Camera is underexposing
 

Hi,

I'm a little bit perplexed as to why my new camera is consistantly underexposing my shots. I've been using my Olympus E620 with the Zuiko 12-60mm f/2.8-f/4.0 lens to take some close-up shots of leaves and flowers. Being a bright lens, with a 25cm minimum focus distance I thought it would have been ideal for this, but now I'm not so sure.

Now it was a little on the dull side so I set the ISO @ 400, set the camera on to aperture priority and opened it right up as wide as it would go to get a shallow dof. When I come to download my shots on to the computer they're all underexposed by approximately one f-stop. Is there something wrong with the camera or something wrong with the settings I chose? Or should I have just dialled in +1 of exposure compensation to correct things?

The thing that is really bothering me though is there, hidden away within the camera menus, another setting that I may need to adjust that will correct this and if so what am I looking for?

You don't say if you are shooting raw or jpeg? If it's raw then they always produce flat images. The fact that it was a dull day will reduce the vibrancy of the image making the shot look darker. It could also be that the camera under-exposes the shots when you do close-ups. What does the histogram say? On my D3 I usually have it set to -0.3 or -0.7 I this give the best outcome in most situations. :D

How do you know that it is underexposing by about one stop? Have you checked exposure using the histogram on the camera and on the PC? Have you got areas which begin to clip as you increase the exposure?

You don't say what metering you are using, all of them will give slightly different results perhaps any problem might lie there?

There is another possible problem occuring here, and that is if your eye is not actually at the viewfinder when you release the shutter, light will enter and change the exposure the camera thinks it needs, underexposing the shot. This is a particular problem with Macro when the camera is pointing down at flowers and there is brighter light from above, if the viewfinder is not covered the shot will be under exposed.

You've not got the camera set to -1 exposure compensation have you?! ;)

I was shooting in raw on this particular occasion, using digital esp metering and looking at the histogram on the camera the main peaks were gathered just slightly left of centre, but in the raw plug-in on my computer they were even further over to the left. Of course, once I started editing them I increased the exposure values and increased the saturation values to give them a little more sparkle.

Now I'd much rather the images are slightly under-exposed than over-exposed as you can usually recover the details lost in the shadows, but you can't do the same to highlights that have been clipped, so I guess I maybe blowing this slightly out of proportion. Still it's interesting and informative to hear you thoughts on this to see if there is something I may have overlooked.

In response to Flake's query about covering the viewfinder fully, for some of the shots I was using the live view window as the camera was either too low down or too far out in front of me to use the viewfinder for some shots, so that shouldn't be an issue with those shots. On the shots I took with my eye to the viewfinder, it does have a good eyepiece that is effective at sealing out the light once my eye is pressed against it.

Hopefully that may have given you a bit more to go on and Chris I hadn't dialled in any negative exposure compensation. If anything I'd tried adding 1 stop of exposure compensation.

The histogram on the camera is only "representative" of the image (according to Nikon at least) which sounds like a small "get out" clause to me, but it could explain the differences between the histograms. Otherwise I'm stumped!

[quote=ianpinion;6494]I was shooting in raw on this particular occasion, using digital esp metering[B] and looking at the histogram on the camera[/B] the main peaks were gathered just slightly left of centre, but in the raw plug-in on my computer they were even further over to the left.
.[/quote]

Chris is on the right track here when he states that the histogram on the camera is only a representation. Indeed it is, and, perhaps more importantly, it is a representation of the small embedded jpeg file that all RAW images contain and not of the captured RAW data itself. This viewed jpeg image has also been subjected to any default or personal settings. Not owning your particular camera I have no way of knowing what functions or settings are available so will use Canon by way of example. With these cameras there are various user settings such as Portrait and Landscape etc, and when used the captured jpeg image will be processed in-camera in a way that Canon think a Portrait or Landscape image should look like i.e. Landscapes are usually processed with more saturated greens which are not personally to my taste. The user also has access to each of these 'styles' and can reduce such things as brightness, contrast, saturation and sharpness. So the long and the short of it is, that whilst you may be shooting RAW, the displayed and now processed jpeg image will be in keeping with the style set for jpeg. There are also other settings such as white balance where the user can set for instance 'cloudy' which will also affect the embedded jpeg. For this reason I as a matter of habit always have the style set to 'Faithful' so that the viewed jpeg image is a little more in keeping with the RAW image. Now, the settings probably are different on your particular camera but what's important here is the general principle i.e. that the histogram viewed on the camera is only a representation and more, is a representation of the embedded jpeg image and as such should only be [I]used for guidance[/I].

There are also sound reasons where one should expose a bit more to the right and here's a good link to a short essay explaining the principles and reasoning behind it. [URL]http://www.luminous-landscape.com/tutorials/expose-right.shtml[/URL]

Thanks for your reply Forseti. Most informative, as always.;) Now Olympus cameras do have tonal settings, but these are labelled as Vivid, Natural, Portait, Muted, Monochrome and Custom. I can also adjust the contrast, sharpness and brightness too. The only adjustment I made there was to the sharpness as with one of my other lenses it has a can sometimes look a little soft. I also tend to try and switch the noise reduction filter to either low or off as I find this can also soften the image.

Now for the shots in question I changed between the vivid, natural and portait settings on the tonal choices but the result was almost the same as under-exposing was concerned.

I had a bad habit of keeping my exposure compensation at +1.I was getting an awful lot of rejections-poor lighting on my microstock site.I now alter it to suit the light.I was also advised to keep the iso at 100 which is complete bollacks.
Time and expierance will make you fully understand what your camera is capable of produding with any given setting.
You could fill a small library with the opionated tosh spoken by alot of photograhers but really the best way to learn is to shoot,keep shooting and enjoy the expierance.
NB.I stick to neutral as i like the subdued color...

If it was me first thing I would do in that situation is use use spot or partial metering.