D300 BUG in Aperture Priority & Shutter Priority Mode

On Mon, 14 Jan 2008 13:06:40 +1100, Pete D wrote:

>> Just a wild guess, but is there any chance that the D3 is
>> considering the focal length of the lens? If it is too great, a
>> very "smart" camera might want to make sure that the shutter speed
>> is sufficiently high, to avoid excessive blur. It might think that
>> 1/4s is too slow, but can't get a faster shutter speed if it can't
>> open the lens up beyond f/2.8. Again, I'm not saying that this is
>> the problem, but if it is, a higher ISO (or some Auto-ISO mode), or
>> a reduced focal length might eliminate the "LO" warning.
>>
>
> And it can read your mind to know exactly what you are shooting?

Sure thing, Pete. My cameras are *really* talented. But they
wouldn't need to know what I'm shooting. Focal length information
is already known by cameras, as you can see by checking EXIF data.
Most (or all) cameras would know nothing about the movement of
objects in the frame, but I didn't assume that. What's already
known to a degree (for typical shooters) is the shutter speed
necessary to reduce the effect of camera movement to a level that
also reduces blur to a level that produces acceptable sharpness,
depending on the finickyness(sp?) of the photographer. The greater
the focal length, the faster the required shutter speed. When
shooting handheld, of course. The use of a tripod changes
everything. Or almost, as some cameras can even use IS or VR while
on a tripod these days.
 >> Stay informed about: D300 BUG in Aperture Priority & Shutter Priority Mode 

"ASAAR" <caught.DeleteThis@22.com> wrote in message
news:c72mo3p8vsspn7edkanq7q9g7puicimj8u@4ax.com...
> On Mon, 14 Jan 2008 13:06:40 +1100, Pete D wrote:
>
>>> Just a wild guess, but is there any chance that the D3 is
>>> considering the focal length of the lens? If it is too great, a
>>> very "smart" camera might want to make sure that the shutter speed
>>> is sufficiently high, to avoid excessive blur. It might think that
>>> 1/4s is too slow, but can't get a faster shutter speed if it can't
>>> open the lens up beyond f/2.8. Again, I'm not saying that this is
>>> the problem, but if it is, a higher ISO (or some Auto-ISO mode), or
>>> a reduced focal length might eliminate the "LO" warning.
>>>
>>
>> And it can read your mind to know exactly what you are shooting?
>
> Sure thing, Pete. My cameras are *really* talented. But they
> wouldn't need to know what I'm shooting. Focal length information
> is already known by cameras, as you can see by checking EXIF data.
> Most (or all) cameras would know nothing about the movement of
> objects in the frame, but I didn't assume that. What's already
> known to a degree (for typical shooters) is the shutter speed
> necessary to reduce the effect of camera movement to a level that
> also reduces blur to a level that produces acceptable sharpness,
> depending on the finickyness(sp?) of the photographer. The greater
> the focal length, the faster the required shutter speed. When
> shooting handheld, of course. The use of a tripod changes
> everything. Or almost, as some cameras can even use IS or VR while
> on a tripod these days.
>

Sorry, should I have included the smiley.
 >> Stay informed about: D300 BUG in Aperture Priority & Shutter Priority Mode 

On Tue, 15 Jan 2008 06:06:59 +1100, Pete D wrote:

> Sorry, should I have included the smiley.

Grrrr.




<g>
 >> Stay informed about: D300 BUG in Aperture Priority & Shutter Priority Mode 

Gisle Hannemyr <gisle+news@ifi.uio.no> wrote:
> Chico <somewh... RemoveThis @mexico.com> wrote:

>> set the camera in Manual Mode at ISO 200 and balanced the
>> exposure. It read 1/4 second @ f/2.8. You can use any metering
>> method for this.

> That is 4 EV.

4 LV. Not 4 EV.
EV is after the light has passed the lens.[1]
LV is what a hand held meter can measure --- the general light
independent of any lens and f/stop.

4 LV after f/2.8 is 1 EV (assuming the open lens is f/2..

Of course, the light reaching the metering sensors is less than
that, they only get a part of the light, the rest going to AF
sensors and the "matte" screen --- but for "the metering sensors
need EV -2 or more light" this is completely unimportant --- you
are not expected to know how many percent of the light actually
goes to metering, you just need to know how much light arrives
past the lens.


> The Exposure Metering Range of the D300 in 3D Matrix is supposed to
> to operate 0-20 EV. Your scene is clearly within this limit.

If it was stop down metering with f/4 (and hence EV 0), the
camera _might_ have reason to warn that the meter returns the
lowest possible value --- and hence would be unreliable.


I had that kind of "fun" with my 20D, an f/4 lens and much darkness
--- the metering was out of bounds, the shot well underexposed
(IIRC the metering did think it was EV 1, it's low end).
Unfortunately Canon does not do any "LO" when the meter hits
rock bottom. Fortunately, histograms were already invented.

-Wolfgang

[1] Think it through. If you put on a f/10 mirror lens with
a 3 stop ND filter at the very same amount of light light
on the wall, you get much less light for metering into
the camera. Thus LV is constant, but EV lens dependent,
and thus TTL-metering depends on the lens.
 >> Stay informed about: D300 BUG in Aperture Priority & Shutter Priority Mode