PDA

View Full Version : Deep skies - how do i avoid the wash out?



abstraction
20-02-2012, 9:01pm
Hi. Yes, pretty much a beginner, despite a few years of photography.

I can't seem to manage the balance between bright skies and colourful earth. The sky is washed out or the earth is dark. I assume it's partly aperture, and direction of light source probably as well, but i'm not achieving it. I'm wondering if someone can give me tips, including if possible examples of settings that achieve those defined clouds, deep blue skies without losing the earth. I have a Canon 600d.
Thanks!

rodw
20-02-2012, 9:33pm
I'm only new too and I am sure others can contribute much more advice than me.

I bought a video training course before going off on a holiday and my photos improved out of sight as I went back to doing the things I did before I had an all singin all dancin auto mode DSLR. I came back with some of the best photos I've taken for years.

From memory, use 100 ISO (lowest I have is 200) and keep your aperture down to get longer exposures to get the best colour out of the sky. 3 weeks of cloudless weather also helped!

I think the sky is bluer with the sun behind you

http://i210.photobucket.com/albums/bb270/rodweb/Trips/2011-07-23%20Outback%20Qld/DSC_8559.jpg

Than if you are shooting into the sun
http://i210.photobucket.com/albums/bb270/rodweb/Trips/2011-07-23%20Outback%20Qld/DSC_8555.jpg

These pics are in the middle of the day so the lighting was pretty harsh (as was the country)

abstraction
20-02-2012, 9:57pm
Thanks Rod - that's a great start. Interesting contrast between the two skies. Nice subject, too.

arthurking83
20-02-2012, 11:02pm
The length of the exposure makes no difference to how dark or contrasty the sky turns out(relative to the ground).

It's the overall exposure balance (Ev balance) that helps you get a nicely coloured sky and well exposed foreground.
What you probably want to find info about is Exposure values(Ev) and how they balance relative to each other.
The other term of importance is dynamic range.

You can do this in many ways:

1. Time of day.
If you are shooting at midday in clear skies(in Aus), then the harsh bright sunlight lights up the ground very brightly, and due to this fact, the high Ev value of the ground basically forces the sky to render quite darkly by comparison. So if you shoot at a predetermined aperture value(say f/11) and the ground requires a shutter speed of about 1/500 for that aperture value, at 1/500 and f/11, you are almost certain to get a 'blue sky'.

2. use filters
GND .. Graduated Neutral Density filter helps to balance exposures between one part of a scene and another. They come in varying degrees of strength.
In a situation where the sun is lower to the horizon, or if it's partially or almost fully cloudy, you would use the GND with the dark section at the top of the scene.
eg. if the ground requires a shutter speed of say 1/30s at this same f/11, even a cloudy sky will blow out to almost white as you probably need a shutter speed more like 1/200 or even more to render a darker sky. The problem here is that this is where you need to find a balance between the correct exposure between this 1/30 for the ground and 1/200 for the sky.
A 3 stop GND is about perfect for this situation. The 3 stops of light at the top of the filter will bring the required exposure for the sky down from 1/200, down to about 1/60.
The difference between 1/30 and 1/60 in exposure terms is easily manageable on a raw file in PP
Polarisers also help somewhat, so they come under the umbrella of filters too, they are more limited in use compared to a GND(or a selection of various GND filters) but they both have their strengths and weaknesses.
Polarisers don't always produce a perfect result, if you are not careful, but for me, they are indispensable. I almost have one glued to my main lens.

3. HDR
Software version of a GND. Where a GND physically limits the amount of light in a part of the scene in one shot, HDR is so easy to do now with all this automated software ability.
In the above situation where you need 1/200 for the sky and 1/30 for the ground .. instead of using the GND, and it's associated problems, you literally shoot multiple exposures, get them onto a computer and run these multiple exposures through a HDR software program which it combines the images into a single image.
You woudl shoot at least one at 1/30(for the ground) and one shot at 1/200 (for the sky), but in normal usage you woudl also shoot one for the mid tones too(say at 1/100 or so) and usually the more exposures the better(control) you get of the final rendered image.

My preference was always, and still is to use methods 1 and 2, and I've done about 2 or 3 images with HDR in my 100k image pile sitting on my PC.
I'm not a big fan of HDR, even if it looks 'perfect'. I like photography for the technical challenge is provides .. as well as the finished product.

Having said that too, I reckon I'd get into it more if my software of choice had any HDR ability within itself at all .. but until it gets added to the software, I'll never really know.

There's probalby some other way to get this exposure balance done correctly, but it's now late and my brain has faded .......

BUT!!, I've seen this regularly from many newbies, where they think that an ND filter, a solid version of a GND, will also get them a better rendering of the sky.
The issue is not shutter speed alone, it's abut exposure and more importantly exposure balance.

An easy test to see how exposure balance is easy to see for yourself is to use the camera as a spot meter.

Set the metering to spot on your 600D. Set the operation mode to Manual(for now) Set and forget the aperture value(f/11 is good)
Holding by hand next time you're out, point it at the sky, and watch the meter reading. Without adjusting the aperture and only working with shutter speed: change the shutter speed so that the meter is reading an exposure level of -1Ev for a blue sky, or about 0 to +1Ev for a sky with clouds in it.
Now as quickly as you can, hopefully without any major change in lighting, point it at a dark part of the ground(not a white wall, green grass, or a brownish patch of ground.
Do the same with only the shutter speed, and change it to about a 0Ev value in the viewfinder reading of the meter level.
You may find that when pointed at the sky, the shutter speed may be at this 1/200s, and when pointed at the ground, it may be at 1/30 or 1/60s or so.
(note that the exposure values are just random numbers, and not a fixed value to work with .. it changes with each and every scene, time of day and filter usage)

This difference in exposure requirement is what the problem is, and without a method of balancing exposure to suit, you will always get 'washed out sky or dark ground'.

abstraction
21-02-2012, 1:12am
This is a brilliantly detailed answer. Thank you. It's going to take some experimentation when I get a chance (currently work travel) to get the ideas grounded in my mind. I was at the Taj Mahal yesterday. Would have been nice to play with the ev there.

swifty
21-02-2012, 5:17pm
Erm..what AK said.
My basic explanation is: the reason the sky is washed out relative to the ground or the ground is too dark relative to the sky is because that's the way the scene is.
Your eyes and brain can dynamically switch quickly to interpret both brightness but a single photo can't. It has a limited dynamic range (DR).
So use one of the methods that AK wrote to balance the light or capture more dynamic range.

My preferred method is shooting in favorable light conditions.
But that isn't always possible.
Have a look at one of AP member Dtoh's tutorials. A masterful craftsman in both the capture and processing of photos.

Cyza
21-02-2012, 5:33pm
this six minute video is very very simple and matches exactly what you're after
http://www.youtube.com/watch?v=AWPLpz8uXjw
assuming you have editing software

arthurking83
22-02-2012, 7:52pm
That video is proof for why you want to use Swifty's preferred method of photography.
1/100s of photography and 6m 34.99s of tedium!! :p

In that scene(in the video), you can get a nice photo from a single exposure if you shoot in the 'right light' or use filters.
" ... halos around trees that are kind'a unavoidable ... " doesn't interest me in any way ;)

mugget
25-02-2012, 8:18pm
Good info there. I look at this in a similar way to what swifty says about how the brain and eyes read a scene.

I forget where it was, but the point was that our eyes will correctly expose all areas of a scene at the same time, which is obviously not possible with current camera technology. So it's always going to be a trade-off/balance between the focal point/what you want to expose correctly. Maybe sometimes you'll choose a compromise and not any one part of the photo will be perfectly exposed, but you are able to show what you want.

Actually, going on from that subject I think that sometimes people put undue importance on getting a 'perfect' exposure. Really photography is about capturing your own vision, or a particular look or feeling that you want to convey. (Perhaps that look or feeling is a well exposed ground and sky, in which case you need to do some tricky editing or play with lens filters :p) But I tend to not worry so much about a 'perfect' exposure, rather I think about what kind of scene I want to portray - and that may be dark and underexposed, or it could be bright and overexposed (if that makes sense.)

Epicaricacy
02-03-2012, 1:22am
That was a really helpful answer AK, thanks! Always good to get some light shed on situations like this... Although not too much light we hope. :D

ameerat42
02-03-2012, 8:13am
Just to add to AK's explanation...

First, a couple of questions:
1. At what stage of the imaging process do you find you get the exposure mismatch between ground and sky?
2. How do you work on your images, and is there much post-processing involved?
3. Do you first work on raw images, or are they jpegs straight from camera?

The raw images can record more variation in luminance (brightness/tones) than a jpeg.
If you process/develop/convert a raw image properly, you can maintain a much better exposure balance between the sky and ground.

(That's all.)
Am.