A simple diopter question...

It's really a shame that manufacturers did not develop a standard used by all, and use standard nomenclature for there diopters. Bronica, for example, lists their standard eyepiece as a negative diopter value but the lens is certainly a positive lens. Go figure.

voceumana said:

It's really a shame that manufacturers did not develop a standard used by all, and use standard nomenclature for there diopters.

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There is a standard nomenclature, which is the optics unit "diopter".
One finds it on eyepiece correcting attachments as on close-up lenses.

Many here mix that up with "eyepiece", as in the USA a eyepiece also is called diopter.

Bronica says its standard eyepiece has a negative diopter value even though it is a positive lens. It does not help to clarify the situation.

AgX said:

There is a standard nomenclature, which is the optics unit "diopter".
One finds it on eyepiece correcting attachments as on close-up lenses.

Many here mix that up with "eyepiece", as in the USA a eyepiece also is called diopter.

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Yah, 'diopter' is in common. But is the strength (indicated on the diopter eyepiece)

1. Relative to what is the standard eyepiece strength so it is incrementally stronger/weaker than 'standard eyepiece' strength by whatever value, or
2. is it the Absolute diopter strength of the lens in the eyepiece?!

M Carter said:

That's more what I'm hoping to find... so after your paragraph saying "+1.5 offset my eye needs a true diopter -2.5" and so on... and then standard eyepiece and I need a +1.5 or +2.5... not sure if I'm reading this properly, but in the simplest terms - if I need a +1.5 reader for reading and 1-meter-ish work, then I need something around a +1.5 diopter, depending on how the manufacturer dealt with it??

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Right...the key question is "How did the manufacturer deal with the labelling of the Accessory's strength?"...Do you

1. buy an accessory called '+1.5' which is stronger relative to the standard eyepice by that amount, or
2. do you buy an accessory called '+2.5' which has an absolute strength optically which can be measured by optician?

Going back to Bronica which was brought up, Bronica state they offer range of -4.5 to +1.5...but standard eyepiece is -1.5

• so, from Bronica, you buy -2.5 or -3.5 or -4.5 if you need Negative correction from standard or
  you buy -0.5 or +0.5 or +1.5 if yoiu need Positive correction from standard Absolute strength of the diopter lens.
• But for another brand you buy -3 or -2 or -1 for negative offset from standard, or
  buy +1 or +3 or +3 for positive offset from standard

for the exact same six corrections!
Canon, for example, says their dioptric corrections are 'not true'. for the Canon F-1 accessories..you buy Relative offset strengths for the Canon F-1