DOF - Probably a dumb question

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vecsri

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Richard Black
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Most things i like to try and work out as best i can for my self, but without a 50mm to ahnd i cant :(

I hear alot of people talking about use a 1.4 50mm prime lens for low light affairs.

I know you use a low fstop for dof, do you notice when you use it on 1.4 say ina room fo people?
Or is it you're so far back it keeps most in that focus range?

if that makes sense?

Say if i was taking a photo in a club or a pub, with bad lighting, would most stuff be out of focus and just the peron,/object i'm photographing in focus?
 
You can work it out yourself ... just go to DOF Master, plug in the numbers relating to your camera, lens, aperture, and subject distance ...
 
vecsri said:
Most things i like to try and work out as best i can for my self, but without a 50mm to ahnd i cant :(

I hear alot of people talking about use a 1.4 50mm prime lens for low light affairs.

I know you use a low fstop for dof, do you notice when you use it on 1.4 say ina room fo people?
Or is it you're so far back it keeps most in that focus range?

if that makes sense?

Say if i was taking a photo in a club or a pub, with bad lighting, would most stuff be out of focus and just the peron,/object i'm photographing in focus?
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Hi,
The reason f.1.4 is popular is it gives you a brighter image in low lighting.
You wouldn't however normally take pictures at maximum aperture, because A] Very few lenses perform at their best until you stop down to around f5.6 /8 ..and B] Yes the depth of field on a 50mm lens would be very shallow at apertures wider than f4, bearing in mind that the greater the camera to subject distance, the dof proportionately increases.
Cheers:thumbs:
 
~So the further back you get the less apparent 1.4 would be?
Reason i ask is, if i take a photo of a rose close up at 2.8 only part of the rose is in focus,. i was wondering if i took a photo of a person from a ditance would only his nose be infocus, but thinking about it, thats daft.

cheers chaps
 
Not so sure about that, what's the point of buying a 1.8 lens and then in low light depending on a massive ISO or slow shutter anyway?

OP - you are right though as already stated, the DOF would be very short. Which, if you're rubbish like me, means most you're shots will be basically OOF - I'm having a nightmare with the 85mm/1.8 :(
 
i stop mine down to f2, you end up with some nice singled out people from a crowded room, just have to make sure they arent moving too fast or you end up with oof shots
 
vecsri said:
~So the further back you get the less apparent 1.4 would be?*
Reason i ask is, if i take a photo of a rose close up at 2.8 only part of the rose is in focus,. i was wondering if i took a photo of a person from a ditance would only his nose be infocus, but thinking about it, thats daft.

cheers chaps
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*Answer to first point is yes, but read my previous thread
Answer to 2nd point is, well no because you should focus on the eyes :thumbs:
 
You'll get very shallow DOF, just enough to put a person in usually. To illustrate; this was taken with an f0.95 50mm FD lens (though aperture was somewhere from 1-1.3 according to notebook)
2573819378_22225e9bf2_d.jpg
 
TheKrikkitWars said:
You'll get very shallow DOF, just enough to put a person in usually. To illustrate; this was taken with an f0.95 50mm FD lens (though aperture was somewhere from 1-1.3 according to notebook)

*A rare beasty...who made lenses this big, apart from Canon and Schneider Kreuznach? :thinking:
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Reet, i tihnk i'll have to get my self one and try
 
ivortripod said:
TheKrikkitWars said:
You'll get very shallow DOF, just enough to put a person in usually. To illustrate; this was taken with an f0.95 50mm FD lens (though aperture was somewhere from 1-1.3 according to notebook)

*A rare beasty...who made lenses this big, apart from Canon and Schneider Kreuznach? :thinking:
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It was a one off loan, now I just need a briefcase full of money to buy one myself :P
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and would you also get slightly more depth of field with a smaller (non ff )sensor ?
 
Yes, DOF is larger with a crop sensor, since you'd be standing further back and hence focusing further away.
 
cannon shooter said:
and would you also get slightly more depth of field with a smaller (non ff )sensor ?
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pearce_jj said:
Yes, DOF is larger with a crop sensor, since you'd be standing further back and hence focusing further away.
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Correct, eg, DOF at 50mm f/2.8 on Canon APS-C camera is greater than 80mm f/4 on a 5D. Actually 1 & 1/3 stops deeper (So equivalent to f/4.5 on FF)
 
Me thinks me needs some books and do some serious reading because I haven't a clue what you guys are talking about....It's rubbish when your new to something and you don't get what people are talking about!!

Books and back to school it is ;)
 
Paulmack said:
Me thinks me needs some books and do some serious reading because I haven't a clue what you guys are talking about....It's rubbish when your new to something and you don't get what people are talking about!!

Books and back to school it is ;)
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Hi Paul,

I'm not sure which part(s) of the thread you don't understand so my apologies in advance if I'm telling you something you already know.

DOF - In simple terms it refers to the portion of the image that is in focus. This is varied by controlling the aperture (adjusted in f/ numbers, f/ stops or just stops) of the lens. A rough guide to help understand it is to remember that the smaller the f/ number eg. f/1.4 or f/2.0 the shallower (or smaller) the depth of field will be. f/11 or f/16 on the other hand will give you a large depth of field.

Another factor that will effect the depth of field is the distance between you and your subject. If you take two photos of the same subject using the same aperture but from different distances then you will see the DOF increase as you move further away.

HTH :)
 
Chris L said:
Hi Paul,

I'm not sure which part(s) of the thread you don't understand so my apologies in advance if I'm telling you something you already know.

DOF - In simple terms it refers to the portion of the image that is in focus. This is varied by controlling the aperture (adjusted in f/ numbers, f/ stops or just stops) of the lens. A rough guide to help understand it is to remember that the smaller the f/ number eg. f/1.4 or f/2.0 the shallower (or smaller) the depth of field will be. f/11 or f/16 on the other hand will give you a large depth of field.

Another factor that will effect the depth of field is the distance between you and your subject. If you take two photos of the same subject using the same aperture but from different distances then you will see the DOF increase as you move further away.

HTH :)
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No you were right to assume I know nothing, I am quite literally just learning the basics, so thanks. What you say seems to make sense to me, so basically the aperture is an invisible circle within the frame and the lower the number the smaller the circle? and only the part of the image within the circle would be in focus??

Anyway I have been the library and picked up a few books to keep me going over the weekend and enlighten me further...fingers crossed!!
 
Depth of focus vs depth of field
While the phrase depth of focus was historically used, and is sometimes still used, to mean depth of field, in modern times it is more often reserved for the image-side depth. Depth of field is a measurement of depth of acceptable sharpness in the object space, or subject space.

Depth of focus, however, is a measurement of how much distance exists behind the lens wherein the film plane will remain sharply in focus. It can be viewed as the flip side of depth of field, occurring on the opposite side of the lens.

Where depth of field often can be measured in macroscopic units such as meters and feet, depth of focus is typically measured in microscopic units such as fractions of a millimeter or thousandths of an inch.

The same factors that determine depth of field also determine depth of focus, but these factors can have different effects than they have in depth of field. Both depth of field and depth of focus increase with smaller apertures. For distant subjects (beyond macro range), depth of focus is relatively insensitive to focal length and subject distance, for a fixed f-number. In the macro region, depth of focus increases with longer focal length or closer subject distance, while depth of field decreases.

Right...have you got that? :bat:
 
ivortripod said:
Depth of focus vs depth of field
While the phrase depth of focus was historically used, and is sometimes still used, to mean depth of field, in modern times it is more often reserved for the image-side depth. Depth of field is a measurement of depth of acceptable sharpness in the object space, or subject space.

Depth of focus, however, is a measurement of how much distance exists behind the lens wherein the film plane will remain sharply in focus. It can be viewed as the flip side of depth of field, occurring on the opposite side of the lens.

Where depth of field often can be measured in macroscopic units such as meters and feet, depth of focus is typically measured in microscopic units such as fractions of a millimeter or thousandths of an inch.

The same factors that determine depth of field also determine depth of focus, but these factors can have different effects than they have in depth of field. Both depth of field and depth of focus increase with smaller apertures. For distant subjects (beyond macro range), depth of focus is relatively insensitive to focal length and subject distance, for a fixed f-number. In the macro region, depth of focus increases with longer focal length or closer subject distance, while depth of field decreases.

Right...have you got that? :bat:
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Clear as mud:lol::suspect::gag:
 
ivortripod said:
Depth of focus vs depth of field
While the phrase depth of focus was historically used, and is sometimes still used, to mean depth of field, in modern times it is more often reserved for the image-side depth. Depth of field is a measurement of depth of acceptable sharpness in the object space, or subject space.

Depth of focus, however, is a measurement of how much distance exists behind the lens wherein the film plane will remain sharply in focus. It can be viewed as the flip side of depth of field, occurring on the opposite side of the lens.

Where depth of field often can be measured in macroscopic units such as meters and feet, depth of focus is typically measured in microscopic units such as fractions of a millimeter or thousandths of an inch.

The same factors that determine depth of field also determine depth of focus, but these factors can have different effects than they have in depth of field. Both depth of field and depth of focus increase with smaller apertures. For distant subjects (beyond macro range), depth of focus is relatively insensitive to focal length and subject distance, for a fixed f-number. In the macro region, depth of focus increases with longer focal length or closer subject distance, while depth of field decreases.

Right...have you got that? :bat:
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You just spoilt my saturday night now!! haha
I actually thought I understood something before but now im even more confused than ever.... The books are open and now im revising, gonna get my head round this sooner or later.

Thanks anyway...and sorry to the OP for taking over your thread, in the future I will start my own for this type of stuff :D
 
Paulmack said:
What you say seems to make sense to me, so basically the aperture is an invisible circle within the frame and the lower the number the smaller the circle? and only the part of the image within the circle would be in focus??
not quite right paul ..the aperture is a series of small blades within the lens they are arranged so that they make a circle, and put very simply ,,if you used a small aperture ( larger f stop number say f 22 )you would generaly get a larger depth of field that is, something six feet in front of you is in focus and so is something hundreds of feet away ,even out to infinity (in focus ) but if you used a larger aperture ( smaller f stop number ) say f 2 if you focused on a models eyes her/his nose would be out of focus. its the distance either closer to or further away from the lens that is in or out of focus. ( i hope that makes sense the way i put it down ) gary
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