Focus Points on Thirds?

ChrisJ

On many occassions I feel slightly limited by the focus points on my 20D. Since the rule of thirds has been around for a long time, why don't camera manufacturer's allow focusing on some of those points? Instead of just the diamond shape, I want the corners of the box as well.

Anyone know? Optical limitation? It looks like the 1Ds Mark II has 45 points, but still leaves out the corners of the box.

FocusPoints.jpg

Picture/1000 words: This is a picture of 20D focus points. I would like to add the Red points.

pathfinder

That's a great question, Chris, I have wondered the same thing for a long time as I tried to get an AF point on the 1/3 position, and had to settle for focus/recompose.

I suspect it is more difficult to build AF sensors farther from the center of the optical axis of the lens, but I am not an optical engineer, so that is just a guess. It seems so obvious; there must be a physical reason there are no more peripheral AF sensors in pro level cameras.

mercphoto

It is my understanding that Canon considers the four corners that they added to the 20D to be on the thirds already. Its the very reason why the 20D has a diamond pattern for AF sensors, rather than the cross pattern that is typical of this level of camera. Whether those extra four sensors really are on thirds or not is another story. The ones you added, to my eye, look too far out to be truly thirds as well.

Bob Bell

Rule of thirds is a rule easily broken.

Your sensor dots are a lot wider than usable thirds. You control composition with your eyes since you an always find a sensor point to have in focus. If you need the lines to be there as a guidline, take the focus screen out and make very thin lines. I think there is a company that offers this on pro bodies or at least puts the 2x3 and 4x5 ratios on the focus screen.

cmason

I am old fashioned and prefer to focus and recompose, so I ignore all those focus pts anyway. Over the years I have gotton used to imagining the thirds anyway, mf cameras didnt have any dots at all.

I think it would be cool to create a 'thirds' overlay for the LCD so you can check it after the shot...

pchr

I think I have a memory of Minolta doing a camera with focus points on the thirds. I might be making that up.

I agree with cmason, I'm a big fan of focus and recompose, it seems like a fairly natural way to work. I even did that with my EOS30, which had that bizarre eye control thing going on.

ChrisJ

mercphoto wrote:

The ones you added, to my eye, look too far out to be truly thirds as well.

You're right, the red dots are off the thirds, more like quarters... on some shots, I just want extra points there (or in that neighborhood, maybe a little narrower) for whatever reason.

ChrisJ

pchr wrote:

I think I have a memory of Minolta doing a camera with focus points on the thirds. I might be making that up.

I agree with cmason, I'm a big fan of focus and recompose, it seems like a fairly natural way to work. I even did that with my EOS30, which had that bizarre eye control thing going on.

I used to focus and recompose with my Elan all the time. Everything I've read and experienced with my 20D seems to discourage it. My focus gets off more often than not.

I can almost always get the shot I'm taking to work, but it takes an extra step.

Bob Bell

I found the website with focus screens with lines on them. I don't see any consumer bodies listed but a 20D screen is cake to replace so I'm not sure if anyone else makes these.

http://www.brightscreen.com/croplines.html

cmason

Bob Bell wrote:

I found the website with focus screens with lines on them. I don't see any consumer bodies listed but a 20D screen is cake to replace so I'm not sure if anyone else makes these.

http://www.brightscreen.com/croplines.html

"Consumers who already own the Canon D30, D60, 10D, 20D, 30D, Rebel,
Fuji S1, S2 & S3, Nikon D100, D200, D70/50 or Kodak 14N cameras can send
camera bodies to be fitted with a new screen & 8x10 crop for $ 200.00 +
$ 32.00 return SHI standard FedEx delivery charges or + $ 52.00 Overnight."

http://www.brightscreen.com/digitalcameras.html

Bob Bell

cmason wrote:

"Consumers who already own the Canon D30, D60, 10D, 20D, 30D, Rebel,
Fuji S1, S2 & S3, Nikon D100, D200, D70/50 or Kodak 14N cameras can send
camera bodies to be fitted with a new screen & 8x10 crop for $ 200.00 +
$ 32.00 return SHI standard FedEx delivery charges or + $ 52.00 Overnight."

http://www.brightscreen.com/digitalcameras.html

Wow that is pricey for something that takes 1 minute of work.

Bob Bell

I just found out that Katz Eyez offers grids now.

http://www.katzeyeoptics.com/page--Custom-Grid-Crop-Lines--gridlines.html

I have one of their screens with a split prism and they work well.

I guess I should stop looking before I find a 100 links

cmason

Bob Bell wrote:

I just found out that Katz Eyez offers grids now.

http://www.katzeyeoptics.com/page--Custom-Grid-Crop-Lines--gridlines.html

I have one of their screens with a split prism and they work well.

I guess I should stop looking before I find a 100 links

Bob, does that screen you have still have the autofocus indicators? Do you get the red focus pt dots? If not, how do you know what focus pt the camera is using? I assume you can still use the focus confirmation in the viewfinder

Bob Bell

cmason wrote:

Bob, does that screen you have still have the autofocus indicators? Do you get the red focus pt dots? If not, how do you know what focus pt the camera is using? I assume you can still use the focus confirmation in the viewfinder

The squares aren't on the focus screen. They are on another screen that shines onto the focus screen. If you look at your body upside down you will see the screen with the squares on them.

I have noticed the red squares lighting up in manua focus with Zeiss so I guess its some kind of focus lock notification or something.

Hope this helps.

jerek

.
Try using only manual focus, if possible. It also changes the way you take pictures.

Auto focus is good for quick snapshots or if the target is on move, but in my opinion manual focus gives much more freedom.

Most of you will disagree, but i'll live with that

docwalker

I will do the grid line modification for $50 dollars on D200 bodies only.

Or you could find the setting in the menu and turn it on yourself.

I use the focus and recompose myself. I actually get really ticked when a camera thinks too much for me. I was shooting this weekend and could not figure out why the focus was randomly changing. It took me a minute to realize that someone checking out my camera earlier had flipped the focus control to the diamond setting. I usually keep it center spot locked so that I can use the focus/recompose properly.