Qkano <snapper@xxxxxxxxxxxxxxxxxxx> writes: > <<< > But, in fact, the claim of "no cropping" is an irrelevancy. So long > as the two photos were really made on the same size film and enlarged > the same amount, and so long as they show the points we need to > measure (which they do), then cropping stuff off around the edges > makes no difference. >>>> > > Well, it's pretty good evidence to me that they lied ;o) Yes. > It's not an irrelavancy in the question as written because > 1) they didn't mention enlargement > 2) the images were presented at equal size (on my monitor anyway) Either the problem is unsolvable, or we have to assume something about the degree of enlargement. Clearly the necessary assumption is that the enlargement is the same in both cases. > I suspect they said "no cropping" because, unlike many modern > digital camera users, film users realise that cropping a neg/print > does not change the focal length of a lens. They said "no cropping" > to remove the possibility that the two images were shown at > different magnification: they srewed up because the format they > showed was not that they claimed. Never occurred to me, but in fact two equal-sized prints with no cropping from the same format *does* imply the same enlargement, as you say. And as you say, the enlargements not matching the aspect ratio of the format claimed does throw everything into doubt! > They also asked the question "how much further away" without hinting > that you would have to move up as well as back to obtain the results > showm. At least they didn't ask *how far* up you'd have to move! > Of course, in reality it's a simple test: the flaws in the question > didn't take a lot of finding though: both of the above points were > blindingly obvious .... I was a bit croggled at the concept that this might require too much mathematical sophistication from a photography student. (Then again, my degree is in math.) -- David Dyer-Bennet, <mailto:dd-b@xxxxxxxx>, <http://www.dd-b.net/dd-b/> RKBA: <http://noguns-nomoney.com/> <http://www.dd-b.net/carry/> Pics: <http://dd-b.lighthunters.net/> <http://www.dd-b.net/dd-b/SnapshotAlbum/> Dragaera/Steven Brust: <http://dragaera.info/>
