Re: sensor size

"Scott W" <biphoto@xxxxxxxxxx> wrote:
> "Philip Homburg" <philip@xxxxxxxxxxxxxxxxx> wrote:
>> In article <vgivr1hob31vidqrdo7q1cih9agosniog0@xxxxxxx>,
>> rafe b <rafebATspeakeasy.net> wrote:
>>>As photographers, we're gatherers of light.
>>>Big cameras gather more light than small ones,
>>>and it almost always shows in the end, if you
>>>care enough to look closely. This applies in a
>>>totally fair, just, equitable and non-discriminatory
>>>manner to both film and digital cameras.
>>
>> Except that if you fix subject distance, field of view, and depth of
>> field,
>> the total amount of light across the frame tends to be more or constant
>> (independent of the frame size).
> This is true

Right. It also means that the claim that smaller formats have more DOF is
false.

>> Larger formats can 'store' more light. But once you find a system that is
>> big enough to handle the amount of light you've got, there is no point of
>> selecting even bigger systems.
>
> This is not complete true. If you fix the subject distance, field of view
> and depth of field then a larger sensor will be using a lens at a higher f
> number, this can either reduce the cost of the lens or if you keep the
> cost the same improve the quality. There is a limit to this of course
> since the lens can get pretty large, but not as large as you might think
> since the aperture of the lens would stay the same.

In real life if you actually take pictures, one either has enough DOF or not
enough, and linear changes in DOF tend to be relatively small compared to
the size of what that "enough" is. The experience here is that up to 645,
lack of DOF isn't really a problem, and only becomes an issue at 6x7.

> In the end there is a trade off between the cost of larger sensors and the
> cost of the lenses that are used. As the number of pixels increase the
> need for a larger sensor is going to also increase, not just for capturing
> more light but also to keep the cost of the lens within reason.

Another thing here is that the amount of charge you can store is
proportional to the area of the individual pixel, so the best SNR and
dynamic range you can get from a sensor is limited by the size of the pixel.
I've seen comments from D2x users to the effect that it requires correct
exposure and has very little room for boosting shadows without noise, and
even the 20D has worse noise at ISO 100 than the 10D/300D.

David J. Littleboy
Tokyo, Japan


.

Relevant Pages

  • Re: Dumb Question on Lenses
    ... DOF of f/2.8, when your f/5.6 only allows it to be within the ... It needs something to latch on to, ... sensor instead of the eye, ... Would that plane be within the DOF of the wide open lens, ...
    (rec.photo.digital.slr-systems)
  • Re: What make a lens normal ?
    ... There is a 12mm lens made by Voigtlander ... Since we were talking about the smaller APS sensor I was confining my ... Even if the materials cost is equivalent. ...
    (rec.photo.digital)
  • Re: P & S and depth-of-field
    ... with the small sensor. ... All of my P&S cameras are capable of f/2.4 or wider. ... ones from 6 years ago has an f/2.0 lens on it. ... DOF is a direct function of f-stop. ...
    (rec.photo.digital)
  • Re: Point and shoot with the largest CCD ?
    ... So what is the PS with the largest CCD for consumers at the moment? ... but only if the maximum aperture of the lens is increased too. ... A 36x24mm sensor will have much lower noise at high ISOs than a small sensor, but a lot of that will be offset by the need to use higher ISOs because of the slower lens. ... camera cost stayed pretty much the same regardless of format while lens and film cost increased linearly with area. ...
    (rec.photo.digital.slr-systems)
  • Re: Panasonic G1 - some AF numbers
    ... They don't price it based on how much it costs them to build, they price it based on how much they think the market will pay. ... It's the smallest interchangeable lens, relatively large sensor, P&S. ... weight is worth the extra cost. ...
    (rec.photo.digital)