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04-15-2012, 02:47 PM   #1
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New camera mode idea: Av-R (Av Relative)

I thought of this and wondered what opinions people have of the idea. I don't expect any camera manufacturer to introduce it as it's of (very?) limited use, but if my K200D had it, I would use it.

This is based on wanting to avoid a lens being wide open (for sharpness) but still allowing in a good amount of light where possible.

As we all know, in Av mode you set the aperture and the camera does the rest. That's fine for primes and fixed maximum aperture zooms, where a change of focal length (where possible) cannot affect the aperture. However, on a zoom with a variable aperture (such as a kit lens or super-zoom), if I want to avoid using the lens wide open at all focal lengths without changing it every time I zoom in or out, then I need to set the aperture beyond the maximum at the longest focal length (at f/8 for example). But at 18mm on a kit lens, f/8 is not necessary to keep it from being wide open, f/5 would be fine.

The solution would be a camera mode that could be set to keep the aperture a given amount (one stop, for example) from the maximum at every focal length of the lens at all times. So, for a kit 18-55 f/3.5 - f/5.6 zoom, if I set my imaginary Av Relative mode to one stop, it would always keep it one stop from wide open regardless of focal length, therefore the camera would use f/5 to f/8, going from wide to telephoto. That way I avoid the loss of sharpness of using the lens wide open (kit lens at 55mm, I'm looking at YOU), but also avoid fiddling with the aperture with each focal length change in order to maximise light entry to keep shutter speeds as high as possible and ISO as low as possible.

I get the feeling my explanation is maybe not the best, but in my head the idea is clear. I just wanted to throw it out there to see what people think.

04-15-2012, 02:54 PM   #2
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i remember that if i were to use P mode with MTF priority, it would stop down my DA*55 to f2. not sure if this works on other lenses though
04-15-2012, 02:55 PM   #3
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I believe that this is what the MTF program line tries to do, but I could be wrong. As far as I understand, it tries to select the sharpest aperture at any given time.

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04-15-2012, 02:57 PM   #4
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Isnt this Av-R type feature more or less covered by using MTF if P mode?

MTF stops the lens down to the manufacturers recommended 'best' aperture for any given lens. For example, with the K-7 and the 18-55 WR kit lens, MTF stops the lens down 2/3 of a stop over the zoom range. (I have the camera set to use 1/3 stops. It may well use a full stop if your camera is set the alternative way)

I this this is close enough to what you are asking for?


Last edited by wizofoz; 04-15-2012 at 04:00 PM.
04-15-2012, 05:09 PM   #5
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Actually this is what you get using a lens with aperture ring in non-A position. I agree it sounds very useful under limited light conditions where one would like the lens to be 1/2 or 1 stop down from full open. In fact it's what I do (for theatre photography) but I only have lenses w/aperture rings, and I never use the A setting.
04-15-2012, 06:11 PM   #6
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I like the idea, it offers more control than just the MTF in P line.

I also want a MTAv mode (Minimum T, A varying), so that I could use my front wheel to set my minimum shutter speed to say 1/200, and control the aperture fixed. Like Auto ISO speed, but much finer and easier to control.
04-15-2012, 09:45 PM   #7
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Yes, something like this was suggested in another thread recently, but without relativity. With any lens, let's have the option to set min-max shutter speeds, same as ISO. With A-type or AF lenses, we need options to set min-max apertures, absolute or relative. This should be attainable with firmware upgrades -- but probably not for my K20D.
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