how to achieve rule of third when using centre focus ?

[Ganesh Mahadevan]

hi

the camera is set to centre focus which is the best focus point of camera i suppose.
with that now trying to apply rule of third on the focused subject.

if rule of third is applied then the best/centre focus is lost..!
if centre/best focus is on then rule of third is lost..!

how to achieve rule of thirds when the subject is in middle of the frame and centre focus is on that subject ?



kindly share your thoughts please.

[NorthernFocus]

How to do so can depend on which camera you are shooting. Three possibilities are:

1) Put the camera in single focus mode rather than continuous focus. In this mode when one presses the shutter half way down the camera will achieve focus and lock. If one continues to hold the button half way you can then reframe the subject and fire the shutter.

2) Use "back button focus". Most modern dslr cameras have a button on back of the camera that can be programmed for autofocus activation in lieu of the shutter button.

3) Use manual focus.

[DougR]

You can use focus and recompose or use another focus point:

[Geoff F]

One word of warning about the focus, hold shutter half way to lock and recompose method.

Depending on your camera and the metering option selected, your metering can change when you recompose. Should be OK when using Evaluative, or similar, options but you can end up with unexpected problems when using other options such as spot metering etc.

[William W]

the camera is set to centre focus which is the best focus point of camera i suppose.
with that now trying to apply rule of third on the focused subject.
if rule of third is applied then the best/centre focus is lost..!
if centre/best focus is on then rule of third is lost..!
how to achieve rule of thirds when the subject is in middle of the frame and centre focus is on that subject?

What camera are you using?

Whilst there are several techniques to achieve the goal, some methods might not be appropriate nor possible, with some cameras.

WW

[dje]

One word of warning about the focus, hold shutter half way to lock and recompose method.

Depending on your camera and the metering option selected, your metering can change when you recompose. Should be OK when using Evaluative, or similar, options but you can end up with unexpected problems when using other options such as spot metering etc.

Yes this is why back button focus has an advantage as it separates focus and metering activation. It does require extra discipline though - one must remember the extra step each time a shot is taken. Having a separate step for focus though isn't a bad thing as it encourages one to think about focus for each shot.

Dave

[Manfred M]

As others have said, there are a number of work-arounds, but they depend on your camera, the subject material you are shooting and your own personal preferences. I have switched to a continuous focus, single focus point, back button focus and use the focus and recomposed method on most of my shots.

[Ganesh Mahadevan]

thanks all for your inputs

i got the possibilities...will try those.

[Ganesh Mahadevan]

What camera are you using?

Whilst there are several techniques to achieve the goal, some methods might not be appropriate nor possible, with some cameras.

WW

i am using Canon 650D

[William W]

i am using Canon 650D

Thank you for answering.

As Manfred specifically has pointed out, the method that you choose to use should be dependent upon many factors, including but not limited to: The Subject; and The Shooting Scenario.

***

I will assume:

1. a generally static Subject
2. simple overall lighting conditions
3. reasonable Camera to Subject Distance
4. midrange Aperture is used

*

I assume you are new to these techniques and if so, I’d encourage you to PRACTICE this BASIC technique, as I outline it below and in shooting conditions as I described above - before you launch forth attempting more complex shooting scenarios and camera techniques.

*

I suggest:

1. If you have played with the Custom Function C Fn. IV-6, then reset it to the default “0” position
2. Set the MODE DIAL to a Creative Zone Mode (P; Av; Tv or M)
3. Set Evaluative Metering Mode
4. Set One-Shot AF
5. Do NOT set Continuous Shooting
6. Set the AF to Centre Point only

*

To make the picture, use the HALF DEPRESS Shutter Release to attain AF using the Centre Point AF area.

If you are not in M Mode, then this will also assess the Exposure that the camera computes as correct.

Whilst still holding the Shutter Release in the HALF DEPRESSED position, RECOMPOSE the FRAMING of the shot as desired. The AF (Auto Focus) and the AE (Auto Exposure) will be locked so long as you keep the Shutter Release Half depressed.

*

Once you have mastered the basic technique above, then I suggest you look at more complex shooting scenarios and the possible solutions for them. For example, but not limited to:

1. Short Subject to Camera distance and/or very shallow DoF (Depth of Field).
Possible solution: Do NOT recompose by rotational panning or tilting the camera, but use Camera a movement (‘dolly-panning’), parallel to the Plane of Sharp Focus.

2. Complex Lighting Scenario (one example Backlit Subject)
Possible solution: separate AF and AE by activating Custom Function - C Fn. IV-6 set to “1” will enable [* Button] to control AF and [Half Depress Shutter Release] will enable and LOCK AE.

3. Moving Subject
Possible Solution: Shoot slightly wide, to allow Crop in Post Production.

WW

[jcuknz]

One word of warning about the focus, hold shutter half way to lock and recompose method.

Depending on your camera and the metering option selected, your metering can change when you recompose. Should be OK when using Evaluative, or similar, options but you can end up with unexpected problems when using other options such as spot metering etc.

Is not focus lock or exposure lock designed to handle this problem when it exists?

[jcuknz]

double post I think

[William W]

Is not focus lock or exposure lock designed to handle this problem when it exists?

Yes they are, but:

I am not answering for Geoff, but, I understood Geoff's comment to be a warning to a novice and be based upon whether (or not) the AUTO EXPOSURE LOCK was attributed to the 'Half Depress Shutter' as well as Auto Focus Lock being attributed to 'Half Depress Shutter'.

As I mentioned, with Canon, there are "Custom Functions" which can separate the AF Lock and AE Lock: other manufacturers have other methods.

I understood Geoff to be mentioning that if the functionality of the camera was set such that AE is NOT locked with 'Half Depress Shutter', then there could be trouble and a surprise exposure: likely not too much trouble if Evaluative (Canon) or Matrix (Nikon) metering were selected, but if CWA (Canon) or Spot Metering were selected, then, upon recompose the metering could change . . . and if in an automatic Camera Mode (P Av Tv) then that new meter reading will control the exposure.

It is bit convoluted to get most Canon DSLR's into that scenario, but it is easier with other cameras, perhaps easy to inadvertently do it: and at the time of Geoff's comment the OP had not disclosed what camera was being used.

WW

[george013]

hi

the camera is set to centre focus which is the best focus point of camera i suppose.
with that now trying to apply rule of third on the focused subject.

.

First I would reconsider that statement.

George

[William W]

On an EOS 650D there are nine (9) AF points. These are arranged in the common 9 point array which is found in many Canon Cameras.

Although all AF Points are Cross-type Sensors in the EOS 650D; the outer ring of eight AF Points are rated with a ‘sensitivity’ at F/5.6. But the Centre AF point is rated with a ’sensitivity’ at F/2.8, which, in simple terms, renders the Centre AF point by comparison to the other eight AF Points, a very high-precision AF Point when combined with lenses having a Maximum Aperture of F/2.8 or larger.

As one other example - (as I understand the physics of it? - ?and I am open to correction/comment/expansion ?) - the Centre AF point will be more sensitive than any of the other eight AF points, when combined with a Lens having a Maximum Aperture of F/4.

If by "best", the OP is measuring the AF Points on the 650D in terms of ‘sensitivity’: then the Centre AF point is, indeed “the best.”

WW

[george013]

On an EOS 650D there are nine (9) AF points. These are arranged in the common 9 point array which is found in many Canon Cameras.

Although all AF Points are Cross-type Sensors in the EOS 650D; the outer ring of eight AF Points are rated with a ‘sensitivity’ at F/5.6. But the Centre AF point is rated with a ’sensitivity’ at F/2.8, which, in simple terms, renders the Centre AF point by comparison to the other eight AF Points, a very high-precision AF Point when combined with lenses having a Maximum Aperture of F/2.8 or larger.

As one other example - (as I understand the physics of it? - ?and I am open to correction/comment/expansion ?) - the Centre AF point will be more sensitive than any of the other eight AF points, when combined with a Lens having a Maximum Aperture of F/4.

If by "best", the OP is measuring the AF Points on the 650D in terms of ‘sensitivity’: then the Centre AF point is, indeed “the best.”

WW

I don't know that specific camera, it is a normal DSLR from Canon.
With Nikon, and I assume all marks with DSLR's, the autofocus is done with open diafragma.
I was wondering about "the best focuspoint". The AF works or doesn't work. If it doesn't work, the lens is positioned in the nearby position, I think. The "not be able focussing" mode is shown and/or activated.

George

[William W]

What defines a 'normal' DSLR? - Probably easier to classify by other methods:

There are no "normal" DSLR's in the sense of 'normal' being "standard issue": each DSLR is different, even if that difference be slight.

DSLR's can be classified into groups in many ways, but usually by; functions and/or specifications.

A really simple example (for Canon DSLR):

We could group various series/models if they have the functionality of the "Quick Control Dial"; and included, but not limited to, would be: D30; D60; 10D; 20D; 30D; 40D . . . and 5D . . .; and 6D and 7D . . .

On the other hand we could group those models which do not have the QCD including but not limited to: 300D; 350D; 400D; . . . and 1000D . . .

Similarly we could group DSLR’s by sensor size:
APS-C: D30; D60; and 300D; 350D . . . and 10D; 20D; . . . and 7D . . .

Or by those having Spot Metering: 30D; 40D; . . . and 5D . . . ; and 6D; and 7D . . .

***

What is relevant to this thread?

Firstly (and hopefully obviously) a relevant fact is that we are discussing a specific camera: that is the Canon EOS 650D. (That's why it was important to establish that information from the OP, so as to best answer the question which was asked. As already mentioned, other circumstances and solutions might apply if a different camera is being used.)

One other point which is most relevant to this thread is that Canon's TR&D has invested heavily and developed the functionality / sensitivity of the AF Points and also the inter-relationships between Camera Body and Lens during the AF activity: so therefore the issue which is very pertinent to the OP’s question and the discussion it is not a simple matter of if, an AF either works or it doesn’t work; but rather how effectively each AF point will work; and more importantly the COMPARISON between the degree of efficiency of each AF Point.

***

The guts of the matter - the OP's assumption is correct about the Centre AF Point of the EOS 650D:

The 650D inherited the 60D's phase AF, 9 points: however the centre point on the EOS650D is an F/5.6 Vertical/Horizontal Cross (+) which is overlayed with an F/2.8 Diagonal Cross (x) - this fact renders the Centre AF Point of the EOS 650D superior to and better than, the other eight AF Points. This is exactly which is what the OP assumed and that assumption is indeed correct.

***

(one of many) First Source REFERENCE MATERIAL:

Here is one of many information and learning sheets supplied by Canon: it is less technical than many of the CPN Data Sheets and White Papers, but it supplies a good overview and introduction and explanation as to why on the EOS650D, the Centre AF Point is ‘the best’ (see especially the last diagram).

WW

[george013]

What defines a 'normal' DSLR? - Probably easier to classify by other methods:

There are no "normal" DSLR's in the sense of 'normal' being "standard issue": each DSLR is different, even if that difference be slight.

DSLR's can be classified into groups in many ways, but usually by; functions and/or specifications.

A really simple example (for Canon DSLR):

We could group various series/models if they have the functionality of the "Quick Control Dial"; and included, but not limited to, would be: D30; D60; 10D; 20D; 30D; 40D . . . and 5D . . .; and 6D and 7D . . .

On the other hand we could group those models which do not have the QCD including but not limited to: 300D; 350D; 400D; . . . and 1000D . . .

Similarly we could group DSLR’s by sensor size:
APS-C: D30; D60; and 300D; 350D . . . and 10D; 20D; . . . and 7D . . .

Or by those having Spot Metering: 30D; 40D; . . . and 5D . . . ; and 6D; and 7D . . .

***

What is relevant to this thread?

Firstly (and hopefully obviously) a relevant fact is that we are discussing a specific camera: that is the Canon EOS 650D. (That's why it was important to establish that information from the OP, so as to best answer the question which was asked. As already mentioned, other circumstances and solutions might apply if a different camera is being used.)

One other point which is most relevant to this thread is that Canon's TR&D has invested heavily and developed the functionality / sensitivity of the AF Points and also the inter-relationships between Camera Body and Lens during the AF activity: so therefore the issue which is very pertinent to the OP’s question and the discussion it is not a simple matter of if, an AF either works or it doesn’t work; but rather how effectively each AF point will work; and more importantly the COMPARISON between the degree of efficiency of each AF Point.

***

The guts of the matter - the OP's assumption is correct about the Centre AF Point of the EOS 650D:

The 650D inherited the 60D's phase AF, 9 points: however the centre point on the EOS650D is an F/5.6 Vertical/Horizontal Cross (+) which is overlayed with an F/2.8 Diagonal Cross (x) - this fact renders the Centre AF Point of the EOS 650D superior to and better than, the other eight AF Points. This is exactly which is what the OP assumed and that assumption is indeed correct.

***

(one of many) First Source REFERENCE MATERIAL:

Here is one of many information and learning sheets supplied by Canon: it is less technical than many of the CPN Data Sheets and White Papers, but it supplies a good overview and introduction and explanation as to why on the EOS650D, the Centre AF Point is ‘the best’ (see especially the last diagram).

WW

First thanks for your time and your answer.

I experienced with my camera, D700, difficulties with focusing on vertical lines. I went to Nikon, they checked it and said it was normal behaviour for the non-crosstype sensors out off the center, However, I think it behaves different as my former, stolen, D700.

I give it a further thought, the relation F-nr and AF. At this moment I can only see a minimal DOF, meaning a maximal difference in sharpness with a minimal difference in distance.

I'm still thinking of what TS said, the best focus point. Is this the quality of focus or the ability to focus.

George

[William W]

You’re welcome George.

I hope Post #17 benefits others, too; especially the OP and others who use Canon DSLR's and seek a better understanding of the nuances of the Canon AF system.

Regarding your specific concerns about your own camera, a Nikon: I expect that there are many similarities with the Canon and the the Nikon Systems, but I am not equipped to comment with authority on the minutia of Nikon DSLR's.

WW