Maximum Aperture on 240mm f5.6 Symmar-S?

[tgtaylor]

I have this lens: http://www.bhphotovideo.com/c/product/800666580-USE/Schneider_240mm_f_5_6_Symmar_S_Lens.html

As you can see from the specs, the maximum aperture is listed as F-45 and F-45 is the maximum aperture marked on the lens scale. However the aperture marker continues past the F-45 mark and the iris blades continue to close and it looks like it reaches F-64 at the very end.

1. Is F-64 the smallest aperture?

2. Since the iris continues to close past the F-45 mark, why isn't the smallest aperture listed in the specs and on the lens scale?

Thomas

[ic-racer]

I have this lens: http://www.bhphotovideo.com/c/product/800666580-USE/Schneider_240mm_f_5_6_Symmar_S_Lens.html

As you can see from the specs, the maximum aperture is listed as F-45 and F-45 is the maximum aperture marked on the lens scale. However the aperture marker continues past the F-45 mark and the iris blades continue to close and it looks like it reaches F-64 at the very end.

1. Is F-64 the smallest aperture?

2. Since the iris continues to close past the F-45 mark, why isn't the smallest aperture listed in the specs and on the lens scale?

Thomas

Some aperture scales had dots for f64 and f90 like this picture. You can add the dots yourself or have SK Grimes do it. Close enough for B&W but probably not reliable for exposing chromes on a log-scale like this.
http://static.photo.net/attachments/bboard/00U/00UVSK-173259684.jpg

[tgtaylor]

There are no "dots" on the scale nor is there any indication in the specs that an aperture smaller than F-45 is obtainable.

Thomas

[ic-racer]

There are no "dots" on the scale nor is there any indication in the specs that an aperture smaller than F-45 is obtainable.

Thomas
You can add the dots yourself or have SK Grimes do it.

[Jmarmck]

Isn't this a shutter question? Perhaps a CLA is in order?
This is my first impression but I could be wrong.

[tgtaylor]

You can add the dots yourself or have SK Grimes do it.

But how many dots would you add? Does the lens stop down to F-64 or does it go all the way to F-128 or even smaller?

One of the questions is why wasn't this indicated on the scale or in the specs?

Thomas

[vinny]

on my modern copal shutters, the aperture scale is perfectly linear so the distance from 45 to 64 is the same as 32 to 45. Put on a piece of chart tape and add a couple dots. If there's room to hit 90 or 128 then eat your heart out. Why you'd want to go beyond f64 is beyond me.

[IanG]

Some aperture scales had dots for f64 and f90 like this picture. You can add the dots yourself or have SK Grimes do it. Close enough for B&W but probably not reliable for exposing chromes on a log-scale like this.
http://static.photo.net/attachments/bboard/00U/00UVSK-173259684.jpg


I think all Symmar S lenses were in late the last SynchroCompur shutters or Copals (most of them), the spacing between the marked f stops is constant unlike the earlier Compur etc . So they don't need the dots because that end of the scale isn't cramped.

My 240mm Nikon-W is in a Copal 3 that's marked to f64 but actually stops down slightly past f90. My late Compurs have half stop click stops, I think larger lenses were 1/3rd stop per click in late Compurs.

The minimum aperture is a Schneider thing. My 210 Symmar S Copal 1 has an f64 minimum marked aperture but the Copal 1 shutter I bought yesterday was from a Rodenstock 210mm Sironar and that has f64 as well.

Ironically my Schneider 150mm f5,6 Xenar (last batch produced) has a scale to f64 but my West German Zeiss 150mm f4.5 (linhof select) is only marked to f32

Ian

[tgtaylor]

If that's the case then it stops down to F-128. But why wouldn't Schneider indicate that either on the lens scale or in the literature?


. Why you'd want to go beyond f64 is beyond me.

Read my last post in the Salt Print Thread for a reason why. The further I went beyond F-45 the sharper the foresail became but I was afraid to go all the way because I was unsure of the aperture and hence the exposure.

Thomas

[Drew Wiley]

I thought I was the one who made the most typos. You already stated the maximum aperture in your own question. It's f/5.6. What you obviously mean is minimum aperture.

[IanG]

You get degraded results stopping down too far, from diffraction, Schneider may be more defensive than other companies. If you're doing contact prints then it's far less of an issue compared to enlargements.

Try the lens at f64, f90 see what it's like.

Ian

[Dan Fromm]

Hmm. According to http://www.ground-glass.net/large-format/copal-shutters, a Copal 3's largest opening is 45 mm in diameter and its smallest is 2 mm. 240/45 = 5.33, so if the shutter's diaphragm is fully open at f/5.6 the front cell magnifies the aperture by a factor of 1.05. Then the 2 mm smallest opening will give an exit pupil of 2.1 mm, minimum aperture (focal length/exit pupil's diameter) of f/114.

[ic-racer]

But how many dots would you add? Does the lens stop down to F-64 or does it go all the way to F-128 or even smaller?

One of the questions is why wasn't this indicated on the scale or in the specs?

Thomas

Two dots. F-64 and F-90.

Manufacture realizes that setting those small apertures can be problematic. If you come from high-to-low and stop at the mark the aperture size is different than if you come from low-to-high and stop at the mark. You are probably better off marking it yourself so you know if you always want to set it from high-to-low or the other way.

To me, those marks are for the experienced user that understands focal spread, print viewing distance, parallax error reading precision instrumentation, logarithmic progressions, aperture size in relation to focal length, film latitude and backlash in mechanical assemblies.

[djdister]

As others have noted, the absolute minimum aperture possible may not be considered acceptable for practical use, and so will not show aperture settings like f90 or f128.

One exception is Process lenses, which are often labeled down to f128 or f256. But the operational shooting parameters in a process camera setting are quite different from pictorial photography.

[Dan Fromm]

Don, a shot taken at f/128 will make a perfectly acceptable contact print. Enlarging is pretty much out, though.

[Sal Santamaura]

...a shot taken at f/128 will make a perfectly acceptable contact print...The acceptability of such a contact print will depend on which person is passing judgement. Copacetic to some, intolerable to others. :)

[Dan Fromm]

Sal, f/128's limiting resolution is ~ 11 lp/mm. The generally accepted discernable minimum is 8. I wouldn't do it, but its been done.

Cheers,

Dan

[Sal Santamaura]

...f/128's limiting resolution is ~ 11 lp/mm. The generally accepted discernable minimum is 8..."Generally accepted discernble" is copacetic for some. On the other hand, if I'm going to the trouble of making a contact print from a large format negative, as I do using a 240mm lens on whole plate, my ability to discern hews closer to Ctein's "perfect sharpness" criterion of 30 lp/mm. Therefore, I strive to avoid shooting apertures smaller than f/45. It's not always possible, but a worthwhile goal in my opinion.

[Drew Wiley]

Just the opposite with process lenses. They were intended to routinely be used at f/22, never ever at tiny apertures. What would be the point? Their primary application was much more demanding than ordinary taking photography, so their published images circles and apo design were standardized for perfect dot shape within this circle, at the published f-stop and specific recommended degree of magnification. So why do their aperture scales go way way down. Helliff I know. But that might just have been how apertures of that vintage were made in general, so that's what they employed as well. Of course, for our own kinds of applications we can bend the rules any way we wish. I often use process lenses for enlarging, and find them optically superior to most official enlarging lenses anywhere from f/11 down. And I mounted one for 8x10 camera use, and typically shoot it at f/45 or f/64 with great results. But there will be a tad of diffraction loss apparent at f/64 in a big print. I never stop a 4x5 lens smaller than f/32, for the same reason.

[Dan Fromm]

"Generally accepted discernble" is copacetic for some. On the other hand, if I'm going to the trouble of making a contact print from a large format negative, as I do using a 240mm lens on whole plate, my ability to discern hews closer to Ctein's "perfect sharpness" criterion of 30 lp/mm. Therefore, I strive to avoid shooting apertures smaller than f/45. It's not always possible, but a worthwhile goal in my opinion.

Sal, Ctein trumps me.

Cheers,

Dan

[Oren Grad]

Sal, Ctein trumps me.

Cheers,

Dan

Dan, I asked my 270 G-Claron once - did an aperture bracket through f/90 and contact printed the negatives just to see for myself. f/64 was fine, f/90 was visibly less nice. I don't know whether this was purely a quantitative resolution effect, or something about the qualitative character of the image at that aperture as a function of the optical design and the geometry of the iris.

This was printing with a glass sandwich, not the kind of lab-grade-super-vise-death-grip needed to properly replicate Ctein's paper resolution test. So I wasn't maxing out resolution to begin with.

[Jim Jones]

Weston apparently got by with apertures smaller than f/90 for contact prints of a few subjects. It's never worked for me.

[ic-racer]

Blind dismissal of one aperture or another without knowledge of viewing distance or focal spread suggests ignorance of the concepts at hand.

[Taija71A]

... A shot taken at f/128 will make a perfectly acceptable contact print...


... Sal, f/128's limiting resolution is ~ 11 lp/mm...
___

Uh-oh...

I hope, that this thread doesn't break out into... A 'heated' discussion of the Rayleigh-Airey Resolution Criterion. :)
--

-Tim.
_________

[djdister]

___

Uh-oh...

I hope, that this thread doesn't break out into... A 'heated' discussion of the Rayleigh-Airey Resolution Criterion. :)
--

-Tim.
_________

Indeed, and math formulas will undoubtedly follow...
128595

[Dan Fromm]

Dan, we don't really have to pursue this even thought there's always the joy of wrangling.

I think I gave a good answer to the OP's original question (how small is small?) in post #12.

[djdister]

Dan, we don't really have to pursue this even thought there's always the joy of wrangling.

I think I gave a good answer to the OP's original question (how small is small?) in post #12.

Yep, and thank heavens because my math skills wouldn't hold up anyway...

[Bob Salomon]

The maximum aperture is the largest one, 5.6.

You are looking for the minimum aperture.

[tgtaylor]

Hmm. According to http://www.ground-glass.net/large-format/copal-shutters, a Copal 3's largest opening is 45 mm in diameter and its smallest is 2 mm. 240/45 = 5.33, so if the shutter's diaphragm is fully open at f/5.6 the front cell magnifies the aperture by a factor of 1.05. Then the 2 mm smallest opening will give an exit pupil of 2.1 mm, minimum aperture (focal length/exit pupil's diameter) of f/114.

Thanks Dan. I'm going back to shoot that Windjammer in San Francisco Bay from the same location that I shot it last. This time, though, I'll stop all the way down and expose for f-128 (a little more light never hurts). The ships foresail is furled and secured with a rope wrapped around its length and I want the fibers of that rope as sharp as possible. I like my salt prints sharp.

Thomas

[Drew Wiley]

There are several reasons why people stop lenses way down beyond what is optically wise. For one thing, most traditional users of camera 8x10 and larger never have a consistent film plane. Big film often bows or sags in a conventional holder; so small f-stops help. This is a far more serious factor than many people realize. And endless diatribes over lens performance are actually skewed almost to the point of being meaningless by this one single fact. There are, of course, ways to improve or cure this. The other reason is for overall depth of field issues. Someone shooting ULF might resort to the smallest stops possible, because pronounced diffraction in the resultant contact print might be far less obnoxious than almost nothing being in true focus. I don't shoot anything larger than 8x10 myself, and never ever stop the lens down smaller than f/64, and won't even do that if I plan to make a print larger than 20x24. F/45 os generally as small as I prefer to go with 8x10 film. Anything smaller than that, and I can see a bit of fine detail degredation even through the loupe. Of course, it the subject
is flat, like in a process camera application, even wider stops can be sucessfully used. But process cameras also their big films on truly flat vacuum easels.

[Jim Jones]

Thomas -- I would expect a noticeable loss of sharpness throughout the subject at f/128, but a picture is worth a thousand words on forums. Please do reshoot at f/128 and post comparison images.

[ic-racer]

Thomas -- I would expect a noticeable loss of sharpness throughout the subject at f/128, but a picture is worth a thousand words on forums. Please do reshoot at f/128 and post comparison images.

At what viewing distance? Or to put it another way, could you imagine a viewing distance where you would not notice "loss of sharpness throughout the subject at f/128."

[Drew Wiley]

Or to paraphrase Jim, one look at an actual print is worth more than a thousand posts based upon calculator postulates. But lots of us already know the answer.
It isn't like this kind of hasn't been tested a few thousand times before. You can see it right on the groundglass.

[Taija71A]

... But lots of us already know the answer. It isn't like this kind of hasn't been tested a few thousand times before. You can see it right on the groundglass.

___

+1.

They Didn't say... "f/128 And Be There" .......... For Nothing!!! :)

Then again... "Sharpness is a Bourgeois Concept".
~~ Henri Cartier Bresson ~~ .
--

-Tim.
_________

[Jac@stafford.net]

Thanks Dan. I'm going back to shoot that Windjammer in San Francisco Bay from the same location that I shot it last. This time, though, I'll stop all the way down and expose for f-128 (a little more light never hurts). The ships foresail is furled and secured with a rope wrapped around its length and I want the fibers of that rope as sharp as possible. I like my salt prints sharp.

The subject's foresail might be as secure as one can imagine, but between its minor movement and the motion below your tripod and a breeze - all compounded by diffraction and the limits of salt printing will likely yield no improvement.

But enjoy.
.

[tgtaylor]

Went back out and reshot the Windjammer but this time I set the tripod right in front of the catwalk instead of behind it and the foresail issue disappeared. Exposure was 1/15 second at F-45 on Delta 100 which gave it a 1/3 stop extra exposure. The negative developed fine with no vignette problems - it may have been that I failed to close the camera properly which caused the issue in the first place as everything went smooth yesterday. I've learned that the bellows must "snap" into place when closing or there will be issues.

Here's the print which I will probably title Windjammer.

https://farm8.staticflickr.com/7366/16214235289_1291cc8c28.jpg

I'm quite satisfied with it and will mount and frame it this weekend. For an introduction to the ships history, see http://www.nps.gov/safr/historyculture/balclutha-history.htm. The Balclutha appeared in the 1935 film Mutiny on the Bounty starring Clark Gable which won best picture of the year award. This movie is being broadcast this Saturday night on PBS in California (KQED) so if you have the chance to watch it look for the Balclutha.

Thomas