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Old Jan 8, 2010, 1:15 PM   #1
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Default Need help to figure out how to use P mode

I need help to figure out how to use the P mode because the K-x manual is of very little help

When is-it appropriate to use the P mode instead of Av or Sv or M?

This is all that was said about the P mode from the K-x owner's manual:

''Automatically sets the shutter speed and aperture value to obtain the
proper exposure according to Program line when taking pictures.
You can also use the e-dial to change the shutter speed and aperture
value while maintaining the proper exposure''

I don't understand what it says. Could someone please explain in clearer terms

thanks
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Old Jan 8, 2010, 1:36 PM   #2
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OK,

In full auto mode the camera selects all the elements to get a proper exposure. You as the photographer don't adjust anything.

P mode takes it a step further. P mode is intended for people that still want the camera to do the Lion's share of the work. P mode will typically start you off with the same aperture / shutter speed settings that full auto will. BUT, there are two ways that YOU as the photographer can tell the camera to do things differently.

1) Program Shift. This is what the manual is talking about. There are 3 parameters that control exposure - ISO, Aperture and shutter speed. Assuming you keep ISO constant - you can change the other two parameters to get different benefits while still maintaining the same exposure. Huh? OK, let's say at ISO 100, a proper exposure is F8 at 1/100. You could change the aperture to f5.6 and increase shutter speed to 1/200. You have the same exact exposure. BUT you've changed 2 aspects of the photo. First, the f5.6 vs. f8 will result in a shallower depth-of-field meaning less of the image will appear in focus. Second, the faster shutter speed will freeze more subject movement. A one-stop shift isn't as noticable. But if you do a 2 stop shift from F8 1/100 to f4 1/400 (both settings are the same exposure) you could see a dramatic difference in the photo.

What the program shift allows you to do is turn the wheel one direction and the camera raises shutter speed / reduces f-number or turn the dial the other way and the camera lowers shutter speed / increases f-number.

The idea behind this is - the majority of the time you want to take the camera's word for things but on occasion you recognize the need for either more / less Depth of field (more DOF for more of image in focus - like scenic shots or group photos OR you want more shutter speed to stop subject movement - or even less shutter speed to show movement).

If you find you constantly want more control of depth-of-field or shutter speed then it's time to move into Aperture priority or Shutter Priority or full Manual.

2) The second thing most P modes allow you to do is apply Exposure Compensation. The idea of EC is you as the photographer recognize that the camera's metering is going to under or overexpose the shot. So you intentionally tell the camera you want to over or underexpose the shot. A great example now is snow. If you take a photo out in the snow the camera will try to expose the snow as grey. So photos can look dull. By "overexposing" the shot by +2/3 or +1 EC you actually end up with a more realistic exposure.
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Old Jan 8, 2010, 1:59 PM   #3
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Thanks JohnG for providing explanations, it is a bit clearer now.

However, if my understanding is correct, the entire P mode can be substituted by either Av or Tv right?

in Av: you set the ISO, EC, Aperture, WB and the camera decide shutter speed

in Tv: you set the shutter speed, ISO, EC, WB and the camera decides the Aperture

so what does P do that Av or Tv cannot? it is still a bit nebulous to me

from the film SLR, I am familiar with Tv (Canon AE-1) and Av (Pentax ME, Nikon FG) and M (Pentax K1000). I have never owned a camera with P mode before so I don't know what to expect

thanks
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Old Jan 8, 2010, 2:03 PM   #4
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What P mode does that the others do not is it does the first settings for you. You don't have to do anything. In AV you MUST select an aperture value. In P mode you don't have to select one to start with. In TV, you MUST select a default shutter speed. In P mode you do not.

Again, P mode is for the person who 90% of the time doesn't care what aperture or shutter speed is used (caveat - typically P mode, like full auto, won't select low shutter speeds). In addition, P mode should automatically enable flash when the camera decides it is needed. TV and AV mode will NOT automatically engage flash.

So, AV and TV require a bit more input from the photographer. P mode will do everything for you just like auto mode but lets you adjust the guess the camera makes.
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Old Jan 8, 2010, 2:34 PM   #5
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thanks JohnG again. It is clear now.

I guess I could use P mode instead of Autopict on my K-x that tends to choose very slow shutter speed even if the built-in flash is used (1/4 to 1/8 sec) because for some reason when I shoot indoor, the autopict defaults to night portrait mode which uses slow shutter speed

talking about flash. I read somewhere that using an external flash meant for film SLR will damage the DSLR because of the huge voltage burst sent to the flash mounting (something like that) is that true? I have a couple old generic flashes that I used with film SLR. It would be nice to be able to use them again on my K-x
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Old Jan 8, 2010, 3:03 PM   #6
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P mode - what JohnG said.

But there's a couple of other wrinkles with the Pentax cameras when it comes to P vs. Auto (green) mode. In green auto mode, the camera forces you to use the "bright" setting (camera default). Personally, I find that over-saturated and far prefer the "natural" setting, so I never use the green mode (I'd disable it if I could, but I can't). And yes, sometimes the camera chooses weird combinations when left to its own devices.

So P mode is good if you don't want to think about things. I do probably 80-90% of my shooting in P and try to always leave the camera set that way when I'm finished using it. It's great for the quick, grab the camera and press the shutter type of picture because I don't have to worry about how it's set up. If I want a specific aperture, I turn the dial and the camera instantly changes to Av mode. Same thing if I want a specific shutter speed - no need to change the mode dial to switch to Tv. And I can hand my camera to my other half (who doesn't know what aperture means much less what it does) set to P and he'll take some excellent pictures. About the only time I take it off P is when I want a specific shutter speed AND a specific aperture - then I use TAv (where the camera will then meter and set the appropriate ISO) or M.

For your flash question - your flash might or might not be safe for a dSLR. I'm the last person to answer any flash question as I'm so clueless when it comes to it, but there's a website that lists all sorts of flashes and indicates if the trigger voltage is too high or not. If in doubt, there are devices you can get that will make it safe to use ones that are too high.
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Old Jan 9, 2010, 7:05 PM   #7
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Mantive,
First, don't even try your off camera flash until you check the flash voltage! you can damage the camera badly. If you have a volt meter, you can check it yourself (off camera) by charging the flash, hold the leads to the ground and trigger contacts on the shoe, and then fire the flash and take a reading. There is some controversy on what is an acceptable voltage, some say 30vlt some say 10 or even 5vlts and I can't tell you what it is on the K-X.

Now, as for auto, P, or other modes... I have questions myself. some are saying that P mode will choose the best settings for you as far as the camera thinks is best. From my experience, 90% of the time if I use P mode indoors, the camera sets the aperture to high and the speed to low for me and refuses to let me select the settings I want, even when using flash. (and I have the menu set to choose speed over aperture also) On my K20 today, I was indoors using the 12-24mm - 540 flash and shooting a group ranging from 6 to 12ft away. when I turned the camera on, I tried P mode to see what it would give me. It chose f:4 @ 1/30th sec. that setting gave a blurry pic that was way over exposed. I went to TAV mode, upped the shutter to 1/90th sec ISO 200 and got what looked on the screen to be a perfect exposure, so I went with that. When I got home and looked on my computer... the whites were perfect, everything else was under exposed and rather soft and noisy. So, whats a person to do?
Another thing, John G, says, that you have to choose a shutter speed or aperture when using TV, AV, TAV mode. Perhaps I'm doing it wrong but, when I use those modes, I press the green button and it gives me a setting just like the P mode does and I'll change it from there. How should I be doing this?
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Old Jan 9, 2010, 9:25 PM   #8
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GW - you and John are both right. Like John said, Av, Tv and TAv all expect you to input the appropriate number(s). If you don't change anything on the camera, it will maintain the number you input for every frame after. Normally you do that by changing the wheel. But if you don't want to specify an aperture or shutter speed you can push the green button and the camera will do it for that scene. The figure the camera chooses won't change if you go to another scene, like it will with P mode. Not all cameras add that function to the green button, but they all otherwise work the same with Av allowing you to change the aperture etc.
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Old Jan 9, 2010, 9:48 PM   #9
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MG the k-x doesn't have a TAv but has a Sv....is that the same thing???



also my K-X doesn't have TV..but does movies tho...
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Old Jan 10, 2010, 8:39 AM   #10
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No, they don't work the same - I'll have to bear in mind that the Kx doesn't have the TAv mode, one of the differences between the KX and the K7.

TAv - you set both the aperture and the shutter speed you want and the camera chooses the ISO. With Av, Tv and P you choose one of the values while the camera chooses the others. With M you have to choose all three values - aperture, shutter speed and ISO - auto ISO doesn't work in M.

In Sv mode, you choose the ISO and the camera chooses the shutter speed and the aperture. I used to use this a lot with the K10. The K10 was really noisy at ISO 1600, so I had the auto ISO set to 100-800 and then pretty much left Sv set to 1600. If I wanted to use 1600 for something, I just switched to Sv and took my picture. Only problem with the K10 was that Sv was right next to P and I can't tell you how many times I accidentally switched to Sv as I took the camera out of the bag and didn't notice, once ending up shooting Great Egrets in bright sunlight at 1600 ISO. I'm one who appreciates the mode lock on the K7. I don't use it much with the K20 and K7 (I've used the ISO button on the K7 instead).

One question I have about the K-X - in your reading, have you run across something called the program line? The K20 and K-7 both have the ability to change what they call the program line and I wondered if this might be something that was left off the K-X, being an entry level camera. What the program line does is allow you to influence what the camera will use for a "proper exposure" in P mode. You can choose to have the camera almost always shoot at a lens's "sweet spot" where it's supposed to be sharpest (most useful for shooting with FA and DA lenses which the camera can identify), or have it emphasize faster shutter speeds or greater depths of field. There's also the default normal setting, which is what you would get leaving the camera totally to its own devices. It's not something that's really necessary, but there have been times I've been really happy to have this feature and wondered if the K-X had it also.
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