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02-14-2008, 08:30 AM   #1
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is TAv unique to Pentax?

Simple question here. I love the TAv mode on my Pentax K10D. Do other makes of dslr have this mode? I did a little quick searching on the internet but Googling "TAv mode" just brings up lots of references to Pentax. Still, I find it hard to imagine that such a great idea hasn't been implemented in cameras from Nikon or Canon. Anybody know?

Thanks in advance,

Will

02-14-2008, 09:26 AM   #2
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TAv is basically M + Auto-ISO (except you can use EV comp in TAv, which you generally cannot in M).

I don't know if the other manufacturers offer Auto-ISO in M mode. Note that Pentax does not.
02-14-2008, 09:53 AM   #3
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QuoteOriginally posted by RBellavance Quote
TAv is basically M + Auto-ISO (except you can use EV comp in TAv, which you generally cannot in M).

I don't know if the other manufacturers offer Auto-ISO in M mode. Note that Pentax does not.
Thanks. I know what TAv is--I use it frequently--so I'm still wondering if anybody else offers the same functionality, whether it's through a special TAv mode on the mode dial, or through the ability to use auto-ISO in M mode, or any other way.

Will
02-14-2008, 10:18 AM   #4
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Yes it is unique. See the TAv picture and discussion here on the first page of this link:
Pentax K10D Review: 1. Introduction: Digital Photography Review

I have used all of the k10d exposure modes (EXCEPT the green mode I am proud to say ) and I like them all. I was using only M for a while, and using the green button to quickly get me close, and then I would tweak with the e-dials. I don't use the TAv much, but that is just me. I find myself using P more and more, because on the k10d with the 2 edials, P mode is like Tv and Av all in one. If you select the auto ISO, it is Tv, Av and TAv all in one (since each can be changed independently). If you push OK and set ISO, it is like Tv, Av, and Sv, all in one. Oh well, you get the picture...


Last edited by PentaxPoke; 02-14-2008 at 10:25 AM.
02-14-2008, 10:24 AM   #5
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Anything I've read about TAv from Pentax claims that they introduced it and that no body else has it on their cameras. I don't use it much, but I did have a shot over the weekend where I needed manual control and exposure bracketing. Very handy.
02-14-2008, 11:10 AM   #6
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PentaxPoke, thanks for the link to the dpreview.com review. I haven't reread that for a while and didn't remember the bit that claims TAv is an innovation with the K10D and unique.

Thanks to all. I continue to think TAv is one of the better features of the K10D. I know that I'd miss it if I switched to anything else, even if the anything provided other advantages.

Will
02-14-2008, 11:58 AM   #7
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As RBellavance said, TAV basically is M + Auto ISO.

Nikon D40 and (possibly) D40x have that.
02-14-2008, 11:58 AM   #8
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Nikon's AutoISO works in all modes. I found out by accident because I was trying to shoot manual with external stobes but all my pics came out too bright. It was because the AutoISO was trying to compensate for the dark room. AutoISO is controlled from the menu system. And it has been confirmed on the D300 (I had it on D70, D80, and D200).

02-14-2008, 12:08 PM   #9
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What's unique and cool about the TAv mode is that it's on mode dial, easily accessible. What's not cool IMHO is how it's implemented: with auto-iso, what I usually want is the best IQ (lowest ISO), until the shutter speed goes below a certain threshold, and THEN the ISO should be raised. You sort of get this with Av and ISO set to auto, but the camera picks the shutter speed according to 1/focal length -- this works great if you're concerned about camera shake, but not so good if you want to stop motion.

Also, in TAv mode it drives me crazy when the camera would rather over expose the image rather than boost the shutter speed. The camera will warn you (ISO warning) but the whole point of using these semi-idiot modes is that you're working fast and don't have to fiddle with the dials.

So TAv mode is great idea, but Nikon basically does it better with auto-iso.
02-14-2008, 12:14 PM   #10
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QuoteOriginally posted by twinda1 Quote
...
Also, in TAv mode it drives me crazy when the camera would rather over expose the image rather than boost the shutter speed.
...
Wait, the camera will never boost the shutter speed in TAv mode, right? That is the point of the mode, you set the aperture and shutter and it picks your ISO for you, the only thing the camera can change is the ISO, so it will never boost your shutter speed, you have to do that.
02-14-2008, 01:08 PM   #11
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QuoteOriginally posted by jbmiller Quote
Nikon's AutoISO works in all modes. I found out by accident because I was trying to shoot manual with external stobes but all my pics came out too bright. It was because the AutoISO was trying to compensate for the dark room. AutoISO is controlled from the menu system. And it has been confirmed on the D300 (I had it on D70, D80, and D200).
M + Auto-ISO for Nikons, I wonder how the meter reads. Does it become a light meter? Or does it become a target EV value like the other semi-auto modes?

QuoteOriginally posted by twinda1 Quote
What's unique and cool about the TAv mode is that it's on mode dial, easily accessible. What's not cool IMHO is how it's implemented: with auto-iso, what I usually want is the best IQ (lowest ISO), until the shutter speed goes below a certain threshold, and THEN the ISO should be raised. You sort of get this with Av and ISO set to auto, but the camera picks the shutter speed according to 1/focal length -- this works great if you're concerned about camera shake, but not so good if you want to stop motion.
TAv mode means you are telling the camera that you MUST use the specified Aperture and Shutter speed. The camera will give you the ISO for your desired Aperture + Shutter Speed combination at your desired exposure level. There is no range of ISOs that the camera can choose with those 3 other things locked by the user, there'll only be one.

Aperture, Shutter Speed and ISO have to work together and balance each other out. You can't have f/2.8, 1/60, and ISO 800 expose identical to f/2.8 1/60 and ISO 200.

If you were only talking about the implementation of Auto-ISO, and not TAv mode... Av Priority is a depth of field priority mode, it's intention is not to stop motion, so choosing a shutterspeed to make sharp pictures with narrow or wide depth of field seems reasonable to me. I would recommend using other modes for stopping motion such as the Tv mode. Auto-ISO in Tv mode will stop the camera down to the minimum aperture before increasing ISO. This is one of the much more suitable modes for stopping motion.

QuoteOriginally posted by twinda1 Quote
Also, in TAv mode it drives me crazy when the camera would rather over expose the image rather than boost the shutter speed. The camera will warn you (ISO warning) but the whole point of using these semi-idiot modes is that you're working fast and don't have to fiddle with the dials.

So TAv mode is great idea, but Nikon basically does it better with auto-iso.
Once again, TAv mode means you are telling the camera that you MUST use the specified Aperture and Shutter speed. You are overexposing because there is too much light for your current setting. The camera can go as low as ISO 100, and you are REQUIRING an Aperture or Shutterspeed that will let too much light in. The camera is already warning you that this will happen and you still take the picture? I don't see how that's a fault of the cameras.

If you want the camera to be willing adjust shutter speeds to anything necessary to maintain exposure, then once again, don't use TAv mode. Use P mode and take advantage of the hyper-program features would be my recommendation.

You're fine for believing that the Nikon system is better, as it makes no difference to me. But I find my Pentax system much more flexible than the Nikon overall in terms of exposure control (based on my experiences using a D200).
02-14-2008, 01:41 PM   #12
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The way the Nikons have it (as M+auto-ISO) is better because you can define in the menue the exposure time at which the ISO is getting up. That's something I really miss on my Pentax.

Last edited by blende8; 02-14-2008 at 01:51 PM.
02-14-2008, 01:45 PM   #13
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Yes, in TAv mode you set the shutter speed and aperture and the camera picks an ISO from a range. That's how Pentax defines TAv mode, and that's how it's implemented. All I'm saying is TAv mode would be much more useful if there was an option to treat the shutter speed that you set as a threshold, and not as an absolute value. If the ISO range is 100, 200, 400 and 800, that gives you 4 stops of exposure -- if the camera is also allowed to automatically boost the shutter speed, then you can have probably at least another 4 stops.

To make this more concrete, this is my application for TAv, and why I find it inadequate: I'm indoor by a big window chasing an 18 month old around. I want f/2.8 to get a decent DOF, and 1/125 to prevent motion blur. The light is variable depending on where the kid is in the room in relation to the big window, so I pick ISO in the range of 100-800. This works great when the kid darts away from the window, and the camera boosts the ISO. But now he runs back to the window, and the camera drops the ISO down as far as possible, and then starts flashing the ISO warning tell me that the image will be over-exposed. Once ISO 100 is reached, the camera should just boost the shutter speed ('cause I'm busy trying to nail focus), but instead it just blows out the image. Sure, I could set the shutter speed initally so that exposure is correct right next to the window, but then away from the window the camera-picked ISO would be unnecessarily high.

No combinations of modes + auto-ISO on the K10D will do what the Nikon does with its "threshold" auto-iso implementation. This is an easy modification to the firmware if Pentax chooses to do it.

-T

Last edited by twinda1; 02-14-2008 at 01:57 PM.
02-14-2008, 01:49 PM   #14
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QuoteOriginally posted by AVANT Quote
The camera can go as low as ISO 100, and you are REQUIRING an Aperture or Shutterspeed that will let too much light in. The camera is already warning you that this will happen and you still take the picture? I don't see how that's a fault of the cameras.
Nope, it's not a fault of the camera -- I just want to be able to tell it to do something else that I find more useful.
02-14-2008, 01:50 PM   #15
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Somewhat related question, Can you set the auto ISO range to be different for the various modes? I'd like to have a wider range available on the TAv mode to allow more adjustment with the shutter/aperture combos, but in the others I'd like to keep it low to keep IQ up and pretty. Not a huge deal to change it, but seems like with all this technology i should be able to save settings. I assume you can only have it different for the user setting?
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