What are the Green f-stops for on 250/ 5.6 sonnar lens?

[jason_byrley]

Just got this optically and cosmetically beautiful lens in the mail

this A.M. Here's my question: on the F stop ring, to the left of

the "B" mark, there are f stops, colored in green. Yes, I originally

believed that they were for longer exposure times (4,8,15,30,60,125

are the #'s printed on it) however, I cannot select them for use. The

slowest I can select is "B"; I mean the ring seems to just stop there

and cannot move further to the left. I'm not about to try and force

anything.

ALSO...Does anyone know if it's possible to unlink the exposure ring

and the F stop rings? On my 80 mm, you have to push in a button on

the lens to make them move together. This is just the opposite, they

won't un-link unless I sort of pull the F-stop ring towards the

camera body first.

Any help is greatly appreciated!

[q.g._de_bakker]

Jason,

 

These green figures (not f-stops) are just a reminder of what speed to use when using smaller apertures. No more.

 

For instance, at EV 6, f/11 will be opposite "B" (which now means 2 seconds), and f/22 opposite "4". This means you must use a 4 second shutterspeed when using f/22. You obviously can't set any speed left of "B", no. But you can set f/22 and "B", and keep the shutter open for 4 seconds, the length of time that was indicated in green.

 

The aperture-shutterpeed link on your C type 250 mm lens does indeed work the other way round as on a CF or later lens.

To unlink the shutterspeed and aperture rings you must use the metal tab next to the right of the EV-index triangle. Press it and you will indeed "pull the F-stop ring towards the camera body".

[ernie_gec]

I agree with everything Q.G. wrote, but can't understand what pracrtical purpose these green figures ever served, given the universal problem of reciprocity failure at these times. The worst thing anyone could do is rely on them as aids to exposure determination.

[jason_byrley]

Thanks, Q.G.

Just to make sure of one thing, in your example, if EV =6, f/11 will be opposite "B". But on this lens with this example, that makes f/22 directly opposite "8", not "4" from what I see. Just making sure...

[jerry_lehrer]

Ernie and Jason

 

All my H'blad CT* lenses have that scale beyond B. The manual

clearly states what they are for, so I see no need to get in a

snit about it.

 

No, not all films have the same reciprocity function about them.

 

Jerry

[ernie_gec]

Gerald:

 

"universal" is a different word that "same." In time you'll learn to read more carefully.

[q.g._de_bakker]

Jason,

 

You wrote:

"if EV =6, f/11 will be opposite "B". But on this lens with this example, that makes f/22 directly opposite "8", not "4""

 

That's right. I forgot about and skipped f/16. My fault, sorry!