Can someone explain 1:1 to me?

I keep reading about macro photographers here striving towards 1:1 reproducction ratio. I am trying to figure out what is the big deal? As long as the subject fills the frame, isn't it all good? What is so special about 1:1? Also, I am a bit confused about the term 100% crop. What exactly does that mean?

:oops: Sorry for the dumb questions. But I keep seeing these terms thrown around, and I am not 100% clear on their meanings.

Hi John,

People use the term 1:1 because it conveys a meaning - about the size of the subject. It's an "old" term from the film days that describes the reproduction ration of the image captured to the size of the medium.

In the case of 35mm film (what most ppl use underwater) a 1:1 reproduction ration means that the subject photographed is 36mm across by 24mm tall.

Digital cameras with their all-different-sized sensors make the term somewhat more complicated to use, however, the main point is to convey the size of the frame captured.

When I say I captured a shot with my D100 that is 1:1 (35mm equivalent) I mean that the image captured shows something (a coral polyp for example) that is 36mm across x 24mm tall. Since I'm using an "old" standard (35mm equivalent) it doesn't matter how big the sensor on the D100 is, it could be 1.6x crop, 1.3x crop, or full frame - what matters is that the area photographed is 36mm x 24mm.

Cheers

James

So it is just the size of the subject being shot?

So why then do I hear that certain lens/port combinations prevent 1:1? Is it a matter of not being able to get close enough the the subject?

Man, I can't wait for the day that this stuff makes sense to me!

...goes back to reading the Wiseman Beginner Features...

Yes, it just describes the size of the area photographed. Certain lenses/ports can do it and others can't. It's a very useful term.

Cheers

James

1:1 doesn't actually refer to the size of the subject, it's the size of the image of the subject that is transferred on the film (or sensor, in a digital camera). 1:1 means the image that is transferred on the film is the same size as the actual object - so a 36mm x 24mm object will completely fill the frame. Of course, that's the image on the film - so when you make a print, it's considerably larger than life-size (a magnification of almost 9 when you make a 4x6 print!).

In general, yes, you just need the subject to fill the frame - but sometimes your subject is very small. 1:1 is frequently used as the differentiating point between "macrophotography" and just "close-up photography".

Being able to do 1:1 reproduction is generally a function of being able to focus your lens close enough to the camera to get this much magnification; shooting through ports and water also affect the apparent magnification and focusing, too.

Also if this helps, 1:1 can be referred to as "Life size" meaning that the image on a 35mm slide is the same size as the actual physical subject. 2:1 means the image is twice the size of the actual subject. 1:2 is half the size. Lifesize is relative to the medium the image is captured on.

A good model of these ratios can be seen by looking a Nikonos close-up/macro framers.

Also, I am a bit confused about the term 100% crop. What exactly does that mean?

I am not sure on this one?..... 100% crop means there's nothing left! right?

When you view an image on a monitor at its full size 100% (maybe to view small detail or sharpness) and you remove/crop a section of the image, that section has then become a 100% crop.

PauP

Also if this helps, 1:1 can be referred to as "Life size" meaning that the image on a 35mm slide is the same size as the actual physical subject.

When we display say a 6 megapixel (3000 x 2000 pixels) image on the web (say here on this forum) we need to resize it to something that will show up on the screen. I usually resize to 600w x 400t pixels for use on the web.

That means that each pixel in the original image does not show up in the 600 x 400 websized image. The pixels are "thinned out" so to speak.

A 100% crop would mean that you would take a section of the 3000 x 2000 image (say 600 x 400 pixels) and show that here at "full sized" or 100% crop. Meaning that we would see each of the pixels as it appeared in the full sized 6 megapixel image.

It's a good way to judge how good the image acutally is - seeing each pixel as it was actually recorded.

Cheers

James

What 1:1 means:

Take a photo of a nudibranch with your macro lens set at 1:1, using your old film camera.

Capture nudibranch and take it home with you.

When you develop the trannie, place nudibranch on slide. The actual nudibranch should be the same size as the image on the slide (unless they shrink when you take them out of the water).

Simple!

It's a bit of a pointless term when talking about digital images with APS-sized sensors.

It's a bit of a pointless term when talking about digital images with APS-sized sensors.

It's no more pointless than referring to lenses in their 35mm equivalent focal lengths. As James posted above, if he states "captured a shot with my D100 that is 1:1 (35mm equivalent)" he's still referring to the same size subject. By qualifying that it's in 35mm terms, a common frame of reference is established.