Anyone use Sunny 16 with non-standard apertures?

[IloveTLRs]

I use my Summar a lot, but it's got the old apertures on it. I find myself actually looking at blades and adjusting them visually before taking pictures.

Anyone else using this combination?

 

[Nikanon]

Not really recommended, its like trying to draw a straight line or cut a straight line by eyeballing it, it wont be precise, but then again, how precise is the sunny 16 rule, just make sure you give proper development

 

[removed account4]

sorry to suggest this, if you have already tried it ..
can you just go between fstops and not be all that accurate
on the exact aperture ?

sunny 11ish isn't really all that exact ...

good luck!
john

 

[Ed Sukach]

I use my Summar a lot, but it's got the old apertures on it.

??? Curious.

This is the first I've heard of "The Old Apertures".

"f/Stops" are defined as ""f" (focusing length - the distance from the aperture to the film plane) divided by the diameter of the aperture."

How did the "old" f/stops differ?

- Or are you referring to "T" stops?

 

[BetterSense]

I'd also like hear about these old f-stops. There doesn't seem to be any more logical way to generate apertures than to start multiplying by the square root of 2 starting with 1.

 

[removed account4]

sorry, i now realize after reading this again this morning
your lensmaker used a different system for your diaphragm numbers.

a lot of the old lensmakers used their own system for diaphragm numbers.
they weren't standardized until the early 20th century ..
there is an explanation of fstops and their history
here: http://en.wikipedia.org/wiki/F-number


http://en.wikipedia.org/wiki/File:DiaphragmNumbers.gif
this shows many of the other systems and their fstop cousin ...

you could see if your lens maker is there
and see how your diaphragm numbers relate to modern fstops
so you won't have to guess anymore ..
you could also measure the pupil and divide it into the focal length
to find out for sure ..

good luck!

john

 

[Xmas]

f/12.5 is not that difficult?

If it is an uncoated summar it will not be a '*T' stop anyway.

There is a x1.25 safety factor in the film speed.

Exposure meters are newfangled.

Noel

 

[IloveTLRs]

My photos have been coming out alright, thankfully.

Is f12.5 closer to f11 or f16?

 

[ntenny]

Is f12.5 closer to f11 or f16?

You gotta do arithmetic. 12.5/11 is just a hair over 1.1, squared is somewhere between 1.2 and 1.3, so a third of a stop, more or less. 16/12.5 of course comes out to the other 2/3 of a stop.

Do they go in increments of a stop from there? 12.5, 17.7, 25, 35, or something close to that?

-NT

 

[IloveTLRs]

No, f12.5 is the maximum (I mean minimum.) So f12.5 is literally 12.5, not the equivalent of f16 or something. That does help.

 

[steven_e007]

I've got a few lenses with none standard f number sequences on them. They are mostly large format things...

Years ago some manufactures used really wierd methods of denoting the aperture and you get sometimes numbers that make no obvious sense, so you need to consult the sort of table someone has already published, but the traditional f-number sequenced but based on a different starting aperture is no big problem.

I think the traditional sequence (f2.8, f4, f5.6, f8, f11, f16, f22, f32, f45) was only accepted as a standard in 1949? Prior to that the 'continental scale' was also popular (f2.2, f3.3, f4.5, f6.3, f9, f12.5, f18, f25, f36, f50). It seems to tie up better with some traditional lens designs, actually. F4.5 and F6.3 being common maximum apertures for many pre-war lenses. The numbers are still 1 stop apart, they will still represent a doubling or halving of the exposure as you go up or down the sequence, just the same.

If you use the sunny 16 rule you are guestimating anyway. All lenses transmit different ammounts of light depending on how many glass/air surfaces there are and whether and what type of coating. A modern coated triplet will be much faster than a pre-war uncoated 6 element lens (that was the reasoning behind T-stops, wasn't it? But they never caught on...) Additionally, film speed varies with development techniques and old shutters are rarely accurate...

I usually use FP4+ which is rated at EI 125, but few of my shutters do 1/125 sec, so I round to 1/100 when using the sunny 16.

So, it is all guestimation.

Why not just use the sunny 18 rule? If you pictures seem a bit under exposed, half the film speed next time? Or call it the sunny 12.5 rule?

If you want to be accurate with your exposures and meter carefully, you need to do an exposure test anyway to find a film speed. Once you have a speed for a given aperture, regardless of what the number is, just walk up and down the sequence in stops...

 

[removed account4]

hi steve

yeah
some of the aperture numbers are kind of strange.
i have a lens with levers and the numbers are the actual diameter of
the hole ... and while i did the math and figured out what the relative fstop might be
(now i am not so sure of the focal length ) i learned last week that the maker used those
numbers as the number of times you multiplied the exposure wide open, so #7 meant if it was 10seconds open wide
it was a 70second exposure ( 10*7 ) with hte 7 lever.
it is so much easier with fnumbers


ilovetlrS -
the table i linked to has a lot of the old scales AND all the intermediate fstops
and f12.5 is in there. the inbetween stops are 1/3 stops, so full stops backwards from f12.5 is easy ...
( full stops in bold ) 12.5 12.25 11.13 10 9 8.66 8 7.7 6.3 5.66
going forward ( if you had them ) would be
12.5 14.14 15.81 16 17.32 18 20 22.36 22.6 25

as steve suggests, at f12.5 you are just underexposing your film a tiny bit, at least now you know relative to f8 where f10 is ( 1 full stop in between! )

good luck!

john

 

[bruce terry]

I use my Summar a lot, but it's got the old apertures on it. I find myself actually looking at blades and adjusting them visually before taking pictures.

Anyone else using this combination?

Yeah, weird old stuff. The Leica O serie is even more thought-provoking with shutter speeds marked in metric slot widths of 500-200-100-50-20. Matched against the (sensible) modern standard of 500-250-125-60-30 the O’s middle three speeds are about ⅓ overexposed.

Not just that, but forced to apply the old european aperture sequence to the modern sequence you get: f3.5>f2.8, f4.5>f4, f6.3>f5.6, f9>f8 and f12>f11 ... the old apertures delivering about 1/3 underexposure, more or less balancing-out the ⅓ shutter speed overexposures.[/U]

There are two absolutely-no-big-deal exceptions:
In bright scenes, 500th max speed combined with the Elmar’s stop-down limit of f/12 delivers slight underexposure but that can only help as we're dealing with Sunny Sixteen here!
In low-light, stuck with 1/20th (vs 1/30th) at the Elmar’s wide-open limit of f/3.5, a dash of overexposure is surely welcome!

Sunny Sixteen bottom line proof is:
iso100 is f16@125th, or f11@250, or with the O, f12@200.

Silly stuff ... but it works fine ... ... for me.

PS - Pretty impressive, looking INTO an aperture to set it !!!!!