Crop factor and lenses

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Originally Posted by Inkanyezi

. . . the Nikon E has an optical system before the sensor, which decreases the focal length of the lens (at the same time increasing its relative aperture).

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No, I don't think this is throwing a spanner into the works - the lens itself doesn't change - the additional optics behind the lens it what changes.

This is not unlike adding an extender between the lens and the body to increase the effective focal length of the lens - the extender in effect becomes part of the lens, and the real/actual focal length is increased. I use a 2.0 Ex with my 70-200 quite a bit - so the combination is in effect a 140-400 mm lens.

G

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Originally Posted by oldgreygary

Thanks for the further analysis and images which have added to my understanding. The illustrations with the explanations have clarified and cleared my confusion. I think that part of my misunderstanding has been created when I have read articles that have been written about lenses that say a 50mm lens becomes a 75mm lens on a 1.5 crop camera. I will read future articles with my newly acquired knowledge to have a better understanding of what is being talked about. As has been explained the amount of information coming through the lens is the same. But, it is the sensor size that is determining what gets recorded onto the card. I hope that I have understood that right!?

Cheers for now

Gary

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Gary:

You've got it.

Now if only everyone else could get it. :D

Glenn

I think Oskar was working on his camera pre or during WWI and it was only in 1924 that Leitz released the camera :)
I was reading Wiki entry on Leicas to check my faulty memory of the days when I worked with them. Had forgotten they had two viewfinders, compose and r/f side by side on the back :) Normally I guestimated distance and set it with the lens lever.
I have always believed [ as #20 ] that the zoom lens is a prime lens with adjusting adaptors up front ... there was an interesting 'cut-away' photo of one recently but I cannot find it:( One of our moderators posted it.

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Originally Posted by oldgreygary

I think that part of my misunderstanding has been created when I have read articles that have been written about lenses that say a 50mm lens becomes a 75mm lens on a 1.5 crop camera.Gary

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I see the problem that writers frequently try to condense what they are writing and hope the reader knows enough to accept this or not question it ... I was picked up for this recently :(

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Originally Posted by jcuknz

I think Oskar was working on his camera pre or during WWI and it was only in 1924 that Leitz released the camera :)
I was reading Wiki entry on Leicas to check my faulty memory of the days when I worked with them. Had forgotten they had two viewfinders, compose and r/f side by side on the back :) Normally I guestimated distance and set it with the lens lever.
I have always believed [ as #20 ] that the zoom lens is a prime lens with adjusting adaptors up front ... there was an interesting 'cut-away' photo of one recently but I cannot find it:( One of our moderators posted it.

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I always find it interesting as to how some decisions that were made back in the past continue to to affect us, even though the reasons for the original decisions are no longer valid. The 50mm "normal lens" is one that Oskar Barnack left us with, and of course the 24mm x 36mm full frame sensor (or negative is the other).

While looking for an off the shelf film solution for his miniature camera, picking motion picture film was a natural move; the material was being turned out by a number of manufacturers and processors were available for that format. The actualy cine format gave an image that was too small, so he used a double frame image. Ninety years later, we still use this format in full-frame cameras, probably because of the legacy lenses out there (and implied legitimacy) of this format. Based on computer screen sizes (and before that paper sizes) there was never a good match between the 35mm image capture format and how things we photographed with it were displayed.

I understand that the standard gauge railway track has an even longer history as I remember reading that it can be traced back to the width of a Roman chariot that was pulled by two horses.

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Originally Posted by GrumpyDiver

I understand that the standard gauge railway track has an even longer history as I remember reading that it can be traced back to the width of a Roman chariot that was pulled by two horses.

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And the diameter of the Space Shuttle's booster rockets were determined by a horses ass. :D

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Originally Posted by AB26

And the diameter of the Space Shuttle's booster rockets were determined by a horses ass. :D

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OK Andre, you're going to have to explain that one - please.

I've heard about the railway gauge, and it seems plausible - history tends to stick around.

Glenn

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Originally Posted by GrumpyDiver

I always find it interesting as to how some decisions that were made back in the past continue to to affect us,
I understand that the standard gauge railway track has an even longer history as I remember reading that it can be traced back to the width of a Roman chariot that was pulled by two horses.

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Me too :)

I have read it somewhere that the size of the space shuttles can be traced back to those horses since the size of the American continental tunnel is based on that and resulting loading gauge and the shuttle modules had to be carried by rail to the Cape. :) Though if America and Russia had been freindly there were probably russian cargo planes capable .. don't know ... just a hunch.

OH! I see Andre got there first :)

EDIT ... personally my prime interest is in narrowgauge, real NG like Cripple Creek RR .. 2ft ... which now I come to think about it is why I like bridge cameras and MFT :)