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06-10-2008, 12:46 AM   #1
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How Macro is Macro?

Don't I just have a way with words? Just bear with me for a second...

I recently got a DA 18-250. A great lens for what it is (at least, in my highly unprofessional opinion). Played around with it for a while, and when I looked at the specs, the max magnification is listed at 0.28X, which makes it a 1:3.6 mag ratio (assuming I can still do basic math).

I have definitely seen lenses listed as "macro" with 1:3 and 1:4 mag ratios.
By that logic, does the 18-250 qualify as a "macro"?

I know true macro is considered 1:1.
So the question is: how far does one stretch "macro"?

And as a side question, how do you calculate the mag ratio?

Cheers,
Tim.

06-10-2008, 01:45 AM   #2
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In old days any lens which could reach 1:5 mag ratio might be called a macro lens. It's just a marketing trick I think.

A true macro lens (imo) should have at least 1:2 mag ratio. A macro lens w/ 1:1 mag ratio is called life size macro lens.
06-10-2008, 01:55 AM   #3
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Anything below 1:2 is not really a macro lens, IMO.

I have an old A lens zoom that says macro on it. Can go down to 1:4.5. Pft.
06-10-2008, 01:59 AM   #4
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I dont mind if macro was 1:0.9


cheers

06-10-2008, 03:21 AM   #5
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I usually call 1.9:1 as macro.

Last edited by ddhytz; 06-30-2008 at 03:38 PM.
06-10-2008, 03:36 AM   #6
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QuoteOriginally posted by ddhytz Quote
I usually call 1.9:1 as macro.
I've managed to do that with a couple of extension tubes. Fun stuff.
06-10-2008, 04:05 AM   #7
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i don't understand the numbers...
06-10-2008, 04:51 AM   #8
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QuoteOriginally posted by TimB Quote
Don't I just have a way with words? Just bear with me for a second...

I recently got a DA 18-250. A great lens for what it is (at least, in my highly unprofessional opinion). Played around with it for a while, and when I looked at the specs, the max magnification is listed at 0.28X, which makes it a 1:3.6 mag ratio (assuming I can still do basic math).

I have definitely seen lenses listed as "macro" with 1:3 and 1:4 mag ratios.
By that logic, does the 18-250 qualify as a "macro"?

I know true macro is considered 1:1.
So the question is: how far does one stretch "macro"?

And as a side question, how do you calculate the mag ratio?

Cheers,
Tim.
Macro, while truely defined as 1:1 has been used for many years to define the ability to close focus.

It is easier to say macro, because every one identifies this with close focus, as opposed to saying "close focusing" or by stating a reproduction ratio that many will not understand.

It is not a perfect world.

06-10-2008, 05:29 AM   #9
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The red focus indicator dot on a Takumar 135mm lens as taken with an SMC Takumar 55/1.8 and 57mm of extension tubes (100% crop). I'm not smart enough to figure out what macro ratio that works out to.



And a 100% crop of a metric ruler with the same setup. The markings are 1mm apart. Again, I lack the brains/know-how to figure out the ratio.

06-10-2008, 05:39 AM   #10
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Damn... i bet it took more than a quick minute to photograph those huge millimeters.

Excellent! the weekend is only 3.2 meters away!

mike
06-10-2008, 05:39 AM   #11
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QuoteOriginally posted by Mike Cash Quote
And a 100% crop of a metric ruler with the same setup. The markings are 1mm apart. Again, I lack the brains/know-how to figure out the ratio.
Regarding the second image, Mike I'd say that comes perilously close to 10:1
06-10-2008, 05:57 AM   #12
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QuoteOriginally posted by ftpaddict Quote
Regarding the second image, Mike I'd say that comes perilously close to 10:1
it looks like 20 : 1 on my 22 inch screen. BUT What people forget is that macro (1:1) not related at all to crops, and print size, but to size on the sensor.

the ruler is only 1:1 if we see all the frame and can count 24 ticks (or less) across the 24mm width of the ASP-C sensor. The image is 665 pixels wide on a sensor that will be 3000 pixels wide, or 22% of the frame, assuming a crop only and no resize. this leaves it very close to 1:1 for a full frame of the ruler.
06-10-2008, 11:12 AM   #13
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Original Poster
Is there a way to calculate the mag ratio from focal length, focus distance, etc.?
It seems like it should be possible, but I can't figure out how.
06-10-2008, 11:18 AM   #14
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QuoteOriginally posted by TimB Quote
Is there a way to calculate the mag ratio from focal length, focus distance, etc.?
It seems like it should be possible, but I can't figure out how.
On a full frame/35mm film camera, being able to focus on a ruler and get close enough to only be able to capture 36mm along the horizontal line of the frame equals 1:1 magnification (because FF means roughly 36mm horizontally and 24mm vertically). You can do the math from there.
06-10-2008, 11:53 AM   #15
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Hey Mike, that Tak is starting to rust! (or maybe that is some other gunk)
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