New 58/1.4 has Focus Shift?

[glenerrolrd]

Great tests ..but they don t support the premise that focus shift isn t relevant. If you look at the example shot at F4 ..you can easily see that plane of focus lays around the +10 . If the D800 was adjusted for this setting the lens align target would be sharper ....so you are giving up some of the resolution possible with the lens due to focus shift .

On a flat surface (as the lens align target shows ) this would certainly be relevant . On a 3 dimensional surface it may not .....as the DOF shows acceptable sharpness over a range that covers the target .

I have several lenses that exhibit this type of focus shift and you can adjust your shooting in most cases to work around it . But its easier if you optimize the focus point around F2 and accept that at F1.4 you would be slightly front focused ...or just keep in mind that at f2.8 and f4 you might be a little back ..

 

[Jan Brittenson]

You need to be more specific with what you mean by "sharp". This lens is high-resolution, but it's not high-contrast. The f/4 zero plane above outresolves the D800E, but the contrast isn't high enough to give a sense of crispness. Nowhere within the critical DoF (defined as outresolving the camera) will it produce high contrast, which is a good thing for a lens like this.

 

[glenerrolrd]

You need to be more specific with what you mean by "sharp". This lens is high-resolution, but it's not high-contrast. The f/4 zero plane above outresolves the D800E, but the contrast isn't high enough to give a sense of crispness. Nowhere within the critical DoF (defined as outresolving the camera) will it produce high contrast, which is a good thing for a lens like this.

I follow your observation ...but I can see that the 10 is higher contrast than the 0 ..which normally implies that its sharper . Isn t the point of highest contrast where the exact plane of focus resides ?

If I can see it in the example ..not sure I follow you statements ..they imply that the sharpness with be the same throughout the critical DOF .

 

[glenerrolrd]

Ok I reread your statements and you appear to be saying that ..as long as the plane of focus falls with the critical DOF (which is dependent on the sensor) ...the impact of the focus shift will not affect resolution .

Its differences in contrast within the CDF that I am observing and these can be adjusted in post ?

 

[ohnri]

Imatest of the 58mm f/1.4

This may lend some clarification.

LensRentals.com - Nikon 58mm f/1.4 is (hopefully) Not About the Numbers


-Bill

 

[Jan Brittenson]

MTF50 represents a 1-stop attenuation, so is a measure of contrast more than resolution.