effective focal length of 50s

[tom0511]

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Does anybody know how much the effective focal length cany vary?

My 50/1.4asph seems considrably longer than my Tri-Elmar at 50mm.

Any ideas?

[artur5]

I don't know about the 50/1.4 ASPH., but the older Summilux 50 non Asph was supposed to be 51 mm.

Also, on my Elmarit 90 current model, there´s a little number engraved on the distance scale, just under the yellow "feet" mark. It means the difference on 1/10 from the nominal focal lenght according to the following rules:

85 = 88.5 effective focal

90 = 89 mm "

95 = 89.5 mm "

00 = 90 mm "

05 = 90.5 mm "

10 = 91 mm "

15 = 91.5 mm "

20 = 92 mm "

 

Maybe there are similar marks on other lenses as well, It would be interesting if someone could add further information.

Regards

[cbretteville]

Puts lists the numbers for 50mm lenses (except the Elmar):

 

00 - 50.0mm

10 - 51.0

11 - 51.1

13 - 51.3

15 - 51.5

17 - 51.7

19 - 51.9

22 - 52.2

 

 

My 50 'cron and 90 Elmarit-M have such markings, but my 50 Elmar-M and 35 'lux ASPH (my most modern lens) dosen't. So the the 50'lux might not either.

 

- Carl

[tom0511]

Puts lists the numbers for 50mm lenses (except the Elmar):

 

00 - 50.0mm

10 - 51.0

11 - 51.1

13 - 51.3

15 - 51.5

17 - 51.7

19 - 51.9

22 - 52.2

 

 

My 50 'cron and 90 Elmarit-M have such markings, but my 50 Elmar-M and 35 'lux ASPH (my most modern lens) dosen't. So the the 50'lux might not either.

 

- Carl

 

Thanks for the info, my 50/1.4asph has the number and itsays 14, so its an effective 51,4mm lens.

My Tri-Elamr does not have the number but is definatly a little shorter at 50mm.

 

regards, tom