9

It is typically called "lens compression," where things farther away appear nearer to the subject/closer together. And the opposite of this is typically called "lens distortion," where something closer to the camera appears larger than it should... like someone's nose in a portrait. Neither effect actually has anything to do with the lens,...


6

Long focal lengths (ie, high zoom factors) tend to remove depth because as the camera is far away, everything is shot from the same angle and this removes perspective. But is is really the distance that does it, cropping a picture taken with a shorter lens (but from the same place) would yield the same result.


4

Flat light. That is, light that is either from behind the camera and very close to parallel to the lens' optical axis (such as an on-camera flash) or extremely well diffused such as on an overcast day. Smaller apertures (larger f-numbers) combined with longer focal lengths that force shooting from further away to get the same framing will tend to "...


4

The earliest investigation of the right constant c that I am aware of is Petzval's 1859 On the camera obscura. The paper is predominantly about a new lens design he has created but he begins with an investigation of the optimum radius of a pinhole for resolution of the image. Resolution is defined as the ability to discern the difference of two very close ...


1

Optically, a long lens is said to compress perspective. When a longer focal-length is used, the relative distance between scene elements is shorter. You can visually play with the concept using the Nikon Lens Simulator. In it, choose a lens which a high zoom ration, say a 28-300mm and play with the zoom slider. You will see the scene looking flatter as you ...


1

After doing some research (this thread being a particularly useful one: https://www.dpreview.com/forums/thread/4392551), it seems that certain Sigma lenses are incompatible with newer Canon models like the M50. You'll either have to wait for a firmware update (if they offer one), sell the lens, or wait until you get a new body (check to make sure it works ...


1

It sounds like you have a bad connection, an incompatible connection or a bad lens. Clean the contacts on the lens and camera and coupler. If it persists, try the lens on an EOS EF mount body. If it still happens you have a bad lens. I suspect that it's the coupler.


1

Yes, on your lens you will have the full range, from f2.8 and up, at all focal lengths.


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