Orphi's Photos
As per my invitation Orphi has linked through to some of his photos on his blog that he's not happy with.
I pulled his photos into a folder so I could get at the EXIF information. For those wondering cameras store extra information regrading f-stop and shutter speeds inside the images and this is accessible either through a photo programme or by right-clicking the file in Windows and selecting Properties then the Details tab.
The first thing I note is that despite being landscape shots Orphi's Finepix S304 camera (aka S3800) loves a aperture of 2.8 which is the widest that camera can go.
Now you may recall Depth of Field (DoF) the wider the aperture the shorter the DoF this was a simplification as I didn't go into details about hyperfocal distance; time to do so.
Again keeping things simple the hyperfocal distance is the point at which everything from half the hyperfocal distance to infinity is in focus. I recommend reading this article about it for more details. So the hyperfocal distance depends on the focal length the aperture and something called the "Circle of confusion" which differs from camera to camera and lens to lens.
So digging out the manual for the S304 the focal length is 6mm - 36mm it has f-stops of 2.8, 4.8, and 8.2 and I've also dug out a circle of confusion value of 0.005mm
So using the equation H=(f^2/Nc)+f I get these figures
| A/d | 6mm | 36mm |
| 2.8 | 2.6m | 93m |
| 4.8 | 1.5m | 54m |
| 8.2 | 0.9m | 32m |
Well at f/2.8 and a 6mm focal distance I'll guess Orphi's focussed on the centre of the photo which appears to be roughly at the 2.6m range as shown in the table above, that means everything from half that point, i.e. 1.3m, to infinity will be in focus. Which is pretty much everything in the photo.
Okay time to use the excellent DoF calculator found here. Use the 1/2.5" sensor as the closest available match, plug in the f/2.8 6mm and 2.6m and we get what I've already stated. But what if Orphi had taken a step back perhaps the same distance back as our focus point and then zoomed in to get the same shot?
Well aperture stays the same at f/2.8 let's set the zoom so that the focal distance is 12mm and now the focus point is 5.2m away. We know see that only the range between 3.4 and 11m will be in focus. That will keep everything in the foreground clear, but will start to blur the background. If he'd pointed the camera at the point he was orignally standing at 2.6m away, but obviously kept the same zoom level then the range is between 2 and 3.5m that would leave only the very closest objects in focus and blur everything in the background.
So final technical point is why everything seems so bright and over exposed, well that'll be that wide open aperture. We can either knock down the aperture a notch (thus also adjusting our DoF) or speed the shutter up. Sadly on the S304 you can't alter the shutter speed manually, however we can try the next best thing which is the EV or exposure compensation.
In essence this is a short-cut to cutting down or increaseing the brightness without fiddling directly with aperture, shutter speeds or ISO settings. Positive numbers allow more light in, negative keeps it out. According to the manual you can have -2.1 to +1.5 so for this scene with this camera I'd have dialed in a figure of -0.6 and seen how it turned out
Okay we've dealt with focus and exposure let's look at composition.
First off it's a landscape shot, but the stream runs vertically so first off I'd switch orientations. To work with this shot that means cutting out an area 576 by 768 pixels. Using my paint package I create a new layer and colour in a section of that size in red (because it shows up better), I'll add in my Rule of Thirds lines, then set the layer to a 50% transparency so I can see through it. Now I can move the red layer across the picture until I see a composition I like.
Cut that out and paste it as a new image, then add in a gradient blur mask, and adjust the exposure. Then finally tweak the slight blue cast.
et voilà.
5 comments:
If you were cropping that image in the GIMP, you wouldn't need to paint a red layer with rule-of-thirds lines. The crop tool greys out the trimmed region of the image to make it easier to see the effect of the composition, and it gives you the option to show centre lines, thirds lines, or golden-section lines over the region you are looking at.
The GIMP is free software - free as in speech, as well as free to use - available for Windows, GNU/Linux, and MacOS.
1. Oh, that's interesting. I thought I stripped the EXIF data before uploading… Oh well, I guess not!
2. I thought EXIF just stores the make and model of the camera, and the date the photo was shot. I wasn't aware it contained any useful data. (How the heck are you reading it BTW?)
3. That is a small improvement on my original image, but let's face it, it was a pretty uninteresting shot to start with. (Too many branches in the foreground obscuring the view, etc.) I'd be more interested in seeing if you can do something with the fallen tree shot, or maybe one of the lake shots.
PS. How did you get the image to be green rather than blue?
Dan - Thanks for the reminder about Gimp, hadn't realised it did that; personally never quite got on with it.
Orphi - re EXIF data as I say I'm just reading it from Vista's file properties.
Amusingly I was going to have a look at the fallen tree next, not sure which or maybe both.
As for getting the image to be green rather than blue - simple, I removed some of the blue :-) To be complex I could have bumped up the green channel, then had to bump up the red to stop it having a green cast; much simpler to decrease the blue channel slightly.
Oh, so Vista adds EXIF reading? That's interesting.
XP has too. It's surprisingly handy if you know it's there :-)
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