another AF point selecton option I would like in future

[sarangiman]

Customization would be huge, in general.

I personally use the 'all cross-type' option; however, having an option for 9 or 11 or whatever number would be great.

And while we're on the subject, if you look at the mapping of the 9 points --do we even know if those are all cross-type?

Also, for the 9 points, why don't they enable the top-most/bottom-most center sensors (which are cross-type)? Why have that rectangle shape when you could have more of a diamond spread (more AF spread... which is what more photographers, in my understanding, who custom select points typically want anyway)?

At any rate, full customization would just allow photographers to use what they need, which would offer an incredible advantage in terms of speed in fast-paced shooting scenarios.

 

[briansquibb]

Customization would be huge, in general.

I personally use the 'all cross-type' option; however, having an option for 9 or 11 or whatever number would be great.

And while we're on the subject, if you look at the mapping of the 9 points --do we even know if those are all cross-type?

Also, for the 9 points, why don't they enable the top-most/bottom-most center sensors (which are cross-type)? Why have that rectangle shape when you could have more of a diamond spread (more AF spread... which is what more photographers, in my understanding, who custom select points typically want anyway)?

At any rate, full customization would just allow photographers to use what they need, which would offer an incredible advantage in terms of speed in fast-paced shooting scenarios.

1D4 9pts(outer) are 3 points in each of 3 rows

 

[sarangiman]

1D4 9pts(outer) are 3 points in each of 3 rows

I see. My point is that the 5DIII has a cross-type AF point above the upper-most, center, selectable AF point in 9pt mode (and one below the lower-most, center, selectable AF point). Why not use these in the 9pt mode instead of ones closer to the center? You'd get more AF spread... and like I said, photographers are typically talking about more AF point spread, not less.

Enabling those (to create a diamond like spread of selectable AF points) gets you one step closer to an area of the frame that has no AF points at all. I don't really understand decisions such as these. Maybe I'm missing something.

Either way, customizability would solve issues like this in one gigantic sweep.

 

[wickidwombat]

I'm not sure why they made the double cross sensors in a straight line like they did maybe for action or something but to me it would have made more sense to make the sensors nearest the rule of thirds intersections double cross type

the reason for having an option to limit selection to 5 is speed of changing points on the run, more point more time more chance of error

 

[psolberg]

honestly, I just want full viewfinder spread on FF cameras. canon and nikon's points are all bunched up together. the 5DmkIII in some modes you can't even see what da hell you're shooting because it is like a fly infestation landed on your lens.
SPREAD THEM!

 

[kdsand]

honestly, I just want full viewfinder spread on FF cameras. canon and nikon's points are all bunched up together. the 5DmkIII in some modes you can't even see what da hell you're shooting because it is like a fly infestation landed on your lens.
SPREAD THEM!

SPREAD THEM!

Heard that before.

 

[wickidwombat]

interestingly on the fuji x10 AF point selection is an eve grid with full screen coverage only available in live view but its not fast perhaps it just uses a contrast detect system

neuros article explains well why AF points dont spread out in the phase detect AF system i'm sure he will post a link in here soon

 

[sarangiman]

honestly, I just want full viewfinder spread on FF cameras. canon and nikon's points are all bunched up together. the 5DmkIII in some modes you can't even see what da hell you're shooting because it is like a fly infestation landed on your lens.
SPREAD THEM!

+1. Keep preaching sense, psolberg.

 

[Loswr]

neuros article explains well why AF points dont spread out in the phase detect AF system i'm sure he will post a link in here soon

Since you asked... Canon EOS DSLR Autofocus Explained

The relevant part:

AF Point Coverage

For many people, this is a big issue in comparing cameras. While it would be wonderful to have AF points available over the entire extent of the frame, there are technical limitations on the spread of the AF points - at best, they can only occupy the middle area of the frame, because of simple geometry and optics. In a nutshell, there are four reasons for this limitation:

• Size of the secondary mirror. Light for AF passes through the semi-transparent part of the main mirror (most is reflected up to the viewfinder), then is reflected off the secondary mirror down to the AF sensor. There is limited space behind the main mirror, based on the necessary geometry (i.e. the main mirror has to be at a 45° angle to the incoming light, and the secondary mirror has to be behind the main mirror and at an angle of 90° to the main mirror, so it's length is limited by the distance between the main mirror and the image sensor).
• Distortion. With many lenses, the edges of the frame are subject to distortion (barrel/pincushion), and that reduces the accuracy of phase detect AF.
• Vingetting. The AF system needs a certain amount of light to work. Almost all lenses vignette to some degree, meaning there might not be enough light at the edges of the frame. For example, the EF 17-40mm f/4L has >2 stops of vignetting wide open at the wide end - that means at the edges of the frame, you're below f/5.6 and AF sensors would not have enough light to operate (i.e. in dim light you'd be below the EV sensitivity of the sensor).
• Temperature. Canon has stated that larger AF sensors are more susceptible to changes in temperature with the result that they change size, getting either larger or smaller as the temperature rises and falls. That reduces the accuracy of the AF system overall.

It's worth noting that none of these limitations apply to contrast detect AF, so using LiveView you can autofocus right out to the edge of the frame.

 

[sarangiman]

Thanks for the concise explanation, Neuro.

Temperature. Canon has stated that larger AF sensors are more susceptible to changes in temperature with the result that they change size, getting either larger or smaller as the temperature rises and falls. That reduces the accuracy of the AF system overall.

I myself have found varying optimal MA on different days. Haven't quantified it rigorously, but it's certainly believable based on my experience w/ the 85/1.2 on different days (now that it's warmed up in Seattle, I have a new temperature to compare to the performance throughout the winter).

 

[briansquibb]

My D30 only has 3 AF points