In Defense of Program Auto-Exposure

<p>The "P" (Program Auto-Exposure) mode on my K100D sometimes serves me very well in tricky exposure situations, as in the two shots below. EXIF tells me that the first was 1/350 sec at f/8, and the second was 1/90 sec at f/5.6, ISO 400. Minimal post-processing in #1 (shadows/highlights) and none in #2. Both were taken at Chincoteague Island, VA, last weekend. <br /> <br /></p>

<p>I deliberately put the sun behind one of the posts here:</p><div></div>

<p>Sometimes the afterglow is more impressive than the actual sunset:</p><div></div>

<p>In allot of ways, ''P'' mode is one of the best. Even in P mode, you can adjust the Aperture or shutter speeds as well as EV. So in allot of ways it is no different that setting it to AV or TV mode.</p>

 

<p>I'm a firm believer in the P setting, especially at night after the sun goes down. It seems to really pull out great exposures in low light situations.</p>

<p>P is great unless shooting multiple exposures for HDRI</p>

<p>I don't see any point in using Aperture Priority or Shutter Priority program modes, if you don't have a preference for a particular shutter speed or aperture, and just want a balance of the two. Full Program exposure, with the camera setting both aperture and shutter speed, is by far my favourite exposure mode. Second preference would be full manual, still using the camera's metering, but dialing in both values.</p>

<p>For the type of shooting that I do, Program works great. When I got my first cameras there was no automation (or if there was I couldn't afford to even know about it, much less have a camera that had it). Eventually I moved up to a body with Aperture Priority, and really liked that. Where I wanted to over or under-expose from a meter reading manually I could now use the Compensation control (as long as I wanted to stay within the range, otherwise back to manual of course). From there it was on to cameras with Program Auto, but I always had one that you could shift the program on. I used Minolta at first, then moved to Nikon, and all through that I had the various Pentax lying around too. If I didn't like the combination of aperture and shutter that the camera selected it was easy to shift one or the other and keep the same exposure value. If I wanted to over or under-expose that was easy as well. I know there are situations where setting the shutter speed and aperture manually are preferred, but I've never understood those people who insist that everyone should be always "using Manual" when all they do is center the meter anyway. </p>

<p>James,<br>

You actually bring up a very good example (great pics by the way). The key here is the subject matter. You created a wonderful sillouette (actually two) by allowing the camera to meter the background either by spot metering or having the camera average the whole scene and thus the sky gets the preferred treatment because there is so much of it in the scene. In that scenerio, the camera meter was your friend. Now, lets change the subject matter. Lets put a beautiful model on the dock. We'll have her seated near the edge and perhaps leaning against a post in the foreground. Using the same matrix metering that worked so well for the sillouette in now your enemy. She would just be a shadowy figure in the foreground. Without resorting to flash, you would need to use spot metering on the model. But, that can be tricky also. Where do you put the spot? Lets have some fun...<br>

Lets turn the girl around. She's enjoying that beautiful sunset and is just lost in her own thoughts. It's your luck day! She has dark hair and she just put on a medium grey sweater. Perfect, you spot meter the sweater because ALL camera meters are based upon 18% grey (your medium grey). This exposure will be perfect, but it's blurred because she's getting cold and reached over to pull out her bright yellow windbreaker which she just put on. Now what? If you meter her hair, the yellow jacket will be over exposed making look more like a bug light than a girl lost in her thoughts. Meter the bright yellow and everything will go dark because the yellow is more akin to the bright sun than it is to our friend 18% grey. So what do you do? The truth is, you hurry up and find SOMETHING that is close to 18%. In this case, I would swing the camera over and meter the post as weathered wood is pretty close to our 18% target value. What if there isn't something grey nearby? Perhaps she's against a white fence?<br>

Corny example, I know. But, the point is that things happen and although camera meters are a good thing, they can be fooled in certain situations. This is because they rely on REFLECTED light from the scene. The lesson to be learned here is not that you should always run around in manual mode. The lesson is that you should know the LIMITATIONS of the in-camera meter and how to work around the problem (as in meter the post) or how to bypass the problem entirely by grabbing an ambient meter, metering the light and getting the shot in manual mode. Once you learn these things, then you are in the drivers seat. Then you will no longer be "getting the shot". Instead, you will be making the shot that others can not get.<br>

Mel</p>

 

<p>One advantage of using aperture preferred is that if you leave it set at f/8 or f/11 you are in the sweet spot of best lens performance. Most lenses do their best in this range.</p>

<p>Mel - I completely agree with everything you say. Your examples are excellent ones. Thanks to all for comments.</p>

<p>My recollection is that none of the single e-dial, 6-megapixel bodies (including the OP's K100D) had P-shift (shiftable program AE), --it is this reason that I got in the habit of shooting Av most of the time.</p>

<p>The results from Program AE vs. Av or Tv aren't necessarily going to be all that different, and will probably result in fewer bad choices. Every now and then with Av I blow an exposure, particularly when I hurriedly try to use daylight fill flash and my aperture is too wide for the x-sync limited shutter speed. I tend to use Av more because I know what I'm shooting and whether I want f/11 or f/5.6 for depth-of-field reasons though if I got more comfortable with P-Shift/HyperProgram it would probably be smarter.</p>

<p>If you have a dual dial camera, P/A is equally good as Av and Tv, the issue is the fact that most Pentax DSLRs save the D, K10D, K20D, K-7 are single dial.</p>

<p>I usually leave it on P when I set my camera up for the morning on trips. As my sleep deprivation wears off, and my ability to focus improves, I revert to either Av or manual.<br>

<br /> <br /> With the green button I prefer manual, with the program line set to aperture priority. Like this I have way more control.</p>

<p>The problem with program I have, is if you are changing the EV comp, why not just adjust the shutter using manual? You can always hit the green button if you go the wrong way, of do a 180 and find yourself shooting into the sun.</p>

<p> </p>

<p>I mostly use TAv. That means TAv with ISO 200-3200 saved as USER for photos without flashlight , and ordinary TAv with ISO 100-400 for flashlight situations. Very convenient. I control all three parameters instantly, and can choose what tripple combination that I prefer adapted to the conditions of every single shot and what I want to get out of it.<br />Mostly I also use single-spot AF. EV is normally set to +0.3, since my Pentax cameras (K20D and K-7) often tend to give exposures that I find a little too dark otherwise.<br />Auto is great if I have not time to consider things thoroughly enough, but want to take a quick picture.</p>