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The exposure latitude of the film
If you want to take pictures with a Minox A, Minox AX or even a Riga Minox, you have to determine the exposure time yourself. However, the following considerations are also interesting for exposure with Minox B, BL, C, LX and EC. Either for manual exposure (except EC) in certain situations or when setting the ISO value.
Black and white films have always had a certain exposure latitude. Today’s color negative films have a very large exposure latitude compared to the 1950s.
Take a look at the following series of exposures made by Canadian Film Lab (canadianfilmlab.com) with four different modern negative films (Fuji 400H, Portra 160, Portra 400, Portra 800):
The exposure brackets range from an underexposure of 3 f-stops to an overexposure of 4 f-stops. Usable pictures were taken over a total of 7 f-stops!
What does that mean for us? Let’s take the exposure times of a Minox A IIIs. They range from 1/2 s to 1/1000 s, i.e. 9 f-stops. If we were to set a 1/100 s, we would still have usable images from 3 f-stops down (1/1000 s) to 4 f-stops up (1/5). So regardless of whether the optimum exposure time is 1/5 s or 1/1000 s, the image would still be OK at 1/100 s. That is fantastic!
It would be even better to choose 1/50 s, because the films would rather be overexposed than underexposed. However, the higher risk of blurring due to camera shake at the lower exposure time speaks against this.
However, you must keep the following in mind. Strictly speaking, this large exposure latitude only applies to the above-mentioned films tested. An Ektar 100 must be exposed more precisely. There I would assume -1 f-stop up to +2 f-stops. But at least 3 exposure stops. At 1/100 s this ranges from 1/20 s to 1/200 s.
Then, of course, you have to realize that especially in scenes with a high contrast range, the exposure latitude of the film is needed to capture the shadows and highlights of the individual image well. The image shown above in the test series had a low contrast range, so it was unproblematic in this respect.
It therefore makes sense to determine the optimum exposure time or at least to narrow it down a little. This brings us to the following methods.
Determining the correct exposure time
Estimating the exposure time
Gray wall, Android app “Lightmeter”
100 ASA, f 3.5 -> 1/2000 s
The easiest way is to estimate the exposure time using the Sunny 16 rule. As the Minox only has one aperture value, the application of the rule is simplified as follows. Exposure time in full sunshine (light value 15)
speed = 20 * ASA value of the film used
for example for a 100 ASA film:
20 * 100 = 2000 (1/2000 s)
Thank you xkaes from subclub.org for this method.
The screenshot on the right shows the Android app “Light Meter EV for Photography” set for Minox with a 100 ASA film. The measurement was taken on a gray wall with a cloudless sky in Germany in the morning at the end of September. The value corresponds exactly to the method above.
With a little practice, you can use the following table to estimate the exposure time yourself. The table applies to the Minox A IIIs, the Riga Minox and all other Minox models with an aperture of 3.5 and for films with 100 ASA. Other film speeds can be easily converted.
Measuring the exposure time
You can use a light meter for measuring, either an external one or a built-in one (with the Minox B, BL, C, LX or EC).
The most convenient way to measure exposure accurately is with a smartphone app. Since you always have your phone with you, this is the most practical way. There are many lightmeter apps, but I personally prefer this one.
The best and most stylish external light meter for the Minox A IIIs and the Riga Minox is the Minox exposure meter. It has been specially developed for the Minox A and manufactured by Gossen:
It even has its own viewfinder, which corresponds exactly to the Minox angle of view. It also mechanically stores the measured value. So you look at the scene through the viewfinder and press the metering button for 3 seconds. The pointer is then fixed and you can read off the value at your leisure.
If you decide to get one, you need to make sure that it still works properly. Although the devices are of very high quality, they could be inaccurate due to their age.