The KIWI project – macro photography with Zenit 3m

A film photography project to discover the macro capabilities of an old Soviet camera that we bought for a few Euros. We learned a lot about macro photography on the way. Here is the project documentation (slow to download due to hi-res photos):

You can find the full review of the camera and lenses we used here. Below are the lessons learned during the project.

How to measure lens magnification

Magnification is a very important factor when we speak about macro lenses. We wanted to show the magnification of our old Russian lenses but there was no data on it; especially not on usage for reverse macro or with macro tubes. So we had to measure magnification.

To put it simple: lens magnification is the ratio of the size of the projected image on the film plane and the object’s real size.

Magnification = projected image size / object size.

And how to measure it? Just put a piece of translucent paper on the back of the film frame and focus the lens to a tape measure from the closest possible distance. Then you should simply divide frame width by the length of the tape measure visible in the frame.

Magnification = frame width / tape measure lenght in the frame

Modern macro lenses usually have a magnification ratio around 1. This means they can map the object onto the film or sensor in full 1:1 scale. If you make a print or display the image on a monitor you get an enlarged image of the object. Magnification greater than 1 belongs to the world of the so-called extreme macro photography. Our old lenses had an excellent magnification.

How to determine exposure compensation for macro tubes

It is a common misbelief that you don’t need exposure compensation when you use macro tubes. Wrong. You need exposure compensation. The reason is the change in the aperture value of your lens caused by the macro tube. Let’s see why.

The aperture value (or f stop) is the ratio of the aperture diameter to the focal length of the lens. For example in case of an 50mm lens with an aperture diameter of 25mm the f stop is 2.

f stop = focal lenght / aperture diameter

A macro tube extends the focal length of the lens. In theory, you can calculate the changes in the f stop values. The problem is that the formula is quite complicated. Besides, why calculating when there is a simpler method?

Take a camera with the macro tube and the lens you would like to use. Take another similar camera with a similar lens but no macro tube. Set both of them to the largest aperture. Turn them to the wall. Now stop down the aperture of the lens without macro tube until both finders show an equally lit picture. The difference in the aperture values of the two lenses is the exposure compensation you need.

(Of course, you don’t have to worry if you use TTL metering. It makes this whole thing unnecessary.)

The Zenit 3m 4 parts macro tube set we used in the project requires 0, 0.5, 1 and 2 stops exposure compensation. This applies for the Helios-44 and the MIR-1 lens as well.

Exposure compensation for reverse macro

You use the same lens just reversed. Do you need exposure compensation in this case?

The answer is: yes. The reason is the same as in case of the macro tubes: reversing the lens changes the focal length. Now let’s see the exposure compensation we had to use in this project for the reverse macro shots:

the Helios-44 required +1 stop more light
the MIR-1 required +2 stops

How to ruin a good shot with a bad shutter speed

Macro photography is challenging. You have to take lots of factors into account: magnification, working distance, exposure compensation, depth of field, etc. And the shutter speed is no exception. But what can be wrong with the shutter speed?

You measure light, calculate exposure compensation and select an appropriate aperture to have the desired depth of field: this is how you determine the required shutter speed. Normally. But not with a macro tube on.

Greater magnification rerquires narrower angle of view in a given target distance. Narrower angle of view equals longer focus length. No surprise that macro tubes and reverse macro increase the focal length of the lens. All in all, when you use macro tube or reverse macro, you generally have longer focal length so you should be aware of shutter times.

Problem 1: handheld shots

The reciprocal rule says: if your shutter speed is slower than the reciprocal of the focal length of your lens, you must use a tripod. If you choose slower shutter speed, your handheld shot will be blurry because of the camera shake.

For handheld pictures: shutter speed >= 1 / focal length

Having an 58mm Helios-44 normally allows you to take sharp hand-held shots with 1/60s. But not with macro tubes or reverse macro which increase the effective focal length. 1/250s worked for us if held steadily but we were more relaxed with 1/500s.

Problem 2: mirror flip-up shake

Early Zenit cameras are known to have very strong camera shake caused by the unsophisticated mirror flip-up mechanism. Longer focal length is more sensitive to camera shake. In general, there are 2 options to address this issue:

Use faster shutter speed
Use a mirror lock-up mechanism
Faster shutter speed is not always a viable option. And you have no mirror lockup on a Zenit 3m. What to do?

The solution is the self timer. Zenit 3m self timer flips up the mirror 1-2 seconds before it fires the shutter. This time is enough for the camera shake to be absorbed.

Special effect

No, this is not photoshop. Not even a trick with the shadows.

Zenit 3m inherited its shutter from the Zorki rangefinders. It’s a Leica-type rubberized silk courtain shutter made in the USSR. It’s not too reliable, especially not after more than 40 years. If it gets jammed it can produce interesting effects like this one:

If the shutter had worked fine this photo would have been underexposed like the left side. The second curtain slowed down in the middle so that part got more light and therefore was perfectly exposed. Then the second curtain got jammed for a while (not more than a fraction of a second) making the right part of the photo overexposed.

How do we know what the shutter did? It’s simple. We fired it after removing the film cartridge so we could see the slowdown and the jam.