Reproduction ratio 1:1

meow wrote:

Gilbert1 wrote:

meow wrote:

He means (he thinks) the height of a full frame sensor is about the same as the height of a US quarter.

Actually, the classic definition of macro is that the scale is at least 1:1. It has been watered down, so now many people call any closeup a macro.

It's maybe easier if you think about film. Pretend you photograph, say, a small coin at 1:1 with a film camera. Then, when you have developed the film, you can put that frame over the real life coin and you will see that the picture of the coin will cover the real coin exactly. The object has the same size (in mm or inches) on the film (or sensor) as it has in real life. That's all it means.

Thanks. It makes it more clear to me. But my question then is, what is the big advantage of this? Because in a photo editing program I'm going to enlarge that little coin.

OK. Say you want a picture of a car standing 10 meters from where you stand and you can't get any closer. You shoot it with a 50mm lens (full frame eq). The car is pretty small in the picture so you crop it and enlarge the crop. Now you have a picture of the car filling the frame, but it will look pretty crappy, because the resolution will be low (few pixels). Had you instead used maybe a 200 mm lens, the car had filled the frame to start with and you could work with the full resolution image in your editor.

This is the same thing. If you want that coin to fill the frame, the quality of the photo will be better if you can accomplish that in the camera already.

There's nothing magical with 1:1. There are macro lenses that give you 2:1 or even more. It's mainly that 1:1 is the smallest scale for true macro, so manufacturers like to put that on their lenses. 0.9:1 wouldn't sell as well, I suspect.

Thanks.

What a very clear explanation. I'm very happy with it :-).

And how useful this DPReview forum is! :-). This way we can help each other.