Interestingly, I could not find any mention of the hypothetical EP-1 and EP-2. Maybe they just didn't exist. Perhaps these were specialized piece products for science or the military.
A light meter was developed at NIKFI (Research Film and Photo Institute, established in 1929 in Moscow).
The device was produced by the forces of MKIP (Workshops for instrumentation, Moscow). Since 1956, MKIP has been part of the Moscow Design Bureau of Cinema Equipment.
I don't think it's worth explaining that in the USSR the specialized film and photo research institutes were primarily engaged in non-consumer goods.
MKIP exposure meters are considered professional instruments. Partly because in the early 50s, any electronic device for photography was professional by default. Amateurs used paper exposure meters.
But we will still pay attention to several unusual properties of the exposure meter below. I believe that belonging to professional equipment is not an empty formality.
By the way, I have not seen the decoding of the letter combination “EP” anywhere. Well, “E” is understandable, exposure meter. What does "P" mean? Maybe just "professional"? Although this option seems unlikely to me, in fact.
Model EP-3, apparently, was produced in 1951-1952.
With the hero of the EP-4 review, it's easier. The years of issue were engraved on the cases. My copy is dated 1953 and has the number 1109. Georgy Abramov's website contains photos with engravings of 1953, 54 and 55. Moreover, on one of the photos on the device of 1953, there is a very small number - 246.
From the photo, it is logical to assume that the EP-4 model was produced in 1953-55 and the production volume amounted to 2.5 thousand copies. This is a hypothesis.
Consider the device itself.
Exposure meter MKIP EP-4
EP-4 is a direct descendant of the 3rd model. All logic remained unchanged, but the designers did a good job of improving ergonomics.
The device has become more compact and lighter, although there is clearly a lot of metal under the bakelite covers of the case.
The body still consists of two parts that can rotate relative to each other. So, the light receiver can be turned to the side of the calculator (to measure illumination) or to the opposite side (to measure brightness). Or in general, point to the side (to expose from around the corner, why not).
We will consider the part of the body with the light receiver as the upper one. Two folding nozzles are fixed on the upper part.
One nozzle - from small lenses arranged in the form of honeycombs - for measuring brightness. This attachment narrows the coverage angle of the photocell to 45 degrees.
The second nozzle - with frosted glass - for measuring illumination.
The nozzles are fixed on the upper end of the device in a rotary mechanism. The currently used nozzle covers the light receiver, and the second one is simply fixed on the reverse side.
Quite simply and rationally. At EP-3, the nozzles were removable and this corny led to loss, which is demonstrated by the example of my copy.
The design of EP-4 was changed according to the principle “I carry everything with me”.
To change the nozzle, you need to take the flat metal lever (seen in the photo) to the opposite side of the device. The latches will release and the springs will recline the nozzles a little.
Next, they need to be turned to the desired side and pressed to snap the latch.
To measure low brightness, a metering mode is provided without nozzles and with a fully open aperture. In this case, the coverage angle of the photocell in the shaft is limited to about 100 degrees.
In this mode, the nozzles are placed on the sides of the device and they are held by springs at a certain angle. In old low-quality photos, I always wondered what kind of mustache it was.
Already mentioned diaphragm.
To expand the measurement range, MKIP exposure meters are equipped with a diaphragm in front of the photocell shaft. Unfortunately, the range of brightness change from 35–50 to 140–200 apostilles does not tell me anything. But I would venture to suggest that this range is somewhat wider than traditional amateur tasks.
The EP-4 aperture control is implemented more conveniently - through a small knurled wheel. The multiplicity factors from 1 to 200 are applied on the wheel.
Those. using a diaphragm, you can reduce the luminous flux up to 200 times.
The wheel is fixed with a click on the values of the coefficients 1, 2, 10, 20, 50, 200.
On the bottom of the exposure meter is a galvanometer scale and a rotating exposure calculator.
An arrow moves on a scale behind the glass. The scale is marked with numbers from 1 to 10.
The number indicated by the arrow must be multiplied by the magnification factor corresponding to the degree of aperture opening. This is how the conditional intensity of light will turn out.
On the left side of the device, next to the leash that releases the nozzles, there is a small black button, when pressed, the galvanometer needle is fixed at the current value. So, you can measure from a position in which it is inconvenient to look at the scale. Then fix the arrow and already turning the device to the desired side and look at the scale.
Let's move on to the calculator. Everything here is generally similar to EP-3.
There are 3 disks. From inner to outer it is:
I. Motionless. Aperture scale f1–f45 at the top and metering type indices (brightness, low brightness, illumination) at the bottom.
II. Mobile. Exposure scale from 1/5000 second to 2 minutes at the top and sensitivity selector lever.
III. Mobile. The sensitivity scale is from 4 to 2000 GOST units on top and the scale of conventional light intensity from 0.25 to 2000 parrots is on the bottom.
The top disk of the calculator is covered with a round plastic plate of a purely decorative nature.
Here, if you have not paid attention, I want to focus on some of the values \u200b\u200bmarked on the calculator.
Well, f1 and f45 are, although extreme, but not beyond reason.
How about a shutter speed of 1/5000, for example? Or a sensitivity of 2000 GOST units. 1953, for a second.
Even if we assume that the extreme 1-2 stops on the scales are made simply to understand how much we deviate from the measurement, resting on the performance characteristics of our equipment, all the same, the scales are redundant for a classic photo.
I assume that the light meter was also used (mainly?) for scientific (including military) purposes, where:
a) shooting scenes can have a huge spread in light intensity;
b) highly specialized shooting equipment and photographic materials can be tailored for specific non-standard tasks and have extreme characteristics.
Something like that.
The procedure for working with the exposure meter.
Suppose we are measuring brightness. In this case, a honeycomb filter is put on the light receiver.
1. Suppose, with the aperture open, the galvanometer needle went off scale. We begin to cover the diaphragm. Similarly, with k-th = 2. When turning the wheel to k-t = 10, the arrow stood in the middle of the scale. It suits.
2. Look at the scale. Unfortunately, my copy of the arrow no longer moves. Imagine that the arrow points to the number 5.
3. The number 5 must be multiplied by a set of 10, corresponding to the applied aperture. It turns out 50. This is the intensity of light in conventional units.
4. Rotating the outer (III) disk, look at the lower scales and set 50 opposite the “brightness” index on the inner disk (I).
Please note that the original factory-applied indexes have been manually corrected. Lines are manually drawn from the indices to the side - pointers. I think this was done with manual individual adjustment of the exposure meters.
5. Rotating the middle (II) disk we catch the sensitivity on the outer (III) disk into the frame. Let's say we have 65 GOST units.
6. Everything. In the upper part of discs I and II, expoparas lined up. For example, now you can shoot at f5.6 and 1/200.
Exposure meter MKIP EP-4 was completed with a leather case with a zipper. Compared to EP-3, the case has become more compact. However, this eliminated the possibility of using the device with the case partially removed.
In general, I find the use of the MKIP EP-4 light meter convenient. All controls are well thought out. Build quality is top notch. Dimensions are not so much higher than the usual values for such devices.
That's all I have about this incredibly interesting device.