A simple diopter question...

[voceumana]

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.

 

[AgX]

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

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.

 

[voceumana]

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.

 

[wiltw]

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.

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?!

 

[wiltw]

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??

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