Originally posted by jstevewhite Dynamic range and low-light performance are tightly coupled.
In sensor technology they are. The lower the noise floor, the higher the dynamic range. Almost all of the DxOMark results basically measure noise. That is, however, completely independent of sensor size.
Originally posted by jstevewhite Smaller sensors are noise limited; it's *not* just the lenses, and the lens on the Q camera is not 'slow'.
Smaller sensors are not intrinsically noise limited. Why would they be? Why would a sensel produce more noise just because there is less sensor around it?
The lenses on the Q camera are slow like hell.
A widest aperture of f/1.9 for a 8.5mm lens may sound fast, but if you express it in full-format terms, you see that a full-frame camera can take the same pictures with a 47mm lens that has a widest aperture of f/10.5.
Originally posted by jstevewhite If the camera has an 8.5mm f1.9 lens, and your light meter says 1/50 @f1.9, *that's what you shoot at*.
Of course. I have never said anything else.
With a Q camera and the 8.5mm lens, you never shoot with a focal length of 47mm.
If you want to predict the kind of images you can get with the Q standard lens, it can be useful to hypothesise about an equivalent lens on a full frame camera. That lens would be a 47/10.5.
Originally posted by jstevewhite ...but it's NOT a 10.5 when it comes to exposure, period.
That doesn't make sense. You're right that it isn't an f/10.5. Nor is it a 47mm. That's why I said people should not refer to the lens as a 47mm f/1.9 lens. There is an equivalent full frame lens which is a 47/10.5. For this one f/10.5 counts for DOF and exposure. You cannot separate DOF and exposure.
Originally posted by jstevewhite Your aperture for exposure is f1.9, NOT the "calculated based on format and DOF" 10.5; because, in the end, and 8.5mm lens is an 8.5mm lens, no matter what the format of the sensor;
Correct. Note however, that DOF and exposure of an 8.5mm lens at f/1.9 on the Q camera are identical to that of an 47mm at f/10.5 on a full frame camera.
Originally posted by jstevewhite It's also not a "slow" lens; it's f1.9. f1.9 is f1.9 is f1.9.
Is it a wide lens?
The focal length of 8.5mm suggests that it is an ultra wide, provided you are using a full frame or APS-C sensor as a reference.
Of course you know that 8.5mm is not ultra-wide within the Q-system. You know that in order to judge its AOV in terms of the full frame "normal" reference of 50mm (or 43mm), you need to convert by the crop factor. You have to do the same to judge the lens speed. Just as "8.5mm" only sounds ultra-wide, "f/1.9" only sounds fast. The lens is slow, no arguing about that.
Ever wondered about the "fast" Olympus lenses for their small sensors? Well, they are not as nearly as fast as their sensor-relative f-ratios make them appear to be.
Originally posted by Clicker You shouldn't stress over technicalities if
the tool does what you want it to do Sure, but in order to predict whether a tool would be able to do something for you, it is useful to resort to some technicalities.