OK Lets leave it at that, but because I've already enlarged the 10mm LHS to nearer to the 20mm RHS (but still not enough) I'll post that image because I'm sure that other people are interested in the practical side of photography.

The camera/tripod wasn't moved between shots. A Novoflex 5 B&S head was used and it has gone sightly off vertical.
A Pan and Tilt would have been better.

The test is very simple for anyone else to do.
Takes about 2 mins. use a piece of wood if you
haven't got a 3ft ruler.

You can see clearer that the perspective isn't the same for a 10mm and 20mm from the same distance.

I might continue this on a blog.




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I presume that you mean this thread in which almost EVERYONE was wrong and I was right!
If there was a competion for the dumbest forum this one would probably win

I would have expected that by now you would have all read a basic book on photographic perspective

Richard is of course spot on Glamour photographers have long since realized that a wide angle lens makes peoples boobies (mostly women) look much bigger. You can't get the same effect with a standard/tele lens no matter where you plonk it. This has been done to the extreme by sites such as pinupfiles (dot com warning distorted nudity). Bill Brandt also did it.

I've just taken this quick shot of a 3ft ruler with a Sigma 10-20mm at 10mm and 20mm on a tripod at a fixed position. I would have liked to have used 10mm and 35mm, but didn't want to change the lens. So rather than a comparison between WA and STD.... It's between two WA's.




You can see that even from the same distance it's the lens that fixes the perspective, you can't enlarge the 10mm shot to look like the 20mm shot because the included angle of the sides of the ruler is different.

The included angle of the sides of the ruler are...
10mm = 27.5deg
20mm = 17.1deg
These would stay the same on enlargement due to the different perspectives.

There have also been some shots of castles on here recently showing quite clearly the perspective ONLY obtainable from a wide angle lens.
Very often the Vanishing Points from a WA shot are actually within the frame or just outside like this.... This isn't distortion it's WA perspective.




Where JR is confused is with 2D Flat Copy which has the VP's at Infinity so you can enlarge that to get the equivalent view to a tele, because perspective isn't involved.

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I've got a Canon EE-S screen, but haven't got round to
cutting it down for a K-5 yet.

Looks like RH could do with one in his Canon.......
Took all the trouble to do a 17 shot test with two
expensive 50mm f/1.2 - f/1.4 lenses and was about
5 -10 metres different with the distances as mentioned in
the comments. You can see it on the paving flags.
Sadly most Internet lens tests are like that

http://ricehigh.blogspot.com/2013/01/luxury-50mm-lens-fight-ef-5012l-vs-cz.html

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Believe that if you want to

In practise you can't actually tell where a camera is focussed and where it is out of focus either through the viewfinder or on the screen as in this typical 50mm at f/5 shot. That's why most lens tests you see on the web aren't of any use. Each shot is actually focused on a different spot in most of them.

Stop being rude mentioning 4GEE on here........
http://explore.ee.co.uk/ee-network/4gee

http://www.urbandictionary.com/define.php?term=gee

What does a name matter. To me a Ferrari is a Fiat

More theory It's heavily documented elsewhere that modern screens are manufactured for brightness and not accurate viewing. They have extra grooves cut into the fresnel rings which can cause false images. Most people concerned about large aperture lenses and better viewing install Canon EE-S screens.

In the darkroom days it was well known that the only accurate method of focusing a negative was by looking at the grain through a grain magnifier.

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That's fine in theory, but in practise......

http://www.slrgear.com/articles/focus/focus.htm

As this graph shows, manual focusing through the viewfinder was indeed a complete non-starter of an idea.

As I said earlier if you can't see where the point of focus is. you won't see where it goes out of focus. If you could all the people asking for full frame just so that they can have OOF/Bokeh backgrounds could just put the back of the subject at the change point from focus to OOF making the background very blurred...... Just not possible partly because DOF in practise doesn't follow the theory.

Even electronic AF systems struggle to detect a difference at f/5.6 and smaller.

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DOF preview (optical) is absolutely useless. It was a feature put on for the moaners. They used to complain that cameras such as the ME Super hadn't got it.

You can't even see the parts through the viewfinder that are IN FOCUS never mind the change from in-focus to out-of-focus

It's also unlikely that the small viewfinder image would have the same DOF as the one calculated for say an 8x10 print.

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A lot of lens patents never get put into production and the 16mm
looks like it could have been for the K-01

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