Re: [pinhole-discussion] Polaroid exposures
Correction... I meant to write f16 @ 1/125 sec instead of 1/100 sec (as indicated below). Bill- The Painted Horse wrote: Hi Guillermo, Thank you for your reply. Obviously, I miscalculated the math for my exposures (*sigh*). However, just to clarify..on the calculations given below, wouldn't it be f16 @ 1/100 secs and not 1/25 sec? I apologize if I am incorrect, but I'm trying to understand the basis for the formula and the 804 film is ASA 100. Given this, wouldn't the initial exposure (not factoring in reciprocity) then be around 10 sec. rather than 40 sec? ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.p at ???/discussion/
Re: [pinhole-discussion] Polaroid exposures
Hi Guillermo, Thank you for your reply. Obviously, I miscalculated the math for my exposures (*sigh*). However, just to clarify..on the calculations given below, wouldn't it be f16 @ 1/100 secs and not 1/25 sec? I apologize if I am incorrect, but I'm trying to understand the basis for the formula and the 804 film is ASA 100. Given this, wouldn't the initial exposure (not factoring in reciprocity) then be around 10 sec. rather than 40 sec? To answer your question I had taken a metered reading of the northern sky rather than the snow for these exposures. The reflection was just too bright from the snow for me to think I would get an accurate reading. The reading came to EV16. Now, here is the part that, looking back, I can't explain...somehow I came to an exposure of 15 minutes. Please don't ask me how I did this, as now that I am thinking about it, I have no idea. Nontheless, an obvious miscalculation on my part. Unfortunately the snow has melted but I will be out again this weekend to try once more. Thanks again! Bill- G.Penate wrote: Bill, Using sunny/16, your exposure should be f/16 @ 1/25 secs. There are about 10 stops separating f/16 from f/500, therefore for your camera, the uncorrected exposure time should be around 40 secs (2^10 * 1/25). Could you tell us what's your metered or estimated uncorrected exposure time and actual exposure times you have used? Guillermo ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.p at ???/discussion/
Re: Re: [pinhole-discussion] Polaroid exposures
EV 15: 1/125 @ f/16, 1/60 @ f/22, 1/30 @ f/32, 1/15 @ f/45, 1/8 @ f/64, 1/4 @ f/90, 1/2 @ f/128, 1 sec @ f/180, 2 sec @ f/256, 4 sec @ f/360, 8 sec @ f/512.
Re: [pinhole-discussion] Polaroid exposures
- Original Message - From: photoe...@aol.com Hi this is Lonnie. Your exposure, I would try 4 to 8 seconds in bright snow with a bright sky, which would probably give you a EV15 to EV16 with an ISO 100 film. Glad to hear you are using an 8x10 camera. I am thinking of making an 8x10 camera out of banker boxes. Hi Lonnie, EV15 equates to an exposure of f/16 @ 1/125 secs (for instance), which pretty much confirms Sunny/16 for ISO-100. Would you care to elaborate how and exposure of 4 to 8 secs could be a proper exposure when the aperture is f/500? Thanks, Guillermo
Re: [pinhole-discussion] Polaroid exposures
Hi this is Lonnie. Your exposure, I would try 4 to 8 seconds in bright snow with a bright sky, which would probably give you a EV15 to EV16 with an ISO 100 film. Glad to hear you are using an 8x10 camera. I am thinking of making an 8x10 camera out of banker boxes. Lonnie
Re: [pinhole-discussion] Polaroid exposures
In a message dated 4/4/01 10:40:37 AM Pacific Daylight Time, paintedho...@in-tch.com writes: The prints keep coming out real light. Dont forget,with polaroid film,too light is too long of an exposure..try to expose the next shot for 1/2 as long.. Just my 2 cents.. Harry A HREF=http://www.figurefoto.com/;Figurefoto.com/A
Re: [pinhole-discussion] Polaroid exposures
Bill, Here is a brief analysis I've done: Assuming bright open sky conditions, shooting snowy scenes call for about +2 stops from whatever the meter indicates for the snow. Using sunny/16, your exposure should be f/16 @ 1/25 secs. There are about 10 stops separating f/16 from f/500, therefore for your camera, the uncorrected exposure time should be around 40 secs (2^10 * 1/25). According to Ilford HP5 reciprocity correction, 40 sec exposure should become 200 secs exposure. But according to Polaroid.com, an exposure of 40 secs needs a correction of -2.7 f/stops for 804 film. reciprocity corrections in f/stops do not equate exactly to corrections of doublings of exposure time, but assuming they do, 40 secs should become around 260 secs (2^2.7 * 40). BTW, it is not a good idea to use reciprocity corrections charts for one film and apply them to a totally different film/technology/manufacturer. Could you tell us what's your metered or estimated uncorrected exposure time and actual exposure times you have used? Guillermo - Original Message - From: The Painted Horse paintedho...@in-tch.com I could use some help here. We just got a wonderful spring time snowfall yesterday (10) and it got me out and about with my 8x10 pinhole camera (due to the extra light reflection of the snow). I tried using Polaroid type 804 ASA 100 (first time using this film) and I can't seem to get the exposures correct. The prints keep coming out real light. Now, I could keep adjusting the time exposures but it is expensive film and I really don't want to use the whole box of film as testing material (that is, if I can help it). The camera is a normal focal length (13 inches) Leonardo 8x10 and the pinhole is F 500. Anyone out there do 8x10 pinhole Polaroids? For some reason the time charts I use for Ilford HP5 aren't working. And yes, I calculate for the difference in the film speeds. Any help would be appreciated.
