Are you a macro maniac or just interested in larger than life shots of your miniatures collection? There’s no need for blurry, out of focus pictures anymore as Mandi shows you how to get up close and personal with the new LOMO LC-A Instant Back+!
One thing you might have noticed when dealing with instant backs (be it the Diana or Lomo LC-A one) is the little close-up lens in the package. The instructions say to install it between the lens and the instant film. So far, so good.
But what happens when you forget (by chance or on purpose) to put that in?
Taking a closeup shot using the LOMO LC-A with the regular distance settings would normally result in a blurry image. It can be nice, for sure, but you’re probably looking for a sharp image this time around. This is where physics and the accompanying math come into play. To make a long story short: without a correction lens, you can set the camera to infinity and shoot something from a 9-10cm distance to get a sharp image.
The Lomo LC-A has a 32mm lens. This number, the so called focal length, says: when you set focus to infinity (before you ask “how can you focus on infinity?”: take 15 billion kilometers, in our case that should be close enough to infinity…) the image taken of the object at this distance is perfectly projected on screen or film situated 32mm behind the lens.
You might have noticed that when setting the focus to a closer range, the lens moves away from film towards the object. The same thing happens when installing the instant back, but instead of moving the lens away from the film, you move the film further away from the lens, therefore you have to get closer to whatever you take a shot of. Now that is a lot of hocus-pocus, but some clever people did the calculations already and left us with a nice formula:
1/S1 + 1/S2 = 1/f
S1 is the distance from the object to the lens, S2 the distance between lens and film and f is the actual focal length of the lens. Measuring the extra distance that the instant back construction causes, we get S2=48mm. f is still 32mm, so:
1/S1 + 1/48 = 1/32 → S1 = 96mm
…which is the perfect distance for an object to project a sharp image (when the Lomo LC-A is set to infinity). If you’re into math, you can also calculate the perfect Instant close-up object distance when the Lomo LC-A is set to 0.8m!