Enlarger light meter that displays lux or ftc?

[hal9000]

I would like to get a luxmeter for use with my enlarger to measure the absolute level of light (in lux or footcandles) hitting my easel with a small (i.e. 2-5mm) probe. The very nice devices from Heiland and RH Designs automate everything with automatic contrast / exposure times, but they do not have modes to just display absolute light readings (at least not the Heiland Splitgrade from experience and not the Analyzer based on my reading of the instruction manual). I know the Gossen Labosix digital S has such a mode, are there any other reasonably priced luxmeters with small probes that anyone can recommend? I don't need a built-in enlarger timer.
I intend to use it for determining exposures after calibrating paper/film on my own (I like to tinker ) and also as a simple measure of repeatability i.e. when changing enlarger height or for exposing contact prints.

 

[Chan Tran]

I really don't know of one. There are Lux meters outhere but were designed for higher level of illumination and the receptors are larger than 5mm.

 

[Mike Wilde]

An analyser timer like colorstar will get you there

I know you say you don't want a timer, but the guys doing the measuring in this situation are all after adjusting the time.

My Colorstar does many things, but one thing it does is read light intensity, either through the densitomiter function, or the ananlyser function. It has a 4mm aperture adapter. They used to also offer a 1mm adapter probe for slide duping,etc. I don't know if Lici/Spectrastar still has a stock of old parts to sell in this regard. E__ got me mine.

 

[Lee L]

I have a Beseler Analite 500 that reads out in seconds. It also has a table in the instructions to convert those readings to ftc when set at an ANSI paper speed of 100. I don't think the meter's been made for quite a while. The probe on it is about 2mm square. The instructions also have charts for estimating paper grades based on shadow and highlight readings.

I also have a Gossen Luna Pro F (a Profisix in EU if I'm not mistaken) with an enlarging attachment that has a larger probe (maybe a 4-5mm square). The Luna Pro F has a conversion chart to give ftc readings from incident mode readings, so I'm sure a little testing would allow you to build a custom conversion table. The -3 to +3 scale on the Luna Pro is very amenable to a quick reading of contrast range in the negative to get a good idea of what paper grade to use.

Lee

 

[Ken N]

ZoneMaster II has Densitometer mode

I intend to use it for determining exposures after calibrating paper/film on my own (I like to tinker ) and also as a simple measure of repeatability i.e. when changing enlarger height or for exposing contact prints.

The ZoneMaster II has a Densitometer mode that should suffice for this purpose. I do agree that changing head-height is probably the biggest "challenge" with the ZoneMaster II, but this would address this for you. However, even an inexpensive Ilford meter would help greatly in this aspect.

Ken

 

[Nicholas Lindan]

I would like to get a luxmeter for use with my enlarger to measure the absolute level of light (in lux or footcandles) hitting my easel with a small (i.e. 2-5mm) probe. ... I intend to use it for determining exposures after calibrating paper/film on my own (I like to tinker ) and also as a simple measure of repeatability i.e. when changing enlarger height or for exposing contact prints.

My company, Darkroom Automation, makes just this meter, it retails for $79 + postage. DigitalTruth is the net dealer for DA’s products if ordering by credit card. Details can be found at www.darkroomautomation.com

The meter reads in absolute stops of light: 9.99 stops is roughly max black on Ilford MGIV in 2 seconds; 0.00 stops is max black in 2048 seconds. The meters are calibrated to read absolute light intensity within 0.01 of a stop using a precision closed-loop Ulbricht light source. The meters measure in stops as that is the system used in photography for controlling exposure.

The meter also functions as a projection densitometer and can measure negative density as either absolute or above B+F. Density is displayed in 0.01 stop units, multiply by 0.3 to convert to OD.

As an aside: Lux and footcandles are measures of photoptic radiation. A true luxmeter has [or should have] the same spectral response curve as the eye. This is different from the response curve of photographic paper. Different papers have different spectral response and the response curve changes between chloride papers, bromide papers and multicontrast papers. For a given light source, meter and paper it is possible to calibrate the system and form a relationship of meter reading to print density. Darkroom Automation meters ship with calibration curves for Ilford MGIV FB, RC and FB papers when used with a tungsten enlarger light source - this data is easily converted to work with different light sources such as cold light and LED. The meter has the spectral response of a silicon blue cell.

Additionally lux, footcandles and lumens are in linear units such as watts and square meters but photographic materials have a logarithmic response. To make photographic sense of lux one must first take the logarithm of lux and then convert the logarithm from base 10 to base 2. The Darkroom Automation meter reads directly in Log[base 2] units - stops.

 

[ath]

Have a look at the Hauck or Kaiser Trialux series. They are calibrated to show the lux values. Kaiser has the manual on their hompage for download (in german) http://www.kaiser-fototechnik.de/. Don't know, if they are still availabe new.