Most OOF Blur Lens

[K-amps]

For a given frame;

which Canon lens would give most Out of focus blur? Would 200/F2 be more than 85/1.2? Would 600/4 be more than 200/2?

Is there a calculator to calculate this? DoF master can do the DoF, but has no place to enter frame dimensions.

 

[rs]

In simple terms, the larger the entrance pupil, the shallower the DoF. Which means the 600/4 wins at 200mm, but the legendary 1200/5.6 beats it at 214mm.

However, throw in distance from subject (taking into account framing and MFD), and you've got quite a complex calculation.

This might help you: http://www.cambridgeincolour.com/tutorials/dof-calculator.htm

 

[chromophore]

In simple terms, if we fix the subject magnification by adjusting the distance between the camera to the subject, then the size of a blur circle for a background object at infinity is going to be proportional to the entrance pupil diameter, regardless of the actual f-number or focal length.

For example, if you take a 50mm f/1.0 lens, and a 600mm f/4 lens, the entrance pupil diameters at infinity focus are going to be 50mm and 150mm, respectively. Taking these as approximations to the entrance pupil diameters when both lenses are focused so that the image magnification are both at 0.01 (i.e., in each case the subject is located at a distance such that one meter of subject height will correspond to an image height of 1 cm), then for objects behind the subject, infinitely far away, the blur circle from the 600/4 lens will be approximately three times the diameter of the circle produced by the 50/1.0.

However, this scenario is not applicable when background objects are not infinitely far away, which is almost always the case. The reason is that when objects not in the plane of focus are relatively near that plane of focus, the effect of f-number on blur circle diameter is stronger. Therefore, a lens like the 85/1.2L will exhibit a more rapid increase in the blur circle diameter as a function of background separation from the subject, but achieves less maximum blur than a slower but longer focal length lens like the 300/2.8. Again, the comparison we are speaking of is for a constant subject magnification.

This is why very fast aperture lenses of modest focal length have a distinctive look: although you could get more background blur with a telephoto lens, the combination of a relatively short focal length and a very fast aperture results in an image where you can see more of the background (field of view is larger), but the drop-off in sharpness is more dramatic. More background blur alone does not create this look.

 

[chauncey]

OOF is but part of the equation...it's the quality of the OOF area, called bokeh, that sets these lenses apart.
http://www.thephoblographer.com/2013/10/27/five-lenses-bokeh-drool/#.VhoU92eBdr8
http://www.itsjustlight.com/photography-gear/best-canon-lenses-bokeh/

 

[Tuke]

With this site: http://dofsimulator.net/en/ and "Lock frame" box crossed you get the easiest answer to your question!

50mm, f/1.0
- background blur: 1.138mm
- depth of field: 12.5cm

85mm, f/1.2
- background blur: 1.532mm
- depth of field: 15.7cm

200mm, f/2.0
- background blur: 2.162mm
- depth of field: 26.2cm

600mm, f/4.0
- background blur: 3.243mm
- depth of field: 52.5cm

1200mm,f/5.6
- background blur:
- depth of field:

These are from full body shots. In macro distances the dof is yet another thing/problem.

 

[jrista]

In simple terms, the larger the entrance pupil, the shallower the DoF. Which means the 600/4 wins at 200mm, but the legendary 1200/5.6 beats it at 214mm.

However, throw in distance from subject (taking into account framing and MFD), and you've got quite a complex calculation.

This might help you: http://www.cambridgeincolour.com/tutorials/dof-calculator.htm

The Canon 600/4 has a 150mm aperture, not a 200mm aperture. If it was 200mm, the lens would be f/3. That would be a monstrous lens.

 

[scyrene]

I've considered this myself on and off. As you've all mentioned, it's quite complex as aperture (ratio and physical) interacts with both subject distance and background distance. Anecdotally, I'd say the 100L macro is a surprisingly good contender, when used closed to MFD with a distant background (the 180L must be better; the MP-E can be better, but has much more restricted use situations so it's hard to test side-by-side), the 85L is great, but the MFD is quite long so it's not so much better* (although I often found I needed to stop down as the background was *too* OOF sometimes) - but then the 500L+2x even stopped down to f/10 can produce lovely smooth backgrounds too, although something about that combination can make for busyness. I'd imagine the 200L or 400L, especially with extension tubes could be at the upper end, but all the (super) super teles are likely similar.

Sorry if I'm rambling

*using with extension tubes helps of course.

 

[Dylan777]

Having to own 85L f1.2, 200f2 and 400f2.8 IS II, I like the blur on 200f2

 

[rfdesigner]

In simple terms, the larger the entrance pupil, the shallower the DoF. Which means the 600/4 wins at 200mm, but the legendary 1200/5.6 beats it at 214mm.

However, throw in distance from subject (taking into account framing and MFD), and you've got quite a complex calculation.

This might help you: http://www.cambridgeincolour.com/tutorials/dof-calculator.htm

The Canon 600/4 has a 150mm aperture, not a 200mm aperture. If it was 200mm, the lens would be f/3. That would be a monstrous lens.

For the record, my scope is a 1500mm/F5.. 1ft aperture. No Autofocus.. and it's a b***h to focus! DoF is simply absent.

Image taken during the drive development, hence the wires.

 

[rs]

In simple terms, the larger the entrance pupil, the shallower the DoF. Which means the 600/4 wins at 200mm, but the legendary 1200/5.6 beats it at 214mm.

However, throw in distance from subject (taking into account framing and MFD), and you've got quite a complex calculation.

This might help you: http://www.cambridgeincolour.com/tutorials/dof-calculator.htm

The Canon 600/4 has a 150mm aperture, not a 200mm aperture. If it was 200mm, the lens would be f/3. That would be a monstrous lens.

You'd think I could handle simple division, eh?

Thanks for correcting me!

 

[K-amps]

In simple terms, if we fix the subject magnification by adjusting the distance between the camera to the subject, then the size of a blur circle for a background object at infinity is going to be proportional to the entrance pupil diameter, regardless of the actual f-number or focal length.

For example, if you take a 50mm f/1.0 lens, and a 600mm f/4 lens, the entrance pupil diameters at infinity focus are going to be 50mm and 150mm, respectively. Taking these as approximations to the entrance pupil diameters when both lenses are focused so that the image magnification are both at 0.01 (i.e., in each case the subject is located at a distance such that one meter of subject height will correspond to an image height of 1 cm), then for objects behind the subject, infinitely far away, the blur circle from the 600/4 lens will be approximately three times the diameter of the circle produced by the 50/1.0.

However, this scenario is not applicable when background objects are not infinitely far away, which is almost always the case. The reason is that when objects not in the plane of focus are relatively near that plane of focus, the effect of f-number on blur circle diameter is stronger. Therefore, a lens like the 85/1.2L will exhibit a more rapid increase in the blur circle diameter as a function of background separation from the subject, but achieves less maximum blur than a slower but longer focal length lens like the 300/2.8. Again, the comparison we are speaking of is for a constant subject magnification.

This is why very fast aperture lenses of modest focal length have a distinctive look: although you could get more background blur with a telephoto lens, the combination of a relatively short focal length and a very fast aperture results in an image where you can see more of the background (field of view is larger), but the drop-off in sharpness is more dramatic. More background blur alone does not create this look.

You start off explaining it very well. ..... but forget to answer my question regardless, I did learn from it.

Can you explain this and I quote ''Therefore, a lens like the 85/1.2L will exhibit a more rapid increase in the blur circle diameter as a function of background separation from the subject, but achieves less maximum blur than a slower but longer focal length lens like the 300/2.8''

 

[K-amps]

In simple terms, the larger the entrance pupil, the shallower the DoF. Which means the 600/4 wins at 200mm, but the legendary 1200/5.6 beats it at 214mm.

However, throw in distance from subject (taking into account framing and MFD), and you've got quite a complex calculation.

This might help you: http://www.cambridgeincolour.com/tutorials/dof-calculator.htm

Thank you, but my first stipulation was for a given frame, which DoF calculators ignore. You are right, fix the framing, and it gets quite complex. Interesting discussion.

 

[K-amps]

OOF is but part of the equation...it's the quality of the OOF area, called bokeh, that sets these lenses apart.
http://www.thephoblographer.com/2013/10/27/five-lenses-bokeh-drool/#.VhoU92eBdr8
http://www.itsjustlight.com/photography-gear/best-canon-lenses-bokeh/

Thanks; I specifically asked for out of focus blur, not Bokeh. Discussing Bokeh is very subjective... Perhaps a question for a different thread.

 

[K-amps]

With this site: http://dofsimulator.net/en/ and "Lock frame" box crossed you get the easiest answer to your question!

50mm, f/1.0
- background blur: 1.138mm
- depth of field: 12.5cm

85mm, f/1.2
- background blur: 1.532mm
- depth of field: 15.7cm

200mm, f/2.0
- background blur: 2.162mm
- depth of field: 26.2cm

600mm, f/4.0
- background blur: 3.243mm
- depth of field: 52.5cm

1200mm,f/5.6
- background blur:
- depth of field:

These are from full body shots. In macro distances the dof is yet another thing/problem.

Sir, thank you for dumbing it down for me... You understood the question perfectly, and your esp is also sensational, in that you guessed the application as well... full body shots .... Very helpful Answer. Takes a bow.

 

[K-amps]

I've considered this myself on and off. As you've all mentioned, it's quite complex as aperture (ratio and physical) interacts with both subject distance and background distance. Anecdotally, I'd say the 100L macro is a surprisingly good contender, when used closed to MFD with a distant background (the 180L must be better; the MP-E can be better, but has much more restricted use situations so it's hard to test side-by-side), the 85L is great, but the MFD is quite long so it's not so much better* (although I often found I needed to stop down as the background was *too* OOF sometimes) - but then the 500L+2x even stopped down to f/10 can produce lovely smooth backgrounds too, although something about that combination can make for busyness. I'd imagine the 200L or 400L, especially with extension tubes could be at the upper end, but all the (super) super teles are likely similar.

Sorry if I'm rambling

*using with extension tubes helps of course.

We should meet over a cuppa ... and ramble some more on this topic

 

[K-amps]

Having to own 85L f1.2, 200f2 and 400f2.8 IS II, I like the blur on 200f2

Thanks Dylan. I think I would like the 200F2 blur as well... just from some shots I have seen of the lens. But let me ask you, if you took a full body shot of your kid (or any subject filling a fixed part of the frame) , with all 3 lenses, (meaning you would have to physically move back for longer FL lenses); then for which of these three would you have the most background blur (not best Bokeh, but quantity of blur).

Heck if you can run a little test and post pics, I will pass on the favor to the next guy that has a similar question

Deal?

 

[scyrene]

I've considered this myself on and off. As you've all mentioned, it's quite complex as aperture (ratio and physical) interacts with both subject distance and background distance. Anecdotally, I'd say the 100L macro is a surprisingly good contender, when used closed to MFD with a distant background (the 180L must be better; the MP-E can be better, but has much more restricted use situations so it's hard to test side-by-side), the 85L is great, but the MFD is quite long so it's not so much better* (although I often found I needed to stop down as the background was *too* OOF sometimes) - but then the 500L+2x even stopped down to f/10 can produce lovely smooth backgrounds too, although something about that combination can make for busyness. I'd imagine the 200L or 400L, especially with extension tubes could be at the upper end, but all the (super) super teles are likely similar.

Sorry if I'm rambling

*using with extension tubes helps of course.

We should meet over a cuppa ... and ramble some more on this topic

Sounds good to me!

 

[Dylan777]

Having to own 85L f1.2, 200f2 and 400f2.8 IS II, I like the blur on 200f2

Thanks Dylan. I think I would like the 200F2 blur as well... just from some shots I have seen of the lens. But let me ask you, if you took a full body shot of your kid (or any subject filling a fixed part of the frame) , with all 3 lenses, (meaning you would have to physically move back for longer FL lenses); then for which of these three would you have the most background blur (not best Bokeh, but quantity of blur).

Heck if you can run a little test and post pics, I will pass on the favor to the next guy that has a similar question

Deal?

I would say 200mm @ wide open due to the fl and f2 still my favorite. 85L f1.2 II is neck to neck. Big pros, weight, f1.2 and of course $$$.

Here are few shots from 200f2 @ wide open. I don't recall last time I shoot smaller than f2 with this lens.

 

[scyrene]

Having to own 85L f1.2, 200f2 and 400f2.8 IS II, I like the blur on 200f2

Thanks Dylan. I think I would like the 200F2 blur as well... just from some shots I have seen of the lens. But let me ask you, if you took a full body shot of your kid (or any subject filling a fixed part of the frame) , with all 3 lenses, (meaning you would have to physically move back for longer FL lenses); then for which of these three would you have the most background blur (not best Bokeh, but quantity of blur).

Heck if you can run a little test and post pics, I will pass on the favor to the next guy that has a similar question

Deal?

I would say 200mm @ wide open due to the fl and f2 still my favorite. 85L f1.2 II is neck to neck. Big pros, weight, f1.2 and of course $$$.

Here are few shots from 200f2 @ wide open. I don't recall last time I shoot smaller than f2 with this lens.

I covet that lens more than any other. Such a pity it's so expensive - even more than the 300L II in street prices here

 

[chromophore]

In simple terms, if we fix the subject magnification by adjusting the distance between the camera to the subject, then the size of a blur circle for a background object at infinity is going to be proportional to the entrance pupil diameter, regardless of the actual f-number or focal length.

For example, if you take a 50mm f/1.0 lens, and a 600mm f/4 lens, the entrance pupil diameters at infinity focus are going to be 50mm and 150mm, respectively. Taking these as approximations to the entrance pupil diameters when both lenses are focused so that the image magnification are both at 0.01 (i.e., in each case the subject is located at a distance such that one meter of subject height will correspond to an image height of 1 cm), then for objects behind the subject, infinitely far away, the blur circle from the 600/4 lens will be approximately three times the diameter of the circle produced by the 50/1.0.

However, this scenario is not applicable when background objects are not infinitely far away, which is almost always the case. The reason is that when objects not in the plane of focus are relatively near that plane of focus, the effect of f-number on blur circle diameter is stronger. Therefore, a lens like the 85/1.2L will exhibit a more rapid increase in the blur circle diameter as a function of background separation from the subject, but achieves less maximum blur than a slower but longer focal length lens like the 300/2.8. Again, the comparison we are speaking of is for a constant subject magnification.

This is why very fast aperture lenses of modest focal length have a distinctive look: although you could get more background blur with a telephoto lens, the combination of a relatively short focal length and a very fast aperture results in an image where you can see more of the background (field of view is larger), but the drop-off in sharpness is more dramatic. More background blur alone does not create this look.

You start off explaining it very well. ..... but forget to answer my question regardless, I did learn from it.

Can you explain this and I quote ''Therefore, a lens like the 85/1.2L will exhibit a more rapid increase in the blur circle diameter as a function of background separation from the subject, but achieves less maximum blur than a slower but longer focal length lens like the 300/2.8''

I did not forget to answer your question. The purpose of my response was to explain that your question does not furnish a sufficient set of conditions to uniquely answer it, because the amount of blur is not purely a function of the lens: it is a function of an interaction of lens and distance between subject and background.

Another thing I must point out is that DOF says almost nothing about the extent of blur: the DOF only indicates the range of distances at which objects appear acceptably sharp. Therefore, any DOF calculators or formulas that do not specifically calculate the blur circle diameter will be irrelevant to your question.

Years ago I wrote a program that would display a chart of the blur circle diameter as a function of image magnification, f-number, focal length, and distance between subject-in-focus and background. It's sitting on some backup drive somewhere so I would need to dig it out. The point is that a lens with a large entrance pupil may achieve more blur of background objects very far away, but the rate at which the blur circle diameter increases can be slower than another lens with a smaller entrance pupil diameter. This is precisely what happens if we compare an 85/1.2 against a 300/2.8. If you take headshots with both lenses at the same image magnification, and in both shots, you focus on the eyes, you will find that with the 85/1.2, the subject's nose will be much more blurry than with the 300/2.8. But a very distant background will be more blurry on the same shot at 300/2.8 than at 85/1.2. The slope of blur circle diameter as a function of subject-background separation is greater with the 85/1.2 but the asymptotic behavior of blur circle diameter is such that the 300/2.8 will achieve more blur.