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Questions tagged [field-curvature]

The tag has no usage guidance.

3
votes
2answers
174 views

How to reduce landscape curvature?

My camera is a Nikon D610 which I used with a Sigma 12-24 wide angle lens. Can anyone recommend a software product to straighten up horizons with? I have attached an example where I have a curved lake ...
9
votes
4answers
2k views

What is the advantage of a lens with a curved focal plane?

In this answer it is noted that: many lenses intended specifically for portraits or fisheye lenses, are designed to have a spherical field of focus What advantages does having a spherical (or ...
4
votes
3answers
319 views

Are points off-center from the lens axis out of focus? [duplicate]

If I take a picture of a flat surface perpendicular to the direction of the lens (i.e. the surface is facing directly at the camera), and I focus on the center, are the points off center in perfect ...
25
votes
5answers
4k views

What is the shape of the focal plane?

This is something I just realised I don't entirely know the answer to, so I'm going to ask it here as I think it's interesting. In most non-scientific writing on depth of field, diagrams generally ...
19
votes
4answers
14k views

What swirly bokeh technique is this and how can I achieve it?

What is the technique used to capture this image? How can the result be achieved? I know that it can be achieved in a digital darkroom but how can I replicate the effect straight out of the camera?
3
votes
4answers
788 views

What is the best lens for shooting flat surfaces?

For a long time, I was making closeup photographs of flat surfaces using my cropped DLSR and Canon EF 50/1.4 lens. The scene was illuminated by an external flash. The focusing distance was the closest ...
16
votes
3answers
8k views

What is the cause of this non-uniform bokeh effect?

A friend of mine is thinking of buying a used medium-format film TLR camera (a Mamiya C330), and he showed me some of the test shots he'd taken with it. I was struck by the curiously non-uniform ...
4
votes
1answer
555 views

Do lenses have focal planes or focal spheres/ellipsoids?

The title says it pretty much all. I'm asking this because I find myself always using the focus point in the center, and after I focused, I rotate my camera to make the framing right. However, if ...
9
votes
1answer
689 views

Is the focus plane of a fisheye lens inherently curved?

After shooting of a fisheye lens earlier this week, I noticed that what is in focus does not seem to lie on a flat plane as it would for a rectilinear lens. Now, I am aware that lenses usually exhibit ...
14
votes
2answers
2k views

What are the use cases of a Petzval lens?

I am interested to know when would one use these lenses and what are they best suited for?
8
votes
2answers
6k views

If the focal plane is curved, should the outer AF points work correctly or front-focus?

Many (all?) lenses have a (slightly) curved focal plane. In general it's close enough to flat that you don't really notice it, but under certain conditions it may become apparent. As I understand it ...
8
votes
2answers
9k views

What does “Flat Field Focus” mean?

Looking at lenses, specifically sigma macro lenses, I noticed that it had a ""Flat Field" front lens element". What does this mean? And how is it different to the norm?