longest exposure time.

[dreamingartemis]

Hi,
Just wanted to see if anyone has encountered situations where they had to exposed their negs using an enlarger for an insane amount of time because the negs were thick.

Let me start off first, I've only been doing this for a while but last night I was doing a printing job for a client and had been doing test strips. But for the life of me, I couldn't get the blacks or whites, just very faded grey. I keep increasing the time and even bumped the filter to 5 and still, it was dull grey.

I had reached 150 seconds when I decided "screw this, I'm pushing it to 200 seconds". Finally the blacks and white showed up correctly and so decided to do a full print, to my horror when the image showed up, while one side was properly exposure but the right side wasn't, I looked at the negs again careful and noted that there was definitely a tree there (the photos was a picture of 2 trees, the left tree was now properly exposed but the right one was under!).

Realizing that the only way I was going to get a properly a exposed print, I did a test on the right side. Even 200 seconds wasn't enough, it took up to at least 400 and the aperture on the lens was as wide as it could go! So now printing it was going to be a 2 fold operation, first I had to exposed the whole print for 200 seconds, then burn the right side (the second tree) for an additional 200 seconds!

So here I was, in the darkroom, with 2 cardboards dodging and burning the photo just to get it properly for over 400 seconds. While it wasn't something to talk about but I felt pretty happy at my first attempt and hopefully the client will be happy.

I've heard of people who had to sometimes exposed for 30 minutes before, has anyone does such a thing before? Or is there some other way I could have avoid the problem of doing such long exposure?

[Andrew K]

My record for printing black and white was 8 minutes for the basic exposure, plus a couple of minutes burning in...it was a bit of a crop though, as the enlarger was about 8ft from the printing paper

Although when I was prinitng Cibachromes I can remember having to use an enlarger with the wrong mixing box....45 minute exposure for a 60 x 40 inch print!

And maybe not the longest time, but around 15 years ago I ran a customer black and white lab, and was asked to contact print some glass plates...they were so dense that my exposures were done by firing a Metz 45 flash 5 times on manual from about 1ft to get a correctly exposed print....

[Vaughn]

Ten hours for a carbon print under a 175W merc vapor lamp. The previous 6 hour exposure was the better print, though.

I have worked on a silver print for 15 minutes -- but the base exposure was 25 seconds and the rest was burning in...

[dreamingartemis]

My record for printing black and white was 8 minutes for the basic exposure, plus a couple of minutes burning in...it was a bit of a crop though, as the enlarger was about 8ft from the printing paper

Although when I was prinitng Cibachromes I can remember having to use an enlarger with the wrong mixing box....45 minute exposure for a 60 x 40 inch print!

And maybe not the longest time, but around 15 years ago I ran a customer black and white lab, and was asked to contact print some glass plates...they were so dense that my exposures were done by firing a Metz 45 flash 5 times on manual from about 1ft to get a correctly exposed print....

Holy crap! 45 minutes and 5 minutes with flash for another job?! You should have charged for "work hazard"!

[dreamingartemis]

Ten hours for a carbon print under a 175W merc vapor lamp. The previous 6 hour exposure was the better print, though.

I have worked on a silver print for 15 minutes -- but the base exposure was 25 seconds and the rest was burning in...

.....how did you even determined the exposure time? Either you guessed it right or there was a lot of test strips.......10 hours......

[keithwms]

Well why not first dupe the thick neg onto something much more sensitive e.g. film. The problem here is that you have an ~ISO 3 material. You can dupe it to film and rate that film at whatever you please.

[NormG]

Do these long exposure times have any effect on the negative in the carrier? The reason i ask is that i recall somebody once commenting on an out of focus print because the negative warped due to the heat from the lamp.

[dreamingartemis]

Well why not first dupe the thick neg onto something much more sensitive e.g. film. The problem here is that you have an ~ISO 3 material. You can dupe it to film and rate that film at whatever you please.

I guess I could expose it to a medium format film instead that has a higher ISO rating. but I would have to do it in pitch darkness

[dreamingartemis]

Do these long exposure times have any effect on the negative in the carrier? The reason i ask is that i recall somebody once commenting on an out of focus print because the negative warped due to the heat from the lamp.

An excellent question....any takers?

[Vaughn]

Do these long exposure times have any effect on the negative in the carrier? The reason i ask is that i recall somebody once commenting on an out of focus print because the negative warped due to the heat from the lamp.

I would heat the negative up in the enlarger of about a minute (by turning the lamp on) and let the negative "pop". I then would start my exposure. I would keep the enlarger on during the 15 minutes or so of burning.

Others use a glass negative carrier.

The 10 hr exposure:

No test strips. My average exposure time was two hours. This particular neg had a large area of high density (sun on granite -- I could barely make out detail in the highlights with an intense light behind it) so I just exposed a bit more than a stop more -- 6 hours. The print looked very good, but I though I would add just a little more than a half-stop more exposure to see what it looked like...ten hours.