I know that if one can afford it a fast glass is the way to go. But even though in good lighting what would be the ideal f stop between f/2.8-f/11? I know at f/11 there would be strong DOF and shallow at f/4, but?
There's no simple answer to this question. Having tried fast glass I've decided that it's not the best for me. The 400mm f/2.8 was too heavy and required stopping down for adequate DOF and image quality; IMHO there's no point buying a fast lens if I'm not willing to use it at maximum aperture. I favor portability over maximum aperture; my 280mm lens is f/4 and my 400mm and 560mm lenses are f/6.8
Doug's advice is good - a couple of other things to keep in mind :
-- Most lenses will give better results stopped down from their largest aperture. So an f/2.8 lens at f/4 will probably outperform an f/4 lens at f/4.
-- Depending on the body you have, you may need f/5.6 to maintain autofocus
-- Along the same lines, you'll have more options with teleconverters if you have a faster max aperture, since autofocus will be maintained
Since you mentioned f/11, I'm assuming you're talking about more than the max aperture of the lens, right? In that case, it really depends on your needs for a particular shot, in terms of shutter speed and DOF. At that point, assuming the light it good, it's a purely artistic decision.
David
f/11 was just an example. I'm debating weather I should get the new 150-500 OS HSM for that extra reach and f/6.3 or get used to my 70-200 with 2xTC at f/8 where it's the sharpest. but DOF I find isn't quite shallow enough? just don't know yet.??
Fast lenses lat you reduce your depth of field to to blur your background, Considered by most to be a desirable effect in bird portraits. Most lenses are sharpest when stopped down a stop or two. If you are shooting with an f5.6 lens, stopping down is going to give you f8 or f11. This may simply be too slow to eliminate motion blur. and probably isn't going to give you that nice bokeh so widely prized.
There are other advantages to fast lenses, such as giving a brighter view in the viewfinder and maintaing autofocus capabiltiies with teleconverters attached.
The downside to fast lenses are size, weight, and cost. If you aren't dissatisfied with the photos you're getting without using big glass, then there's no reason to switch.
Most dedicated bird photographers either have, or lust after, a long fast lens.
What f/stop is best! WOW! Now that’s what I called a loaded question!
From my own point of view! and what works best for me is this;
I never stop down any further than f/11 because that’s diffraction territory! However, I never say never!
I only shoot wide open when I need too or must smooth out that background!
Now, if I’m using a 600mm f/4 and I stick a 1.7x TC on I’ve increased the focal length to 1000mm and the aperture to f/6.7 but the effective depth of field is still f/4. So please bear that in mind!
Depending on many variables I tend to shoot my big glass between f/7.1 and f/8 to ensure I have the complete bird in focus (but it does all depend on the pose of the subject and my position)! However this isn’t always what I what to convey to my viewer so I may choose too stop down or shoot wide open to convey what I see in my minds eye!
Bear in mind that f/2.8 is fast for a 300mm lens as f/4 is fast for a 600mm or f/5.6 is for an 800mm.
Also the aperture chosen determines your shutter speed. At f/4 your shutter speed will be faster than at f/11 (if it isn’t your exposure will be out!). So if you need to shoot a bird in flight then shutter speed will be a greater consideration! Therefore shoot wide open i.e. f/4. However your ISO setting (assuming you're shooting digital) can be cranked up; too up your DOF or f/stop and shutter speed. If you do this you start a trade off! i.e. noise and so forth!
The lighting will also determine your f/stop choice too!
My best advice is to get out there and try shooting various f/stop’s off the same subject and look at the results back on your computer later! It’s the best way to really understand it! Shoot at f/4 will give ‘x’ and if you shoot as f/11 it’ll be ‘x’. Once you understand that then you be able to decide how you want to communicate the setting in front of you to the viewer! i.e. whether you need to smooth the background or include it in the image (if so just how much).
Smooth the background and the bird POP’s include the environment and it may get lost! But there are times when the environment has to be included i.e. the subject is just too close to the BG or it’s part of the story!
I'm no expert, so this is as much a question as it is an answer, but isn't the distance from your subject going to play a big part is selecting a F/stop for DOF? The way I understand things (please chime in if I'm wrong) the closer you are to your subject, the shallower your DOF will be at any given F/stop.
As a macro specialist, I tend to think about DOF in terms of magnification.
At any given fixed degree of magnification and any given fixed f-stop, the DOF is exactly the same regardless of the focal length of the lens.
So a 1" object that is 1" on the sensor or film, shot at f8 or your favorite aperature, and enlarged in a print so that the object is 8" (or your other favorite number), will have exactly the same DOF regardless if it is shot with a 20 mm lens or an 800 mm lens.
What really screws up this for most people are the following considerations: A wide angle lens takes in far more of the background that a long telephoto. So a 1 mm blob that almost looks sharp with a 20 mm lens is now a 10 mm blob when shot with a 200 mm blob and clearly out of focus. Far less of the background is taken in.
Second, a subject shot with a wide angle *usually* has less magnification, so more apparent DOF.
To get to full frame with the APS sensor SLR's, there is less magnification needed. Less magnification = more DOF. Notice that I did NOT say to get to 1:1, I said to full frame. Going to 1:1 on an APS sensor gives exactly the same DOF as going to 1:1 on a standard frame, given the same f-stop. (And again notice that the lens was not mentioned). At 1:1 on the APS sensors, you'll have a lot less of the object in the frame - remember, the smaller sensor is a cropping of a full frame. It will look a lot bigger in the viewfinder, but still be 1:1.
Last, most people don't print to 8 times the sensor size. They print to 8x10 (or 8x12). For a cropped sensor, this means more magnification of the subject. This really messes with apparent DOF and I really don't want to touch this one. Here is a link
It is a bit technical, but the above essentially summarizes these.
Posted by James Fillip on June 9, 2008 at 11:24 PM
Wow Dan,
Great read, both links.
But it seems like a long way to go to say what's already been said. The crop factor/sensor size seems irrelevant. We all shoot the cameras we shoot, the "crop factor" is what it is. What you see in the view finder is what you get. Thats really not a factor for me. Would the overall shot be different with a 8X10 full frame from the same spot? For sure! But if we were shooting with a different sensor/format we would for sure adjust the comp. to get the results we were looking for. Just like when some of us can't afford a 600mm, we will learn how to get in close enough to use the 300mm.
I also find it interesting that those formulas are said not to apply to macro work, as that is where I really learned the importance of DOF. However I can see the difference and appreciate why it is not the same(but it goes back to my original post about distance from subject).
To close I have another question. If magnification is a factor, would the same print at 4X6 have a different DOF then a print at 8X10?
Posted by Dan Borzynski on June 10, 2008 at 10:20 PM
Yeah, it is a long way to say what has already been said. Unfortunately, there is a lot of mythology out there regarding DOF, cropped sensors and focal length and it gets repeated again, again and yet again.
Now, back your your last question. It actually does get buried in the two articles, but pretty far down and not with a big pointer on it. Here is the short, practical answer: yes. Ignore diffraction, lens sharpness, sensor/film resolution for the time being, losses in the scan/printmaking process, etc (and yes, these are real issues, but I am trying to give a non-technical answer).
Let's use a more extreme case. Suppose you want to go from a 4x6 to a 20x30. Most 4x6 prints, unless you really blow it, is going to look sharp. Now, pick out something in the print which according to the formulas, is "sharp", but just barely. (I am appealing to the formulas to take eyes out of the issue, yet another real issue I am ignoring). When you suddenly blow that 4x6 up to 20x30, that piece which was just barely sharp according to the equations is now not going to be sharp. Even your eyes will be able to pick that out. A sharply defined blob now becomes a soft blob.
It is kind of similar to having something looking sharp in an image shot with a 20 mm lens, ut in the background, while focussed on something in the foreground. Then change a 200 mm lens and focus at exactly the same point. Since that background point is now 10 times larger, it is now an OOF blob. The only difference is that you are looking at the slide/digital file rather than the print.
Behind the scenes is the concept of circles of confusion, which essentially is the defining size limit between what your eyes perceive as sharp or OOF. You need a smaller diameter of circle of confusion to have the same point in a print remain sharp when you go from a 4x6 to a 20x30. To get the smaller circle of confusion, you need a smaller f-stop - in other words more DOF to cover for the greater enlargement and "loss" of DOF in the enlargement process.
Buried even deeper in all this is that greater enlargements and smaller f-stops leave you open to issues surrounding optical quality, diffraction, the limits of the reproduction method and a couple of other real world issues. Also, you can usually pick out a photographer when someone is looking at a print. They are the ones looking at prints way too closely, a sin I know I commit.
For those of you technically minded, I am well aware of the fact that I have really abused things here. I am really only trying to give a practical answer to Jim's question.
(Edit: I vaguely recall that if you are going one stop larger in print size, 4x6 to 6x9, you'll need about one more stop of DOF. I really wouldn't worry too much here, though, since I *think* the circle of confusion recommendations are for an 8x10, and once you get bigger than that, most people will be viewing the prints from a distance, unless of course, they are photographers)
You really opened a can of worms here! By the lense that you mentioned, I am assuming that you want the lense for birding/wildlife. I have the 50-500. It also has a f6.3 for max aperature. If you want to know how the bokeh is, just look at some of my latest posts on this website in the avian gallery. It has nice bokeh. Now, as for DOF, I only saw it mentioned in one other reply here, and that is this: DOF changes! DOF is "determined" by how near or far you are from the subject. So, if you are using f6.3, and are 10 feet from the subject, you are going to get that nice background you desire. I suggest you go to DPreview, and look at their DOF calculator. It will shed some light on the subject for you.
' DOF is "determined" by how near or far you are from the subject '
Or by keeping the focal length the same, changing the magnification.
Don't worry Micheal, you are exactly right! I've found that people who don't spend a lot of time near 1:1 usually think about DOF as relating to the subject distance. I just need to be more careful wording things if I go down that route and since I don't think this way, I can babble a bit before getting it right.
Posted by James Fillip on June 12, 2008 at 5:50 PM
Thanks Dan,
And feel free to "babble a bit". I draw a great bit of knowlage from those posts of yours.
Discussion
12 replies-- Most lenses will give better results stopped down from their largest aperture. So an f/2.8 lens at f/4 will probably outperform an f/4 lens at f/4.
-- Depending on the body you have, you may need f/5.6 to maintain autofocus
-- Along the same lines, you'll have more options with teleconverters if you have a faster max aperture, since autofocus will be maintained
Since you mentioned f/11, I'm assuming you're talking about more than the max aperture of the lens, right? In that case, it really depends on your needs for a particular shot, in terms of shutter speed and DOF. At that point, assuming the light it good, it's a purely artistic decision.
f/11 was just an example. I'm debating weather I should get the new 150-500 OS HSM for that extra reach and f/6.3 or get used to my 70-200 with 2xTC at f/8 where it's the sharpest. but DOF I find isn't quite shallow enough? just don't know yet.??
There are other advantages to fast lenses, such as giving a brighter view in the viewfinder and maintaing autofocus capabiltiies with teleconverters attached.
The downside to fast lenses are size, weight, and cost. If you aren't dissatisfied with the photos you're getting without using big glass, then there's no reason to switch.
Most dedicated bird photographers either have, or lust after, a long fast lens.
What f/stop is best! WOW! Now that’s what I called a loaded question!
From my own point of view! and what works best for me is this;
I never stop down any further than f/11 because that’s diffraction territory! However, I never say never!
I only shoot wide open when I need too or must smooth out that background!
Now, if I’m using a 600mm f/4 and I stick a 1.7x TC on I’ve increased the focal length to 1000mm and the aperture to f/6.7 but the effective depth of field is still f/4. So please bear that in mind!
Depending on many variables I tend to shoot my big glass between f/7.1 and f/8 to ensure I have the complete bird in focus (but it does all depend on the pose of the subject and my position)! However this isn’t always what I what to convey to my viewer so I may choose too stop down or shoot wide open to convey what I see in my minds eye!
Bear in mind that f/2.8 is fast for a 300mm lens as f/4 is fast for a 600mm or f/5.6 is for an 800mm.
Also the aperture chosen determines your shutter speed. At f/4 your shutter speed will be faster than at f/11 (if it isn’t your exposure will be out!). So if you need to shoot a bird in flight then shutter speed will be a greater consideration! Therefore shoot wide open i.e. f/4. However your ISO setting (assuming you're shooting digital) can be cranked up; too up your DOF or f/stop and shutter speed. If you do this you start a trade off! i.e. noise and so forth!
The lighting will also determine your f/stop choice too!
My best advice is to get out there and try shooting various f/stop’s off the same subject and look at the results back on your computer later! It’s the best way to really understand it! Shoot at f/4 will give ‘x’ and if you shoot as f/11 it’ll be ‘x’. Once you understand that then you be able to decide how you want to communicate the setting in front of you to the viewer! i.e. whether you need to smooth the background or include it in the image (if so just how much).
Smooth the background and the bird POP’s include the environment and it may get lost! But there are times when the environment has to be included i.e. the subject is just too close to the BG or it’s part of the story!
This is longer than I expected!
At any given fixed degree of magnification and any given fixed f-stop, the DOF is exactly the same regardless of the focal length of the lens.
So a 1" object that is 1" on the sensor or film, shot at f8 or your favorite aperature, and enlarged in a print so that the object is 8" (or your other favorite number), will have exactly the same DOF regardless if it is shot with a 20 mm lens or an 800 mm lens.
What really screws up this for most people are the following considerations: A wide angle lens takes in far more of the background that a long telephoto. So a 1 mm blob that almost looks sharp with a 20 mm lens is now a 10 mm blob when shot with a 200 mm blob and clearly out of focus. Far less of the background is taken in.
Second, a subject shot with a wide angle *usually* has less magnification, so more apparent DOF.
To get to full frame with the APS sensor SLR's, there is less magnification needed. Less magnification = more DOF. Notice that I did NOT say to get to 1:1, I said to full frame. Going to 1:1 on an APS sensor gives exactly the same DOF as going to 1:1 on a standard frame, given the same f-stop. (And again notice that the lens was not mentioned). At 1:1 on the APS sensors, you'll have a lot less of the object in the frame - remember, the smaller sensor is a cropping of a full frame. It will look a lot bigger in the viewfinder, but still be 1:1.
Last, most people don't print to 8 times the sensor size. They print to 8x10 (or 8x12). For a cropped sensor, this means more magnification of the subject. This really messes with apparent DOF and I really don't want to touch this one. Here is a link
http://www.naturescapes.net/102004/ps1004.htm.
Part 2 is here:
http://www.naturescapes.net/docs/index.php/category-photographic-technique/41-photographic-technique/57-the-mathematics-of-depth-of-field-part-two-crop-factor-magnification-and-the-13-myth
(okay, I'll get the linking right eventually)
It is a bit technical, but the above essentially summarizes these.
Great read, both links.
But it seems like a long way to go to say what's already been said. The crop factor/sensor size seems irrelevant. We all shoot the cameras we shoot, the "crop factor" is what it is. What you see in the view finder is what you get. Thats really not a factor for me. Would the overall shot be different with a 8X10 full frame from the same spot? For sure! But if we were shooting with a different sensor/format we would for sure adjust the comp. to get the results we were looking for. Just like when some of us can't afford a 600mm, we will learn how to get in close enough to use the 300mm.
I also find it interesting that those formulas are said not to apply to macro work, as that is where I really learned the importance of DOF. However I can see the difference and appreciate why it is not the same(but it goes back to my original post about distance from subject).
To close I have another question. If magnification is a factor, would the same print at 4X6 have a different DOF then a print at 8X10?
Now, back your your last question. It actually does get buried in the two articles, but pretty far down and not with a big pointer on it. Here is the short, practical answer: yes. Ignore diffraction, lens sharpness, sensor/film resolution for the time being, losses in the scan/printmaking process, etc (and yes, these are real issues, but I am trying to give a non-technical answer).
Let's use a more extreme case. Suppose you want to go from a 4x6 to a 20x30. Most 4x6 prints, unless you really blow it, is going to look sharp. Now, pick out something in the print which according to the formulas, is "sharp", but just barely. (I am appealing to the formulas to take eyes out of the issue, yet another real issue I am ignoring). When you suddenly blow that 4x6 up to 20x30, that piece which was just barely sharp according to the equations is now not going to be sharp. Even your eyes will be able to pick that out. A sharply defined blob now becomes a soft blob.
It is kind of similar to having something looking sharp in an image shot with a 20 mm lens, ut in the background, while focussed on something in the foreground. Then change a 200 mm lens and focus at exactly the same point. Since that background point is now 10 times larger, it is now an OOF blob. The only difference is that you are looking at the slide/digital file rather than the print.
Behind the scenes is the concept of circles of confusion, which essentially is the defining size limit between what your eyes perceive as sharp or OOF. You need a smaller diameter of circle of confusion to have the same point in a print remain sharp when you go from a 4x6 to a 20x30. To get the smaller circle of confusion, you need a smaller f-stop - in other words more DOF to cover for the greater enlargement and "loss" of DOF in the enlargement process.
Buried even deeper in all this is that greater enlargements and smaller f-stops leave you open to issues surrounding optical quality, diffraction, the limits of the reproduction method and a couple of other real world issues. Also, you can usually pick out a photographer when someone is looking at a print. They are the ones looking at prints way too closely, a sin I know I commit.
For those of you technically minded, I am well aware of the fact that I have really abused things here. I am really only trying to give a practical answer to Jim's question.
(Edit: I vaguely recall that if you are going one stop larger in print size, 4x6 to 6x9, you'll need about one more stop of DOF. I really wouldn't worry too much here, though, since I *think* the circle of confusion recommendations are for an 8x10, and once you get bigger than that, most people will be viewing the prints from a distance, unless of course, they are photographers)
Or by keeping the focal length the same, changing the magnification.
Don't worry Micheal, you are exactly right! I've found that people who don't spend a lot of time near 1:1 usually think about DOF as relating to the subject distance. I just need to be more careful wording things if I go down that route and since I don't think this way, I can babble a bit before getting it right.
And feel free to "babble a bit". I draw a great bit of knowlage from those posts of yours.