Stouffer's 4x5 step wedge for exposing negative?

[jvuokko]

Salihomba, that's awesome. Never thought that!

jeroldharter, I don't open to maximum aperture in the fear of uneven light.

One thing that I haven't tried is to fit smaller diffusion chamber and try to use 2.8/50mm enlarging lens. It's two stop faster than my 6x9 lenses and perhaps smaller chamber also gives brighter light.

These enlargers are Meopta Magnifax 4 with multigrade diffuser head and condenser are cheap and lightweight Meopta Opemus 5 (only up to 6x6).
I have never before considered them slow or dim enlargers, especially Magnifax 4 gives too strong light for normal printing, I have to adjust light intensity to lower settings usually.

[jvuokko]

Actually, how should light metered?

From Davis' book I understand that incident light meter with semiphere removed should give EV 4 readings when pointed directly upwards to the lens and light?
Perhaps I missunderstood, that way I got EV 10 readings for ISO 100 when the step wedge + negative got about right exposure.

With hemisphere on it's place I got EV 2.

From glossy photograph paper at the enlarger's easel, I got EV 5 readings for ISO 100 with a spotmeter when exposure seems to produce nice scale to the negative.

The right reading should also be able to meter thru the step wedge's step 10 when a spot meter is pointed directly upward, but it's bit hard.


Acrylic plate and strong back light is easier to meter, just meter light thru acrylic plate and add 5 stops overexposure and there it is.

[ic-racer]

What are other options? Use of darkroom and enlarger, but as I use also orthopan and full orthochromatic films, the color of enlarger light source can affect results too much.

What are you trying to accomplish?

If you are comparing a single film across a number of development times or development menthods to determine gamma the enlarger light color will not mater. The exposure time and ev will probably not matter either, unless the film has very bad reciprocity characterstics and the time is greater than 1 sec or less than 1/1000.

If you intend to compare the relative speed of one film to another or set up an independent ISO testing station, then enlarger light color will have an effect, but that type of test might be better done with an in-camera test (like a zone I, 0.1 log d test).

[jvuokko]

What are you trying to accomplish?

If you are comparing a single film across a number of development times or development menthods to determine gamma the enlarger light color will not mater. The exposure time and ev will probably not matter either, unless the film has very bad reciprocity characterstics and the time is greater than 1 sec or less than 1/1000.

Normal development calibration, but the film is not sensitive to the red light. Althought I don't thing it's a big problem as long as I get curves. I can always figure out the real speed later in normal daylight test.

Regarding the enlarger problem; I found easy solution. Just took off the lens and now I have a lot of light that is even enough
Actually found this one from the btzs's web site's forum where Davis has wrote same tip to someone who had similar problem with too dim enlarger.

Now I am glad that I have light intensity adjustment in my enlarger's head. I can easily set the level of light low enough that it's suitable also for faster films

[younghoon Kil]

then use your camera/lens combination, focus to infinity, and then place the camera/lens close to a window with semi transparent glass, make sure that sun light on the glass is even and bright.

lens toward the window. meter the semi-trans glass, put it on Zone X, then place your film holder, pull out slide out, insert lami-slide in, expose, pull out lami-slide, insert normal slide, done! next film!

When I want to shoot a Stouffer's 4x5 step wedge(TP4x5-21 or TP4x5-31) regardless of time and light conditions, can I shoot it towards the LED Video Light instead of the window?

- https://www.amazon.com/gp/product/B07WD6QXMJ/

[esearing]

When I want to shoot a Stouffer's 4x5 step wedge(TP4x5-21 or TP4x5-31) regardless of time and light conditions, can I shoot it towards the LED Video Light instead of the window?

- https://www.amazon.com/gp/product/B07WD6QXMJ/

Most light sources would likely have a hot spot in the center. Use something to diffuse the light so it is evenly illuminated from center to corner. A piece of white poster board well lit will achieve same result.

[younghoon Kil]

If I can use such a High CRI LED panel, I will place an acrylic plate in front of the LED panel.
Thanks.

[bnxvs]

Wow. You spend so much time building tools for easily exposing sensitograms. In my humble opinion, it is much easier to spend time once and make a simple sensitometer. All you need for this - an arduino (Uno, Nano etc), a piece of LED strip (preferably high CRI), a i2c light sensor module (such as BH1750 or max44009), some buttons, a piece of milky white acrylic glass and a mosfet transistor key. And, of course, the stouffer's scale (T2115 for example).
You can precisely set the illumination (within 1 lux) and any, even the shortest "shutter speed" (up to nanoseconds), since the response time of the LEDs and the mosfet is very short.
Also, within certain limits, you can adjust the illumination using PWM.
Combining illumination with "shutter speeds" (more precisely - LED turn-on time) in certain proportions, you can get very accurate parameters of illumination both in units of lux per second (H) and the logH, as you wish.
p.s. To evaluate the results of density measurements with a densitometer, you can use the online script that I made for this: https://bnxvs.shinyapps.io/cc_film_plot/

[Ricardo Maydana]

Una diapositiva de cuña de paso para pruebas. cámara con lente de 210 mm enfoca en el infinito y luego la coloca cerca de la placa acrílica junto a la ventana, luego trata la placa como Zona X, mide y dispara.

La cuña de stouffer va dengro del chasis o en la camara antes del chasis eso te permite hacer varias sin tener que hacer un sancwich con la cuña

[s389]

can we use tracing paper instead of acrylic plate?

Another solution is to use Linhof holders that are made for negative or glass plate and are built with a spring.