Why is there much more details in the sky when it is reflected?

<p>Hi, any idea why is there much more details in the sky (see a,b) when it is reflected?<br /> F3, Tmax400, light yellow filter<br />I suspect that there is some polarizing effect on the water surface, but I would have expected a lighter effect since the actual sky was not that hazy. Anything else?<br /><br /></p><div></div>

<p>Because the reflection isn't perfect, some of the light is lost. In this photo, the sky is overexposed, completely washed out, while its (partial) reflection is not.</p>

<p>That could be the answer, the exposure was f8 1/250, so enough to overexpose a quite luminous sky, as I remember. Any rule about this kind of attenuation caused by reflection (-1,2,..stops)?</p>

<p>I don't know how many stops. BTW, I should have said that some of the light goes into the water, not that it is lost.</p>

<p>Also, the color of the reflection is shifted some. B&W films have a color response slightly different from our eyes, causing a tendency for clouds to blend with the sky. A yellow filter helps correct this. (Wratten No. 8, also known as Y1.)</p>

<p>The filter was a B+W 021M MRC Light Yellow Filter Factor 1.5 (0,6 stop).<br>

So, there is three effects: less luminosity due to partial reflection (when the sky is overexposed), a color shift (blue?) caused by the reflection (when a yellow filter is present), and some light polarization if I remember well what I was supposed to learn at school.<br>

Thank you for your help, I am going to explore this phenomenon with all available ponds, lake & rivers..</p>

To the eye the sky and the reflection look the same but take a spot meter reading of the sky and the reflection. You should see a two or three stop difference. The water reflects only part of the light from the sky. Take a look at a window outside on a sunny day. You will see the outdoor scene reflected on the window and it will look as bright as the actual scene. To the eye they will look the same but a spot meter will show a five or six stop difference. Again, the light is only partially reflected. Good thing too. If it were all reflected it would be awfully dark in the house even in the daytime (unless you opened the window to let the light in).

<p>Physics lesson.</p>

<p>Physics + something = Monet<br>

http://www.musee-orangerie.fr/en/article/claude-monets-water-lilies</p>

<p>Glass at n=1.5 reflects about 4%. A little less for water at n=1.33. Then maybe a little more, as sky and water polarization are the same. About 4.5 stops for 4%.</p>

<p>So you mean that, in the photo above, the sky is overexposed about 4-5 stops to get the same details as in the pond reflection?</p>

<p>Any rule about this kind of attenuation caused by reflection (-1,2,..stops)?<br>

Basically the sky is over exposed relative to pond and the rest of the scene. I don't believe there's any compensation in the camera for this. Its not uncommon, the camera simply does not have the exposure lattitude to get good exposure through out the scene. If you spot metered the sky and the pond, you would see the difference. But the scene itself is not over exposed, in fact the shadows are almost blocking up areas so you really can't compensate you way out of this dilemma. You could next time try a graduated Neutral Density Filter to bring the sky down while leaving the rest normal.</p>

<p>Yes, this kind of filter would be a good idea, but how did Lord Ansel make this one?<br>

https://artblart.files.wordpress.com/2012/09/4-web.jpg</p>

<p>You mean Ansel Adams? It would be good for you to read his 3 books on photography and understand what he called the zone system and how he processed his film (individual sheets) and how he printed. in that photo I'm pretty sure he used (ferrocyanide) on the branches and of the tree and some of the reflections to bleach them whiter. Also he developed his film in such a way that he opened shadows and pulled down the highlights shortening development time. </p>

<p>One tip. If your camera allows for live view, set your exposure for spot focus, take your exposure through live room and move your spot around near the horizon line between the green and the sky, you want to just get it to where you see some detail in both. Than lock your exposure and recompose or however you do it on that camera and shoot in Raw. Often, you can have enough detail in both the dark parts and the light parts to then work it in post. In raw sometimes you can bring back a couple or more stops from the hi's and the lows, but it will take some work in post.</p>

<p>You just found out why people like me use grad ND filters for the vast majority of exposures that include the sky. If you overdo it its easy to reduce the effect in Lightroom for example. But to me its better than merging two or more exposures for most of my shots, and certainly better than over-exposing the sky to the point where you have lost all the detail, as happens here. </p>

<p>I did think, when switching to DSLRs from very contrasty 120 slide film, that the better dynamic range of the Dslrs might mean I didn't have to use grads. But it didn't.</p>

<p>The 4% is for normal incidence, so looking straight down into the water. For other angles, one polarization decreases, the other increases, so it might be a little more than 4%. But then again, for water (n=1.33) it is less than for glass.</p>

<p>https://en.wikipedia.org/wiki/Fresnel_equations</p>

<p>if you want to get it exact. Three stops (12.5%) might not be so far off at some angle.</p>

<p>Interesting mix of traditional silver emulsion and digital photography in the replies to Didier's question.</p>

<p>Glen's explanation and other comments resolve the initial question, but in practice, whether film or digital, the already mentioned graduated neutral density filter (3 stop?) can avoid post exposure remediation in these cases. Barry mentions zone system balancing and some post treatment. Also, if sufficient information (or detail) in the sky is already in the negative, selective area printing in the darkroom can sometimes do a good job. I don't have enough experience with graduated ND filters (problem with using RF type cameras for most of my shooting) so I can just imagine you might want a soft edge grad rather than a hard edge one in this case. Well defined linear horizons can probably be best shot with the latter grad.</p>

<p>Shooting under mixed cloud + sunlight may also be useful to enable the foliage bright spots and shadows to better reproduce under cloud shade, although the differences in luminescence between sky and land may still be a problem. Film has only so much latitude.</p>

<p>Barry, yes (who else?). Actually I own "The making of 40 photographs", and a few of his best photo books, and I have gone through his zone system, which as you know is difficult to apply with 36 exposures rolls. Regarding this lake, and whatever the treatment he applied in developping and printing it seems obvious to me that he had enough details in the sky and the lake. My point is that he had few stops between both, and no differencial filter. Also: "One tip. If your camera allows for live view..." it does, this is a F3..<br /> David: "for the vast majority of exposures that include the sky", Yes, I agree, although I prefer trying different exposures to swithching filters constantly very close to the front lens.<br /> Glen: ok, with three stops there should be an exposure with enough details everywhere.<br>

Arthur: I am not that smart, what I did (see the full photo below) was to meter under the bridge and take 0 and -1 stop (this one is the -1, f8 1/250), and to hope for the best. There was too many variables for my pre-transhuman brain. However, in retrospect I should have done more with this pretty place (even as I ended up with plenty of details in the shadows). What would you have done in front of this one, with a ~spot centered camera, Tmax400, light (this one) and medium yellow filters, polarizer filter, monopod, plenty of film?</p><div></div>

<p>Hi Didier, <br>

Thanks for the info. I guess in your case and without a grad ND filter I would simply meter to obtain a good balance between shadow and highlights and forget the sky, either leaving it go white as you have and/or eliminating the sky altogether. from the framing (composition). The crop or full frame photo you show in the directly above image seems to me to be like that and it is I think very good as it is. Probably enough shadow detail where necessary, and no burnt out highlights. I normally limited spot meter on fully lit green foliage, but like to use average wide range metering on scenes like this one or on the blue sky away from the sun which seems to represent sunlit landcape scenes.</p>

<p>I have limited mental approaches to photography (and to other things!), but I always try to either reject parts of what I see that I cannot, or do not want to, show and try to arrange the rest to be within the 5 or so stop range of my film (or the range of of my digital camera). That is not to suggest that sometimes completely featureless black or white zones are not effective. Thay can be I think.</p>

<p>Hi Arthur, I considered at some point metering on the bright field on the left background, or on the bunch of irises on the left (I focused on it, 40mm Ultron), but I knew that the right side would have been buried in the dark. What is not obvious on this vignette is that under the bridge there is a mixture of everything, so I chose everything..<br />"That is not to suggest that sometimes completely featureless black or white zones are not effective" well, I am not yet at this point, in a few decades maybe..</p>

<p>Right, given the amount of good subject matter in your shadow areas that was a good metering decision (under the bridge), but you may also want in those cases to check the luminescence of brighter areas to be sure you do not overexpose the rest. I like this image as much or more than your (albeit peaceful and calm) first one, in view of the bridge subject. With a lot of green matter a green filter can sometimes be useful (like orange-yellow, orange or red,it can darken skies more effectively than the yellow filter).</p>

<p>As those several decades are in large part behind me I do gravitate more recently to images that are less complex (in the amount of subject matter) and this often helps me in getting andwiorking with strong subject matter, and also because of that, letting some areas go very dark or very white. It is part of a minimalist landscape approach that micheal Kenna (michaelkenna.net) has shown us in much of his own work (although I prefer his earlier work to the more recent often more "busy" work). But that is a question of interest and taste for subjects and less a technical matter in regard to exposure or resolution.</p>

<p>Didier, sorry bout the live view part, that was meant for if you were to shoot digitally. You can't really say how many stops difference between the sky and lake when he shot it, one could only guess. But I'm pretty sure he metered and exposed such a way generally as to expose for where he wanted to retain detail in the shadows and then metered to see how many stops difference in the brightest part of the sky, noted the difference and then when he developed, he pulled development time to keep the highlights from getting developed. They used to say "expose for the shadows, develop for the highlights" back in my murky school days. There's a guy who shows photos in the Leica and Rangefinder forum here on p.net named Charlie Lemay. He posts photos in the picture of the week threads and uses what he calls the "Zone simple system" or something like that. He is very willing it seems to share what he's come up with, and it might be worth seeing what he has to say about how he goes about things. I forgot something else, what time did you take the picture, sometimes shooting a scene at the right time of day makes the difference from a beautiful print and print with a blown-out sky. </p>

<p>"check the luminescence of brighter areas to be sure you do not overexpose the rest." yes that was why I took also a -1stop, the 0 is a little overexposed in this area. And there is still details in the dark shadows in the -1, thank you Tmax400.<br>

"minimalist landscape approach that micheal Kenna (michaelkenna.net) has shown us in much of his own work": yes, but that does not rule out keeping the information intact. This may not be necessary on a print observed at a certain distance, but this add a feeling of ~quality to the result. See for example the full screen view of this pair of Rembrands.<br>

<a href="http://www.louvre.fr/en/portraits-maerten-soolmans-and-oopjen-coppit-rembrandtan-exceptional-acquisition-exhibited-musee-du">http://www.louvre.fr/en/portraits-maerten-soolmans-and-oopjen-coppit-rembrandtan-exceptional-acquisition-exhibited-musee-du</a><br>

Barry: actually, like large format film, digital photography allows tailor-made development, which 35mm film cannot. And as you pointed out, the exposure - development coupling is essential for real good photography. <br /> thank you for the tip about Charlie Lemay, I will explore this track<br /> "shooting a scene at the right time of day makes the difference": definetly yes, one should first select a time, and then manage to get there accordingly. I hiked 2 times up this place to get this one :<br>

<a href="/photo/18109050&size=lg">http://www.photo.net/photo/18109050&size=lg</a><br>

I new the time at sunset when the shadow on the bottom would reach the foot of this summit. It was moving fast, I was late and I had to climb fast, and take the time to set up my stuff calmly. Lot of fun.</p>

<p>Didier, I know the view camera uses sheet film. What I was pointing out, and you seem to already have known it, was because large format is single sheet development, you can individually, push or pull development. More difficult to do with 35 mm obviously. But Charlie claims to have figured out a system so, I'd be curious as how that turns out, if its of any use to you.</p>