Olympus E-PL1 and ISO 100

All images - Olympus E-PL1 14-42mm kit lens ISO 100

The base ISO for all the Olympus Pen m4/3 cameras is apparently 200. However up to the E-PL2 all of the cameras provide an ISO 100 option. Apparently what happens when you take an image at ISO 100 is that it is taken at ISO 200 and "pulled" back to ISO 100. 

There seems to be a view that this narrows dynamic range and that using ISO 200 is the "better" option.

However I've always used ISO 100, and one of my reasons for getting an E-PL1 again rather than an E-PL2 was because of this.

Why?

For my uses I've always found ISO 100 gives better results. The seemingly small step from 100 to 200 adds, I believe, luminance noise. The pictures appear slightly more "grainy". Images at ISO 100, if correctly exposed (more later) are much smoother and cleaner to my eyes, producing a better looking image. I also don't see any significant reduction in dynamic range again if correctly exposed.

As part of a general ongoing moan, about how many people who claim to be photographers don't seem bothered about doing things properly, the expectation that the "right camera" will just do everything for you is both naive and ridiculous. It seems to me that too many people just accept what comes out their camera. They seem to have neither the inclination nor the ability to put some thought into what they are doing. 

Exposure is a case in point. I rarely accept what a cameras meter is telling me, and in the case of m4/3, virtually never. All the Olympus and Panasonic cameras tend to overexpose as far as I'm concerned. (Not confined to m4/3 incidentally, both my Nikons also do it) I suppose its got something to do with all those years I spent shooting transparencies. For landscape photography particularly, punchy rich deep colour is the order of the day and overexposure can reduce a landscape photograph to a bland nothing. Add in to this the "problem" that digital capture tends to produce less contrast than film and you have the potential for producing pictures that lack impact.

In real world terms what this means is that I generally shoot with either -0.3 or -0.7 dialled in as exposure compensation. This then gives me a basic raw image that has the range of tones that I like and can then be processed in firstly ACR and then Photoshop to produce an image that has "punch", good colour and yet doesn't have blown highlights. This may require adjusting levels on part of the image rather than the whole thing.

So with care and thinking about the end result when I shoot, I'm able to get very high quality images from these cameras at ISO 100. Virtually noiseless, with no dynamic range problems and capable of being reproduced at large sizes.

Fortunately the E-P3 is retaining 100 ISO as a manual option, which is good to see.

Exposure

Just read a fascinating article by a post-production specialist who works with photographers on large advertising projects. He was writing about how to handle images with a large dynamic range and offering some advice on "How to shoot wrong, to get the get the right result"

His basic idea was that for digital raw files you should always shoot with slight overexposure.

The reason for this was that raw files have 1 to 1 1/2 stops of latitude for highlights. He sees the problem in images as being the noise created when shadows are lightened. The theory is that using Photoshop -

1) you expose for the shadows (add 1 to 1 1/2 extra stops of exposure)

2) in raw conversion pull back the exposure to bring the highlights back (don't use recovery)

3) now lighten your shadow areas as required

His contention is that when you now lighten the shadows you will create less noise because these areas were correctly exposed in the first place.

I was pleased to read this since its basically what I've been doing for years.

The common advice is to expose to prevent burnt-out highlights. This seems to be almost universal. There is this determination to preserve highlights at all costs, often to my mind resulting in a poorer image.

I first used this technique of overexposing when I used the Kodak 14n full-frame 14MP DSLR a few years ago. This camera suffered from very bad noise and artefacts, particularly in the shadow areas, and it was essential to expose correctly for these. Fortunately the sensor had incredible leeway in the highlights, up to 3 stops. I've never seen this since however.

This image was taken on the Kodak. A very difficult image to expose for. This was how the raw file looked before processing.

As can be seen I was able to restore the highlights, and lift the shadows in the boat without creating a lot of unpleasant noise. Exposing for the highlights would have resulted in an image like this.

Lightening the bottom of the image would have resulted in a great deal of noise being generated.

The theory does assume that the camera sensor has a good dynamic range. However I've used this successfully on all my cameras including m4/3. If in doubt, bracket the shot if possible, as that will cover you.

The writer calls this technique "one shot HDR" and can be seen as such. Often it just isn't possible to take several shots without anything changing in the image. There is a way to do HDR by creating three different versions of the same file. However the above technique does much the same in one shot.

Finally, a word on histograms. While these can be useful, to my mind many photographers become obsessed by them. You should always use your eyes to rate whether an image looks right.

I sell 1000's of images every year, most are published in magazines or books. Every file that I send out either to a library or a client has the following done to it.

In levels in Photoshop I adjust the RGB output level boxes to 5 and 250, instead of 0 and 255.

This takes out a pure black and a pure white, which is essential for printing. A pure white will result in no ink being sprayed onto the paper, resulting in the surface showing through. A level of 250 means that something will be there, changing a pure white into a very light grey. This means that your file is now printable.