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Help with re-production ratio


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#21 herbko

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Posted 18 March 2004 - 04:32 PM

It's linear. 1:6 is 6 x 36mm = 216mm.
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#22 randapex

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Posted 18 March 2004 - 04:45 PM

So, to clarify this in my mind, Herb, you're saying the image is approx. 1/6 life size?

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#23 herbko

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Posted 18 March 2004 - 05:00 PM

So, to clarify this in my mind, Herb, you're saying the image is  approx. 1/6 life size?

Rand


Yes. The image as captured on the 7mm CCD in the 5050 is about 1/6 the size of the subject.
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#24 randapex

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Posted 18 March 2004 - 05:50 PM

Thanks Herb, and everyone else. This has been an intersting thread for me. It would seem to me now, as Herb figured out, an area of coverage would be a better way to designate a digital image as being a "Macro" shot.
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#25 tshepherd

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Posted 18 March 2004 - 07:02 PM

I'm with, well, ummmmm, was it Eric, or Craig, or James, or whoever...

Seriously, a ratio (1:1) does nothing to tell you about the size unless you define one of the two sizes, i.e. qualify it as 1:1 in a 35mm equivalent. It seems to me that most people are implicitly referring to the 35mm equivalent when they say 1:1, much like we define the crop factor on sensor size relative to 35mm.

Just my $0.02

#26 craig

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Posted 19 March 2004 - 01:54 AM

You're right, Tom. It's just that the usage is technically incorrect and if you read further on lenses and optics it can get you into trouble. f-numbers, ISO's, depth of field, etc. all get confusing when you aren't careful to account for sensor size. That's why I try to always the qualified term. I don't want to contribute to making a misunderstanding ingrained.

I think the estimate of 1/6 life size is a good one. That's about 2/3 apparent life size for 35mm as Ryan said and the correct notation would be 1:6. Unfortunately, sloppy usage of these terms is pervasive in photography in general.

At our most recent photo contest, macro was defined as the largest dimension being no greater than 11" or about 1:8 for 35mm. No problem since that was stated up front, but in reality the winning shot was much bigger. It was shot with a 5050 so the actual magnification had to be no more than 1:50. As far as I could tell, it may have actually been an infinite focus shot. I personally think that any shot involving the hyperfocal distance is not macro! :lol: I think it's too bad that people view anything that's not wide angle as being macro since macro in a broad sense is characterized by inherently limited depth of field. If your entire frame is in focus then its either a crop, a totally flat subject, or not macro.
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#27 yahsemtough

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Posted 19 March 2004 - 05:22 AM

Impeach the results! LOL

I think it was the confusion in how to punch the chad.

Sorry, I digress, for what it is worth I like the "equivilent". In the end, as long as the rules are clearly stated or defined I don't think it matters if the definition is technically correct. It matters only that you use the definition in terms of how they are stated.
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#28 lewinp

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Posted 29 March 2004 - 11:49 AM

one comment on a very nice shot -

you may want to experiment with having the subject go diagonally across the frame. In additional to letting it be a little larger in frame (regardless of the reproduction ratio), it will make it a little more dynamic. Having the subject align more or less with the vertical edge of the frame makes it look very static.

I think you have a very nice feel of the strobe. It does not bother me that part of the subject has soft focus, because the light plays cross its back in a soft and hard way, too.