In February I am giving a talk on photography to the NH Adobe User’s Group. As part of that, I’m roughing up some graphics to use in my brief explanation of photography terms. Hopefully I will find time to do this on an ongoing basis before the talk, so I can get my reader’s feedback. Please let me know if the graphics, and explanations make sense. Thanks!
This will come after descriptions of camera parts. So there are not some labels on the camera body. I felt this topic would take the longest to create graphics for, and result in graphics for other topics. So it’s a bit out of order.
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There seems to be a misconception that macro photography just means being close to your subject. In fact, by definition, macro photography actually deals with the size that an image is recorded on your particular medium, either film, or CCD/CMOS. From wikipedia.org:
Macro photography is close-up photography; the classical definition is that the image projected on the “film plane” (i.e., film or a digital sensor) is close to the same size as the subject. On 35 mm film (for example), the lens is typically optimized to focus sharply on a small area approaching the size of the film frame. Most 35mm format macro lenses achieve at least 1:2, that is to say, the image on the film is 1/2 the size of the object being photographed. Many 35mm macro lenses are 1:1, meaning the image on the film is the same size as the object being photographed. Another important distinction is that lenses designed for macro are usually at their sharpest at macro focus distances and are not quite as sharp at other focus distances.
Huh?
It’s actually pretty simple. If you think of it in a visual way. I’m going to use film plane regardless of the fact I actually shoot in digital, its still the same thing. Lets look at it graphically.
If I use a lens that can reproduce at a 1:1 ratio, then the image of the item is recorded on the film plane at actual size. Take the image of the Lego soldier on the right to be the real world. Using 1:1 you see on the left (image cropped to fit in camera shell) that only some of the soldier will be in the photo. What is captured in the photo will appear to be very large when viewed. Directly bellow is an example of what recording at 1:2 would look like. The image recorded is half the actual size of the object.
For an extreme example, bellow is what recording 2:1 would look like. The image would be recorded at twice the actual size.
Who cares?!
At first it might not be so evident why this really matters. It all has to do with resolution. Given using the same camera for every photo, you can’t go in and change the physical size of your sensor (excluding changing to a medium format camera, etc), you have to change the projection of the image. If you make the projection of the image larger, then you have the ability to record more detail. Lets take a look at an over simplified, and a bit exaggerated visual.
In this first image, lets pretend that we’re looking at how a 1:2 ratio would look. The image on the left is like viewing the image in real life. The super imposed grid represents the pixels of the sensor on your camera. Each one can only record 1 color. The image at right is what the sensor records. Take special note of the cross marks on the soldier’s chest.
Notice how not all of the detail is recorded. It looks pixelated, because it is. Now remember, I’ve manufactured these results, though I feel I’ve done them correctly and consistently, they are a bit overexerted to make the point simple.
Now lets take a look at an image if we were able to record it at 1:1 ratio. If you haven’t guessed it already, there is more detail.
Even though the sensor and resolution stay the same size, you are able to record more detail because the image is projected larger.
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There are other nuances to macro photography, like depth of field among other things. That will get covered in other parts. This snippet is just to explain why reproduction ratio matters. Please, comment and let me know what you think. It will help me help the attendee’s better. Remember, if you’d like to come, the meetings are open to the public, and we always enjoy new faces!
