Diopter settings (1 Viewer)

[ReinierB]

I have been looking at this for several times and still don't know what is meant with "dpt", "diopter correction at infinity" and "diopter adjustment" on the website of Swarovski. Can anybody explain it to me? I do not wear glasses, so I have the meaning it is not important to me at all. But is that true? Is it only important when the eyesight of both eyes is not the same? So you can correct it? What does 7 dpt mean?

 

[Wasabrot]

I have been looking at this for several times and still don't know what is meant with "dpt", "diopter correction at infinity" and "diopter adjustment" on the website of Swarovski. Can anybody explain it to me? I do not wear glasses, so I have the meaning it is not important to me at all. But is that true? Is it only important when the eyesight of both eyes is not the same? So you can correct it? What does 7 dpt mean?

View attachment 1545736

Diopter correction of infinity 7dpt means that you can focus 7dpt beyond the normal infinity point or better when you are short-sighted up to -7dpt you still can focus your binocular to have a sharp image at maximum focus point.
If you have -7.25 or more dpt you have to wear contact lenses or glasses.

+/- 4dpt diopter adjustment says that your eyes can have up to 4dpt different values onte to the other. If you have a bigger differnce you need again at least one contact lens or glasses.

 

[ReinierB]

Thank you! So I am "safe" having +1 in one eye and +1.5 in the other.

 

[Elkhornsun]

It is a theoretical construct as no optical device truly can focus at "infinity". The optics can change as focus distance changes and no idea why 100 meters is not used as with stating the field of view.

 

[Binastro]

Post #4.

Optics certainly can focus at infinity, that is how they are designed.

In practice if one focuses on a star the difference is not detectable with any binocular and probably not with any telescope.

The difference between 100 metres and infinity is significant and can be seen in most binoculars.

B.

 

[Maljunulo]

It is a theoretical construct as no optical device truly can focus at "infinity".

Can you expand on that statement, please?

 

[Binastro]

Infinity is easiest to understand with parallel rays, if necessary with long baselines, say the radius (1 astronomical unit or about 93 million miles) of the Earth's orbit, which gives distances in parsecs if the rays are not quite parallel.

Infinity has been well understood for centuries.

However, if one digs deeper into time, space etc. one can complicate matters.

But opticians and mathematicians use infinity.

New forms of physics continually turn up, especially on the internet.

There is a post elsewhere that claims FOV depends on objective diameter, again an individual take on new laws of physics.

B.

 

[tenex]

still don't know what is meant with (1)"dpt", (2)"diopter correction at infinity" and (3)"diopter adjustment"

(1) You can search online for "what is diopter" (and skip the more cursory blurbs that aren't real explanations). It's useful to know. For example:

Dioptre - Wikipedia

en.wikipedia.org

(2,3) Explained above in post #2. 7dpt is a lot, and in servicing one could ask to have that reduced in favor of close focus. I did that with my SLC 42 but the benefit is quite modest. Mainly I found all that extra travel annoying.