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01-17-2012, 08:52 AM   #2146
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QuoteOriginally posted by Kryscendo Quote
Right.



And again, a telephoto/fast lens would give you the appearance of even shallower depth of field because, all together now children... telephoto lenses compress space.

Very good class
Extra credit: So do Wide-angle lenses!

('compression' happens because of distance to subject, not because of some innate property of a telephoto lens. This is useful to know in discussions of perspective shift by moving-to-reframe. In practice, a telephoto lens is used to create compression 99% of the time, because when you're shooting stuff that's really far away, you're probably going to be shooting telephoto, not wide-angle or normal and cropping. But it's not the lens that compresses, it's the distance. I'll take my extra credit via paypal.)

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Last edited by jsherman999; 01-17-2012 at 09:21 AM.
01-17-2012, 09:16 AM   #2147
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QuoteOriginally posted by falconeye Quote
As for birders ... I really would prefer to shoot with a 300mm lens on a 36MP full frame camera (and crop) than a 300mm lens on a 16MP APSC camera. Everybody who tried to frame a bird at flight with a ~500mm (35mm equiv.) lens will understand why. Agreed, 36MP FF cameras are only going to appear this year, but still, they are the desirable thing for birders.
Yes, if such a full frame camera gives you APS-C-sized crops that rival cameras like the K-5 in both resolution and high ISO noise/DR performance, it's desirable. But let's wait and see - the proof of the pudding is in the eating!
01-17-2012, 09:22 AM   #2148
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QuoteOriginally posted by gazonk Quote
Yes, if such a full frame camera gives you APS-C-sized crops that rival cameras like the K-5 in both resolution and high ISO noise/DR performance, it's desirable. But let's wait and see - the proof of the pudding is in the eating!
D4x == 36MP! I'm doubting the D800 will, though.
01-17-2012, 09:23 AM   #2149
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QuoteOriginally posted by Pål Jensen Quote
I've never said that you never need shallow DOF, but shallow DOF is available on APS.
To a large extent it is. And indeed when I shot with film, I mostly stopped my M-50/1.7 down to at least f/2.8 even when shooting without tripod in low light, because the DoF at f/1.7 simply was too thin. But I still think I have quite a few shots with that lens @1.7 that work best with that thin DoF, and in order to do achieve equivalent shots with my K10D, I would need a fairy-tale 33mm f/1.1...

01-17-2012, 09:25 AM   #2150
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QuoteOriginally posted by jsherman999 Quote
D4x == 36MP!
That's just rumors - isn't it?
01-17-2012, 09:34 AM   #2151
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QuoteOriginally posted by gazonk Quote
That's just rumors - isn't it?
Of course. It's actually a bit frustrating in Nikon land now, because they're being uncommonly and successfully tight-lipped about it.
01-17-2012, 09:41 AM   #2152
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QuoteOriginally posted by jsherman999 Quote
Of course. It's actually a bit frustrating in Nikon land now, because they're being uncommonly and successfully tight-lipped about it.
Like Pentax they have an issue with Sensor supply right now. No point announcing something that you aren't sure of a date on.
But they have done a good job of keeping anything new hidden (Also wasn't the FF factory destroyed last January meaning all new tooling and a new plant - tough year for Nikon)
01-17-2012, 10:00 AM   #2153
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QuoteOriginally posted by jsherman999 Quote
Extra credit: So do Wide-angle lenses!

('compression' happens because of distance to subject, not because of some innate property of a telephoto lens. This is useful to know in discussions of perspective shift by moving-to-reframe. In practice, a telephoto lens is used to create compression 99% of the time, because when you're shooting stuff that's really far away, you're probably going to be shooting telephoto, not wide-angle or normal and cropping. But it's not the lens that compresses, it's the distance. I'll take my extra credit via paypal.)

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If you frame a portrait with someone square in the middle and a telephone in the background with an 85mm, the pole will look a lot closer than if you used an 18mm, stepped up closer, and had the exact framing on the person.

01-17-2012, 10:13 AM   #2154
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QuoteOriginally posted by Kryscendo Quote
If you frame a portrait with someone square in the middle and a telephone in the background with an 85mm, the pole will look a lot closer than if you used an 18mm, stepped up closer, and had the exact framing on the person.
Yes, because you moved forward after you put the 18mm on, which reframes and changes perspective with regard to object distances.

However, if you took the shot with the 18mm and the 85mm from the exact same position, then cropped the 18mm shot to the same FOV as the 85mm, it will have the exact same 'compression' effect. It's the distance to subject that compresses, not something innate to the telephoto lens.

You would probably never crop an 18mm that much, you'd just use a longer lens. This is why people mistakingly think that it's some property of the telephoto lens that compresses the space, and it's not, it's the distance to subject.

Knowing this really only has applications in figuring out how to frame a shot, keeping the subject the same size without radically changing the relationship to background when you have to move around for whatever reason. In practice a telephoto can be used to 'compress' things more effectively than a wide-angle lens because you don't have to crop the telephoto image at all

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01-17-2012, 10:17 AM   #2155
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QuoteOriginally posted by jsherman999 Quote
But it's not the lens that compresses, it's the distance
This is simply said and very right, the only thing which matters is the distance what ever lens you use.
01-17-2012, 10:35 AM   #2156
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compression

Wrt compression

I don't think that the way this was described above is helpful. That it is the distance rather than the lens which does the compression. Moreover, hesitate to accept any argument which depends on cropping. Cropping is able to change the rules of most of the games here. A large trap

I think of compression in terms of ray parallelism: the more parallel the rays, the more compressed the image will appear. And believe it or not, a lens with a very small FoV forces rays to be rather parallel ... You would get the same compression with a small forground and small backgrund subject sitting on the two edges of a table. Distance is not required here.
01-17-2012, 10:54 AM   #2157
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QuoteOriginally posted by falconeye Quote
Wrt compression

Moreover, hesitate to accept any argument which depends on cropping. Cropping is able to change the rules of most of the games here. A large trap
Cropping can be useful in describing how some things are related, though, or how some things really are the same when we think they're different. In this case it serves to show how the 'compression' effect is related to distance to subject, not to a special property of telephoto focal length.

QuoteQuote:
I think of compression in terms of ray parallelism: the more parallel the rays, the more compressed the image will appear. And believe it or not, a lens with a very small FoV forces rays to be rather parallel ... You would get the same compression with a small forground and small backgrund subject sitting on the two edges of a table. Distance is not required here.
If you choose very small subjects, your ratios to subject size and foreground-background object distance are probably going to be about the same, though, when you see compression on the table top. Think of a photographing a small train table landscape, with little fake trees, etc. You would be able to get down there with a 50mm and find a distance to a foreground tree that 'compresses' the background nicely - and then if you shot those little trees from exactly the same position with a 24mm and cropped to the 50mm FOV, the 'compression' would look exactly the same in that crop - because the distance to that little plastic tree didn't change.


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01-17-2012, 10:55 AM   #2158
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QuoteOriginally posted by stanleyk Quote
Wow, as a person who uses both a Full Frame camera and K5, I have to say you guys are really making a mountain out of a mole hill on this DOF issue.
+1

The visible difference between the two at 1 stop apart is pretty much imperceptible.
01-17-2012, 10:55 AM   #2159
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QuoteOriginally posted by Pål Jensen Quote
shallow DOF is available on APS. There are several examples posted on this forum where no one can say it isn't shot on FF. A 50/1.2 on APS will give you shallower DOF than what is useful....
are you saying that A50/1.2 on a FF slr like MZ-5n does not have useful DOF? remember that Canon has an 85/1.2, and it is designed mainly for FF sensor. and FF camera users mainly shoot with that lens at f1.2. if DOF is really not useful at such fast aperture speed, then the 85/1.8 should be more than enough. sorry, I just don't get what you are trying to justify.
01-17-2012, 11:09 AM   #2160
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QuoteOriginally posted by Aristophanes Quote
+1

The visible difference between the two at 1 stop apart is pretty much imperceptible.
It's around 1.3 stops.

So the DOF difference between say f/4.5 vs f/2.8, or f/2.8 vs f/1.8 is imperceptible in all situations? I guess I can't agree.


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Last edited by jsherman999; 01-17-2012 at 11:18 AM.
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