Reproduction Ratio

[novice9]

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can someone please explain how to compare these following reproduction ratio stats to one another.

 

leica 75 2.0 "1:7"

 

nikon zoom lens "0.15x"

 

so, is the nikon lens equate to 1:15 in leica terms, which means its maximum reproduction ratio is less than the leica lens, or is is rather 1/15, in which case the nikon lens would i believe be slightly better?

 

 

thanks much.

[Guest trond]

Dear Novice9,

 

A reproduction ratio of 1:7 is the same as 0.1428X, or slightly less than 0.15X, which is 1:6.67 the other way around.

 

In other words the nikon zoom will give a 5% higher reproduction ratio than the 75 cron.

 

Probably not that visible in the images.

 

Best regards

 

Trond

[adan]

Take 1:7 and divide the 7 into 100 - I.E. Leica 75 repro ratio is 0.143x

 

Alternatively, divide 100 by 15 (or 1.0 by 0.15 - same thing) to get 1:6.7

 

So yes, that particular Nikon zoom frames 5% tighter

___________

amazing how great minds think alike.....

[novice9]

thanks so much, that's very helpful.

 

as a follow on question, is there any easy way to compare the reproduction ratios of the 75 and 90 crons at given distances from the subject? ie, i realize the 75 has a higher max reproduction ratio (7 vs. 9, though you'd have to stand so close to the subject you would be a distance that the 90 could not focus, if i understand correctly), but at any given distance from the subject that may not be the case. is there a cross over point, or does the 90 cron always yield a better reproduction ratio at the minimal distance that 90 can focus at?

 

thanks!

[adan]

At any given subject distance, the 90 will always produce a larger image, right down to the minimum focus limit of .9 meters.

 

Generally this is true through the range of focal lengths - given a fixed distance to the subject, the reproduction ratio/image size will be directly proportional to the focal length. The rule breaks down if one gets too close to "infinity" - either an infinitely short or infinitely long focal length - but a 14mm lens will make the subject 1/2 the size of a 28mm lens, and so on.

 

As an aside - this (longer focal length + fixed subject distance = tighter framing) is true of all prime lenses, but not true for many modern macro-zooms. I was just playing around with a prime Leica 180 and a Sigma macro 70-200 f/2.8 on my Canon 5D. At 3 meters (10 feet) the prime 180 actually framed substantially tighter than the zoom at "200," which was framing like a 135.

 

There was a thread about this recently - the effect has the silly name of "breathing" and just means that the zoom-makers achieve close-focus in a small package by modifying the focal length as well as the "focus" per se. But it can come as a shock if you are trying for a head-shot at a concert and expect your 200 or 300 zoom to frame the way your old prime 180 or 300 lens did at 3 meters.

 

=:^o