effective or nominal

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karlmera
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effective or nominal

Post by karlmera » 29.09.2012 16:44

Is the calculation of dof based on the shown effective aperture of the Nikon AF-S 60mm or on the nominal aperture?

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Stas Yatsenko
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Re: effective or nominal

Post by Stas Yatsenko » 01.10.2012 13:39

The value that camera reports, i. e. the one you can see in the interface.

karlmera
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Re: effective or nominal

Post by karlmera » 01.10.2012 15:47

Yes, that is right. But Nikon reports the effective aperture and Canon shows the nominal aperture. Is your calculation of the dof and the correction factor based on the effective or nominal apertures? The values of Nikon an Canon would be different.

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Stas Yatsenko
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Re: effective or nominal

Post by Stas Yatsenko » 02.10.2012 13:05

We didn't realize there's a difference between Nikon and Canon aperture values. We assume nominal aperture so DOF estimations for Nikon are off for high magnification situations. We will investigate the matter and adjust DOF calculations. Do you happen to know a good web resource that explains it, particularly - calculating magnification?

karlmera
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Re: effective or nominal

Post by karlmera » 02.10.2012 16:46

There is a big difference between Nikon and Canon. At 1:1 Nikon shows the effective aperture of 4,8 with the AF-S 60mm(nominal it would be 2,8, the same like at infinity). And here Canon shows 2,8, but it is effectively 4,8 or 5,6. If you choose 8 with Canon, you have effective 16. If you choose 8 with Nikon, you have effective 8, but nominal perhaps 4. Nominal 16 with Canon would be effective 32, that would be bad for diffraction.


http://macrosmuymacros.com/index.php?op ... 18&lang=en

http://savazzi.freehostia.com/photography/macrodof.htm

https://nikoneurope-de.custhelp.com/app ... e-lens-%3F

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Traceologue
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Re: effective or nominal

Post by Traceologue » 21.10.2012 10:08

Thanks, Karlmera, for pointing out this significant difference between Nikon and Canon camera! So far, I didn't understand why at 1:1 using a 60mm EFS Canon macro objective diffraction was coming as soon as f/8 with the sensor of the EOS 550D while the Nikon equivalent was tolerant up to f/16 (60mm AFS Micro Nikkor + D7000). According to my experience, the Nikon sensors seem less prone to diffraction (little difference between Nikon 10Mp and 16 Mp sensors, more noticeable between 10Mp and 18Mp Canon ones), but such a gap was strange: just the difference between nominal and effective aperture ...

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Stas Yatsenko
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Re: effective or nominal

Post by Stas Yatsenko » 22.10.2012 12:47

We have fixed our DOF and hyperfocal distance calculator, so it will operate correctly both with Nikon and Canon cameras after the next update. Thanks for bringing this issue to light.

karlmera
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Re: effective or nominal

Post by karlmera » 26.10.2012 11:29

Do I need a software update, do you have one?

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Stas Yatsenko
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Re: effective or nominal

Post by Stas Yatsenko » 29.10.2012 13:50

It's not finished yet, but we will release it soon.

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