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A New Method to Fast Estimate Sharp and Bokeh
- Thread starter qqqwucheng
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Phil V
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You're not hearing this.
I'll try slowly.
You have taken something simple and made it complicated. James should ignore this. Not because I think he should have a narrow source of knowledge, but because it's overly complicated. And because depth of field doesn't require this amount of thought.
Like I said I've been shooting for 30 years and I could give you a 2 hour lecture on depth of field, illustrated with proper photographs too
. It's not that I don't understand your 'method' it's that your 'method' is needlessly complex.
As everyone else has said so too.
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qqqwucheng
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I have said that we can mental calculate rather than using DOF calculator usually.
Firstly, it can quick estimate the location of hyperfocal distance. For example, under a dim light of the scene, I take a full frame camera with 35mm lens. I want to take a deep DOF photo. If the aperture is set to f/11, it's easy to get a deep DOF photo, but high ISO will reduce the quality. So I want to set the aperture to f/5.6 or f/4. If f/5.6 is set, I can quick estimate that the location where 'standard height multiple of short side of view field' equal to 4 is the location of hyperfocal distance (size of short side can be printed to 8inch under 300dpi).
Secondly, it can quick estimate the bokeh degree. For example, I take a full frame camera with 70-200mm lens to take a picture of a background bokeh. For different focal length and f-number, I can quick know the relation of 'standard height multiple of short side of view field' and bokeh degree.
I think the second situation is unnecessary, because LCD can give us intuitive feelings of bokeh degree of background. But for the first situation, the method is usefull. If I don't magnify image on the LCD, It's hard to check whether the photo is sharp. If I magnify image on the LCD, it takes time.
The23rdman
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Phil V
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With the greatest of respect.
[PLEASE DON'T TRY TO BYPASS THE SWEAR FILTER]!
If you need F11, then F5.6 won't be enough, you don't need high ISO you need a tripod.
Like I said before, and you've just proved, this kind of twaddle gets you in a knot that has nothing to do with creating images.
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OR - I could look at the scene, select f/11, focus where I need to, push the trigger. And move on.
Which gets me what I need.
You have some very odd ideas.
What you say though is utter rubbish. "I want to take a deep DOF photo. If the aperture is set to f/11, it's easy to get a deep DOF photo, but high ISO will reduce the quality. So I want to set the aperture to f/5.6 or f/4. If f/5.6 is set" is utter codswallop (unless you want to shoot a landscape at 1/4000???!)
I could go out there today, shoot a landscape at f/11 and ISO 100 shooting hand held and get exactly what I need.
Can we see some of your work where your theory and calculations have worked well, above any beyond normal practices? You seem to have read lots of obsolete theory and your arguments for it suggest you lack the practical experience?
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kendo1
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LOL
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qqqwucheng
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You are out of context. I said "under a dim light of the scene".
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qqqwucheng
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F5.6 is hard to use in this case, if F5.6 can meet the situation, I will use F5.6. If I want to captured a man, tripod is useless.
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As Phil said, use a tripod or up the ISO? I can shoot at ISO's on my 6d I wouldn't have dreamt of in my film days (without loss of image quality). You can't defeat physics with a DOF calculator. How is f/5.6 going to work when you need f/11??
Whats a captured man?
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sk66
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I have an app for that.... I never use it for actual photography.
The only time I ever "calculate" anything related to DOF while shooting is when guestimating hyperfocal distance...
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sk66
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That's simple...
With an APS camera set to f/16 the hyperfocal distance (in feet) is the FL as a percentage of itself. i.e. 50% of 50ft for a 50mm lens = 25ft, or 30% of 30ft for a 30mm =10ft. Just as easy is to multiply the first FL number by itself (i.e. 50mm, 5x5=25), and if it's an "in-between" FL round (i.e. 2x3 for a 25mm or 3x3 for 28mm).
F/16 is into diffraction limiting for APS, but probably not enough to offset the DOF benefit. But, if you halve the aperture you double the HFD (f/16 50mm= 25ft, f/8= 50ft) and f/11 will be about in the middle (37ft).
The results are the same for a FF camera set to f/11.
This SWAG method isn't exact, and it has more error for 1.6/1.7x APS sensors than it does for FF/1.5x APS. But just about nothing is exact with HFD, so the results are more than close enough. Just decide if near or far is more important and bias your focus distance guestimate in that direction.
Your method of estimating HFD may be just as quick/easy for you... but honestly, I don't understand it. Subject size/distance is irrelevant...
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TheBigYin
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perhaps it's losing something in the translation from the original Mandarin... let's not pick someones use of the english language apart when its not necessarily their first language chaps...
(yes, I checked the IP of the posts... but if you look at the Android app that the post is subliminally punting, it's from the Chinese Google App Store, so that's a giveaway for everyone...)
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I wasn't picking apart his language skills (why has that been levelled at me twice now?). It was his insistence about the accuracy and importance of his OP despite all the thoughts and evidence to the contrary, then posting up equally complicated arguments for it. That's why I wondered if he could possibly be trolling, nothing more than that.
In fact his language skills are very good, given the complicated and competent language used in his guide :/
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Phil V
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That's exactly my point, f5.6 would never actually work for the example you posted, but it's fine for portraiture, we don't need your guide to tell us that though do we?
sk66
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I think there is an explanation of "how" to mentally estimate DOF in there somewhere... but I'm not getting it.
I also have a way of estimating the actual DOF in inches/feet starting from a known point, which *I think* is similar. But I never actually use it... it's too much mental math to be beneficial for me (maybe I'm not as smart).
And maybe I'm backwards compared to many/most. My first concern (other than hyperfocus) always starts from the point of maximum sharpness... at what max aperture is this lens the sharpest? That is not a variable nor is it determinable with a calculator/formula. From that starting point the only question is "do I need more DOF, or can I tolerate less sharpness?"
If the subject distance is going to be short (for the lens) I know DOF will be short and I know how far I can stop down to increase it (balancing ISO/SS/diffraction).
And if the BG is busy I will first deal with it in another way if possible. If it is not possible and the BG is going to ruin the image, then the only question is "how much less sharpness can I tolerate?" If the BG is not going to ruin the image, then I don't care about it... it's the subject that matters most.
The same is true for light... "can I add light and if not, how much less sharpness can I tolerate?"
In other words, in practice I don't really care about DOF/bokeh at all... only that the image is sharp where I need it to be, preferably as sharp as possible.
Musicman
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sk66
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HoppyUK
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Me too
I don't have an app, but I do have a few key numbers jotted down in a little table stuck inside my lens caps. But in practise I don't use them either, except occasionally the hyperfocal distance settings.In reality, 90% of my photography involves three kinds of images:
- shallow depth of field, so use the lowest f/number that suits other settings. Check, and consider longer focal length or switch to faster prime lens for further subject isolation.
- DoF doesn't matter much, so set a mid-range aperture and prioritise other settings
- maximum DoF, so use the highest f/number that suits other settings. Check by shooting test pic and enlarging and scrolling around on the LCD, or refer to hyperfocal distance table.
For me at least, I don't find optimising DoF to be either difficult or complicated. I guess that over the years I've got to know what's possible and how to achieve it, so have a good idea of what's what before starting. But that's just an understanding of the basics, overlaid with experience - nothing too clever
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Me too
In reality, 90% of my photography involves three kinds of images:
- shallow depth of field, so use the lowest f/number that suits other settings. Check, and consider longer focal length or switch to faster prime lens for further subject isolation.
- DoF doesn't matter, so prioritise other settings
- maximum DoF, so use the highest f/number that suits other settings. Check by shooting test pic and enlarging and scrolling around on the LCD, or refer to hyperfocal distance table.
For me at least, I don't find optimising DoF to be either difficult or complicated. I guess that over the years I've got to know what's possible and how to achieve it, so have a good idea of what's what before starting. But that's just experience, nothing too clever
So much more eloquently put than I managed in a couple of drafts that I abandoned!
OP
qqqwucheng
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It should be that "If I want to capture (or snap) a man".
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qqqwucheng
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It's a good method to estimate hyperfocal distance. But it's hard to find the location of hyperfocal distance (distance scales of autofocus lenses is not enough fine), i.e., I know hyperfocal distance is 25ft or 50ft, but I don't know where to focusing. "standard height multiple of short side of view field" is relatively easy to estimate.
(subject size÷sensor size)≈（focus distance÷focal length）
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qqqwucheng
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When using this method,you don't need the app usually. The app can give you a better understanding of the method. You can also use the app under special circumstances.
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qqqwucheng
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When object is far more than half hyperfocal distance (f5.6), you can get a deep DOF picture.
Terrywoodenpic
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Depth of field is always imprecise what ever you do. (as it relies on final image size.)
Usually, the loss of sharpness due to residual camera shake, has more effect than depth of field at greater distances.
At infinity even micro movements of the camera smudges the image.
What ever stop you set, the point of focus is always sharper than the rest of the field, (whatever depth of field scales might lead you to believe.)
The loss of definition due to diffusion is additive, at a small enough stop the entire image is diffraction limited, and every thing seems equally sharp if set at the hyper-focal distance.
( but nothing is at the maximum sharpness)
I quit worrying years ago...
There really are only thee important scenarios.
Focus on what is important. ( most shots)
If great depth is needed,set the hyper-focal distance, stop down as much as you can (this is usually limited by other factors, such as available light and movement))
If the reverse is required, work at full aperture.
Everything else is likely to be more miss than hit
Usually, the loss of sharpness due to residual camera shake, has more effect than depth of field at greater distances.
At infinity even micro movements of the camera smudges the image.
What ever stop you set, the point of focus is always sharper than the rest of the field, (whatever depth of field scales might lead you to believe.)
The loss of definition due to diffusion is additive, at a small enough stop the entire image is diffraction limited, and every thing seems equally sharp if set at the hyper-focal distance.
( but nothing is at the maximum sharpness)
I quit worrying years ago...
There really are only thee important scenarios.
Focus on what is important. ( most shots)
If great depth is needed,set the hyper-focal distance, stop down as much as you can (this is usually limited by other factors, such as available light and movement))
If the reverse is required, work at full aperture.
Everything else is likely to be more miss than hit
sk66
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Unless the scene actually contains a subject of "standard height" at the appropriate distance, then you're just estimating distance anyway. Because HFD is really only useful when you have important details at very short distances, it is really only useful with shorter FL's. And it's not too hard to estimate shorter distances with reasonable accuracy with some practice.
Once the FL gets to be above around 50mm, HFD becomes pretty useless and the best choice is (usually) just to focus on whatever you want to be sharpest. Once the point of focus is beyond the HFD the DOF *never changes... it is always from the HFD to *infinity.
But you're right, there is no perfectly accurate way of going about it... (well, maybe with a DOF calculator using the appropriate COC, and a digital laser rangefinder or tape measure.... no thanks).
*("infinity" does actually change somewhat)
StewartR
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I dunno. I'd be interested in that. How many PSI do you push at? There's a whole field of human endeavour here that is (I suspect) largely unexplored...
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I think I just used about 4, but it's a balance. Also it depends how tight the aperture is, lol!
Terrywoodenpic
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Relatively low pressure as long as the auto aperture is working properly and said aperture is fast enough for the job(bie) in hand (a**e!)
Don't apply too much pressure - you can do yourself a nasty!!!
All depends on the maximum aperture available and where on the Bristol scale the product falls.
[/JS]
jonbeeza
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Trouble with too much pressure at smaller aperture, results in fissures. Sometimes a wider aperture is not available, only other option was fybogel. I find taking shoots now, is so much more easier. True story that
.
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Trouble with too much pressure at smaller aperture, results in fissures. Sometimes a wider aperture is not available, only other option was fybogel. I find taking shoots now, is so much more easier. True story that
You certainly don't want diffraction by making the aperture too tight, that gets messy.
jonbeeza
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A lens cloth at the ready
.