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09/07/2006 04:48:30 PM · #26 |
Originally posted by fotomann_forever:
Originally posted by GeneralE:
Originally posted by w24x192:
When's someone going to mention hyperfocal distance? |
I meant to about eight posts ago, but didn't because I can never explain it right. |
Yeah, not easy to explain in a few sentences. |
That's why I supplied links to do the explaining for me :) |
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09/07/2006 04:49:40 PM · #27 |
Originally posted by jhonan:
The lens has a scale which looks like this (thanks for the links btw)... |
Remember that the scale is "calibrated" for use with film. There is really only a single plane of focus, everything in front and behind that plane is "a close approximation to being in focus." What appears sharp does so because the loss of sharpness is less than the sensor (or film) can resolve. Using the film-based scale is going to give you slightly fuzzy results at the near and far limits of what the scale sez should be in focus.
That's why, if you compare what the lens scale tells you to my above link, you'll find they match up if you select a Coc of 0.030mm, (typically used for film) but are too liberal if you use 0.016mm (an approximation for many 1.5 and 1.6-crop 6 and 8 MPx cameras.
Edit: Oh, I see you *are* using "fillum"! In that case, you can *almost* get there at 50mm, assuming the 0.030mm CoC. You can get from 6 ft to 585 ft in reasonable focus at f/22. YMMV at the inner and outer limits!
Message edited by author 2006-09-07 16:52:34. |
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09/07/2006 04:50:34 PM · #28 |
Originally posted by Raziel:
Originally posted by jhonan:
The lens has a scale which looks like this (thanks for the links btw);
Yea... now you mention it I was going to ask how to use these DOF index markers... |
The markers just show from where to where the DOF extends for a certain aperture and focus distance. |
Ahh.... So in that diagram when it's set to f16 and focussed at 5m the DOF goes from just under 3m to infinity? |
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09/07/2006 04:54:35 PM · #29 |
Originally posted by kirbic:
Originally posted by jhonan:
The lens has a scale which looks like this (thanks for the links btw)... |
Remember that the scale is "calibrated" for use with film. There is really only a single plane of focus, everything in front and behind that plane is "a close approximation to being in focus." What appears sharp does so because the loss of sharpness is less than the sensor (or film) can resolve. Using the film-based scale is going to give you slightly fuzzy results at the near and far limits of what the scale sez should be in focus. |
Right, I'm starting to understand this now - the 50mm will act like a 75mm when I put it on a D50. So that DOF scale will be cut short at either end. |
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09/07/2006 04:54:53 PM · #30 |
Originally posted by jhonan:
Originally posted by Raziel:
Originally posted by jhonan:
The lens has a scale which looks like this (thanks for the links btw);
Yea... now you mention it I was going to ask how to use these DOF index markers... |
The markers just show from where to where the DOF extends for a certain aperture and focus distance. |
Ahh.... So in that diagram when it's set to f16 and focussed at 5m the DOF goes from just under 3m to infinity? |
Yes, but as kirbic mentioned that scale is calibrated for 35mm film, so just keep that in mind if you use the lens on a digital. You could check some of the graphs and determine what aperture change you need to get the DOF scales to match for film and digital, then you can use the scale for digital. |
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09/07/2006 04:58:37 PM · #31 |
Originally posted by jhonan:
Originally posted by kirbic:
Originally posted by jhonan:
The lens has a scale which looks like this (thanks for the links btw)... |
Remember that the scale is "calibrated" for use with film. There is really only a single plane of focus, everything in front and behind that plane is "a close approximation to being in focus." What appears sharp does so because the loss of sharpness is less than the sensor (or film) can resolve. Using the film-based scale is going to give you slightly fuzzy results at the near and far limits of what the scale sez should be in focus. |
Right, I'm starting to understand this now - the 50mm will act like a 75mm when I put it on a D50. So that DOF scale will be cut short at either end. |
A 50mm is always a 50mm, you cannot change the optics of the lens. The cropping factor just means that you are cropping the centre from a full frame image produced by the lens. The 50mm has the same field of view on a 1.5x cropped sensor that a 75mm gives on a film camera. Since you're cropping a piece of the image, you need a sharped image to make a acceptable print. Take a sharp 8x10 and cropping the centre will give you a less sharp photo if you print it at 8x10. |
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09/07/2006 04:59:17 PM · #32 |
Originally posted by jhonan:
The camera is a FM2n - errrm... yea, 'film', remember that stuff? :) But hey, I like a challenge, and it keeps me happy until my D50 arrives.
Ah, okay... Yea, I have a 28mm which gives a deep DOF. I just thought to myself if I set the aperture on the 50mm high enough, I'll get a similar DOF. But (judging by the links to the DOF calculators) it's not as simple as that. |
In your case, the Nikkor AIS lenses have DOF scales. You don't need the calculators, and it is very simple (as shown in the lens picture you posted) which shows focus from about 9 ft to infinity at F/16. |
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09/07/2006 05:12:41 PM · #33 |
Originally posted by talmy:
In your case, the Nikkor AIS lenses have DOF scales. You don't need the calculators, and it is very simple (as shown in the lens picture you posted) which shows focus from about 9 ft to infinity at F/16. |
Okay, on my lens if I set it to f22 and use the DOF scale; I set the focus so infinity is at the left-most DOF marker.
With this setup the field extends from about 2m to infinity, with maximum (sharpest) focus at about 4m.
So I need to set the focus like this, at f22, on a tripod. And stand about 2m from the foreground subject.
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09/07/2006 05:18:22 PM · #34 |
Originally posted by jhonan:
Originally posted by talmy:
In your case, the Nikkor AIS lenses have DOF scales. You don't need the calculators, and it is very simple (as shown in the lens picture you posted) which shows focus from about 9 ft to infinity at F/16. |
Okay, on my lens if I set it to f22 and use the DOF scale; I set the focus so infinity is at the left-most DOF marker.
With this setup the field extends from about 2m to infinity, with maximum (sharpest) focus at about 4m.
So I need to set the focus like this, at f22, on a tripod. And stand about 2m from the foreground subject. |
Yup!
Shooting film, you'll find that this *may* give pleasing results. Critical inspection may show slight fuzziness at the near limit (2m) and at infinity.
When using on digital, it's still a 50mm lens, but the DoF appears narrower because the sensor resolves more lines per millimeter at the sensor plane than film (smaller CoC). |
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