I mentioned recently but it's petinent to this message. Overexposure at long exposures is lessened by the reciprocity failure. Also keep in mind that in oder to get even one stop of change at long intervals. You have to double the metered time for your pinhole size and then double it again to get one stop change in density at exposures of several minutes or longer. ----- Original Message ----- From: "Colin Talcroft" <ctalcr...@yahoo.com> To: <pinhole-discussion@p at ???????> Sent: Friday, September 21, 2001 11:15 AM Subject: Re: [pinhole-discussion] T-Max reciprocity
> Ricardo asks about T-Max 100 reciprocity failure. I've > been doing my pinhole work exclusively (well, almost > exclusively) with this emusion for several years and > have found this general rule works very well: > > Meter your intended subject as if at f2 for an ASA 100 > film. Take the reading for f2. Add 10 stops of > exposure to that (remembering that adding one stop > means doubling the exposure time). If the resulting > value is 2 seconds or less, expose as indicated. If it > is 2 seconds to 5 seconds, multiply it by 2. If it is > 5 seconds to 10 seconds, multiply it by 5. If it is 10 > seconds or more, multiply it by 10 and then again by > 2. That's all. The only other thing to remember is > that for values on the edge of the ranges (that is, 5 > seconds and 10 seconds) it' s better to err on the > side of the longer exposure. Also, this system seems > to become less reliable with meter values of one > minute or more after adding the ten stops. Such > readings usually need another one or two stops of > exposure. > > For the record, I've used this system succesfully with > pinhole cameras with pinholes equivalent to about > f=125 to about f=500. Getting to know one camera and > one emulsion by taking lots of pictures with the > combination is the best way to learn how to adjust for > reciprocity (in my opinion). After a while you'll put > away your light meter. You'll just know what the > exposure is. > > Give it a try. > > Colin > > > > > Can I find that Ilford reciprocity failure table on > > the web? On which sites > > ? Is there a similar table for T-max 100 ? > > > > Ricardo. > > > __________________________________________________ > Terrorist Attacks on U.S. - How can you help? > Donate cash, emergency relief information > http://dailynews.yahoo.com/fc/US/Emergency_Information/ > > _______________________________________________ > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??????? > unsubscribe or change your account at > http://www.???????/discussion/ >
