Let's set the record straight on Crop cameras and telephoto advantage?

[g dan mitchell]

<p>Greg's reply suggests an interesting - and I think correct - way to recast this question as two questions. OK, maybe three.</p>

<p>1. <em>What is the effect of image resolution provided by a given lens when you change the sensor size?</em> Clearly, if a lens can resolve X lp/mm it can resolve more line pairs on a larger sensor. There is little disagreement about that fact. A more sticky question is how the overall image is affected by the larger image circle that must be captured with a larger format. It is my view, having used both formats, that this cuts both ways but that in the end the larger format "wins."</p>

<p>2. <em>What is the effect of increasing/decreasing the pixel dimensions of a photo?</em> When enlarging an image to the point that pixel resolution (ppi) becomes a concern in the print, there would be advantages in starting with an image with a greater number of pixels. This is the argument of those who point out that you can end up with more pixels in your image if you shoot with the smaller format as compared to shooting the larger format and cropping. (The argument depends on the specific photosite density of the cameras being compared. In addition, it breaks down if you can put the "right" lens on either camera rather than handicapping one by using the "wrong" lens.)</p>

<p>3. Both of these questions finally must be judged by asking: <em>Does it matter?</em> Let's say that we agree that the full frame image can produce higher resolution photographs. That may not matter if you don't regularly make prints larger than 12 x 18 inches, or if you always hand hold your camera, or if you need the faster burst rate of the small sensor camera. Let's say that we agree that the camera with the smaller sensor can put more pixels on the subject with a given lens. That may not matter if you don't shoot at extremely long focal lengths, if you have the right lenses for the larger format, or if your prints from cropped long lenses shots will look great at the sizes you print.</p>

<p>I understand that we seem to have a cultural need to determine <em>The Best</em> of everything. (Witness American Idol, Top Chef, and a host of other examples - all bogus in the end.) Sometimes there is no clear "best" choice. In my view that is clearly the case when it comes to the choice of formats. There are great arguments for both formats - and for others not under discussion in this forum. The important thing is to figure out which of the various advantages and liabilities that come with <em>choices</em> make the most sense for your photography.</p>

<p>Dan</p>