Under-exposing - a consistent flaw?

You're absolutely right - Bridge of Allan faces south towards Stirling, however being a grey and overcast day I've always thought that 1/2 a stop more would have made it a better picture. Compare with this one of 45231 in Glen Beasdale: http://www.flickr.com/photos/neilscottuk/5404064979/

This was taken directly into the sun (it was above the 1st coach if a I remember correctly) on a beautiful day (20C, clear blue skies) in June last year. I overexposed by at least a stop to get the front of the engine picked out, knowing that in bright conditions and being backlit the engine would appear in darkness if I did otherwise. I've never felt that that the rest of the image suffered because of that and it conveys all the tones from black to white.

 

Steam trains are difficult to shoot in poor weather because you are always battling with a compromise to give the loco enough light whilst not losing definition in the white exhaust. I tend to underexpose to retain the exhaust detail, and since I shoot RAW I can pull things back in PS. I do find though that dark areas of images don't like being beaten around too much, and they quickly break down and become subject to unwanted levels of noise.

Best to go 'old school' and do the best you can with the exposure at the time of pressing the shutter. I don't trust my camera metering at all and have my camera on full manual. I shoot test shots prior to arrival of the train and use the LCD screen and histogram to judge how close my settings are. I'd still manually focus the camera if I could - unfortunately modern DC lenses don't have the prism for accurate TTL manual focussing.

There are a few tricks in PS which I find help: I use the levels adjustment a lot, and I select different parts of the image (using the lassoo tool thingy with a healthy feathering) so that, for example, I can isolate the loco away from the exhaust. The shadows/highlights function is good too - it's cheap and dirty - but it's a quick fix.

Underexposing is workable - in fact it's rather scary how much you can pull a digital RAW file - far more than I was ever able to in the darkroom with 35mm!

Overexposing isn't - the detail simply isn't there at all especially in burnt out exhaust. You can dodge out but not burn in. Nuff sed!

 

If shooting jpeg then you are generally trying to get all of the tones mapped correctly in camera, so the jpeg image appears as close to the scene in front of you as possible. There are some situations, such as the Bridge of Allan shot, where it may be simply impossible to keep detail in both the highlights and shadows, as the camera doesn't have the dynamic range to do so. Dull days can also be tricky as the sky can be far brighter than the rest of the scene. In these situations, there are a few possibilities: 1) Use a graduated ND filter to darken the bright portions of the image. This would work quite well in the Bridge of Allan pic, because the bright exhaust is all at the top of the image. 2) Use multiple exposures, one for the shadows, one for the highlights, and blend. Only really works for static subjects. 3) Accept that either your highlights or shadows will be lost and be creative to get the best result you can, i.e. silhouettes and such like. In these high dynamic range situations, there really isn't a "correct" exposure as it has to be a compromise. Personally, I'd rather block up the shadows than blow the highlights as to my eye I find it much more distracting having a blown exhaust or sky that is pure white than having black shadows. Each to their own though, but I remember reading an article on why most peoples vision finds this compromise to be the better one.

In such tricky situations, I'd definitely recommend shooting raw, as you've got at least a stop extra highlight and shadow detail than you have in a jpeg file and that can make the difference between keeping detail and not doing so. For raw exposure, I follow the ETTR concept: http://www.luminous-landscape.com/tutorials/expose-right.shtml This is designed to ensure that your digital raw file has maximum signal to noise ratio and therefore the best quality. It does mean most of your images appear overly bright when taken, so is no good for shooting jpegs, but these can easily be adjusted in the raw converter and it ensures your shadows will be as noise free and detailed as possible. So, in this instance, Neil is correct in his observation that "overexposing" tends to improve the shadow definition, but the whole concept of ETTR is that you make the image histogram as bright as possible, without clipping the highlights (in any of the colour channels, not just the luminosity). Of course, this doesn't solve the problem when the brightness range of the subject exceeds the dynamic range of your camera, as setting the highlights so they don't clip will result in blocked shadows. In this case the only solution is to adopt one of the above 3 strategies (or similar ones I may have forgotten).

It does take a bit of experience to judge how to set the exposure for ETTR, particularly given that the brightest highlight is often the exhaust, and as the train is moving that only appears in the scene at the last minute. However, with experience, you can often find a similar highlight, most often I'll use clouds. If the train is in view for a reasonable distance, you can also fire a test shot and check the highlights before adjusting the exposure for the main shot a few seconds later. The best advice I could give for digital exposure is to learn how to interpret the histogram for your camera.

 

Very interesting link dairypaul. I alluded in my post above to how I seem to get a lot of noise in areas of shadow and dark detail, and perhaps I can now attribute this to balancing my histograms centrally. I'm going to have a go at pushing the histogram across with some test shots and see what I can do when converting the files using my RAW converter.

Reading through that link also reminds me just how mind blowing the science is which goes with digital photography. Understanding the theory is one thing - interpolating that into my own individual practice is another!

 

I get underexposed shos quite often,mostly for a reason. That reason been that i hate ramping up the ISO much above 200. I would rather have an underexposed shot which i can shadow edit in PS than a grainy ISO shot. Sometimes cant be avoided and a lot of shadow enhancment also causes graining so it works both ways.
Its certainly difficult to get it just right in challenging conditions.

 

I certainly wish I was around in the days of film,just so that I could see what it was like. Likewise I avoid doing anything in PS apart from Sharpening and resizing to a more suitable res to keep filesize down. If I need to brighten shadows I do but normally I leave them. Then I get comments telling me I dont know how to use a camera,so I suppose its a case of damned if you do damned you dont. Also,I could be called lazy for not attempting to brighten shots that need it,mainly because they are pure record shots.

I did do a lot of PS correction in 2009/early 2009 but I have now stopped that,hopefully my photography has improved enough not to need it in any great measure......but then it is a godsend having PS as a backup,the amount times I would of mucked up in the days before PC's would be unbelievable. I suppose however there is a learning curve with anything. Only been taking photos since 2006 in any great number,so the first collection on my site is my very first time using "my" camera. I hope people agree that I have improved in terms of how I use a camera not just the camera itself since August 06. I have been using a 40D for 2 years in May,this been my first DSLR. Still got plenty to learn however..........a never ending road!

Cheers,
Mark

 

I think it does a little bit Martin. I read the article that Paul linked to but it meant nothing to me - perhaps you have to have a professional interest to understand something like that or have some kind of qualifications or to have studied the technical side of photography.

I certainly enjoy going out and trying to be creative and get good results - the odd bit of technical knowledge is will help me become a better photographer but the fun for me is just trying to get a photograph you can look back on with some pride.

 

I don't think that live was simpler with film, nor do I think that digital has taken the craft out of photography. Having said that it is different, some things are easier others not so and Photoshop has been both a blessing and a horror story!

Regards

 

I agree the technical side can seem a daunting at times, but if you can understand it a bit then it can help in certain situations. It's one reason why much traditional photography concentrates on "sun over the shoulder" lighting, as the nice even illumination rarely causes difficulty with exposure, which was particularly useful when shooting slides for which the exposure generally needs to be spot on. However, if you can grasp some of the technical stuff, then you'll likely increase the success rate particularly in the more challenging lighting situations (whether you shoot film or digital).

In practical terms, all you need to do to implement the expose-to-the right method is to set your exposure (manually) so the histogram is as far to the right as possible, but without clipping the highlights (i.e. the histogram should not quite have any values that are bunching up against the right hand side). This generally makes the image you take too bright, so when you load it into your raw converter, you adjust the exposure slider to darken the image until the overall brightness looks about right. What you'll find is that this gives you the least noise in the shadows, but without clipping the highlights and losing detail. If you do this and the histogram also clips at the left hand edge, then the brightness range is greater than what the camera can record, and then you have to make some kind of compromise.

To me, the histogram is by far the most useful exposure aid we've ever had, so if you aren't familiar with it, set your camera to display the histogram when you review an image and have look what it looks like, then adjust the exposure and see how it changes. You'll soon get a feel for it. If you don't have a good feel for histograms, then it's well worth reading this article: http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

I'm not sure I completely agree with Martin with regard to film being simpler. Most of the masters of film had a good understanding of exposure that enabled them to capture amazing images in really challenging lighting. Digital hasn't really changed anything in that you can still switch your camera to manual, set the shutter speed, aperture, focus, and fire away (or even switch to auto and leave the camera to it). The way I look at it, the technology has just provided additional features and info that can help you to increase your success rate. The two biggest things that help with that, are real time feedback via the image preview and histogram, and a raw file that enables you to record and recover a greater range of brightness values than was possible with most films. Fundamentally, photography still just revolves around choosing your film speed / sensitivity, setting a shutter speed, aperture and focussing. Whether you do this via the increasingly bewildering range of "auto" settings, or just do it manually is very much down to personal preference, but it doesn't need to be any more complicated than when using film.