DIY Printing Exposure Meter Plans

[Jack Fisher]

A "Build-it" Printing Exposure Meter was described in Photography How-To Guide in 1978. it is simple to build, and back then used only $10 in parts. I built one and have used it for a number of years, until I replaced it with a commercial model. Included in the article are instructions to build as well as how to use. It is especially useful when making different size enlargements from the same negative. ...saves test strips.

Familiarity with small electronic parts and a 25 watt soldering iron is helpful.

I have the 13 page article now on a PDF file about 4mb size, and am willing to email it to anyone who asks. PM or email to:

jfisher (at) plateautel (dot) net

Photos of my unit can be seen here:

http://www.flickr.com/photos/12074354@N00/4727226647/in/set-72157624348319506/

Jack

[emmett]

OMG I made that from that same article in 1978! The toughest part was finding all the parts. I remember having to go to 4 different Radio Shacks. Ah the days before the internet.

[jvpflaum]

Hello Jack,
Is your offer still open? I would like a copy of the print exposure meter plans. I had a copy of that book years ago and it had some great darkroom projects. Can not find a coyp the the publication any where.
Starten up a dark room again and would like a meter to ct down on the test prints.
The OP Amp IC and the photo cell are available on e-bay. A lot better than running to several Radio Shack Stores.
Thank You
John

[ic-racer]

I made one similar in about 1974 with RadioShack parts.(timer also)

http://img.photobucket.com/albums/v670/ic-racer/timer.jpg

[jvpflaum]

Ic-Racer - Nice job. I like the use of the old style metal boxes and a real meter. Do you still have the plans for the exposure meter? Also a question - does your exposure meter do "integrated" or averaging readings or just spot readings?
In to old days some meters could give you an average exposure reading by placing a thin plastic diffuser under the enlarger lens or over the photo cell.
I can not believe we have to back in time just to make a good crisp B&W print that will last more than 30 years. Digital is great instant pictures but - only good for 20 years if stored properly. Looking through our baby photos of our first son, who is now 33, good color prints have "faded", but the B&W work I did back then looks like new.

Thanks - sorry for the rambling.

[ic-racer]

I made the exposure meter circuit from scratch, but it is just a 9v battery, potentiometer, switch, galvometer and CDS cell all in series. I had a diffuser that I placed over the lens to make readings. Amazingly I found that exposure meter in a box of stuff just the other day, though the timer is long, long gone.

The timer circuit was probably similar or identical to this one:
http://www.8085projects.info/image.asp?picture=555%20based%20darkroom%20timer%20circuit%20(a).jpg

[ic-racer]

If I need to do any baseboard metering I use a color meter. Just about all of these have a white channel. These things seem to be pretty inexpensive these days. Someone tried to give me a box of them, but I just picked out a nice Soligor/Melico SM20 and I use that.

http://www.jollinger.com/photo/meters/other/color_analyzer_roundup.html

[Tim k]

If I need to do any baseboard metering I use a color meter. Just about all of these have a white channel. These things seem to be pretty inexpensive these days. Someone tried to give me a box of them, but I just picked out a nice Soligor/Melico SM20 and I use that.

http://www.jollinger.com/photo/meters/other/color_analyzer_roundup.html

At the risk of hi-jacking the thread, how would you use the white channel? I assume we're talking black and white printing. I have acquired a couple of meters, and have absolutely no idea what to do with them.

[ic-racer]

At the risk of hi-jacking the thread, how would you use the white channel? I assume we're talking black and white printing. I have acquired a couple of meters, and have absolutely no idea what to do with them.

On the Melico (and some others, like some Beseler models that operate identical) there are a few different ways to use the white channel as an exposure meter.

1) Null meter
In this case, after the final print is made, turn the white channel calibration knob to zero the meter. Then for your unknown negative, adjust the aperture until the meter is zero again.
2) Read the Scale
The Melico has a calibrated scale for the needle. Once calibrated to a good print, you can read the exposure change needed when the needle is off the zero mark.
3) Use the calibration knob
Probably the least accurate, but the calibration knob is marked in density units. So, you could zero the meter with the calibration know and use the change in density units read off the White knob to calculate the new exposure time.
4) You can also obtain the density range of a negative by reading right off the meter scale in density units after interrogating the high and low values with the spot probe.

Page 8 of the PM2L manual goes into detail in using the meter for B&W:
http://www.125px.com/docs/manuals/darkroom/beseler/Beseler_PM2L_Manual.pdf

[Tim k]

Thanks for the info. Seems simple enough. I'm off to read the manual.

End hi-jack