# Diopter questions (technical..might make your head hurt)



## MisplacedAngler (Feb 25, 2011)

Say I have a camera with the following spec's.

Focus Range:
Normal mode: Wide: 3.9  infinity 
Macro mode: Wide: 3.9  infinity 
Super Macro mode: 0.4"  infinity 

If I get a +2 diopter, how does that affect my focus range?
What about a +4 diopter?
What is the formula for figuring this?

What if these diopters were used underwater?  Would a +4 still be a +4?

+1 to anyone who can answer this.  I think I reached the end of the internet trying to find an answer.  I've found all sorts of answers, but they address one focal length and not a range.  I want to get some diopters so I can do some underwater macro, but I don't want to end up having a focal range of something like 6-7.5" because obviously that isn't very practical...especially underwater.


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## dupek (Mar 27, 2011)

Diopter is not for focal lens, but for vision adjustment. Every one see different. To have sharp, in focus images, while shooting in manual focus, you my need to adjust the diopter to your eye`s.


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## skieur (Mar 27, 2011)

dupek said:


> Diopter is not for focal lens, but for vision adjustment. Every one see different. To have sharp, in focus images, while shooting in manual focus, you my need to adjust the diopter to your eye`s.


 
You are talking about the WRONG diopters. The OP means the diopters that are used for close-up photography that screw onto the end of the lens.

skieur


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## skieur (Mar 27, 2011)

MisplacedAngler said:


> Say I have a camera with the following spec's.
> 
> Focus Range:
> Normal mode: Wide: 3.9&#8221; &#8211; infinity
> ...


 
The diopters increase your close-up range so with a regular lens of 50mm focal length your normal closest focus is 3 feet, then with a +2 you could probably get into 12" or less range. You can put a *2 diopter on top of another diopter such as +4 to get super close as in a couple of inches.

Diopters work best on regular lenses of 50mm up to 200mm. They are difficult to try and focus with, so you screw one on the end of your lens and then move foreward or backward until you are close to sharp and then focus from there. A tripod or monopod is ideal, since even a small camera movement can render the object blurred or soft. Depth of field is very narrow with diopters but the overall image quality is as good as a macro lens if you bought good quality diopters.

skieur


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