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02-19-2015, 12:55 PM   #1
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av or tv

when shooting in continuous focus mode should i be in shutter or aperture priority?
thanks retired

02-19-2015, 01:10 PM - 1 Like   #2
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It depends on your subject. If you are shooting fast action, a common use for continuous focus, 2 ways to go:

Tv: Set a fast shutter to freeze movement. Or, if you want intentional motion blur, use a slow shutter to get the amount of blur you desire.

Av: Set it wide open to get the fastest shutter speed possible for the current lighting conditions.

Don't forget Pentax' wonderful TAv mode. Fast shutter to freeze action, aperture for whatever depth of field and sharpness you want, let ISO drift as needed. If ISO goes too high and gives more noise than you can accept, sacrifice shutter or aperture.
02-19-2015, 02:01 PM   #3
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QuoteOriginally posted by DeadJohn Quote
Don't forget Pentax' wonderful TAv mode. Fast shutter to freeze action, aperture for whatever depth of field and sharpness you want, let ISO drift as needed. If ISO goes too high and gives more noise than you can accept, sacrifice shutter or aperture.
+1 for TAv. I use this when shooting wildlife.
02-19-2015, 02:03 PM - 1 Like   #4
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Another +1 for TAv, you have two wheels - use them!

02-19-2015, 02:49 PM   #5
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QuoteOriginally posted by DeadJohn Quote
It depends on your subject. If you are shooting fast action, a common use for continuous focus, 2 ways to go:

Tv: Set a fast shutter to freeze movement. Or, if you want intentional motion blur, use a slow shutter to get the amount of blur you desire.

Av: Set it wide open to get the fastest shutter speed possible for the current lighting conditions.

Don't forget Pentax' wonderful TAv mode. Fast shutter to freeze action, aperture for whatever depth of field and sharpness you want, let ISO drift as needed. If ISO goes too high and gives more noise than you can accept, sacrifice shutter or aperture.
QuoteOriginally posted by jrpower10 Quote
+1 for TAv. I use this when shooting wildlife.
QuoteOriginally posted by TER-OR Quote
Another +1 for TAv, you have two wheels - use them!
They said it !! ... TAv !!
02-19-2015, 04:24 PM   #6
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thanks all
i will try the tav
02-19-2015, 05:41 PM   #7
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You won't regret it. :-)
02-19-2015, 06:49 PM   #8
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TAv has its negative though.. and a big one.. that is it will tend to pick a high ISO value from the range you give it if your light isn't 'ideal' (for the camera).

And these APS-C bodies aren't super fantastic at low noise at high ISO (comparatively at least). Especially if you plan on bringing out detail from shadows. The K-30 gets funky after ISO 800 and the K-5II after 1600 from my experiences. Beyond that amount, for me, the images lose a lot of detail, became somewhat mushy, and too grainy.

There is NO way to keep the detail and remove the noise at this point. If you apply the Noise reduction, you'll smear some of the detail. But if you don't apply heavy NR, you keep the detail but at the cost of high Noise (grain). You can mitigate this with layers and pulling out parts and doing a lot of hokey pokey on each but it seems smarter to just get the image right as much as possible in camera.

I read night and day people, on these forums talking about how there isn't a problem up to ISO 3200 or even ISO 6400 yet I never see their crisp National Geographic ready images. I mean if ISO3200+ was so hot why shoot ISO80 or 100? haha just slap it on ISO3200 and call it a day. No, there is a trade off there. Even the big Topaz NR software test article on here ended up with some images that looked like they were clay sculptures afterwards.. too smooth. Lower noise though.

In any case, this is a trade off. Unless you have huge amounts of light, you're going to be adjusting one of the others.. shutter speed, aperture, or ISO value.

TAv is great in a pinch. But I'd more get the hang of Av and Tv individually first. It is essentially inverse Sv. I think it could be much more usable on the FF body though.

Av for landscapes or any other time where you don't have to worry much about movement (or do and it is super bright out). Then you can set the aperture to a higher value (5.6 to 11 as example) to find the 'sweet' spot where the lens you are using is the sharpest with lesser vignetting. (If you didn't know it yet, each lens has a sweet spot where it performs the best based on focal length and aperture).

Tv as already mentioned by others for fast movement/action. Low noise is useless if the subject is blurred by motion -- be it their own speed or the photographers hands shaking the camera subtly. At airshows, I tend to set my camera to Tv. This is ok even for that sweet spot issue I mentioned as most airshows are during the day so the aperture will likely be 5.6 to 11 anyways. (But I've also set it to f/8 aperture on bright days and watched the shutter speed to make sure it was still acceptable). For walking around the park I'd probably also chose Tv and set it to 1/60 to -1/250th (depending on the light) watching to ensure the Aperture doesn't go through the roof and keeping the ISO set to lowest value possible (80 on my K-5II).

TAv, I find at least, is beneficial when you setup some very strict rules for the camera based on NR and watch the the ISO value to make sure it doesn't go too high (or just hits the hard limit which has its own problems). At which point you can probably just use either Av or Tv and baby the settings (which you will be doing anyways). This is why I very very rarely using TAv.


TL;DR (the short of the long): I'd not play with TAv until you've got a good working knowledge of Tv and Av first. And when you do use TAv, watch the ISO to make sure it doesn't go sky high.. unless you don't care about grain/noise (which you might not!).

02-19-2015, 09:34 PM   #9
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QuoteOriginally posted by mee Quote
TAv has its negative though.. and a big one.. that is it will tend to pick a high ISO value from the range you give it if your light isn't 'ideal' (for the camera).
The "upper-tier" cameras have a setting for how quickly the camera jumps to a higher ISO, but it's not on the K-30 or K-50. I don't know how well that works with TAv, since the camera is already stuck with the aperture and shutter speed set by the user.

I have used TAv for panning shots of a car at sunset, and it worked well for that. I could set aperture for the right depth of field, shutter speed that worked for panning, AF-C and high-speed drive. Then all I had to do was zoom and pan. I needed the camera to control ISO because of the changing light and the car's lighting. Noise wasn't going to be as important as all the other stuff. It turned out to be bright enough so ISO was always below 800, so it was a great compromise.
02-19-2015, 10:03 PM   #10
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QuoteOriginally posted by Just1MoreDave Quote
The "upper-tier" cameras have a setting for how quickly the camera jumps to a higher ISO, but it's not on the K-30 or K-50. I don't know how well that works with TAv, since the camera is already stuck with the aperture and shutter speed set by the user.

I have used TAv for panning shots of a car at sunset, and it worked well for that. I could set aperture for the right depth of field, shutter speed that worked for panning, AF-C and high-speed drive. Then all I had to do was zoom and pan. I needed the camera to control ISO because of the changing light and the car's lighting. Noise wasn't going to be as important as all the other stuff. It turned out to be bright enough so ISO was always below 800, so it was a great compromise.
Yes, I see the settings on my K-5II but not so much on the others I have used (K-x, K-r, K-30). And the scenario you detailed is a fine example of beneficial use of TAv mode. It definitely has it's purposes. But really think it will see much larger usability out of the FF sensor. ISO 3200 might not be so rough there.. maybe even ISO 6400 could be OK.

Here is one example I just now found on a quick google search between a D610 and the D7100 (nikon bodies).

Nikon D610 noise | Cameralabs

the higher the ISO gets, the more stops is visible between them, with the advantage on the FF body. Not trying to make this a FF thread. Just that TAv seems to have more beneficial spot on a larger sensor.
02-20-2015, 03:38 AM   #11
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QuoteOriginally posted by mee Quote
TAv has its negative though.. and a big one.. that is it will tend to pick a high ISO value from the range you give it if your light isn't 'ideal' (for the camera).
It's not a matter of 'tend to pick a high iso', the camera does not have any options! You fix two parameters, so it needs to adjust the third one. Slow or fast adjustment does not play a role here, that's only applicable when the camera can choose two parameters (e.g. shutter speed and iso).

This is my understanding how it works.

QuoteOriginally posted by mee Quote
And these APS-C bodies aren't super fantastic at low noise at high ISO (comparatively at least).
Wait till you used a CCD based camera (e.g. K100D or K10D) and you will never complain again It's always a balance; FF also has limits although a bit further away Do you want the shot and accept the noise, or do you not want the shot.
02-20-2015, 05:57 AM   #12
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thanks again, i shoot with a k20d ( i know old school) but still a very good camera
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