If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
|
Thread Tools | Rate Thread | Display Modes |
#1
|
|||
|
|||
film vs CMOS
On 2018-08-14 09:08, nospam wrote:
In article , NY wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. |
Ads |
#2
|
|||
|
|||
film vs CMOS
In article , +++ATH0
wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. nope. depth of field is a function of physical aperture. what you describe is f/stop, which is used for exposure purposes, and in some cases (usually movies), t/stops are used, which is actual light transmission through the lens, not a simple ratio. |
#3
|
|||
|
|||
film vs CMOS
In article , +++ATH0
wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. nope. depth of field is a function of physical aperture. what you describe is f/stop, which is used for exposure purposes, and in some cases (usually movies), t/stops are used, which is actual light transmission through the lens, not a simple ratio. |
#4
|
|||
|
|||
film vs CMOS
On 2018-08-25 15:06, nospam wrote:
In article , +++ATH0 wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. nope. depth of field is a function of physical aperture. what you describe is f/stop, which is used for exposure purposes, and in some cases (usually movies), t/stops are used, which is actual light transmission through the lens, not a simple ratio. Are you claiming that focal length has no bearing on depth of field? That's an interesting viewpoint. |
#5
|
|||
|
|||
film vs CMOS
On 2018-08-25 15:06, nospam wrote:
In article , +++ATH0 wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. nope. depth of field is a function of physical aperture. what you describe is f/stop, which is used for exposure purposes, and in some cases (usually movies), t/stops are used, which is actual light transmission through the lens, not a simple ratio. Are you claiming that focal length has no bearing on depth of field? That's an interesting viewpoint. |
#6
|
|||
|
|||
film vs CMOS
In article , +++ATH0
wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. nope. depth of field is a function of physical aperture. what you describe is f/stop, which is used for exposure purposes, and in some cases (usually movies), t/stops are used, which is actual light transmission through the lens, not a simple ratio. Are you claiming that focal length has no bearing on depth of field? for the same subject size and same image quality (coc), no. That's an interesting viewpoint. not really. it's just math. |
#7
|
|||
|
|||
film vs CMOS
In article , +++ATH0
wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. nope. depth of field is a function of physical aperture. what you describe is f/stop, which is used for exposure purposes, and in some cases (usually movies), t/stops are used, which is actual light transmission through the lens, not a simple ratio. Are you claiming that focal length has no bearing on depth of field? for the same subject size and same image quality (coc), no. That's an interesting viewpoint. not really. it's just math. |
#8
|
|||
|
|||
film vs CMOS
+++ATH0 wrote in
: On 2018-08-14 09:08, nospam wrote: In article , NY wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. That is correct. For any given focal length, the smaller the aperature, the greater the depth of field. That is why pinhole cameras focus from closeup to infinity without a lens. |
#9
|
|||
|
|||
film vs CMOS
+++ATH0 wrote in
: On 2018-08-14 09:08, nospam wrote: In article , NY wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. That is correct. For any given focal length, the smaller the aperature, the greater the depth of field. That is why pinhole cameras focus from closeup to infinity without a lens. |
#10
|
|||
|
|||
film vs CMOS
nospam wrote in
: In article , +++ATH0 wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. nope. depth of field is a function of physical aperture. what you describe is f/stop, which is used for exposure purposes, and in some cases (usually movies), t/stops are used, which is actual light transmission through the lens, not a simple ratio. Are you claiming that focal length has no bearing on depth of field? for the same subject size and same image quality (coc), no. That's an interesting viewpoint. not really. it's just math. No matter what the focal length of the lense is, the further away the focal plane is, the greater the depth of field will be for any aperature. As an example, if one is taking a head and shoulders portrait with a large aperature, it is quite likely that part of the subject will be out of focus slighty. Moving back a few feet with the same lense and aperature will result in a deeper depth of field, so that all of the subject should be in focus. The drawback is that the image size will be smaller, and thus require more enlargement to obtain the same size image, with the resulting loss of resolution with the enlarged image. |
#11
|
|||
|
|||
film vs CMOS
nospam wrote in
: In article , +++ATH0 wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. nope. depth of field is a function of physical aperture. what you describe is f/stop, which is used for exposure purposes, and in some cases (usually movies), t/stops are used, which is actual light transmission through the lens, not a simple ratio. Are you claiming that focal length has no bearing on depth of field? for the same subject size and same image quality (coc), no. That's an interesting viewpoint. not really. it's just math. No matter what the focal length of the lense is, the further away the focal plane is, the greater the depth of field will be for any aperature. As an example, if one is taking a head and shoulders portrait with a large aperature, it is quite likely that part of the subject will be out of focus slighty. Moving back a few feet with the same lense and aperature will result in a deeper depth of field, so that all of the subject should be in focus. The drawback is that the image size will be smaller, and thus require more enlargement to obtain the same size image, with the resulting loss of resolution with the enlarged image. |
#12
|
|||
|
|||
film vs CMOS
In article , Tim
wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. That is correct. nope. For any given focal length, the smaller the aperature, the greater the depth of field. in other words, physical aperture. physical aperture is often confused with f/stop. the former is the diameter of the entrance pupil and the latter is the ratio of focal length to that diameter. That is why pinhole cameras focus from closeup to infinity without a lens. pinhole cameras have no refractive elements, so everything is 'in focus' (ignoring diffraction effects and optimal pinhole diameter). |
#13
|
|||
|
|||
film vs CMOS
In article , Tim
wrote: No matter what the focal length of the lense is, the further away the focal plane is, the greater the depth of field will be for any aperature. from your description below, you mean subject distance, not focal plane. As an example, if one is taking a head and shoulders portrait with a large aperature, it is quite likely that part of the subject will be out of focus slighty. Moving back a few feet with the same lense and aperature will result in a deeper depth of field, so that all of the subject should be in focus. The drawback is that the image size will be smaller, and thus require more enlargement to obtain the same size image, with the resulting loss of resolution with the enlarged image. you're changing the distance, resulting in photos with different size subjects, so not a valid comparison. maintain the same subject size at different distances (via different lenses) and the dof will be the same, although the perspective won't be. |
#14
|
|||
|
|||
film vs CMOS
On 8/25/2018 9:13 PM, Tim wrote:
: d thus require more enlargement to obtain the same size image, with the resulting loss of resolution with the enlarged image. https://en.wikipedia.org/wiki/Camera_lens https://en.wikipedia.org/wiki/Cardin...)#Nodal_points The relationship between the censor size (film Size) the focal length of the lens and the aperture, (whether fixed or variable) works the same whether it is digital or a chemical film. One of the laws of nature that can not be altered, which some people thing are no longer in effect. -- 2018: The year we learn to play the great game of Euchre |
#15
|
|||
|
|||
film vs CMOS
On Sun, 26 Aug 2018 01:13:11 GMT, Tim wrote:
nospam wrote in : In article , +++ATH0 wrote: One other factor to bear in mind: the depth of field varies with lens focal length, not field of view of the subject. actually, it's aperture. actually, it's the ratio of focal length to aperture. nope. depth of field is a function of physical aperture. what you describe is f/stop, which is used for exposure purposes, and in some cases (usually movies), t/stops are used, which is actual light transmission through the lens, not a simple ratio. Are you claiming that focal length has no bearing on depth of field? for the same subject size and same image quality (coc), no. That's an interesting viewpoint. not really. it's just math. No matter what the focal length of the lense is, the further away the focal plane is, the greater the depth of field will be for any aperature. As an example, if one is taking a head and shoulders portrait with a large aperature, it is quite likely that part of the subject will be out of focus slighty. Moving back a few feet with the same lense and aperature will result in a deeper depth of field, so that all of the subject should be in focus. The drawback is that the image size will be smaller, and thus require more enlargement to obtain the same size image, with the resulting loss of resolution with the enlarged image. Thee are several ways of thinking about depth of focus and several independent variable to consider. That's why people get so het up when arguing about this: it's too complicated to discuss rationally without mathematics. There is also the complication of whether you mean depth of focus or depth of field. I suggest https://en.wikipedia.org/wiki/Depth_of_focus as a good place to start sorting all this out. -- Regards, Eric Stevens |
|
Thread Tools | |
Display Modes | Rate This Thread |
|
|