August 28, 2014, 03:12:28 AM

Author Topic: aperture!  (Read 4171 times)

jimjamesjimmy

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aperture!
« on: September 19, 2013, 03:38:46 PM »
hi , can someone explain the theory behind choosing the aperture when shooting big landscapes.

i can understand it when shooting portraits or street stuff, for example, focal depth, to get a faster shutter etc

so for example like earlier i was in a farmers field, huge open farmland, but a terrific sunset/moonrise  sun/moon off camera but a lovely pink cloudy sky with some interesting pylons, ive got a polariser and a soft graduated filter to help me out balancingthe sky, lets assume i use the correct hyperfocal distance and focus there on 100 iso, im in manual , now if time value isnt an really an issue, whats the best aperture to use? bearing in mind i can change the time value to get a correct exposure.


this always stumps me, and i just  guess :S!

thanks

Drizzt321

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Re: aperture!
« Reply #1 on: September 19, 2013, 04:28:05 PM »
Well, leaving aside using a smaller aperture to get what you want in acceptable focus, a smaller aperture (to a point) will actually increase the sharpness of your image. Generally for APS-C it tends to be around f/7.1 with FF f/8-11. This also depends on lens, and pixel density of the sensor.

Beyond sharpness, the other thing it can give you is longer exposures. Suppose you wanted some slight movement blur (say you have some slow moving elements in the scene), you need a slower shutter. But then you're over-exposed because you are already at ISO 100/50. You could use an ND filter, or stop down your aperture.
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RAKAMRAK

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Re: aperture!
« Reply #2 on: September 19, 2013, 04:57:13 PM »
hi , can someone explain the theory behind choosing the aperture when shooting big landscapes.

i can understand it when shooting portraits or street stuff, for example, focal depth, to get a faster shutter etc


thanks

Well, exactly for the same reason - depth of (focal) field. In portrait you choose wider aperture to minimize depth of field, in landscape you choose narrowest aperture (without going into the defraction limit territory) to maximize the depth of field. Choosing the correct hyperfocal distance to focus just adds to that. Also remember that with changing aperture, the hyperfocal distance changes for each focal length. What aperture to choose for landscape? If you want the maximus possible sharpness in your composition use the list in the following page so that you do not suffer from the negatives of the defraction limited aperture (last column)

http://www.the-digital-picture.com/Canon-Lenses/Field-of-View-Crop-Factor.aspx

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surapon

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Re: aperture!
« Reply #3 on: September 19, 2013, 05:08:44 PM »
hi , can someone explain the theory behind choosing the aperture when shooting big landscapes.

i can understand it when shooting portraits or street stuff, for example, focal depth, to get a faster shutter etc

so for example like earlier i was in a farmers field, huge open farmland, but a terrific sunset/moonrise  sun/moon off camera but a lovely pink cloudy sky with some interesting pylons, ive got a polariser and a soft graduated filter to help me out balancingthe sky, lets assume i use the correct hyperfocal distance and focus there on 100 iso, im in manual , now if time value isnt an really an issue, whats the best aperture to use? bearing in mind i can change the time value to get a correct exposure.


this always stumps me, and i just  guess :S!

thanks


Dear Friende.
Please go to the link below and  check the DOF as you want, Some time, Difference point of views and Difference Photographer have very difference  require DOF.
Enjoy
Surapon

http://www.dofmaster.com/dofjs.html

Skirball

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Re: aperture!
« Reply #4 on: September 19, 2013, 05:18:54 PM »
If you want the maximus possible sharpness in your composition use the list in the following page so that you do not suffer from the negatives of the defraction limited aperture (last column)

http://www.the-digital-picture.com/Canon-Lenses/Field-of-View-Crop-Factor.aspx

While it’s helpful to know your cameras DLA, that only tells you when diffraction starts becoming a factor, for your camera.  The lens that you use will have a sweet spot as well.  And DLA only applies to images in the focal plane, so therefore if a subject in your image is outside the focal plane, and outside the DoF, you have to choose if you deal with a bit of diffraction in order to get that subject within your DoF.  In other words, it depends.

RAKAMRAK

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Re: aperture!
« Reply #5 on: September 19, 2013, 07:06:40 PM »
However, once the hyperfocal distance is correctly used (as the OP says he/she does) DoF is effectively infinite behind the focal point....... so DLA becomes the only constraining factor.
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takesome1

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Re: aperture!
« Reply #6 on: September 19, 2013, 07:39:57 PM »
lets assume i use the correct hyperfocal distance and focus there


Then we would assume you know the aperture you are using since this is going to change as you adjust.

Like others have said if you have set to the right hyperfocal distance you are set to infinite. But depending on the length of your lens you will have out of focus areas between the camera and focused areas.

The smaller the aperture the smaller the oof area in front of the camera and the more distance and area in focus to infinite. That is where de-fraction as other mentioned comes in to play. If you want the largest focused area you go as high as you can and still feel comfortable with the results. Pixel peeking, even though it is there earlier, you might start seeing signs of it at F/13 on many lenses. For my 24mm lens on a FF body I try and keep it F/13 or larger. I go smaller for effects, for instance so I can get a slower shutter speed for moving water blur.

Often when shooting landscapes I will try to get an object in the foreground so I have a reference point in the picture. Something to add to the intrest. Usually that item or structure is the focal point, not the hyperfocal distance.


jimjamesjimmy

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Re: aperture!
« Reply #7 on: September 19, 2013, 09:26:41 PM »
all great advice, thanks guys,

im still a bit confused! but is this right?..

so, if my aim is to get a sharpest image i can i opt for the smallest aperture before diffraction occurs, the lenses sweet spot as someone mentioned. probably around the f8-13 on my 24mm f.28, then i use the correct hfd and focus there.

does this sound correct?




RAKAMRAK

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Re: aperture!
« Reply #8 on: September 19, 2013, 09:35:47 PM »
as far I understand lens sweet spot is between f/5.6 to f/8 (may be f/9) while DLA (defraction limited aperture) is dependent on the camera body (the sensor) that you are using. So if your aim is the sharpest landscape possible, then first choose aperture (subject to lens sweet spot and sensor of your camera) - let's say you choose f/8. Then calculate the hyperfocal distance for the focal length you are using (28mm you mentioned) and f/8 (hyperfocal distance is dependent on focal length AND aperture) and focus at that hyperfocal distance (keeping the camera on tripod or some fixed base).
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Re: aperture!
« Reply #9 on: September 19, 2013, 09:57:19 PM »
all great advice, thanks guys,

im still a bit confused! but is this right?..

so, if my aim is to get a sharpest image i can i opt for the smallest aperture before diffraction occurs, the lenses sweet spot as someone mentioned. probably around the f8-13 on my 24mm f.28, then i use the correct hfd and focus there.

does this sound correct?
Many landscape photographers start at f/16 and will even use f/22 or higher.  There are other techniques like focus stacking, and use of tilt-shift lenses to get both a foreground and a background object in sharp focus.
 
 
http://improvephotography.com/580/the-ideal-aperture-for-landscape-photography/

takesome1

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Re: aperture!
« Reply #10 on: September 19, 2013, 10:00:08 PM »
all great advice, thanks guys,

im still a bit confused! but is this right?..

so, if my aim is to get a sharpest image i can i opt for the smallest aperture before diffraction occurs, the lenses sweet spot as someone mentioned. probably around the f8-13 on my 24mm f.28, then i use the correct hfd and focus there.

does this sound correct?

I doubt the sweet spot on your 24mm lens is between f/8 and f/13. It is more likely closer to f/4.
But that really doesn't matter if you are trying to take a landscape that captures everything in view. You will want the smaller aperture.

Now for your 24mm if you have it on a FF camera at f/8 your hfd is 8 feet away. For landscape photos using the hfd really isn't going to matter IMO unless you have a close subject to you. It is more important to know if at the distance your subject is if you have an adequate aperture to shoot to infinity.

Go reverse with this and if you have a fast 24mm you can get some bokeh.

takesome1

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Re: aperture!
« Reply #11 on: September 19, 2013, 10:18:46 PM »
all great advice, thanks guys,

im still a bit confused! but is this right?..

so, if my aim is to get a sharpest image i can i opt for the smallest aperture before diffraction occurs, the lenses sweet spot as someone mentioned. probably around the f8-13 on my 24mm f.28, then i use the correct hfd and focus there.

does this sound correct?
Many landscape photographers start at f/16 and will even use f/22 or higher.  There are other techniques like focus stacking, and use of tilt-shift lenses to get both a foreground and a background object in sharp focus.
 
 
http://improvephotography.com/580/the-ideal-aperture-for-landscape-photography/

They do, and an experience landscape photographer will set those aperture's for a purpose.
At f/22 on a full frame the HFD is less than 3 feet from your camera.
The linked article gives a person enough incomplete information as to confuse. I guess that is because it is really just an ad to sell the book.

privatebydesign

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Re: aperture!
« Reply #12 on: September 19, 2013, 10:50:48 PM »
Hyper focal focusing is a very fuzzy subject and is not the way to take great, sharp images.

For a start any HFD calculation is assuming a standard reproduction size and viewing distance, just like aperture, commonly 10"x 8" viewed at 25cm. But computer screen sizes and our cropping abilities have way surpassed those figures now. But the real problem with HFF is that, as with any image, only one infinitely narrow plane is critically sharp, everything else is just on a slope between sharp and the point where everything becomes unacceptably sharp. For landscapes the only way to get good sharp images with vast swathes of scenery in focus is to use tilt. Even when using HFF I will never rely on regular calculators, I consider them way too generous, cut them down a stop or two and they are a bit better, though they never approach the in focus abilities of tilted lenses.

Here is a great example of the differences, look down at the bridge and tower images and crops. http://www.luminous-landscape.com/reviews/lenses/nikon_24_pc.shtml
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ejenner

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Re: aperture!
« Reply #13 on: September 19, 2013, 11:11:17 PM »
The best aperture is the one that manages the tradeoffs between DOF and sharpness and delivers that where you want it in the frame.  Usually you cannot get the whole frame as sharp as possible and it's up to the photographer to decide where compromises can be made.  What I perceive as 'optimally sharp' may be quite different that what someone else perceives as optimally sharp, even for the same scene.

Yes, IMO it's usually non-trivial.  Personally I don't use HFD focusing because the 'acceptable' sharpness is not usually acceptable to me.  So while a HFD calculator may say I can use f8, I find that close subjects and infinity will be softer than I care for.  Stopping down to f11-f16 is going to soften the part that was in the focal plane, but may well sharpen up parts of the image that are close to the edge of the 'acceptable' DOF at f8.

So it's a tradeoff that depends on the scene and between using the best aperture at the center of the lens vs the best at the edges, where to focus in the image and how much to stop down knowing that you are going to soften the 'in-focus' part as you do so.  Even if you don't need DOF, the aperture which gives the sharpest image at the center of the image for a particular lens is usually not the same as the one that sharpens the corners, which may be just as important.

IMO landscapes are definitely not 'f8 and be there'.

duydaniel

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Re: aperture!
« Reply #14 on: September 20, 2013, 12:05:09 AM »
Hyper focus is in theory good but never works in my experience.
For example, my lens 24-105 best sharpness is around f5.6-8
but landscape I need to sacrifice and go to f11

If I want to get everything
Hyper focus distance ideally should be 10 feet from me and that is where I should be focusing
But I found it often make objects at infinity soft.

So I usually focus at infinity and everything seems sharp from a few feet away to infinity.
I am not sure why this hyper focus thing doesn't work for me