Help undstanding lenses

[LaPistola]

Note that it's a 35mm equivalent, not an 'effective' or 'true' focal length.

Fair enough wrong choose of word but if its not an "effective" Xmm focal length then why do so many pro teach that and why do the mags describe this as that?? 35mm equivalent being what they mean by using the word "effective" and like you say if one hasn't used a 35mm camera then they don't know so using the word "effective" is a far better way to put it to said one than saying its lateral meaning "35mm equivalent".

I wouldn't normally question and I don't want to come across as a know it all but what you're telling me is different to what I have been tort and what I have read and what the internet is telling me after doubting myself. I know any one can write anything on the net but its not just from one source.

If you look on Wikipedia you will see a diagram showing the difference.
If you crop a full frame image to the the cropped sensor size you will see an identical image.

I understand this and as far as I can tell I haven't said otherwise other than maybe using the word true in stead of effective. A 50mm lens on a crop sensor camera will take a photo as if you was using a 80mm lens.

A 50mm lens is a 50mm lens.

Yes if we are being literal.

No, focal length isn't always the distance between the lens (when focused at infinity) and the sensor. It's always the distance between an imaginary plane and the sensor

I can see what you mean here as yes a 50mm lens on a crop sensor will still be the same distance away from the sensor so this is where my word "true" could confuse someone. Hands up, fare do's. In my defense it was 4am :O

It's always the distance between an imaginary plane and the sensor

Ill take your word for it, its not what I was tort though.

EDIT. I do think that someone new to DSLR and have never used an old SLR should know what the crop factor is and how it effects them as they may want a wide angle lens for there camera and buy one that quotes wide angle focal's but actually gives them a normal angle once the crop factor comes into play therefore one would have wasted his money.

[greenwing]

Originally Posted by LaPistola

EDIT. I do think that someone new to DSLR and have never used an old SLR should know what the crop factor is and how it effects them as they may want a wide angle lens for there camera and buy one that quotes wide angle focal's but actually gives them a normal angle once the crop factor comes into play therefore one would have wasted his money.

I disagree. It's this sort of thing that leads people to see an FX or EF lens, and imagine that it will have 1.5x or 1.6x the marked focal length on their DX or crop camera, whereas the DX or EF-S lens has the focal length that's marked on it. The best idea for new dSLR users is to use a kit lens and see what focal lengths do what on their own camera.

There's an awful lot of confusion about the issue, and the magazines generally don't help. They started explaining the crop factor years ago when it could reasonably be expected that the majority of dSLR buyers were coming straight from 35mm, and could reasonably be expected to have some idea of what focal lengths do what. They seem to have got into the habit, no matter how irrelevant it is to today's new buyers. I guess they get to use up some column inches without too much effort and recycle the same old stuff on a regular basis.

Chris