Can someone explain what a macro lens is

[sma1mom]

My husband and I are arguing over what a macro lens is. We don't really get what a macro lens really is. How does a 100 mm macro differ from a 100 mm? I understand that it's a 1:1 ratio, but does that mean that what you see in the veiwfinder is different on the 2 different lenses or does it just mean that you can focus closer? Can someone explain or post a link to help us understand.

[Mark_Cohran]

A true macro lens is capable of producing an image on the sensor or film that is equal to the size of the subject or larger (1:1 or greater). So if your subject is 20mm tall, the image on your sensor will be such that the subject projected on the recording media will be 20mm in height as well (or larger). Additionally, macro lenses are generally optimized for a edge-to-edge sharpness (flat field).

[_aravena]

Focuses closer...

[yogestee]

sma1mom,,,,a true macro lens is a lens that can focus down when the image size is equal to the subject size-- 1:1.. 2:1 for example is when the image size double the subject size... 1:2 is when the image size is half the subject size..

For example a button that is 6mm diameter will be 6mm diameter on a 35mm negative..Makes sense??

Jurgen

[Canon Soldier]

ok this all doesnt make sense. Are yall saying the thing that is focused in the frame is life size, or everything, because if everything is double the real size, as in 2:1, then would it just be the same. I still don't get 1:1 vs 1:2 vs 1:8.

[yogestee]

ok this all doesnt make sense. Are yall saying the thing that is focused in the frame is life size, or everything, because if everything is double the real size, as in 2:1, then would it just be the same. I still don't get 1:1 vs 1:2 vs 1:8.

1:1 is when the image size is equal to the subject size.
1:2 is when the image size is half the subject size.
1:8 is when the image size 8X smaller than the subject size.

2:1 is when the image size is double the subject size.

[Greg_C]

ok this all doesn't make sense. Are yall saying the thing that is focused in the frame is life size, or everything, because if everything is double the real size, as in 2:1, then would it just be the same. I still don't get 1:1 vs 1:2 vs 1:8.
Most macro lens have markings on the barrel or in the DoF window that specify the magnification ratio. ie 1:1, 1:2 etc. If you set the focus manually on 1:1 then the object you look through the lens at will be at 1:1 on the sensor. The lens won't always be at exactly 1:1 if you use it on autofocus.

A macro lens is always a exceptionally sharp lens, often sharper than some of the other primes lenses on offer. You can often see Macro written on zooms, all this implies is that at some point on the focal length it can focus 1:1. A true macro like the 100mm macro will always give much better results than a zoom stamped macro.

[Canon Soldier]

1:1 is when the image size is equal to the subject size.
1:2 is when the image size is half the subject size.
1:8 is when the image size 8X smaller than the subject size.

2:1 is when the image size is double the subject size.

yea but what does this mean?!? What do you mean by image size and subject size. Can anybody give an example of a pic taken at 1:1 and a pic taken at 1:3 or 1:4 or 1:5 etc.

[Greg_C]

yea but what does this mean?!? What do you mean by image size and subject size. Can anybody give an example of a pic taken at 1:1 and a pic taken at 1:3 or 1:4 or 1:5 etc.
One of the easiest ways macro photographers work out what magnification ratio they are working at is to take a photo of a ruler.

If I take a shot of a ruler with the lens set at 1:1 (see my post above) then the image on the sensor represents exactly the same measurement as the ruler. If the lens is at 1:2 then the image is smaller than the real life subject.


Remember when you look at the images on a monitor it is easy to blow them up and look at them larger than they are in real life.

Sorry, I don't have any samples to post.

[yogestee]

yea but what does this mean?!? What do you mean by image size and subject size. Can anybody give an example of a pic taken at 1:1 and a pic taken at 1:3 or 1:4 or 1:5 etc.

Ok Canon Soldier,,,subject size is the actual size of the subject,,the thing you are photographing..

Image size is the projected image of the subject onto the media you are using whether it be digital image or film..

[AirBrontosaurus]

Here's a quick and dirty example:

At 1:1

http://farm2.static.flickr.com/1224/931637154_03fe19ae79_b.jpg

Notice how the ant fills the entire screen? That's because this ant was smaller than my camera's sensor. So, at 1:1 (life-size), the ant was able to fit his entire body into the picture.

However at 4:1...

http://farm1.static.flickr.com/220/496672276_6bc869d747_b.jpg

This shot was taken at 4 times life size. Since the ant is not 4 times smaller than my sensor, only a small part of him could get in the shot (in this case, his head). So, the higher the magnification ratio, the "larger" your subject appears on the picture.

Does that make sense?

[Canon Soldier]

hmmm... ok its making sense. thats so cool. So if i took an image at 1:8 like many telezooms, the subject wuld be teeny?? Then wouldnt it always be good to have 1:1? Also, you say it is life size, but i guarantee that ant aint that big, it would be like 3 inches long! I apologize for my ignorace, dont lose patience! yet

[nadtz]

hmmm... ok its making sense. thats so cool. So if i took an image at 1:8 like many telezooms, the subject wuld be teeny?? Then wouldnt it always be good to have 1:1? Also, you say it is life size, but i guarantee that ant aint that big, it would be like 3 inches long! I apologize for my ignorace, dont lose patience! yet

You are confusing 'life size' with 'output size' The ant was 1:1 with the sensor, the resulting image is significantly larger, thus making the ant larger. If you made the jpg 1:1 with the sensor the ant would be life sized.

[WMS]

It is the size of the image as projected on the film or digital sensor which is what counts. Macro is an old term dating from the days when almost all macro photography was taken with a box camera and bellows.

Wayne

[jra]

It sounds like you've got some good advice here. Just to add my bit, life size means that the image size projected on the sensor or film equals the size of the subject in "real life". Of couse, when you view it on your monitor or print it, it will be even larger. One down side of macro lenses is that they are often slower to focus mostly due to the fact that the lens has a much larger focusing range to cover. Some lenses offer a focus limiter switch if you're using the lens in non-macro functions to improve the focusing speed.

[sleibrand]

According to a Tamron rep I met last summer, lens manufacturers put "Macro" designations on any of their lenses that achive 1:3 or higher even though the technical definition for macro used to be 1:1 as mentioned above. So a Tamron 28-75 EX DG IF Macro isn't a true macro lens. Same with many of the 70-300's labeled with macro. The way a lens becomes a macro lens is by allowing you to focus closely enough that a small object will completely cover your sensor. For a 100mm lens, this means that it focuses as closely as about 6 inches where it will have 1:1 magnification. A 150mm macro lens should focus to 9" where it will have 1:1 magnification. A 50mm lens would achieve 1:1 at 3". The distance where you get 1:1 is normally called the working distance of the lens.

In practical terms - the sensor size on a Canon crop camera is about 23mmx15mm. So if you take a picture of a 20mm bug at 1:1, you'll have a bug filling the width of the frame. If you print it at 4x6, you'll have a 6" bug. at 20x30, you'll get a 30" bug.

[apersson850]

Yes, and if you print the image at 23 * 15 mm, you get an actual size bug.

"Macro" on zoom lenses is the closest focusing distance, that's all.

Canon actually sells a "real" macro lens that's not. The EF 50 mm f/2.5 compact macro lens focuses down to 1:2 only. You can buy an additional life-size adapter, to put between the camera body and the lens, to achieve 1:1.

Other lenses, like the EF-S macro 60 mm f/2.8 USM focuses all the way between infinity and 1:1 reproduction without accessories.

Another thing with many macro lenses (briefly mentioned in one post above) is that they are often optimized for high quality at short distances, where regular lenses are usually optimized at infinity. Macro lenses also stress good correction for getting a flat depth of field, instead of the spherical depth of field you get from normal lenses. This is to make the macro lenses better for copy work, where you take photos of flat objects.

[Cassie]

Some lenses offer a focus limiter switch if you're using the lens in non-macro functions to improve the focusing speed.

Thanks for this thread good info.

So to clarify if I'm shooting non-macro subject I would put the switch on full? And if I'm right on top of the subject I would use the closest focus distance? Just recently got my first Macro Lens and want to make sure I'm using it correctly ;)

[Rachel B]

This is a great thread!

[Mark_Cohran]

Thanks for this thread good info.

So to clarify if I'm shooting non-macro subject I would put the switch on full? And if I'm right on top of the subject I would use the closest focus distance? Just recently got my first Macro Lens and want to make sure I'm using it correctly ;)

What do you mean "switch on full?" If there is a focus limiter switch you would want to set the limits appropriate to your subject distance.

[Cassie]

Thanks Mark. There are 3 distances, full, 0.52m-infinity symbol, and 0.38-0.52m. I'm just wonderding if I'm doing say a portrait should I have the switch on full mode. But I guess like you said just set the limit appropriate to subject distance.

I guess I'm not exactly sure what "full" means, lol

[Mark_Cohran]

Thanks Mark. There are 3 distances, full, 0.52m-infinity symbol, and 0.38-0.52m. I'm just wonderding if I'm doing say a portrait should I have the switch on full mode. But I guess like you said just set the limit appropriate to subject distance.

I guess I'm not exactly sure what "full" means, lol


I've never seen a "full" position, but from your description it sounds like that position allows focus over the full distance scale.

Those switches are designed to limit the distance range the lens will attempt to focus to as to allow the lens to focus more quickly when shooting subjects that are further away.

[Cassie]

Thanks for the explanation. Since the weather is getting better I guess I can go out and play with some macro now!