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Old May 10th, 2004, 07:37 AM   #1
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Contrast problems (clouds vs ground, snow vs anything), filters

Hi,

I'm experiencing some contrast related problems and would like to learn from someone more experienced. My problems are roughly these:

1) When shooting outdoors in the winter the snow tends to become overexposed or, alternartively, the rest of the picture gets underexposed.

2) In the summer, on the other hand, the sky gets overexposed and the clouds disappear in the white. If the exposure is adjusted so that the clouds look nice, then the ground is too dark.


I know that to solve this a filter must be used (used yellow filters with B&W photography years ago). There are many options: gradient filters with neutral density, polarizing filters, Tiffen low/soft/ultra contrast filters...

Neutral density gradient filters are not a perfect solution because they just split the image in half along a straight line... So, now I would like to learn about the other alternatives.

So my questions:

- In practice, what is the main difference between Tiffen soft contrast, Tiffen low contrast and Tiffen ultra contrast filters?

- Which one would you recommend for the above situations? And what grade (2,1,1/2,1/4...)?

- Has anyone used both polarizing filters and these contrast reducing filters (but not on top of each other). Any experiences? Which one is better?
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Old May 10th, 2004, 10:45 AM   #2
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"Neutral density gradient filters are not a perfect solution because they just split the image in half along a straight line... "

It's a GRADIENT filter - you can not see a line in the image because the filter goes from clear to yelow or whatever gradualy. It is also very important how you use it: A long focal lens results in using just a small part of the filter, so that "line" is more spreaded on the image. Also, open the irris wide and you get the same effect. I think a graduated filter is the best solution for your problem!

http://www.geocities.com/cokinfiltersystem/graduated_filters.htm
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Old May 10th, 2004, 01:00 PM   #3
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Sorry, I forgot to mention that there is a foreground too in these problematic scenes... I'm trying to be more accurate this time...

Let's assume that the top 50% of a scene is dark green forest and the lower 50% is bright white snow reflecting sun light at noon at a relatively low angle. Then add some action, eg. a person, in the foreground, covering maybe 75% of the picture height. A gradient filter would solve the problem with the snow/forest to some degree but not with the person in the front. Feet would become darker and that might be a bit unnatural. The edge between the forest and snow could also be shap. The gradient isn't. And although the gradient could be made unnoticeable in the bacground, it probably wouldn't in the foreground. So I'm a bit skeptical against the use of a gradient filter. I could try it though.

The problem with sky + gradient is that I am not shooting at sea. The sky does mix with persons, buildings etc. in the foreground. A gradient filter would surely work at telephoto, but not when a trying to capture the end of a building, the ground and the sky... The same problem as with the first example...

So, theoretically, a gradient is not optimal - and because of that I haven't tried it yet. I might try, but I fear that it doesn't really fully solve this problem with mixed areas of high / low brightness.
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Old May 10th, 2004, 01:57 PM   #4
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Practically, you cannot really solve the problem given the characteristics of the CCDs and image processing in the current crop of prosumer cameras.

Maybe, just maybe the DVX-100/80 is adjustable enough to handle this.

Otherwise, it may take one of the pro cameras to solve the problem if, indeed, it can be solved for video.

Can you orient yourself and the subject in the scene so that a poliarizer will help?

Ah, the good old film solution!
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Old May 10th, 2004, 09:07 PM   #5
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Graduated ND filters are your best solution. Various manufactures make grads with hard and soft edges. I use grads fairly often with both my still and video work. The results vary from great to mediocre depending on various factors (many of which Cosmin mentioned). Get a couple of grads and experiment a little . I think you'll be pleased with the results.
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Old May 10th, 2004, 10:01 PM   #6
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Ralf, unlilke the folks who've already posted in this thread, I'm not a professional. But I do have both the low contrast and a polarizer. It turns out that in Honolulu , with very bright sunlight, the Tiffen low contrast is actually available off the shelf in larger (62mm+) sizes at our one good camera shop. So I have one. I opted to try this, by the way, after actually talking with Tiffen. They definitely did not recommend the ultra contrast. Obviously we're not facing the snow issue, but we do get a lot of glare off water if shooting outdoors. The low contrast will flatten out some of the worst glare (example: that blinding spot of light off the metal surfaces of cars or metal parts on a boat), but I don't think it will do much else for the kind of contrasts you're talking about. The polarizer is working out much better, so it may be worth a try. It's okay for the folks like me who are not trying for more than home movies. But from what I can tell, people who really want top results do recommend ND filters. I was advised months ago by someone who owns the same camcorder I do and who obviously has much higher standards than mine to use one.
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Old May 10th, 2004, 11:52 PM   #7
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I would say that given the situation you have described where the foreground figure is positioned across both the bright and dark sections of the frame, that a graduated ND filter will not work well for you. Grads are great for scenics and wide shots where the talent is containable within an area of contrast, not good for shots that involve tilting and lots of foreground.

I would recommend the Tiffen Ultracon for this situation (not sure what Patricia's camera store folk had against them!) It's not perfect but it is the best defense against this kind of difficult contrast. A 2 or 3 strength would probably do the trick in this instance.

Certainly combine the Ultracon with a Pola.
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Old May 11th, 2004, 12:06 AM   #8
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Can't' blame the camera store for the advice. It was the Tiffen rep with whom I spoke. Good thing our camera store does not stock ultracons the way it stocks low contrasts, or I'd have to run out and buy one of those, too, given your advice!
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Old May 11th, 2004, 01:21 AM   #9
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Sorry Patricia, my bad, misread your post. I'm intrigued about that advice coming from Tiffen though--did they give you any reasons why they would not recommend the Ultracon?

To answer one of Ralf's questions, without oversimplifying: the low con raises the shadows, the soft con lowers the highlights (somewhat), but both will initiate a bit of flare in highlights. The ultracon purports to lift the shadows AND reduce highlights without flaring.

Try searching the archives here under "ultracon", we've discussed them extensively in the past.
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Old May 11th, 2004, 01:46 AM   #10
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What happened is that after reading Tiffen's material, I tried to order the ultracon through a company in California. When I told them about hoping it would help with controlling flare and the way everything gets blown out because of the sun in Hawaii, the reaction was that the ultracon was not what I wanted. I was given a number to call to talk to a Tiffen rep, who recommended the low con, which doesn't do it for me, though it does flatten the worst highlights. Anyway, I have figured out why there are so many Hawaiian sunsets recorded - it's a lot easier to get a decent shot when the sun is going down than when it's overhead - and it feels like it's overhead most of the day in Hawaii.

Thanks for your advice, Charles. Time to go check out that ultracon purchase on line this time.
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Old May 11th, 2004, 06:34 AM   #11
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Well, Ralf, maybe you can't work this out with filters alone. When you have a big contrast in the picture, the soulution is to lower the contrast by any means. One is the filter (gradul ND, ultracon...) and onther would be to actualy modify the light. I'm thinking maybe you could use the gradual to stop down the light from the snow and use some extra light for the lower part of the person in the foreground so that the lower part of his body will look as bright as the upper part... Of course you would "aim" the light in such way so it doesn't add to the snow.

You're in trouble! :)
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Old May 13th, 2004, 05:56 PM   #12
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I have similar problems in Alaska. When it's not snowing or raining the results of the said precipitation cause all sorts of exposure problems. What I would give for any sort of digital camera, still or movie, that had something resembling the "exposure range" of the human eye.

I've had best luck with dark circularly polarized filters. But.... As you've noticed and other posters have mentioned, your best bet exposure wise is to let mother nature do the lighting (sunup, sundown). Not always easy or possible, but cheaper than a professional camera and crew.
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Old May 14th, 2004, 03:11 AM   #13
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Partially solved

Thanks for the replies. I needed that kind of community support. I got similar suggestions from Tiffen, too, so I am more confident now...

I went to the Tiffen.com website and the bhphotovideo.com website to compare ultra/low/soft contrast filters. They have some sample images there...

The Tiffen low contrast filter creates such a glow around the highlights in the picture that it does not qualify as a contrast reducing filter only. It looks more like some sort of special effect filter with contrast reduction as a byproduct... The soft contrast filter looks *much* better. A lot less glow around the highlights and it also affects highlights only. I can always use the exposure dial to get the shadows properly exposed - no need to redirect more light there using a filter. Thus no real need for the low contrast filter. The soft con that affects highlights only is enough - and, as I said, it produces a cleaner result.

The problem choosing between "soft contrast" and "ultra contrast" remained, so I emailed Tiffen technical support. I explained a few typical cases and asked for their recommendations for an affordable subset of filters. They said practically the same as Charles Papert... This is what they responded:

1) bright snow below, dark forest above (=shadow), people in the foreground with the sun behind them

"Here, an Ultra Contrast #3 filter is recommended. This filter will help bring some of the highlighted part into the darker forest area to help lighten it up."

I'm not sure if I was clear enough about the fact that the people in the foreground become underexposed too. It is mainly the highlights I need to cut to access larger apertures. But, well, the Ultra Contrast does not have this glow effect that is supposed to still exist to some extent on the Soft Contrast filter, so maybe UltraCon it is better anyway.

2) Sky, clouds, buildings, people

They recommended the same, obvious, solution as many of you on this thread - a polarizer. Tiffens tech support did not mention anything about contrast filters. A polarizer would of course make the clouds more visible. But, if the sky gets overexposed even after applying a polarizer, then I'll probably need a contrast filter, Soft or Ultra.

3) People at sea. The sea is extremely bright so the people tend to get underexposed. Alternatively, the sky gets overexposed.

Tiffen said:

"Here exposure has to be adjusted again and the use of the Ultra Contrast #3 will help reduce the contrast."

So, they did not recommend the Soft Contrast although it would only cut the highlights. Thus I am inclined to believe that the Ultra Contrast filters are truly better and do the exact same job (and more) as the Soft Contrast. At least the UltraCon does not produce any highlight flare. The SoftCon might just a bit...

So, it looks like I'm going to get an Ultra Contrast #3 filter plus a polarizing filter to begin with. Later, with some experience, I can get UltraCon #1 or #5 if I need...

Still, I must dwell on this matter for a while until I am confident of that dropping the SoftCon range from the selection is truly a good idea. If someone can convince me know, even better.

I'll certainly experiment with ND grads and ND filters too, but that's a different story.
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Old May 14th, 2004, 11:57 AM   #14
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Ralf:

Sounds like you are on the right track. I think your decision to go with the Ultracon is a wise one.

I have written here in the past about the various issues with that filter, it does require more attention than most. Allowing ambient light to strike the face of the filter will cause the shadow areas to milk out further than may be desirable. This doesn't even have to necessarily be direct sunlight, even high levels of indirect light can cause this effect. Thus I highly recommend using a mattebox with eyebrow and both siders in concert with an Ultracon to keep the filter "dark". Also be aware that you may find yourself having to dial the blacks down in post, as raw Ultracon footage looks a bit milky.
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