OK, I know what mfa does and how to use it. What I don't know is, what does a value of say 5 relate to?
Is it 5 mm, 5 microns, 5 inches or some other value not based around distance?
fordmondeo I was Soupdragon in a former life. More info | Mar 12, 2015 05:11 | #1 OK, I know what mfa does and how to use it. What I don't know is, what does a value of say 5 relate to? Vaginator9000
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msowsun "approx 8mm"  More info Post edited over 8 years ago by msowsun. (3 edits in all) | Mar 12, 2015 06:52 | #2 It varies with each lens. Each unit represents 1/8 of the depth of field for the lens, focal length, and wide open aperture being tested. In answer to the AF Microadjustment question, the focus shift amount per step (click, tick) is calculated by multiplying the maximum aperture's single-side depth of focus by 1/8. The key phrase is "single-side depth of focus." It equates to half of the total depth of focus, which of course extends equally both in front of and behind the focal plane. Note also that the calculation is based on depth of focus, which is measured at the focal plane and is always equally distributed in front of an behind it, and not depth of field, which is measured at the subject and does not always extend equally in front of or behind it. Note further that the depth of focus is proportional to the focal length and the maximum aperture of the lens; therefore, the larger the maximum aperture and the longer the focal length, the smaller each individual AF Microadjustment step becomes. Mike Sowsun / SL1 / 80D / EF-S 24mm STM / EF-S 10-18mm STM / EF-S 18-55mm STM / EF-S 15-85mm USM / EF-S 55-250mm STM / 5D3 / Samyang 14mm 2.8 / EF 40mm 2.8 STM / EF 50mm 1.4 USM / EF 100mm 2.0 USM / EF 100mm 2.8 USM Macro / EF 24-105mm IS / EF 70-200mm 2.8L IS Mk II / EF 100-400 II / EF 1.4x II
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Mar 12, 2015 07:54 | #3  Permanent banSo far, for me MFA has been nothing but a supreme waste of time. I have a 60D and a 6D, and have tried MFA a few times (6D only, obviously). Out of the 25 or so lenses I've mounted on my 6D, none of them benefited from MFA. I have some mid-level f/1.4 to f/2.8 primes and none of them, nor my photos, benefit from MFA. I seriously tried to use MFA on 3 different copies of the 50 1.8 II. No luck. How MFA affects your lens/camera combo is dependent on lighting brightness and temperature. Even Canon recommends doing MFA at the distance, and in the light you intend to shoot in. WARNING: I often dispense advice in fields I know little about!
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BigAl007 Cream of the Crop  8,120 posts Gallery: 556 photos Best ofs: 1 Likes: 1682 Joined Dec 2010 Location: Repps cum Bastwick, Gt Yarmouth, Norfolk, UK. More info | Mar 12, 2015 13:22 | #4 GeoKras1989 wrote in post #17471553  They are just features I don't need. I don't use the ashtrays in my car, either.
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CanonBob Goldmember 2,063 posts Likes: 52 Joined May 2007 Location: Poitou-Charentes, France More info Post edited over 8 years ago by Canon Bob. | Mar 12, 2015 13:29 | #5 msowsun wrote in post #17471507 It varies with each lens. Each unit represents 1/8 of the depth of field for the lens, focal length, and wide open aperture being tested. Not quite so, Mike. Each unit is 1/8 of the single sided depth of FOCUS......ie, in the image plane and not the subject plane (as depth of FIELD would be) 1Dx2 (2), 5DSR, 1Ds3, 1D4, 5D2(590nm), 5D2(720nm) EF600 EF400 EF300-II EF300 EF200 EF200-II EF180L EF135L EF100 EF85-II EF50L TS-E17/4 TS-E24L-II TS-E45 TS-E90 MP-E65 EF70-200-II EF24-70/2.8-II EF16-35/4 EF8-15/4 EF11-24/4 Zeiss 15/2.8 21/2.8 25/2 28/2 35/1.4 35/2 50/2 85/1.4 100/2 135/2 T/C's L-SC & a WIFE!
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madhatter04 Goldmember 1,930 posts Likes: 52 Joined Oct 2006 Location: Southern California More info | Mar 12, 2015 13:40 | #6 Master of Fine Arts Designer // Art Director // Photographer
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msowsun "approx 8mm" More info | Mar 12, 2015 14:11 | #7 Canon Bob wrote in post #17471956 Not quite so, Mike. Each unit is 1/8 of the single sided depth of FOCUS......ie, in the image plane and not the subject plane (as depth of FIELD would be) Bob Thanks for the correction. It does say that in the quote but it hurts my brain too much to fully understand it. Mike Sowsun / SL1 / 80D / EF-S 24mm STM / EF-S 10-18mm STM / EF-S 18-55mm STM / EF-S 15-85mm USM / EF-S 55-250mm STM / 5D3 / Samyang 14mm 2.8 / EF 40mm 2.8 STM / EF 50mm 1.4 USM / EF 100mm 2.0 USM / EF 100mm 2.8 USM Macro / EF 24-105mm IS / EF 70-200mm 2.8L IS Mk II / EF 100-400 II / EF 1.4x II
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Mar 12, 2015 17:03 | #8 Permanent banBigAl007 wrote in post #17471945 Your car comes with ashtrays still? My two and a bit year old Nissan Qashqai doesn't have Ashtrays or a lighter! I think they stopped fitting them in cars over here about ten years ago, my last one didn't either (there on a 3 year lease). We do still have the "Accessory 12V socket" for plugging other stuff into. So I guess one could retrofit a lighter in it. Alan I am not sure about ashtrays. I don't smoke, so I never looked for them. I do have the 12V socket, without lighter. I use it to charge my phone and LP-E6 batteries. WARNING: I often dispense advice in fields I know little about!
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