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08-17-2009, 05:07 AM   #1
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AF points positions -- Thirds vs Golden Ratio Composition

Traditional aesthetics suggest that objects be placed in a frame according to the "golden ratio". This means that objects should divide the dimensions of the frame by
Code:
1/1.6180339887 : 1-(1/1.6180339887) = 
0.6180339887 : 0.3819550113 =
(roughly) 8/13 : 5/13 =
8 : 5.
As noted by Andreas Feininger in his very recommendable book Principles of composition in photography the common simplified composition principle often dubbed the "rule of thirds" only provides an inadequate approximation. The corresponding ratio is
Code:
2 : 1 =
2/3 : 1/3 =
(roughly) 0.6666666666 : 0.3333333333.
In a soulless technical diversion, I checked where the positions of the AF points of the K100D are, and alas, they correspond to the "rule of thirds".

Question: Wouldn't it be better if the AF points coincided with the golden ratio?

See the illustration below for the difference in positions. The image I used to overlay the golden ratios (yellow) and thirds (blue) comes from Steve's Digicams K100D review and I hope Steve doesn't mind the free advertising of his website.

Note how the photographer placed the head of the dog pretty close to the golden ratio point with considerable distance to the "rule of thirds" point, achieving a much more harmonious composition as a result.

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Last edited by Class A; 08-17-2009 at 07:26 PM.
08-17-2009, 05:24 AM   #2
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Did you adjust the position of the focus points to compensate for viewfinder coverage, or lack thereof?
08-17-2009, 06:48 AM   #3
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QuoteOriginally posted by grainbelt Quote
Did you adjust the position of the focus points to compensate for viewfinder coverage, or lack thereof?
I used the sample image with the focus points overlayed as it was from Steve's Digicams.

For confirmation, I took a picture of the sample image from the screen. Aligning the camera's focus points with the red squares resulted in an image that shows all focus points moved slightly inwards, towards the centre.

So you are right, the viewfinder coverage influences the position of the AF point positions on the final image but only to a slight extend. They still end up being quite close the the "thirds" positions, quite a distance away from the "golden ratio" positions.
08-17-2009, 02:12 PM   #4
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Wan't the photographer just trying to get the whole dog in the picture? Seems to me that if he positioned his head any further down-ůeft, his tail and hind legs would be cut off.

08-17-2009, 02:23 PM   #5
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I would have thought if you applied the rule of thirds the head would be at the upper right focusing sensor, not the lower left,

I don't think the lawn was the subject, with the dog there for the aid of composition, it is the other way around.

But regardless, the sensor pattern is where it is, and you can;t change it.

As for the golden rule, this sounds like the same dimensions as DaVinci's Perfect human form, and while some may argue it is better, the rule of thirds was developed for the format we use because the height is 2/3 the length, so it is better proportion, and more common than the golen rule
08-17-2009, 02:38 PM   #6
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QuoteOriginally posted by Lowell Goudge Quote
But regardless, the sensor pattern is where it is, and you can;t change it.
I know.
The question is: What is the ideal position for the AF points?

QuoteOriginally posted by Lowell Goudge Quote
Yes, and while some may argue it is better, the rule of thirds was developed for the format we use because the height is 2/3 the length, so it is better proportion, and more common than the golen rule
I see what you mean but the golden ratio rule applies to all frame formats. Just by looking at the crosspoints, the positions of the "golden" crosspoints are more appealing to me than the "thirds" crosspoints, the latter being to far away from the centre.

I'd apply your comments backwards and say, the image format should not be 3:2 but 8:5 which would give us a "golden ratio" frame. Still, 3:2 is often much better than the 4:3 format of the P&S models.

P.S.: Please everyone, forget the dog.

Last edited by Class A; 08-17-2009 at 07:27 PM.
08-17-2009, 03:47 PM   #7
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Thirds and Golden ratio should be considered approximations rather than hard and fixed rules to which we should apply all photos to.

But nice technical analysis of the concept - though depending on the subject matter, one rule may be more suited than the other...
08-17-2009, 04:06 PM   #8
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K-7 AF points positions

FYI, using an image from the imaging-resource review of the K-7 I created the below illustration. It shows that the K-7 focus points are not exactly aligned with the "thirds" positions but are still closer to them than to the "golden ratio" positions.

The AF points positions shown below coincide very well with the final positions of the K100D AF points positions (which differ from their positions in the viewfinder crop as shown in the first post). This is not surprising given that the K-7 shows a 100% coverage.

But it is odd that the AF positions are pretty much bang on the "thirds positions" within the context of the viewfinder crop of the K100D. As if the area not shown by the viewfinder was meant to be cropped out. This of course only makes sense assuming that someone tried to align the AF points positions exactly with the "rule of thirds" which may not be true.

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Last edited by Class A; 08-17-2009 at 04:42 PM.
08-17-2009, 04:11 PM   #9
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QuoteOriginally posted by Ash Quote
Thirds and Golden ratio should be considered approximations rather than hard and fixed rules to which we should apply all photos to.
Of course. I couldn't agree more.
AFAIC, there are no rules but guidelines only and adherence to all guidelines can be a good way to create a pleasing but totally tensionless picture.
But sometimes you want to have a subject at the position which is known to instil a feeling of harmony. The "golden ratio" positions are known to achieve this effect whereas the "thirds" positions are not.

QuoteOriginally posted by Ash Quote
But nice technical analysis of the concept - though depending on the subject matter, one rule may be more suited than the other...
Thanks.
Not sure though that the "thirds rule" really has its designated areas of application. It seems to be that it only is a crude approximation of the "golden ratio".
08-17-2009, 06:35 PM   #10
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The rule of 3rds is pretty much taught everywhere in Photography 101. Its simple to remember and apply, though its really just a rough guide.

I was in a Q&A session once with some camera reps (not Pentax, but they position their 9-point focus about the same way) when someone asked them exactly the question why the focus points are placed where they are.
The answer that came was - it follows the Rule of 3rds, and they suggested it would help guide less experienced photographers to compose their shots following the rule.
08-18-2009, 03:50 AM   #11
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An interesting topic and I was wondering, too ...
QuoteOriginally posted by Class A Quote
Traditional aesthetics suggest that objects be placed in a frame according to the "golden ratio".
[...]
(roughly) 8 : 5.
[...]
In a soulless technical diversion, I checked where the positions of the AF points of the K100D are, and alas, they correspond to the "rule of thirds".
QuoteOriginally posted by Class A Quote
I'd apply your comments backwards and say, the image format should not be 3:2 but 8:5 which would give us a "golden ratio" frame.
I agree that the golden rule is the goal and the rule of thirds a dumb approximation only. And of course, just as a guidelines. Ultimately, the brain will decide what looks best -- w/o any reasoning

Now, we got:
  • 2.35:1 (cinema (scope))
  • 1.78:1 (16:9 HD video)
  • 1.62:1 (golden rule -- removal of a square maintains the format)
  • 1.60:1 (8:5 approximation, also used by many widescreen computer displays (like mine )
  • 1.50:1 (3:2 and rule of thirds)
  • 1.41:1 (DIN Ax paper sizes -- removal of half maintains the format)
  • 1.33:1 (4:3)
  • 1.00:1 (square)

So, the golden rule not only happens to be a more pleasing image format. It happens to be an ideal compromise between 3:2 (still) and 16:9 (video) as well. It would be an ideal sensor format for cameras serving both the still photographer and videographer. It is a good compromise between cinema and square, too

And I don't agree that the rule of thirds is applicable because the image format is 3:2 rather than 8:5. IMHO, 8:5 looks better for many subjects than 3:2 -- even with a 3:2 or square image format.
QuoteOriginally posted by Class A Quote
The question is: What is the ideal position for the AF points?
This is the entire point!
The AF points are positioned where they are because they must cover the entire middle area for auto AF point selection to work. This AF sensitive middle area is just a tad larger than the middle third. About the inner 45% (rather than 33%). This number is an engineering decision to make auto AF work. It has nothing to do with helping composition (like 51 AF points are not meant to yield even greater composition with Nikon )...

The Pentax screen has no composition aids. The best are the outer braces with a height useful to align horizons.

I am much more puzzled that Katzeye offers focus screens with rule of thirds rules, but not golden ratio rules. Very disappointing actually.

So, I was delighted to see that the live view screen on K20D and K-7 features 16 rather than 9 (rule of thirds) rectangles. Just use the center of any of the four inner rectangles to apply a 8:5 composition
QuoteOriginally posted by kittykat46 Quote
The rule of 3rds is pretty much taught everywhere in Photography 101. Its simple to remember and apply, though its really just a rough guide.
As the rule of golden ratio is pretty much taught everywhere in Architecture (I know, I grew up in an architect's family -- the golden rule must have been the first thing I learned after walking ). I guess, a building with bad proportions would just be a price too high to pay for oversimplifying lectures. As buildings are so hard to crop

Last edited by falconeye; 08-18-2009 at 05:45 AM.
08-18-2009, 04:51 AM   #12
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I believe that the AF points are where they are for two reasons:

1-The AF points are not "points" but small areas, and they need some room between them.

2-The way the pattern is placed, you get a pretty good coverage of the viewfinder.

There wouldn't be much point, IMHO, in cramming all the AF points in the center of the frame. The way they are placed, about 1/6 (very roughly) of the frame gets covered if you include the two vertical points. It's not much if you think about it! But it's enough since the subject will rarely be completely at the sides.

As others have pointed out, there are no "rules" in photography. the Golden ratio is almost a garantee of having a balanced and harmonius composition, but it's not a garantee that the picture will "work" because of that.

You might even say that by placing the AF points at the Golden ratio, you will intuitively bring photographers to shoot with that ratio in all their pictures, and will thus limit creativity. That may be stretching, however...
08-18-2009, 05:33 AM   #13
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Thanks, Falk, for your interesting posting.

QuoteOriginally posted by falconeye Quote
Ultimately, the brain will decide what looks best -- w/o any reasoning
For sure, but composition aids can be useful to spare the brain the decision that the image isn't that great, long after the shot has been taken.

QuoteOriginally posted by falconeye Quote
This AF sensitive middle area is just a tad larger than the middle third. About the inner 45% (rather than 33%).
Do you have a diagram showing the size of the AF sensors? The outer areas seem to be considerably larger than the centre focus point, however this is just an initial impression I've got after a quick and dirty test.

EDIT: I found a diagram showing the AF areas. May not be very precise as it is from an advertising brochure but one gets the picture.

QuoteOriginally posted by falconeye Quote
The Pentax screen has no composition aids.
Hang on. Your posting made me think about the screen markings again. I too use the braces to align horizons (old-fashioned eye-brain-hand feedback loop with the K100D ) and the braces give me pretty good indication where the focus points are; I see them lighting up anyway, when I select them manually.

But here's an interesting observation I just made based on your remarks. The middle braces stop exactly where the vertical golden sections are. The outer braces vertical heights' do not precisely align with the horizontal golden sections but they aren't far off at all. As a result the position and shape of the braces are quite useful to figure out where the golden ratio crosspoints are.

QuoteOriginally posted by falconeye Quote
So, I was delighted to see that the live view screen on K20D and K-7 features 16 rather than 9 (rule of thirds) rectangles. Just use the middle of any of the four center rectangles to apply a 8:5 composition

Last edited by Class A; 01-14-2010 at 03:49 PM.
08-18-2009, 05:49 AM   #14
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QuoteOriginally posted by bdery Quote
1-The AF points are not "points" but small areas, and they need some room between them.
Yes, the AF areas are no points at all and I'd say they are relatively large areas. A bit smaller wouldn't hurt. I was talking about "points" in the sense that one can use the focus indicator "points" (rather small squares) in the viewfinder as composition aids.

QuoteOriginally posted by bdery Quote
The way the pattern is placed, you get a pretty good coverage of the viewfinder.
Yes, I see your point and I was wondering about some Canon AF point arrangements which seem to cram all points around the centre spot. Useful for object tracking I guess but perhaps not that useful for off-centre composition.

But what is the point of covering the viewfinder? As I see the non-centre AF areas, they are there to avoid recomposition. But AF areas placed at non-optimal places within the image force one to recompose again, don't they?

Don't get me wrong. I also prefer some spread over a arrangement that is too tight and the size of the areas makes it either possible to cover objects at the golden ratio crosspoints or impossible to confine the focus goal at such precision anyhow (choose the alternative you prefer ).

QuoteOriginally posted by bdery Quote
As others have pointed out, there are no "rules" in photography.
Sure. This thread is not about guaranteeing "working" pictures. It is just a discussion about what help the photographer receives if he/she decides with his/her own free will that he/she wants to use a composition according to the golden ratio.

QuoteOriginally posted by bdery Quote
You might even say that by placing the AF points at the Golden ratio, you will intuitively bring photographers to shoot with that ratio in all their pictures, and will thus limit creativity. That may be stretching, however...
I go with the "stretching". By the same token one could argue that the presence of AF makes people shoot sharp subjects and deprive them of some creative fuzzy shots.

If an aid is available you can choose to not want it. In contrast, in case you want it, it is hard to ignore if it is not available.
08-18-2009, 06:04 AM   #15
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QuoteOriginally posted by Class A Quote
Do you have a diagram showing the size of the AF sensors? The outer areas seem to be considerably larger than the centre focus point, however this is just an initial impression I've got after a quick and dirty test.
No, I don't. I just tried it out a while ago. Only the center AF cross is symmetric.

An AF sensor axis is as long as indicated by the center circle markings on the focus screen. The other AF sensors have sensor axes of the same size but they don't intersect in the middle. E.g., the "west" AF point has a horizontal axis extending from the inner circle marking on the right to the big brace marking on the left. But its vertical axis intersects it close to the brace marking rather than at its middle. And the red indicator is where the intersection is supposed to be.

You can actually use it as a feature to focus on an eye using the "north" sensor and avoid focussing on the closer eye brow.
QuoteOriginally posted by Class A Quote
As a result the position and shape of the braces are quite useful to figure out where the golden ratio crosspoints are.
Very nice coincidence.
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