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Is this the field curvature?

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BogWar

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Hello to all members and readers of DPReview!

Is this the field curvature? Photo was taken with the Nikon D5100 camera and Nikkor 50mm f1.8G lens at f4. Edge detect added with ACDsee Photo Studio Proffesional 2019.

Nikkor 50mm f1.8G field curvatrure?
Nikkor 50mm f1.8G field curvatrure?

Below is the same picture with no edge detect effect.

Nikkor 50mm f1.8G at f/4
Nikkor 50mm f1.8G at f/4
 
BogWar said:
Hello to all members and readers of DPReview!

Is this the field curvature? Photo was taken with the Nikon D5100 camera and Nikkor 50mm f1.8G lens at f4. Edge detect added with ACDsee Photo Studio Proffesional 2019.

Below is the same picture with no edge detect effect.
Click to expand...
Sorry, I just don't understand the question. What does ACDsee have to do with the question? Is that a B&W negative effect? The surrounding grass is beyond the subjects and is therefore out of focus. Field curvature can be seen with photos of a detail filled flat wall.
 
ACDSee edge detect allows one to visualize the shape of the zone of sharp focus. Similar tools (edge enhancement tool) are built into many photo editor programs such as Photoshop. The same method of visualizing the field curvature was presented by Sunny Shrestha (https://www.picturecorrect.com/tips/field-curvature-and-depth-of-field/).

As you can see in the attached photo, the focus zone is curved (I'm sending the "positive" version of the photo).

Curved focus zone
Curved focus zone

For comparison, I am attaching a photo taken with the Nikkor 85mm f / 1.8g lens at f5.6. In this case, the focus zone is rectilinear.

Rectilinear focus zone
Rectilinear focus zone

Nikkor 85mm f1.8G at f/5.6
Nikkor 85mm f1.8G at f/5.6
 
I thought so! It's interesting that there are so few complaints about the field curvature of the Nikkor 50mm f/ .8G lens!
 
BogWar said:
I thought so! It's interesting that there are so few complaints about the field curvature of the Nikkor 50mm f/ .8G lens!
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I don't find that particularly interesting - or surprising.

Many (most...?) lenses have a degree of field curvature. It rarely proves to be a problem in real-world photography - particularly if the photographer knows what to expect, composes accordingly and selects an appropriate aperture.
 
Thanks to everyone for your interest in the problem. Thank you also for the advice and links to the articles by Robert Cicala. I read most of them, but probably not all. Maybe some of the DPReview Members know any other interesting articles on this topic? I would be grateful for information or links.
 
BogWar said:
Thanks to everyone for your interest in the problem. Thank you also for the advice and links to the articles by Robert Cicala. I read most of them, but probably not all. Maybe some of the DPReview Members know any other interesting articles on this topic? I would be grateful for information or links.
Click to expand...
Taking an image of a brick wall at relatively close distance can be problematic. If the plane of the sensor is not parallel to that of the wall (axis of the lens perpendicular to the wall), part of the image will be out of focus and this could be confused with decentering or tilt. The solution is to increase the subject distance. For details see here and here .

If the lens is aligned with the brick wall and the image is sharp in the center and blurred at the edges, this could be due to field curvature or lens aberrations.

--
Bill Janes
 
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RCicala said:
rumple said:
RCicala said:
Yes, and [...]
Click to expand...
On another note, Roger, why is there a pot on your head? Are you a pastafarian?
Click to expand...
I am, actually. :-) But the 'pot' is actually the lens cap for a C-4 Optics Hyperfisheye.

2fe7e994643c4a719f052bfc8ec3b57b.jpg
Click to expand...
How did I know the guy with cool stories, has a cool story to go along with the “what’s that pot on your head” question! Very cool, that lens is really something, I’d rather have the Nikon 13mm f/5.6, but either way that is an awesome lens there!
 
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