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  1. #1

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    Ow. My brain hurts

    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
    Technological society has succeeded in multiplying the opportunities for pleasure, but it has great difficulty in generating joy. Pope Paul VI

    So, I think the "greats" were true to their visions, once their visions no longer sucked. Ralph Barker 12/2004

  2. #2
    rbarker's Avatar
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    Yes, reciprocity in this context is more take than give.

    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).
    [COLOR=SlateGray]"You can't depend on your eyes if your imagination is out of focus." -Mark Twain[/COLOR]

    Ralph Barker
    Rio Rancho, NM

  3. #3

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    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.
    Francesco

  4. #4
    David A. Goldfarb's Avatar
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    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.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  5. #5

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    Quote Originally Posted by rbarker
    Yes, reciprocity in this context is more take than give.

    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).
    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.

    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.
    Technological society has succeeded in multiplying the opportunities for pleasure, but it has great difficulty in generating joy. Pope Paul VI

    So, I think the "greats" were true to their visions, once their visions no longer sucked. Ralph Barker 12/2004

  6. #6

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    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.
    Technological society has succeeded in multiplying the opportunities for pleasure, but it has great difficulty in generating joy. Pope Paul VI

    So, I think the "greats" were true to their visions, once their visions no longer sucked. Ralph Barker 12/2004

  7. #7

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    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.
    Francesco

  8. #8
    rbarker's Avatar
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    Quote Originally Posted by mark
    . . . 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.
    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.
    [COLOR=SlateGray]"You can't depend on your eyes if your imagination is out of focus." -Mark Twain[/COLOR]

    Ralph Barker
    Rio Rancho, NM

  9. #9
    Aggie's Avatar
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    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 Thumbnails Attached Thumbnails grafton house 1 upstairs.jpg  
    Non Digital Diva

  10. #10

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    Quote Originally Posted by rbarker
    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.
    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.
    Technological society has succeeded in multiplying the opportunities for pleasure, but it has great difficulty in generating joy. Pope Paul VI

    So, I think the "greats" were true to their visions, once their visions no longer sucked. Ralph Barker 12/2004

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