I thought it might be worth returning to macro again immediately, having started touching on the subject yesterday.
When writing yesterday, I was feeling a little bit guilty about focusing so narrowly (if you’ll excuse my pun) on diopter lenses which generally only work with more expensive cameras such as SLRs / DSLRs / CSCs or bridge cameras. I thought, since this is a budget blog, I should return to the more accessible end of the market, using a mobile phone or cheap compact. In both cases, many have macro modes which allow you to get surprisingly close to small subjects.
“I was feeling a little bit guilty about focusing so narrowly (if you’ll excuse my pun) on diopter lenses which generally only work with more expensive cameras”
Here comes the science bit… I have included this under the title “Macro” because it is generally used to refer to close-up photography. Strictly speaking, though, the term macro isn’t right for most mobile phones or compact cameras, but it is the technical difference which gives these cameras some interesting properties.
Macro: A technical definition. – The ratio of the subject’s size on the film or sensor plane to its actual size is known as the reproduction ratio – macro normally describes reproduction ratios greater than 1:1.
So – now we’ve got this out of the way, why are mobile phones not macro? And what difference does it make?
Well, if you’re old enough to really remember 35mm film, you’ll know it was called this because each shot was taken on a 35mm wide piece of film. This is the same size as the sensor in expensive DSLRs. So, for a photo of a 20mm long insect to fill roughly two thirds of a photo, you would have needed a 1:1 (macro) reproduction.
Your mobile phone, though, will have a sensor which is considerably smaller, typically 1/3 inch, which is just 8.5mm across. This changes the reproduction ration from roughly 1:1 to 4:1. Don’t worry too much about the numbers themselves, but the point is that the insect you’re trying to shoot is now larger than the sensor you’re shooting it with, rather than the other way around.
Now, this reproduction ratio doesn’t mean you will actually be able to focus on something at very close distances (so you may struggle to shoot an insect which fills your whole frame, without some sort of adapter), but it will drastically increase the depth of field which can be achieved at the shortest distances your phone can focus at.
Here is an example, shot using my mobile phone, where you can see that nearly all of the flowers in the photo are in fairly sharp focus:
This increased depth of field is, in my opinion, generally a bad thing in macro photography, where you often want to remove distracting backgrounds with a tasteful blur. However, it does have some interesting applications, and you can have a lot of fun with them.
One of the great things about using a mobile phone is that you can often achieve greater depth of field from close-up of objects that otherwise would be impossible to keep in sharp focus when shooting at a short distance. This might be useful when shooting models, dolls houses, chess boards, or other miniature environments or landscapes. This can create some great fun opportunities to create some fun composite images. (See my articles on software such as PhotoScape or GIMP for some free applications to do this).
And the same shot after playing around with it in some software: