01-16-2012, 09:53 AM
[quote name='nandadevieast' timestamp='1326688922' post='14894']
Thanks.
Blur the background equally...For the same framing or the same distance?
Klaus: Can you elaborate, give me an example of 1.4x method you mentioned.
Brightcolours: What will be the DOF behind the subject wide open, if shot from the same distance from both the lenses? WHAT will be the DOF for the same framing? Which will blur the background more if the framing is same....
In terms of DOF/background blur, will these lenses behave like 60 and 90mm lenses or will they behave like 90 and 135mm lenses on a 1.5 crop camera?
[/quote]
My understanding is that the greater DOF on APS-C comes not from the lens somehow "losing" aperture (which it doesn't) but from the fact that the actual focal length (which is one of three primary factors for DOF) is not changing and therefore is shorter than what you would've been using on 24x36 format (unlike when you're using an extender that narrows the aperture and adds focal length by changing the optical construction of the lens system). Guess it could be verified by shooting same lens on different sensor sizes at identical apertures and distances, then cropping the larger format image to match the smaller one's framing - it's probably going to be identical WRT DOF and perspective. Why the heck should it not - it's the lens that builds the image, the camera only catches it, and how much of it actually makes it into the image is the only thing that differs with sensor sizes.
I guess Brightcolors is going to disagree, though. I wish I could do some testing to learn this for myself but I only have one camera, and the APS-C NEX-3 I have access to cannot mount Canon lenses. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/sad.gif' class='bbc_emoticon' alt='
' />
The 60 is better because it's F/2 for most purposes except maybe DOF calculation - most importantly for available light shooting. Depends on more than just that, the relative distances (camera-subject and subject-background) as well.
I have no experience with the 90 but loved the 60 when trying it out at the local photo fair. Nice portrait lens probably on every sensor size it's working with. Good coverage (about 80mm equivalent FOV - but since I'm not using FF cameras I'm not thinking in terms of equivalence) on my APS-H camera. Autofocus is not exactly top notch though, though I may be spoiled by Canon L and Sigma HSM lenses.
Thanks.
Blur the background equally...For the same framing or the same distance?
Klaus: Can you elaborate, give me an example of 1.4x method you mentioned.
Brightcolours: What will be the DOF behind the subject wide open, if shot from the same distance from both the lenses? WHAT will be the DOF for the same framing? Which will blur the background more if the framing is same....
In terms of DOF/background blur, will these lenses behave like 60 and 90mm lenses or will they behave like 90 and 135mm lenses on a 1.5 crop camera?
[/quote]
My understanding is that the greater DOF on APS-C comes not from the lens somehow "losing" aperture (which it doesn't) but from the fact that the actual focal length (which is one of three primary factors for DOF) is not changing and therefore is shorter than what you would've been using on 24x36 format (unlike when you're using an extender that narrows the aperture and adds focal length by changing the optical construction of the lens system). Guess it could be verified by shooting same lens on different sensor sizes at identical apertures and distances, then cropping the larger format image to match the smaller one's framing - it's probably going to be identical WRT DOF and perspective. Why the heck should it not - it's the lens that builds the image, the camera only catches it, and how much of it actually makes it into the image is the only thing that differs with sensor sizes.
I guess Brightcolors is going to disagree, though. I wish I could do some testing to learn this for myself but I only have one camera, and the APS-C NEX-3 I have access to cannot mount Canon lenses. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/sad.gif' class='bbc_emoticon' alt='
' />Quote:In 35mm terms, the lenses are actually F4 and F2.8...so they will behave like this even on a crop camera, right?
The 60 is better because it's F/2 for most purposes except maybe DOF calculation - most importantly for available light shooting. Depends on more than just that, the relative distances (camera-subject and subject-background) as well.
Quote:Joachim: I like the 60 for its IF, i hate tubular lenses, visually.
I have no experience with the 90 but loved the 60 when trying it out at the local photo fair. Nice portrait lens probably on every sensor size it's working with. Good coverage (about 80mm equivalent FOV - but since I'm not using FF cameras I'm not thinking in terms of equivalence) on my APS-H camera. Autofocus is not exactly top notch though, though I may be spoiled by Canon L and Sigma HSM lenses.