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Old Feb 24, 2006, 3:37 AM   #11
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geriatric wrote:
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Saying that a 50mm lens will be like an 80mm lens due too the crop factor is rubbish.

A50mm lens does not have the same angle of view as an 80mm lens. For portraits you need a minimum of 80mm


I told you someone would let us know if I was wrong.

I guess I confused the crop factor and the angle of view. So an 80mm lens would still produce better results than the 50mm. That's good to know and it may change my purchase decision.

Thanks for the input.

Dave

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Old Feb 24, 2006, 4:31 AM   #12
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"Saying that a 50mm lens will be like an 80mm lens due too the crop factor is rubbish.

A50mm lens does not have the same angle of view as an 80mm lens. For portraits you need a minimum of 80mm"

A 50mm lens on a 1.6 crop factor camera will indeed have exactly the same angle of view as an 80mm on a full frame camera.
The only difference between the two will be that at the same fstop value the 80mm/full-frame will have a shallower depth of field.
And you can take perfectly good portraits with shorter focal lengths...
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Old Feb 24, 2006, 9:38 AM   #13
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jacks wrote:
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A 50mm lens on a 1.6 crop factor camera will indeed have exactly the same angle of view as an 80mm on a full frame camera.
The only difference between the two will be that at the same fstop value the 80mm/full-frame will have a shallower depth of field.
And you can take perfectly good portraits with shorter focal lengths...
Yeah Jacks, that's exactly what I thought! I'm glad your logicseems to match mine! Otherwise I was really starting to get confused!

As Jacks said, the 50mm on a 1.6x crop factor (e.g. Canon XT, 20D, 30D) will have a 80mm "zoom factor" (according to 35mm / full-frame reckoning) but will have a greater depth of field compared to 35mm / full-frame. (note: this is the same as jacks said.. just he wrote it from the perspective of the 80mm / full-frame!) just to confuse us more!

I'd behappily using my 50mm f1.8 lens for portraits and indoor / low level light, but it front focuses, so it's going back to Canon (for a re-calibration!). But I can tell you its focal value is almost exactly the same as the 50mm setting on my 28-135mm lens - that is 80mm in full-frame comparison... (and boy I love that 28-135mm lens!) It stays on my camera 90-95% of the time!

All the best Rowan with your decisions / purchase for your wife!

Paul
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Old Feb 24, 2006, 2:25 PM   #14
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geriatric wrote:
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Saying that a 50mm lens will be like an 80mm lens due too the crop factor is rubbish.

A50mm lens does not have the same angle of view as an 80mm lens. For portraits you need a minimum of 80mm
Why it is rubbish and why one need at least 80mm for potraits? What's wrong with my using 50mm on my 1.6x crop 10D?


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Old Mar 2, 2006, 12:19 PM   #15
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How about the Tamron 28-70mm 2.8?
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Old Mar 2, 2006, 1:03 PM   #16
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plove53 wrote:
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How about the Tamron 28-70mm 2.8?
Focal length and aperture are going to produce different results in regards to field of view (or perspective) and depth of field. For instance on the same camera, 85mm 1.8 will have less depth of field than 50mm 1.8 - hard to say which is 'better' - Similarly, as you get narrower apertures - in this case 2.8 you will have greater depth of field. Given the short focal length (70mm) and 2.8 aperture I wouldn't think a lens like this would make a good portrait lens - IF (note the if here) your goal is shallow depth of field. Something longer at the same aperture would provide a shallower depth of field.

Also, the quality of bokeh differs by lenses. I believe a lot has to do with the construction and number of blades. I'm sure someone will correct me if I'm wrong but I believe the more blades involved, the more 'pleasant' the bokeh. My point here? While two different lenses at the same aperture produce the same exposure they won't produce the same quality bokeh. But again, it depends on the affect you're trying for.
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