Metering Middle Grey

[tgtaylor]

On a recent shot (the Alameda County Courthouse posted in the Kallitype thread) I went with the spot reading of middle grey off a grey card. The sky above the courthouse also registered middle Grey and on the print it is indeed a middle grey. Suppose I would have installed a UV filter on the lens. Would that have "softened" the middle grey renditioned of the sky? Food for thought.

Thomas

[Jim Noel]

Why put q $10 piece of glass in front of a $500+ lens?

[Bob Salomon]

Why put q $10 piece of glass in front of a $500+ lens?

Perhaps he has Heliopan or B+W or Rodenstock MC filters and they are not $10 pieces of glass. Not everyone buys bargain filters!

[Leigh]

Perhaps he has Heliopan or B+W or Rodenstock MC filters and they are not $10 pieces of glass. Not everyone buys bargain filters!
Just to reinforce Bob's comment...

ALL of my 40 or so filters are B+W, at sizes up to 105mm (Rodenstock Apo-Sironar (W) 210/5.6)

Believe me, that 105mm filter did NOT cost $10.

- Leigh

[Drew Wiley]

$10 is all you have left in your bank account after buying 105mm filters!

[Mark Sampson]

I don't know what you mean by "soften" the gray of the sky. Did you want it to be lighter in tone? In any case, a UV filter wouldn't change much.

[Vaughn]

Like Mark, I would say no -- not enough UV at that low elevation to see any difference.

[Bob Salomon]

So do I need to find filters priced more than my lenses? If I borrow a 210 super symmar xl, can I put a $10 filter in front of it since I didn’t buy the lens? I need to know all of the rules before I go out and shoot again! Since film prices keep going up, but lens prices are going down, are my photographs getting worse? Is the film to lens price ratio getting too close for good light to get through? OH NOOOOOO!!!

If your major concern is protecting the front element then use a filter. If your major concern is optimal results then throw that $10.00 filter away and buy a real one!

[Jac@stafford.net]

I am entirely sympathetic to those with modest budgets. Using the correct color contrast lens is important, and the hardest decision. From what I can gather, you could benefit from a K2, or deeper yellow filter.

Remember, black-n-white is color without hue. :) Often you must interpret how color values will render. For example, no clear blue sky means a filter will have no significant effect.

Stay in touch - oh, and what size filter do you need?

[tgtaylor]

I have the Schneider 4"x4" UV-410 (HAZE 1) filter that I paid around $150 new - they are currently priced at $161. It blocks UV below 410 nanometers "effectively reduces or eliminates photographic haze in areas where the atmospheric conditions contain a heavy concentration of dust particles, water droplets, and pollution...Helps eliminate such conditions often found in mountainous or coastal regions, and industrial areas that scatter light and produce a bluish cast that causes film to render a lack of color, contrast and overall image quality..." Would using this filter tone down the grey sky on the print mentioned above? A UV 2A filter is supposedly more effective.

Thomas

[Drew Wiley]

Jac, where on earth would one even find a "K2" filter these days unless they uncovered some Egyptian tomb beneath the dunes? Even that numbering system predates Egyptian hieroglyphics, I think. My point is, if someone does manage to find something like that, and does have the time to scrape the
layers of mold and snail tracks off it, it's certainly not going to help the optical expectations associated with an expensive lens. And Tom - yes, UV filters
can help clear a tad of haze scattering even on the coast using color film, but will be nowhere near as effective as a red or deep orange filter for pan film
in that respect, which allow only long wavelengths through. And one shoe does not fit all in terms of the best filter for each specific type of color film.
For example, I found that a nearly colorless very light yellow UV filter worked best for E100G chrome film at high altitude, whereas a pale magenta 2B
worked best with Fujichrome, and a Singh-Ray KN pale apricot-salmon UV filter for Ektar color neg film. But even some of these product numbers have
since changed to match the digital rather than film camera market. Ironically, certain kinds of expensive multi-coating can be counterproductive with
certain digital sensors. Glad I don't have that problem; but I do believe in high-quality coated glass filters rather than flimsy fragile gels.

[Jac@stafford.net]

Jac, where on earth would one even find a "K2" filter these days

Everywhere except under the rock under which you live.

[Drew Wiley]

Ha! Didn't Wratten itself give up that numbering system twenty years before the Napoleonic Wars? Almost no one even markets them on a no.12 yellow label nanymore. Now filter names sound more like ice cream flavors: Sunkist Lemon Honeybee Yellow, maybe. Mine just says Hoya HMC Y, which is really closer to old no.8. Ho hum. What do you know about rocks, anyway? I thought in that part of the world they're called "erratics". If you want real rock formations, mountains, and glaciers those erratics come from, you'll have to head West. You can keep the loess.

[consummate_fritterer]

I have lots of Wratten gelatin filters in like-new condition.

[Jac@stafford.net]

Ha! Didn't Wratten itself give up that numbering system twenty years before the Napoleonic Wars? [...]

What do you know about rocks, anyway? I thought in that part of the world they're called "erratics".

My memory is likely as old as yours, and our rocks are not from the latest glacier era. We are known as the 'Driftless Area .' You must know of our dolomite.

[Drew Wiley]

Now they call them Fruit Chewie sheets; and they sell for considerably less, digest easier too. True Wratten gels attracted less sugar ants. I use em mostly
in the lab, not in the field, for specialized repro applications. I take good care of them, and fortunately bought certain Wratten items now almost impossible
to find. The general photography items are easy to find; but I use glass filters for those kinds of applications. But some of them had set on a dealers shelf
for a long time before I got ahold of them even forty years ago, and not a single one bears a letter designation, versus the current numerical system. Unfortunately, there's a big gap in my modest collection of official Kodak data guides. The 1947 book is all letter; then my 70's one is all numerical. But I tend to gravitate toward still older editions. I recently acquired a lovely Kodak field-use guide book bound in a thick leather cover, still in beautiful condition.
It even contains actual viewing samples of popular Wratten filters set into pages, obviously letter-labeled back then.

[Pere Casals]

I also agree that UV contribution to exposure would be low at sea level.

In this (wiki) graph we see in red the sunlight spectrum at sea level, so it's easy to figure what exposutre contribution eliminated by an UV filter would be modest.

The yellow graph shows the spectrum outside of the atmosphere, so in high mountain conditions we would have an intermediate situation.

https://upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Solar_spectrum_en.svg/800px-Solar_spectrum_en.svg.png

[Drew Wiley]

Jac - we had localized sheet glaciers only in the northern half of Yosemite Park (not Yosemite Valley itself), and in the Lake Tahoe Basin. The rest were either
valley glaciers or the feeders of them up on the peaks, which have gradually receded, with far less remaining than just twenty years ago. There were ancient
peoples crossing that terrain well before the post-Pleistocene thaw, who were obviously well adapted to it. But for about the last 10,000 or 11,000 years,
as the canyons themselves thawed, the canyons themselves turned into camps and trails. Although the Sierras are mostly granitic, it does contain some
spectacular metamorphic and volcanic sub-ranges. So it's not uncommon to find fascinating dark erratic boulders in otherwise white granite terrain. We never
had loess like the Dakotas and upper Great Plains, but rather big alluvial plains at the foot of the mountains. These held vast herds of megafauna. Apparently
big ice dams would burst far upcanyon and drowned thousands of animals at a time. We'd run into vast jumbles of camel, horse, and mastodon bones. Fossil
ivory itself doesn't keep well except in permafrost, so tusks are very crumbly and difficult to recover intact. I once found an obsidian point embedded in
fossil ivory, substantially older than anything found in North America before, though nowadays they're slowly finding things possibly just as old, maybe 18,000 yrs. It was pretty fascinating to study permafrost soil formations in areas that are now frequently above a hundred degrees F most of the summer.
But wildlife photography would have been quite a challenge back when even a grizzly bear was a modest third-tier predator, and bulb-digging sloths were
as big as bulldozers.

[tgtaylor]

Pere - I think that you graph shows that the Schneider 410 filter blocks all UV radiation up to the 410 mark. I gave this some thought yesterday afternoon and came to the conclusion that the filter would indeed tone down the grey sky in the aforementioned print. At least that is the working hypothesis which I am going to test at the next opportunity to re-shoot the courthouse. There are several UV filters currently on the market with different blocking bandwidths which would seem to indicate that one could fine tune an image. Also, the blue of a blue sky doesn't appear to be homogenous - it appears to have "hot spots" - and I think an appropriate UV filter will tend to smooth those hot spots out.

Thomas

[Drew Wiley]

The density shift using a UV filter will be marginal at best. The point of using them is to cut through haze a tiny bit, and with some films, alleviate inter-emulsion light scattering, leading to a sharper image. Many color films go a little blue at high altitude especially due to excess UV, so stronger or pinkish
versions like a 2B can correct color accuracy as well. But for noticeable contrast increase relative to skies etc, you need at least a distinctly yellow contrast filter per se, and preferably an even deeper color. But don't be fooled about shorelines just cause they're low altitude. There is plenty of UV. The beach can be a great place to get sunburned. Duuuh.

[ic-racer]

I also agree that UV contribution to exposure would be low at sea level.

In this (wiki) graph we see in red the sunlight spectrum at sea level, so it's easy to figure what exposutre contribution eliminated by an UV filter would be modest.

The yellow graph shows the spectrum outside of the atmosphere, so in high mountain conditions we would have an intermediate situation.

https://upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Solar_spectrum_en.svg/800px-Solar_spectrum_en.svg.png

He is taking a picture of the sky, not the sun.