocity effect for the film whereas the shadows are exposed at the reciprocity effect. So the normal development compensation is to reduce development since the relative scene brightness ratio is greater then what it would seem.

    Now having said that, if the scene brightness ratio is such that the highlights and shadows all fall within the reciprocity characteristics of the film then one may decide to develop normally (would increase negative contrast) or even to expand development which would increase negative contrast to a greater extent.
     
  24. mark

    mark Member

    Messages:
    5,264
    Joined:
    Nov 13, 2003
    SO how do you know if the highs fall in the minus 1 sec range?
     
  25. Aggie

    Aggie Member

    Messages:
    4,925
    Joined:
    Jan 1, 2003
    Location:
    So. Utah
    Shooter:
    Multi Format
    my work print doesn't show the meter readings. I only had 2 stops difference. Everything was coated in a fine red dust. The walls had been white washed, but they were even sort of pinkish. To get more of a tonal range that is why I added the 20% more to the development time. On plus minus development, I go by how many stops of seperation there are. for 4 to 5 I do normal. for anything 3 to 2 I do +1. anything from 6 to 8 I would do -1. This is my system. If the readings come out more than the above, then I have to decide if I want more or less contrast for the sceneand do +2 or -2 development. That is when my brain hurts.
     
  26. Donald Miller

    Donald Miller Member

    Messages:
    6,242
    Joined:
    Dec 21, 2002
    Shooter:
    Large Format
    The accurate way to determine where the highs fall is to measure them with a spot meter.

    An example of how this might work and the effects is as follows:

    Lows values measure 4 seconds exposure.
    High values measure 1/15 second exposure

    One would think that normally this would represent a six stop brightness ratio. But when the additional reciprocity is factored in we now have the low values exposed for 8 seconds (proper exposure accounting for reciprocity)and the highlights exposed for 8 seconds (overexposed by seven stops). This pushes the highs up the curve by seven stops. So that we now have a different scene brightness ratio then a simple meter reading would indicate. That is why the departure from normal development procedures in reciprocity is reduced development.