You're right. I've experienced that myself. The two longest exposures
end up being almost identical. I believe that was the case with this
shoot, although it was so long ago I can't remember clearly. However, I
remember what happened 25 years ago better than I remember what
happened yesterday :-).
Paul
On Aug 23, 2005, at 11:59 PM, J. C. O'Connell wrote:
sounds cool. One thing to remember though
is that once you get into the reciprocal
failure mode of a film and want to use
time bracketing, you wont get linear time progressions
for equivilant exposure changes. ( i.e.
the 2.5, 5, 10, 20 sequence will not yield
equal steps in exposure change). This varies
from film to film but in general the longer
the time, the even longer the time you
will need for the same change (increase)
in exposure.
For example I used to do some LF lens tests
across the house indoors at night with tungsten
room lighting, my exposures were typically
20 second at f16, 60 seconds at F22, and 5
minutes at f32 for exact same density (exposures).
As you can see the time increases arent linear.
I think this was on TMAX400 if I recall correctly
and I am sure it will vary from film to film...
I had to find this out by trial and error
sort like what you did...But once I knew
the correct compensation times it was easy to repeat.
jco
-----Original Message-----
From: Paul Stenquist [mailto:[EMAIL PROTECTED]
Sent: Tuesday, August 23, 2005 11:30 PM
To: pentax-discuss@pdml.net
Subject: Re: Survey: Your Most Unusual Shot
I'm game. I've shot a lot of weird things and attempted some rather
difficult shots, but one comes to mind immediately. It was almost 25
years ago, and I was working for Hearst Magazines in New York. We were
running an article about Ford's propane engine cars in Motor Magazine,
and the editor decided we had to have a picture of a propane flame for
the cover. I bought a propane torch and various tips. I found that the
paint scraper tip gave me a nice looking, broad flame. To record the
flame on film, I obviously had to eliminate all other light, so I set
the torch up in my garage after dark. I tried to shoot all our covers
on 4x5 in those days, so I set up my Speed Graphic and loaded ten film
holders with ektachrome 64. To get the flame large in frame, I had to
extend the bellows beyond the 1:1 position, so that increased exposure
considerably. My meter reading and teh macro correction indicated a
very long exposure, so I had a reciprocity failure to factor in as
well. My calculations with the Kodak Photoguide wheels indicated an
exposure of about 10 minutes. To bracket in half stops, I'd half to do
2.5 minutes, 5 minutes, 10 minutes, 15 minutes, and 20 minutes.
Unfortunately, my cable release had no lock mechanism, so I had to hold
the shutter open, while standing in the pitch dark garage. I did
exactly that for over ah hour. The 20 minute exposure was best: a nice
blue flame above a glowing red metal nozzle. A difficult and tedious
job, but well worth the effort.
Paul
On Aug 23, 2005, at 10:26 PM, [EMAIL PROTECTED] wrote:
Okay, I am kind of tired of the large print discussion (and thank
goddess the
political thread has died), so LET'S DO A SURVEY!!!
Also, it might provide me with some inspiration since I am sort of
uninspired
photography-wise these days.
I do realize I still owe people the results of the exposure survey and
I've
got it around here somewhere, but I have to get a new cartridge for my
laser
printer so I can print out all the answers so I can tally them. But I
will do
that, I promise. Maybe when this survey is done.
Well, this isn't so much a survey, actually, as just a sharing thing.
Because
I don't imagine that that many answers will be the same. But if they
are, I
will tally them. :-)
I hope people like it and want to participate. It's sort of like where
is the
weirdest place you have ever done it...
Q. What is the most unusual subject matter you have ever shot? The
most unique? Or the weirdest? Or simply the subject matter that you
have had the hardest time "capturing" (either because it was hard to
get to, or timing, or movement, or whatever)?
Please expound.
A.
TIA, Marnie aka Doe
