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04-30-2010, 08:05 AM   #1
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what is the difference between Av, Tv, and P?

First, I did read the manual and another book but I am missing something obvious. If P changes shutter and aperture automatically based on what I set one of them and this also happens in Av, and Tv, what's the difference?

I thought that if I changes the aperture in Av the shutter setting would be calculated automatic. If I change the shutter in Tv, the aperture is calculated automatic. If I am in P and change either of them, the other one is calculated automatic.

what am i missing? Thanks.

04-30-2010, 09:02 AM   #2
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You aren't missing anything.
In Av, you select the aperture and the camera selects the shutter speed.
In Tv, you select the shutter speed, the camera selects the aperture.
In P, the camera selects both aperture and shutter speed.
04-30-2010, 09:15 AM - 1 Like   #3
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The best way to explain it for me is that P (program) mode is a step between the green mode (auto mode) and Tv or Av modes. I think you could almost call P mode - programed or preferred auto mode. What you do in P mode (on my k10 or k20) is change the f stop or shutter speeds via the wheels and the camera determines the opposite setting, i.e., if you change the f stop the camera varries the shutter speed and vice versa depending on what ISO is set.

What took me a long time to understand is that where the Program come in is WHAT YOU SET THE PROGRAM TO BE (sorry about my emphasis here). In the custom menu there is an option to set the program line preference. On my k20 it can be 1 - normal, 2 - hi speed, 3 - depth, 4 - MTF (manufactures transfer function). These days my camera is set to depth because that's usually what I want my Program mode preference to be - based on my selection of speed or f stop I want the camera program (in P mode) to make the decision giving me the best exposure to maximize the depth of field. If I set it for speed the exposure program makes the choice to find the highest shutter speed it can based on the possible varriables f stop and ISO.

I shot P mode for almost a year before I understood about were the P in program comes in.

Ok, one more thing. MTF mode this is intended to be a mode that if the camera knows the lens on the camera (read Pentax only lens I believe), it will make choices based on what Pentax thinks is the best settings choices for that lenses optics.
04-30-2010, 09:17 AM   #4
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In a way (the way the camera is set from the factory), Av and Tv are a little redundant as both functions are covered in P mode based on whether you move the front or rear dial....

Edit....I just read blackcloudbrew's post above...I wasn't aware of the MTF...

04-30-2010, 09:19 AM   #5
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so in the Av and Tv, I have to select but in P I do not. i can take what the camera gives me and go with it. Av and Tv make me select the best one and does not start out with what it thinks is best?
04-30-2010, 09:41 AM   #6
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QuoteOriginally posted by blackcloudbrew Quote
The best way to explain it for me is that P (program) mode is a step between the green mode (auto mode) and Tv or Av modes. I think you could almost call P mode - programed or preferred auto mode. What you do in P mode (on my k10 or k20) is change the f stop or shutter speeds via the wheels and the camera determines the opposite setting, i.e., if you change the f stop the camera varries the shutter speed and vice versa depending on what ISO is set.

What took me a long time to understand is that where the Program come in is WHAT YOU SET THE PROGRAM TO BE (sorry about my emphasis here). In the custom menu there is an option to set the program line preference. On my k20 it can be 1 - normal, 2 - hi speed, 3 - depth, 4 - MTF (manufactures transfer function). These days my camera is set to depth because that's usually what I want my Program mode preference to be - based on my selection of speed or f stop I want the camera program (in P mode) to make the decision giving me the best exposure to maximize the depth of field. If I set it for speed the exposure program makes the choice to find the highest shutter speed it can based on the possible variables f stop and ISO.
That's a pretty good explanation.

QuoteQuote:
I shot P mode for almost a year before I understood about were the P in program comes in.
That's why I avoided P mode. I didn't know where the camera came up with the settings. On the *ist DS, there are some vague program options that aren't that clear. I also did not like guessing what parameter would be changed if I used Ev compensation. Anyway, it doesn't matter exactly how we use different modes. The main idea is to understand the mode you're in and be comfortable with it.

QuoteQuote:
Ok, one more thing. MTF mode this is intended to be a mode that if the camera knows the lens on the camera (read Pentax only lens I believe), it will make choices based on what Pentax thinks is the best settings choices for that lenses optics.
MTF is basically maximum sharpness and contrast. Pentax FA, FA-J, F-FA, DA and DA-L lenses can all send information to the camera on what apertures maximize these characteristics. Some third-party lenses might be able to do the same thing. The chip in the Pentax-F lenses didn't have enough capacity to store that data.
04-30-2010, 02:48 PM   #7
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QuoteOriginally posted by justtakingpics Quote
so in the Av and Tv, I have to select but in P I do not. i can take what the camera gives me and go with it. Av and Tv make me select the best one and does not start out with what it thinks is best?
Let me try to answer each of these points in order. In Av and Tv you can control the camera settings chosen. The camera metering will always try to give you a good combination but you can vary say the f stop beyond what's given or good for the exposure. In P mode (and I believe this is a true statement) you really can't override the camera's meter balancing out the f stop or speed based on your selection when you change the wheel (f stop or speed) because P mode is really green mode with user selection of f stop or speed. Is that more clear? One thing in this is that the green button on my k10/k20 is always there when pressed in P, Av, or Tv (and other modes) to return the metering back to the best setting the camera thinks for the image). Simplistically Tv & Av modes start at the same place that P mode does from the camera's metering but they let you go beyond (override) the automatic adjustment (program) feature of P mode because you are controlling it. (that might not have been as clear as I like but that's what I'm trying to say.)

Spend some time with each of these an you should get a feeling for this. Honestly what I like about the Tv and Av modes is that I've set mine up so that my exposure compensation Ev is visible in the eyepiece and is adjustable by the wheel, so that if I'm in Av my back wheel adjusts f stop and the front wheel adjusts Ev. Very handy.

Hopefully that helps a bit more.
05-01-2010, 06:48 PM - 2 Likes   #8
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Hi jtp,

I just wanted to make a small correction to blackcloudbrew's first post -- MTF stands for Modular Transfer Function, not Manufactures Transfer Function. . . just being picky.

I can see how you're confused, especially if you have a camera like the K-7 where you have two control wheels, and they can be programmed to a number of different configurations for each wheel. I think that you can probably get the same level of control from each of the modes, controlling Av, Tv, or ISO in different ways in different modes, but that's really the point. The designers of this camera wanted to allow the user to choose not only if they wanted this control, but how exactly the user wants it to be done.

I choose to shoot Av priority, with the rear wheel controlling Av, the front controlling Ev compensation, and Auto ISO, with the Info Menu highlighting the Auto ISO range. I could have the essentially the same control in other modes, but that would require me to develop a different shooting protocol and way of thinking when I shoot, and it's just easier to set up the camera to my preferences than the other way around. This is the reason I prefer to shoot the more advanced bodies -- they allow me to shoot pretty much without having to pause to think about what to do, and I'll be able to set up the next new body to react the same way.

It may sound like a small thing, but photography, for me, allows me to capture the moments I choose, while controlling the most important aspects of how they are captured. The more brainlessly this can be accomplished under varying lighting conditions, the better it is for me.

There is no "right" mode, and using one over another is largely a matter of personal preference, depending on the circumstance. As I stated, most of the time, I shoot Av priority, but there are times when Tv is better, and times when I might want to shoot in "green" mode, TAv, SAv, or fully Manual. The way I discovered preferences and limitations of each mode was to take a bunch of shots in each, make mistakes and then think of how I could have avoided them using the features of the camera. I blew some great shots during this discovery phase, but luckily I don't count on every shot to pay the bills, so I could write off my mistakes as a learning experience and move on, hoping that I learned enough to not make the same mistake in the future. That's the beauty of being a hobbiest shooting digital. You can get almost instant feedback, and your mistakes don't take food from the table.

Unfortunately, some of those great shots blown during the "learning stage" can't be recovered, but I shoot with much greater confidence that I'll be better prepared for future great photo ops in difficult situations, and will be able to handle them more competently. -- BTW the "learning stage" really hasn't ended for me, and since I still make some head slapping stupid mistakes, I'm pretty confident that it never will. . .

Scott

05-03-2010, 11:24 PM   #9
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QuoteQuote:
In Av and Tv you can control the camera settings chosen. The camera metering will always try to give you a good combination but you can vary say the f stop beyond what's given or good for the exposure.
just to clarify this a little... In AV or TV you can select settings that the camera can't balance to obtain correct exposure. An example of this would be selecting a shutter speed that requires an aperture that your lens doesn't have. Although I've never tried this, on previous cameras it would just select the best it could do but the end result is a pic that's not exposed correctly. Another case where Av mode fails you is you select a small aperture (large number) and the resultant shutter speed is too slow to handhold.

QuoteQuote:
In P mode (and I believe this is a true statement) you really can't override the camera's meter balancing out the f stop or speed based on your selection when you change the wheel (f stop or speed) because P mode is really green mode with user selection of f stop or speed.
Yep, you need to play with the exp comp to achieve a bias to the selected exposure (for whatever reason you decide). The P mode does allow you to do things that green mode won't like alter flash exp comp (I think that's one... I don't use green mode).

So I would explain Av, Tv and P modes like this: ("correct exposure" meaning the cameras idea of what's needed for a picture)

Av - You select Aperture and the camera selects a shutter speed to give correct exposure within it's capabilities (may not be possible resulting in incorrect exposure)

Tv - You select shutter speed and the camera selects aperture to give correct exposure within the lenses capabilities (may not be possible resulting in incorrect exposure)

P - The camera selects both aperture and shutter speed. The camera allows the user to override either the aperture or shutter speed and the camera will automatically change the other variable to try to maintain correct exposure. (I imagine you can cause incorrect exposure just like the other modes too by selecting settings that cause the other parameter to go out of range)


I leave my camera in P mode nearly all the time. I use the wheels (K10D and K7 so 2 wheels) to select either aperture or shutter speed to suit the subject if I don't like what the camera has selected. I use the exp comp to alter the exposure to purposely increase or decrease exposure based on a combination of the histogram, preview on LCD and my intent.

Nige.
05-04-2010, 04:30 AM   #10
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If you want to be a photographer, you need to understand exposure, and how Aperture and Shutter Speed determine the final look of the photograph.

Once you understand exposure and the Aperture Shutter Speed relationship to how the final photo will look, you will start to understand the reason for the Av and Tv modes, and the more you understand exposure and the Aperture Shutter Speed relationship, you will start to realize the importance of Manual mode. It's a learning process, and yes, it can take some time, but it is really not that hard to understand once you get into it.

If you don't want to get that involved and just want to take snap shots of family, friends and pets, or vacation shots, then P mode is fine. The camera will do the work for you and give you the results it THINKS you want.

The moral of the story.....You wont always be satisfied with what you get from P mode. If you can live with that, there's not a thing wrong with shooting in P mode.

the corollary....... You wont always be satisfied with what you get from Manual mode either. Even if you think you know all there is to know about exposure, and the aperture and shutter speed relationships.

Ansel Adams was reported to once say that he was happy if he got ONE truly good photo a YEAR, and I think he understood exposure pretty well.

What are you missing? Perhaps picking up a good book on Exposure, there are many out there, and reading a half an hour a day about the subject will give you a better grasp of how it all works.

I think what you are really asking though, is "Hey, I've got these settings on my camera, Av and Tv, so how will they make me a better photographer?"

Read a bit, and be prepared to say "wow, I didn't know that."

Last edited by Al_in_the_Shire; 05-04-2010 at 05:30 AM.
05-04-2010, 04:40 AM   #11
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I personally mainly shoot in Av mode -- it allows me to decide my depth of field, which is probably the most important thing in the kind of shooting that I do. Tv mode is more useful when there is a minimum shutter speed that you want to get to. If you are shooting sports and want to have a shutter speed of at least 1/250 second, you can get there with Tv mode (maybe). Program mode, as others have mentioned, combines both of these modes, but with a twist. You tell the camera what you want the program line to be -- the MTF is supposed to keep the aperture at the sharpest for a given lens, speed tries to get you fast shutter speeds, etc.

Program mode is probably the easiest mode, but one that can lead to poor understanding of the exposure triangle.
05-04-2010, 06:04 AM   #12
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Allow me to say a word on behalf of the much under-appreciated manual ISO:

To me. manually selecting your ISO--whether you're going to shoot manual or in an automated mode--is the way to go.

It's another "selection" like aperture and shutter speed, and in Av or Tv mode, I want to select the ISO for myself--and let the camera make just ONE decision in these two modes.

If I'm outside in bright sun, I don't want the camera giving me ISO 400 if it doesn't need it. In Av mode, I'll start at 100 or 200 manual ISO, see what shutter speed I'm getting at the aperture I selected, and if it's too slow, I'll up the ISO myself. Or open the aperture.

These are decisions I want to make. I don't want the camera doing it because it doesn't know exactly what I'm shooting or how I want it to look.

Last edited by Ira; 05-04-2010 at 09:06 AM.
05-04-2010, 07:41 AM   #13
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This has been a very interesting and useful thread for a K-7 newbie like me. Thanks to all who have contributed.
05-04-2010, 08:49 AM   #14
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Yes Ira, it is another tool in the tool box, and you make a great point about being able to select the ISO you need.

I sometimes forget that one, as I started back when you stuck a roll of 36 exposure 25 or 50 ASA slide film in the camera and were pretty much stuck with it unless you wanted to get the lab to push your developing or had a second camera body loaded with a different ASA.

Great point. Digital makes some things a lot easier today.
05-04-2010, 02:11 PM   #15
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QuoteOriginally posted by snostorm Quote
Hi jtp,

I just wanted to make a small correction to blackcloudbrew's first post -- MTF stands for Modular Transfer Function, not Manufactures Transfer Function. . . just being picky.
I stand corrected and I knew that but forgot to write it. Thanks.
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