Minimum Focus Distance
Feb 16, 2012 19:45:28 #
I just purchased the Sigma 105mm f/2.8 Ex DG OS HSM Macro lens for use with my Canon 5Dc. This is my first time using a true macro lens.
The minimum focus distance is stated to be 12.3 inches, which I always thought referred to measuring from the end of the lens to the focus point. But I appear to be able to focus a lot closer than that. Is the minimum focus distance measured from the end of the lens, or from the sensor plane?
I was out testing the lens and was keeping the end of the lens at least 12 inches from the object. Then I happen to move in another four or five inches and it achieved focus at this point. I am going to do some more testing, but first I wanted to verify when a lens manufacturer states is the minimum distance where they are measuring from.
Thank for any answers.
The minimum focus distance is stated to be 12.3 inches, which I always thought referred to measuring from the end of the lens to the focus point. But I appear to be able to focus a lot closer than that. Is the minimum focus distance measured from the end of the lens, or from the sensor plane?
I was out testing the lens and was keeping the end of the lens at least 12 inches from the object. Then I happen to move in another four or five inches and it achieved focus at this point. I am going to do some more testing, but first I wanted to verify when a lens manufacturer states is the minimum distance where they are measuring from.
Thank for any answers.
Feb 16, 2012 21:12:33 #
I'm no expert, but based on that experience, I'd have to suggest measurement from the sensor/film plane. That would explain why they mark the plane on most cameras that are worth a darn.
Feb 16, 2012 23:36:57 #
RocketScientist wrote:
I'm no expert, but based on that experience, I'd have to suggest measurement from the sensor/film plane. That would explain why they mark the plane on most cameras that are worth a darn.
They don't call you a rocket scientist for nothing!
:thumbup:
Feb 17, 2012 00:12:05 #
Working Distance (WD) is the distance from lens front element to subject. For a true macro lens, Minimal Working Distance (MWD) should provide 1:1 magnification (life-size).
For an APS-C (Canon) sensor, your MWD for a 105-mm lens should be about 162-mm (6.5-inches) to achieve 1:1 mag.
If your lens cannot achieve 1:1 (life-size) magnification, then it is technically not a macro lens. Extension tubes would be required to approach 1:1.
For an APS-C (Canon) sensor, your MWD for a 105-mm lens should be about 162-mm (6.5-inches) to achieve 1:1 mag.
If your lens cannot achieve 1:1 (life-size) magnification, then it is technically not a macro lens. Extension tubes would be required to approach 1:1.
Feb 17, 2012 02:36:39 #
Thank you all, the camera is a Canon 5D, which is has a full frame sensor.
I just checked the Sigma web site (should have done that first) and it states this:
"Focuses down to 1:1 magnification ratio at its closest working distance of 12.3 inches"
Now the part I am embarrassed about. I just realized that I was working with the lens hood attached, and was measuring my distance from the end of the hood, not the lens element.
I just checked the Sigma web site (should have done that first) and it states this:
"Focuses down to 1:1 magnification ratio at its closest working distance of 12.3 inches"
Now the part I am embarrassed about. I just realized that I was working with the lens hood attached, and was measuring my distance from the end of the hood, not the lens element.
Feb 17, 2012 07:43:08 #
wingincamera wrote:
Thank you all, the camera is a Canon 5D, which is has a full frame sensor.
I just checked the Sigma web site (should have done that first) and it states this:
"Focuses down to 1:1 magnification ratio at its closest working distance of 12.3 inches"
Now the part I am embarrassed about. I just realized that I was working with the lens hood attached, and was measuring my distance from the end of the hood, not the lens element.
I just checked the Sigma web site (should have done that first) and it states this:
"Focuses down to 1:1 magnification ratio at its closest working distance of 12.3 inches"
Now the part I am embarrassed about. I just realized that I was working with the lens hood attached, and was measuring my distance from the end of the hood, not the lens element.
WD ( working distance) is front of lens to subject as stated by Nikonian72. FD ( focusing distance) is sensor plane to subject distance as stated by RocketScientist. Two different things.
Feb 17, 2012 07:53:10 #
RocketScientist wrote:
I'm no expert, but based on that experience, I'd have to suggest measurement from the sensor/film plane. That would explain why they mark the plane on most cameras that are worth a darn.
If you look at the top of the camera, you'll see a small white circle with a white line through it. That's where the "film" is - the sensor.
Mar 7, 2012 19:04:54 #
wingincamera wrote:
Thank you all, the camera is a Canon 5D, which is has a full frame sensor.
I just checked the Sigma web site (should have done that first) and it states this:
"Focuses down to 1:1 magnification ratio at its closest working distance of 12.3 inches"
Now the part I am embarrassed about. I just realized that I was working with the lens hood attached, and was measuring my distance from the end of the hood, not the lens element.
I just checked the Sigma web site (should have done that first) and it states this:
"Focuses down to 1:1 magnification ratio at its closest working distance of 12.3 inches"
Now the part I am embarrassed about. I just realized that I was working with the lens hood attached, and was measuring my distance from the end of the hood, not the lens element.
HAHAHA, oh, coming from somerone that bruned a whole roll 36 exposure with the asa on 25 whilehooting 400 film, Never mind, foreget the HAHAHA, as a matter of fact I take it back AHAHAH, there that feels better now that I fessed up
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