Over the wide blue yonder

by Stefan Fletcher January. 18, 2010 3739 views

Changed my mind and decided to include a post about aperture, helped by the fact that Lightroom can sort all my images by f/ numbers.

In photography, aperture is the size of the hole through which light passes. It is measured as this size divided by the focal length of the lens and stated as an f/ value (the “/” is there because it’s a reciprocal value, which is why f/2.8 is bigger than f/4). The narrower the aperture (i.e., the higher the f/ number), the greater the depth of field and inversely. Replace the “f” with a “1” and you get the idea.

Anything wider than f/2.8 is considered fast. At the other extreme, f/64 is sometimes available, but the resulting image is horribly soft due to diffraction [en.wikipedia.org].

Lenses have a “sweet spot”, a combination of focal range (for zooms) and aperture range where they produce their sharpest (highest resolution) images both in the corners and at the centre. Usually, that sweet spot lies in the f/4 to f/11 range. There are exceptions, however. How do you test this? By taking the same image at different apertures and checking the corners and the centre. Alternatively, you can check out the Nyquist frequency values for the lenses reviewed in DPreview.com among others. I won't discuss barrel and pincushion distortion or chromatic aberration at differing apertures - it will only depress you.

Nor is there much point going into aperture for its creative effect – whole books have been written on the subject.

I suppose the same questions apply as yesterday:
• Do you have a favourite aperture?
• Do you think about this when you compose your shot
• Do you use the DOF preview button on your camera? (SLRs only)

FWIW, most of my shots are in RAW taken using a prime lens (i.e., not a zoom) in full manual mode (I must set both the aperture and exposure) at the lowest possible ISO setting. Every keeper is post-processed.

The above captures are posted in increasing order of aperture from f/1.4 to f/32

f/1.4 to make the background blurry (known as “bokeh”, which is Japanese for blur). Why? Because the background was distracting

f/2.8 - again for the bokeh, but mostly for the relation with the foreground

f/4 - I wanted the fissure in sharp relief but needed to keep the nose, eye and chin sharp. This was a compromise, which I think worked.

My first successful image taken with a tilt-shift lens. Note how the glass appears to stand out of the plane of the image. Taken at f/4 to keep the entire subject sharp - remember that tilt-shift lenses are manual focus only, so a narrow depth of field is accordingly harder to achieve.

f/5.6: the background was far enough away to keep things more or less sharp with a very long exposure time (13 seconds). This is always a compromise.

f/7.1: the aim was to keep only the caryatids in focus. I failed

f/11 - again a trade-off between sharpness and capturing the available light without burning the highlights

f/8: my aim was to make keep the entire bas-relief sharp and make everything else OOF without resorting to post-processing. This time, it worked.

f/16: as the aperture grows narrower, exposure lengthens (here, 15 seconds), which means you must have a very good reason - and a tripod - to do this. Mine here was to keep both the modern city foreground and the Acropolis sharp without burning out the highlights. Did it work?

f/22: again, the aim of making everything sharp was paramount (this is one of my early attempts, about three months after I started).

f/32: big mistake. The idea was to keep the Parthenon in focus at the same time as Hadrian's arch in this foreground. I had to post-process this quite extensively to prevent either from appearing soft as a result of diffraction (see link below). Again, an early attempt.

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There are 16 comments , add yours!
Nick Cavell 11 years, 6 months ago

Think the Acropolis shot works well, but the following one lacks contrast and thus interest; the others are interesting.

11 years, 6 months ago Edited
Jarvo J 11 years, 6 months ago

Do you have a favourite aperture? No I use 'em all.
Do you think about this when you compose your shot? Yes, but as often as not I get it wrong.
Do you use the DOF preview button on your camera? Yes, but with my poor eyesight, I struggle to see what's going on when the button is pressed.

11 years, 6 months ago Edited
Mikkal Noptek 11 years, 6 months ago

Very interesting post. It's always fun to try the different choices.

11 years, 6 months ago Edited
Monika 11 years, 6 months ago

great information. it supposed to be basics, yet, I seem to forget to consciously apply this knowledge. I assume I`m normally around the sweet spot (what an expression, love it, thanks:-)) ps. amazed of the result with the tilt shift lens...

11 years, 6 months ago Edited
Brian 11 years, 6 months ago

I usually shoot in Aperture Priority mode and then mess around the the setting depending on what I'm shooting. I'm not comfortable enough to shoot totally in manual all the time. Probably because I normally shoot first and think later, need to flip that around:)

11 years, 6 months ago Edited
Moira 11 years, 6 months ago

Thanks for the lessons. Lovely set . I love no4 especially.

11 years, 6 months ago Edited
Kecskemétiné Nelli 11 years, 6 months ago

I can still enjoy the pictures if I don't understand a single word... I'm very good at reading stuff I have no clue about...

11 years, 6 months ago Edited
Alexandra Pechabadens 11 years, 6 months ago

Tu as une tres jolie photo de fleur la!

11 years, 6 months ago Edited
Sandra Vermeulen 11 years, 6 months ago

[b][u][url=http://www.photonhead.com/simcam/shutteraperture.php?]This site [/url][/u][/b] is nice for those who want to experiment with shutter and aperture but no sense to do it with their camera.
For beginners, this is good to see how your picture could change by experimenting with shutter speed and aperture.

I must confess that I often use a large aperture, for the hazy background.
And, yes, I think of it in advance.
I do not know if my camera has a DOF preview button ;o- , so ... no ... I don't use it. ;o)

11 years, 6 months ago Edited
Tomie Poodle 11 years, 6 months ago

hou! la! je voie que tu veux éduquer les foules....vaste programme!!
tu sais que les programmes des nouveaux appareils sont de plus en plus intelligents...la nouvelle génération de photographe ne s'embêtera plus vec tout ça.
pourvu que la photo soit bonne, le reste ils s'en foutent!

11 years, 6 months ago Edited
Michael Sakowicz 11 years, 6 months ago

Awww, I was looking forward to hearing about 'barrel and pincushion distortion or chromatic aberration at differing apertures.' Oh well... ;)

I guess my basic rule of thumb is to keep the damn thing wide open in low-er light; try to keep it around 10 most of the other time; and close the sucker down, down, down when a tripod and time is avail.

Why am I so angry at my lenses?!

11 years, 6 months ago Edited
Helen Hooker 11 years, 6 months ago

Great set and post Stefan - once again very informative. Like you, I did a search in Lightroom to see which apertures I use most and, as I suspected, I'm a sucker for shallow DOF and lots of lovely bokeh! My most used apertures are 1.8 (on my 50mm prime), 2.8 (my 60mm macro) and 4 (my 24-105 zoom).

I certainly think about choice of aperture when I'm shooting, although sometimes I have no choice - for instance when I'm shooting musicians (not literally of course!) in low light conditions and only a large aperture will cut the mustard.

I tend only to use my DOF preview button when I'm doing still life shots on a tripod with live view - perhaps it's something I should use more....

11 years, 6 months ago Edited
Sandra Vermeulen 11 years, 6 months ago

All your previous post I've seen and I saw many (if not all) pretty pictures.

Why i do not comment / debate at them...
First: English is my native language NOT AT ALL !!
Second: The technical side of photography i'm learning just now myself, so there is nothing I can tell to you or anyone else that you not know.
Third: I know you have a thorough dislike to commentary as: beautiful, gorgeous, pretty, very good, wonderful, breathtaking, etc...
So, I look, enjoy, and continue with my activities. ;o)

11 years, 6 months ago Edited
Soubhagya Sagar Behera 11 years, 6 months ago

very nice.. I loved shot 3 n 7. I havent yet been able to get the hang what tilt shift lenses do, so wont comment on that.

Favourite aperture - lens wise
EF50mm - 1.8 that is why one buys that for! Good for portraits and if-u-can-do-without-wide-angle- night shots.
EFs18-135mm - f/8, cos it is the sweet spot and has heavy vignetting at wide open and atleast 1 stop lower.
EF 75-300mm USM III- f/5.6, even though this is soft at 300mm focal length, i have to compromise cos of lack of IS and want for cheap tele lens as a beginner, but has been serving me well for wildlife till now atleast.

Though the above remains as my default setting while using these cameras, yeah aperture does undergo a required change while as per scene..., and the reasons are more or less the same as u so aptly mentioned above.

Do use depth preview in my T1i many times, but only mostly for wider apertures. Prefer the live view for the narrow ones, cos yeah it gets dark totally! (Try using a reverse mount lens and then one realizes how dark the screen viewfinder gets and then focus it manually, that is some crazy shit)

So what is next? a discussion on shutter and ISO sensitivity too?

11 years, 6 months ago Edited
Riyaz 11 years, 6 months ago

but the photos=by the photos, Its Monday morning syndrome, lol

11 years, 6 months ago Edited
Riyaz 11 years, 6 months ago

wow, a very informative post and demonstrated very well but the photos. The fact that you shoot in manual, shows your knowledge and experience in the field of photography, and its really nice of you to share it.
Love the sharpness in 8 and the lighting in 9.

11 years, 6 months ago Edited
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