Lens magnification and reproduction ratio

millertime · 02-02-2012, 07:55 PM

I'm confused on what these terms mean, and how they relate to what you will see if you were to look through the viewfinder or compare the photo's side by side without being cropped from the same camera with two lenses of the same focal length but different magnification and reproduction values.

Lets use these two as an example using B&H's values under the specifications tab
Pentax SMCP-DA* 300mm f/4 ED (IF) SDM Autofocus Lens 21760 B&H
Sigma 300mm f/2.8 EX DG Autofocus Lens for Pentax 195109 B&H

Could somebody describe what is going to be different between between the two regarding these values?

Adam · 02-02-2012, 08:05 PM

Reproduction ratio and magnification should theoretically be the same.

The reproduction ratio is a ratio of the size of the image to the size of the subject. So, if you have 0.5x magnification, your reproduction ratio would be 1:2, I believe. On the B&H site they would quote this as "2.00". Another example: 0.25x magnification would be 1:4.

With non-macro lenses, the maximum magnification basically depends entirely the minimum focusing distance. The Sigma has a maximum magnification of about 0.14x (the number B&H lists, 0.01x, is wrong), while the Pentax is closer to 0.20x. Technically this means that you can stand closer to your subject when shooting it with the Pentax, meaning it will take up more of the frame. But since with tele lenses, the whole idea is to be able to be far away, these numbers really don't matter. Sure, a minimum focusing distance of 1.4m vs 2.5m is more convenient (and that's thanks to a different optical design), but then on the other hand you've got a slower aperture.

Macro lenses, on the other hand, generally have magnifications of 1.00x and reproduction ratios of 1.00, meaning that your print will be life-size.

millertime · 02-02-2012, 08:23 PM

That is what I wanted to know, thanks!

newarts · 02-02-2012, 09:39 PM

Originally posted by Adam

Reproduction ratio and magnification should theoretically be the same......
Macro lenses, on the other hand, generally have magnifications of 1.00x and reproduction ratios of 1.00, meaning that your print will be life-size.

I'm sure Adam meant to say the image on the sensor will be life-size for magnification/reproduction ratios of 1:1

Magnification on print = ReproductionRatio(PrintWidth/SensorWidth) = (magnification on sensor)(enlargement)

Last edited by newarts; 02-03-2012 at 07:30 AM.

RioRico · 02-02-2012, 11:08 PM

MAGNIFICATION is what happens at the sensor.
ENLARGEMENT happens in the display or print.

I must say that I've rarely run across the term "Reproduction Ratio", probably because it's rather ambiguous. Or maybe I'm just out of touch or sloppy or demented. But here's how I think of it:

Magnification is the ratio of the subject to the recorded image. Let's say I aim a Spotmatic at a ruler. The Spotty's frame is 36mm wide. If I shoot an in-focus picture that captures just 1-36mm, it's 1:1 (1x). If it captures 1-72mm, it's 1:2 (0.5x). If it captures 1-18mm, it's 2:1 (2x).

Enlargement is the ratio of the displayed image to the recorded image. If I take a FF (full-frame, 36x24mm) Spotty frame and make a contact print, it's 1:1. If I make a print (or project onto a screen) so it's 36cm wide, it's 10:1 (10x). If 3.6m wide, it's 100x, etc.

Reproduction Ratio could refer to either Magnification (how the image is captured) or Enlargement (how the image is displayed). I prefer the more specific terms. I'm picky about that.

Adam · 02-02-2012, 11:14 PM

Right- it's the image on the sensor. It all boils down to capturing more detail!

**baro-nite** · 02-03-2012, 06:28 AM

Originally posted by Adam

But since with tele lenses, the whole idea is to be able to be far away, these numbers really don't matter.

I must disagree. The short minimum focus distance of the DA* 200 and 300 lenses is a great feature. The point of a tele is to magnify the image, whether the subject is near or far. A couple of months ago I was doing hand-held shots of hummingbirds and the DA* 200 was perfect, as I was sometimes able to approach its minimum focus distance of about 4 feet, while the relatively short focal length made tracking and focusing on these fast-moving birds easier than it would have been with a longer lens from farther away.

02-02-2012, 07:55 PM	#1
millertime Junior Member Join Date: Feb 2009 Photos: Gallery Posts: 46	Lens magnification and reproduction ratio I'm confused on what these terms mean, and how they relate to what you will see if you were to look through the viewfinder or compare the photo's side by side without being cropped from the same camera with two lenses of the same focal length but different magnification and reproduction values. Lets use these two as an example using B&H's values under the specifications tab Pentax SMCP-DA* 300mm f/4 ED (IF) SDM Autofocus Lens 21760 B&H Sigma 300mm f/2.8 EX DG Autofocus Lens for Pentax 195109 B&H Could somebody describe what is going to be different between between the two regarding these values?

02-02-2012, 08:05 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Reproduction ratio and magnification should theoretically be the same. The reproduction ratio is a ratio of the size of the image to the size of the subject. So, if you have 0.5x magnification, your reproduction ratio would be 1:2, I believe. On the B&H site they would quote this as "2.00". Another example: 0.25x magnification would be 1:4. With non-macro lenses, the maximum magnification basically depends entirely the minimum focusing distance. The Sigma has a maximum magnification of about 0.14x (the number B&H lists, 0.01x, is wrong), while the Pentax is closer to 0.20x. Technically this means that you can stand closer to your subject when shooting it with the Pentax, meaning it will take up more of the frame. But since with tele lenses, the whole idea is to be able to be far away, these numbers really don't matter. Sure, a minimum focusing distance of 1.4m vs 2.5m is more convenient (and that's thanks to a different optical design), but then on the other hand you've got a slower aperture. Macro lenses, on the other hand, generally have magnifications of 1.00x and reproduction ratios of 1.00, meaning that your print will be life-size. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

02-02-2012, 11:14 PM	#6
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Right- it's the image on the sensor. It all boils down to capturing more detail! Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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02-02-2012, 08:23 PM	#3
millertime Junior Member Join Date: Feb 2009 Photos: Gallery Posts: 46 Original Poster	That is what I wanted to know, thanks!

02-02-2012, 09:39 PM	#4
newarts Inactive Account Join Date: Dec 2008 Location: Ames, Iowa, USA Photos: Albums Posts: 2,965	Originally posted by Adam Reproduction ratio and magnification should theoretically be the same...... Macro lenses, on the other hand, generally have magnifications of 1.00x and reproduction ratios of 1.00, meaning that your print will be life-size. I'm sure Adam meant to say the image on the sensor will be life-size for magnification/reproduction ratios of 1:1 Magnification on print = ReproductionRatio(PrintWidth/SensorWidth) = (magnification on sensor)(enlargement) Last edited by newarts; 02-03-2012 at 07:30 AM.

02-02-2012, 11:08 PM	#5
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	MAGNIFICATION is what happens at the sensor. ENLARGEMENT happens in the display or print. I must say that I've rarely run across the term "Reproduction Ratio", probably because it's rather ambiguous. Or maybe I'm just out of touch or sloppy or demented. But here's how I think of it: Magnification is the ratio of the subject to the recorded image. Let's say I aim a Spotmatic at a ruler. The Spotty's frame is 36mm wide. If I shoot an in-focus picture that captures just 1-36mm, it's 1:1 (1x). If it captures 1-72mm, it's 1:2 (0.5x). If it captures 1-18mm, it's 2:1 (2x). Enlargement is the ratio of the displayed image to the recorded image. If I take a FF (full-frame, 36x24mm) Spotty frame and make a contact print, it's 1:1. If I make a print (or project onto a screen) so it's 36cm wide, it's 10:1 (10x). If 3.6m wide, it's 100x, etc. Reproduction Ratio could refer to either Magnification (how the image is captured) or Enlargement (how the image is displayed). I prefer the more specific terms. I'm picky about that.

02-03-2012, 06:28 AM	#7
baro-nite Loyal Site Supporter Join Date: Aug 2011 Location: North Carolina, USA Photos: Gallery \| Albums Posts: 5,294	Originally posted by Adam But since with tele lenses, the whole idea is to be able to be far away, these numbers really don't matter. I must disagree. The short minimum focus distance of the DA* 200 and 300 lenses is a great feature. The point of a tele is to magnify the image, whether the subject is near or far. A couple of months ago I was doing hand-held shots of hummingbirds and the DA* 200 was perfect, as I was sometimes able to approach its minimum focus distance of about 4 feet, while the relatively short focal length made tracking and focusing on these fast-moving birds easier than it would have been with a longer lens from farther away.