how reproduction ratio works?

[Rain13]

Hello,

I was curious how I should understand reproduction ratio. Does reproduction ratio 1:1 at 100mm focal length give the same image as reproduction ratio 1:2 at 200mm focal length? If not than what would be different?
Sigma F1.8 18-35 mm has only 0.23x maginification.
http://www.dpreview.com/lensreviews/sigma-18-35-1-8
Will I have any troubles with that lens because of that little magnification? I mean if I want my images to be crisp sharp with lot of details, will that low magnification be obstacle?

 

[darklamp]

First those 1:1 ratios. What they mean is that the image of the object projected onto the sensor ( or film ) will be the same size as the object itself.

Now that's only going to happen exactly with perfectly flat objects shot square on, but that's how it's measures. So a 1:1 lens used to shoot something that's the same size as the sensor will completely fill the frame with that object.

That ability with the ability to focus close enough is what defines a mscro lens.

Magnification is something else and as Wikipedia have gone to the trouble of going through the gruesome details I'll leave it to them :

http://en.wikipedia.org/wiki/Magnification

All I will say is that magnification is a pretty useless piece of information to most photographers.

 

[mclewis]

1:1 at 100mm is not the same as 1:2 at 200mm.

The reproduction ratio is the size of an object on the sensor relative to the actual object. At 1:1 an photo of an object 36x24mm would exactly fill the frame with a full frame camera as it has a sensor size of 24x36mm.

 

[Rain13]

Thanks. Does it have any impact on sharpness?

 

[Klaus dk]

Thanks. Does it have any impact on sharpness?

No.

 

[Alphoid]

darklamp wrote:
All I will say is that magnification is a pretty useless piece of information to most photographers.

That's a little strong... It's a useless piece of information unless it's really bad.

I have a Tamron super-telephoto lens with a 0.2x magnification ratio. That's about 5 inches. Magnification ratio is generally given at maximum zoom, and gets worse as you zoom out. With that particular lens, at some focal lengths, I cannot even take an in-focus face shot because it cannot zoom that close. And that lens is labeled a 'macro'...

 

[D Cox]

First those 1:1 ratios. What they mean is that the image of the object projected onto the sensor ( or film ) will be the same size as the object itself.

Now that's only going to happen exactly with perfectly flat objects shot square on, but that's how it's measures. So a 1:1 lens used to shoot something that's the same size as the sensor will completely fill the frame with that object.

That ability with the ability to focus close enough is what defines a macro lens.

Magnification is something else and as Wikipedia have gone to the trouble of going through the gruesome details I'll leave it to them :

http://en.wikipedia.org/wiki/Magnification

All I will say is that magnification is a pretty useless piece of information to most photographers.

It is important if you are using a camera to digitise film, or if you have a stamp or coin collection to photograph.

 

[D Cox]

darklamp wrote:
All I will say is that magnification is a pretty useless piece of information to most photographers.

That's a little strong... It's a useless piece of information unless it's really bad.

I have a Tamron super-telephoto lens with a 0.2x magnification ratio. That's about 5 inches. Magnification ratio is generally given at maximum zoom, and gets worse as you zoom out. With that particular lens, at some focal lengths, I cannot even take an in-focus face shot because it cannot zoom that close. And that lens is labeled a 'macro'...

The "macro" label on a long zoom lens is always a lie.

What it means is "focusses a bit closer than you might expect for a long zoom lens".

 

[TTMartin]

Hello,

I was curious how I should understand reproduction ratio. Does reproduction ratio 1:1 at 100mm focal length give the same image as reproduction ratio 1:2 at 200mm focal length?

No a 1:1 Macro lens is based on both focal length and minimum focus distance. You only get 1:1 at the minimum focus distance. The same holds true for 1:2 Macro lens, you get 1:2 at minimum focus distance.

If not than what would be different?

Minimum focus distance of the lens.

Sigma F1.8 18-35 mm has only 0.23x maginification.
http://www.dpreview.com/lensreviews/sigma-18-35-1-8
Will I have any troubles with that lens because of that little magnification?

If you want to do macro photography it would be an issue.

I mean if I want my images to be crisp sharp with lot of details, will that low magnification be obstacle?

Sharpness has no relation to magnification.

 

[TTMartin]

darklamp wrote:
All I will say is that magnification is a pretty useless piece of information to most photographers.

That's a little strong... It's a useless piece of information unless it's really bad.

I have a Tamron super-telephoto lens with a 0.2x magnification ratio. That's about 5 inches. Magnification ratio is generally given at maximum zoom, and gets worse as you zoom out. With that particular lens, at some focal lengths, I cannot even take an in-focus face shot because it cannot zoom that close. And that lens is labeled a 'macro'...

The "macro" label on a long zoom lens is always a lie.

What it means is "focusses a bit closer than you might expect for a long zoom lens".

What a lens label 'macro' means is that the lens has a flat field of focus and that it is capable of 1:1, 1:2, or 1:3 macro photography.

 

[dolbyscat]

Another question on "ratio", is a 1.1 ratio macro lens when used on a full frame camera still 1.1 when used on a crop sensor camera?

Was trying to figure it out myself but this early my brain ain't up to it.

 

[TTMartin]

Another question on "ratio", is a 1.1 ratio macro lens when used on a full frame camera still 1.1 when used on a crop sensor camera?

Was trying to figure it out myself but this early my brain ain't up to it.

Yes, but, the sensor is smaller.

It is exactly as illustrated in this photo. The subject size doesn't change, but, the amount of the subject captured does.

Image from: Camera sensor size: Why does it matter and exactly how big are they?

As far as your final print goes a 1:1 macro lens on a 20 megapixel APS-C camera will appear to have have more magnification than a 1:1 macro on a 20 megapixel full frame camera. But, what the image sensor 'sees' in both cases is the same. The pixels of the APS-C sensor are just more tightly packed, so when you make a print it seems more magnified.

 

[dsjtecserv]

Another question on "ratio", is a 1.1 ratio macro lens when used on a full frame camera still 1.1 when used on a crop sensor camera?

Was trying to figure it out myself but this early my brain ain't up to it.

You mean 1:1 right?

Yes, since magnification/reproduction ratio is the ratio of the size the image of the object on the sensor to the real size of the object, 1:1 always means that the image and the real object are the same size, regardless of how much additional sensor space surrounds the image of the object. The same lens, focused to the same distance, will produce the same magnification on the sensor of any camera it can be attached to.

Dave

 

[dolbyscat]

Another question on "ratio", is a 1.1 ratio macro lens when used on a full frame camera still 1.1 when used on a crop sensor camera?

Was trying to figure it out myself but this early my brain ain't up to it.

You mean 1:1 right?

Dave

--
http://www.pbase.com/dsjtecserv

Like I said it's early here....