What is an f-stop? Focal Distance? Why are my marks missing?
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- Created on Monday, 10 September 2007 04:36
- Last Updated on Friday, 14 December 2012 20:15
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A lens usually has two sets of numbers marked on the side: the f-stops and the focal distances.
The aperture opening is determined by f-stop readings; the wider the aperture, the lower the f-stop number. The distance to where the subject is perfectly in focus is called the focal distance. The f-stops are often numbered with the lowercase letter "f" in front of them as so: f2.8, f4, f5.6, f8, f11, f16 - but not always. If they are not "lettered", suffice it to say that they will still follow the standard f-stop settings and will have the standard f-stop numbers without the letter "f" in front of the numbers: 2.8, 4, 5.6, 8, 11, 16.
On a Lomo lens, the focal distance is almost always measured in meters (unless it has been remarked), so you'll want to use a metric measuring device if at all possible (a meter is 39.370079 inches).
Some lenses can focus very close to the subject, under 1/2 a meter, and a macro-focus lens can focus even closer. Focal distance markings usually have an infinity symbol, which is ∞, marked for the point where the lens can "see" everything after the focus point as in focus. Notice that the infinity symbol looks quite similar to the number "8" laid on its side.
Sometimes, on rare occasion, a Lomo lens will have its f-stops and/or focal distance numbers scratched off or they may even be non-existant (never marked). Sometimes the markings may be there, but the numbers are not correct. Possibilities for the scratched out or wrongly marked settings are that the lens may have been recalibrated (for whatever reason). Non-existant markings could be due to a test lens, or possibly even a pre-production lens. Suffice it to say that we're not always sure why the Russians did this, but these lenses do appear from time to time. Just make sure to buy your lenses from a reputable dealer and ask to make sure that the lens has its markings, and has been properly tested, and you can usually skirt this issue. But, if you do happen to get one of these unmarked/mismarked lenses (which usually sell for much cheaper than other Lomos - and could possibly even be a great buy), then you'll most likely need to send the lens out to a professional lens tech to get it remarked.