DFA100WR Minimum focus distance question

lightbulb · 03-05-2013, 01:25 AM

What is the closest focusing distance when using manual? Am using Sigma 70mm 2.8 macro and when I stack DCR250 with DCR150 raynox it is like 1 cm or less working distance for maximum magnification!

DSims · 03-05-2013, 02:41 AM

It's the same as in AF of course, which is 0.303m according to the markings on mine. At this point (1:1 macro) the front of the lens is 5 inches from the rear mount, so that would put the subject at about 15 or 18 cm working distance. But I don't know how much the Raynox adapters would change this.

Perhaps you're already aware of this, but the great advantage of the DFA100 (besides the WR and rounded blades) is that it's the best all-around macro lens I've seen. It's like it isn't the best macro lens in any one area, but it's the second best macro lens in every area, with no apparent weak points. For example, most macro lenses I've seen or used were weak near infinity or even portrait distances, but the 100WR is not.

lightbulb · 03-05-2013, 07:51 AM

Thanks but this is strange! I sold one (seller Remorse) which has closer manual focus. Anyway will buy another one to try. ... crazy guys everywhere lol....

Na Horuk · 03-05-2013, 11:04 AM

Originally posted by lightbulb

Thanks but this is strange! I sold one (seller Remorse) which has closer manual focus. Anyway will buy another one to try. ... crazy guys everywhere lol....

Keep in mind that wide angle lenses have a smaller minimum focus distance, but they don't necessarily have higher magnification. Magnification is what really matters to macro work, and the modern Pentax primes have true macro, 1:1. Many other brand macros are only 1:2, especially zoom lenses, they often don't even get to 1:2.

SOldBear · 03-05-2013, 01:47 PM

Note that the focusing distance is calculated from the image sensor (or film plane), not from the front element of the lens.

Lenses of the same focal length at the same magnification ratio have the same focusing distance. It's just physics.

Once you add aux. lens (e.g. Raynox DCR250) to a lens, it's a totally different ball game.

lightbulb · 03-05-2013, 04:41 PM

Thanks guys. It all makes sense now.

03-05-2013, 01:25 AM	#1
lightbulb Veteran Member Join Date: Jan 2012 Posts: 691	DFA100WR Minimum focus distance question What is the closest focusing distance when using manual? Am using Sigma 70mm 2.8 macro and when I stack DCR250 with DCR150 raynox it is like 1 cm or less working distance for maximum magnification!

03-05-2013, 02:41 AM	#2
DSims Veteran Member Join Date: Sep 2009 Location: Southern California Photos: Gallery \| Albums Posts: 3,236	It's the same as in AF of course, which is 0.303m according to the markings on mine. At this point (1:1 macro) the front of the lens is 5 inches from the rear mount, so that would put the subject at about 15 or 18 cm working distance. But I don't know how much the Raynox adapters would change this. Perhaps you're already aware of this, but the great advantage of the DFA100 (besides the WR and rounded blades) is that it's the best all-around macro lens I've seen. It's like it isn't the best macro lens in any one area, but it's the second best macro lens in every area, with no apparent weak points. For example, most macro lenses I've seen or used were weak near infinity or even portrait distances, but the 100WR is not. Last edited by DSims; 03-05-2013 at 02:50 AM.

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03-05-2013, 07:51 AM	#3
lightbulb Veteran Member Join Date: Jan 2012 Posts: 691 Original Poster	Thanks but this is strange! I sold one (seller Remorse) which has closer manual focus. Anyway will buy another one to try. ... crazy guys everywhere lol....

03-05-2013, 11:04 AM	#4
Na Horuk Veteran Member Join Date: Feb 2012 Location: Slovenia, probably Photos: Gallery \| Albums Posts: 11,186	Originally posted by lightbulb Thanks but this is strange! I sold one (seller Remorse) which has closer manual focus. Anyway will buy another one to try. ... crazy guys everywhere lol.... Keep in mind that wide angle lenses have a smaller minimum focus distance, but they don't necessarily have higher magnification. Magnification is what really matters to macro work, and the modern Pentax primes have true macro, 1:1. Many other brand macros are only 1:2, especially zoom lenses, they often don't even get to 1:2.

03-05-2013, 01:47 PM	#5
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206	Note that the focusing distance is calculated from the image sensor (or film plane), not from the front element of the lens. Lenses of the same focal length at the same magnification ratio have the same focusing distance. It's just physics. Once you add aux. lens (e.g. Raynox DCR250) to a lens, it's a totally different ball game.

03-05-2013, 04:41 PM	#6
lightbulb Veteran Member Join Date: Jan 2012 Posts: 691 Original Poster	Thanks guys. It all makes sense now.