Home · Register · Search · View Winners · Software · Hosting · Software · Join Upload & Sell

Moderated by: Fred Miranda
Username   Password

  New fredmiranda.com Mobile Site
  

FM Forums | Canon Forum | Join Upload & Sell

1
       2       end
  

Archive 2013 · Need some help from expertise
  
 
robinlee
Offline
• •
Upload & Sell: Off
p.1 #1 · Need some help from expertise


Hello all,

Need someone to confirm that my lens is now front focus? Taken with 5D3 + EF500mm center point focusing + 8 point expandable.

Thank you in advance

Robin

edit: apologies the picture seems to be smaller than I thought




Mar 24, 2013 at 10:51 PM
Monito
Offline
• • • • •
Upload & Sell: Off
p.1 #2 · Need some help from expertise


Based on the uncropped full image posted, it seems the focus is good, neither front nor back.

I will let the experts who have that lens and camera combination weigh in with more detail and suggestions for Micro Adjusting and testing.

Regarding posting images, you posted a good size, 1024 pixels wide. Too wide can blow up some forums (FM is tolerant and will only blow up the one post with the image). You could additionally make a 100% crop pixel for pixel of an area around the bird, particularly the detail on the ground in front and behind of 1024 pixels wide, and post that.



Mar 24, 2013 at 11:02 PM
Monito
Offline
• • • • •
Upload & Sell: Off
p.1 #3 · Need some help from expertise


One point about depth of field: the thumbnail idea is that there is 2/3 of the depth behind the point of focus and 1/3 in front, but that breaks down near the minimum focus distance and it becomes more nearly half and half. So don't let that aspect fool you. It looks like that photo was shot near the minimum focus distance.



Mar 24, 2013 at 11:04 PM
Jefferson
Offline
• • • •
Upload & Sell: Off
p.1 #4 · Need some help from expertise


What shutter speed? What aperture?...and ISO?


Mar 24, 2013 at 11:15 PM
robinlee
Offline
• •
Upload & Sell: Off
p.1 #5 · Need some help from expertise


Hi Monito,

I guess the uncropped did not tell a lot, but I have 50% crop attached below and it is resized to 1024 resolution which I hope will give a clearer view. I guess the bird was in the minimum focusing distance but I did get focus confirmation before I hit the shutter likewise, no beep sound when it does not get focus.

Jefferson: shutter speed was 1/500 sec, F4, ISO 800








Mar 24, 2013 at 11:19 PM
Jefferson
Offline
• • • •
Upload & Sell: Off
p.1 #6 · Need some help from expertise


I see nothing sharp except maybe the cone under the bird's tail...


Mar 24, 2013 at 11:23 PM
Jefferson
Offline
• • • •
Upload & Sell: Off
p.1 #7 · Need some help from expertise


That's a better image...


Mar 24, 2013 at 11:24 PM
robinlee
Offline
• •
Upload & Sell: Off
p.1 #8 · Need some help from expertise


Hi Jefferson,

Exactly what I see in my screen. I have provided 100% crop of the bird and the cone under the bird's tail.






Mar 24, 2013 at 11:37 PM
PetKal
Offline
• • • • • • •
Upload & Sell: On
p.1 #9 · Need some help from expertise


It's backfocused......that happens all the time with perfectly calibrated lenses/cameras, on a target like yours. The reason is a compound one......the AF sensors are generally larger than we think + the AF system has a design tendency to focus on the closest object/detail.
Using a precision AF sensor that comes with more recent cameras helps with that problem.
Also, sufficient DoF mitigates (conceals) the problem.

I run into that thing all the time with shots like this when I just do not have enough DoF with a very long lens combo. Have to make absolutely sure thru VF verification that I've got AF placement on the eye, and not on the tail of the bird.

Edited on Mar 25, 2013 at 09:12 AM · View previous versions



Mar 24, 2013 at 11:46 PM
Imagemaster
Offline
• • • • • • •
Upload & Sell: On
p.1 #10 · Need some help from expertise


Why would you expect the camera to know what you want it to focus on in that scene? If you had used spot focus on just the bird, there would not be all those other focus points trying to focus on something with more contrast than the bird.


Mar 24, 2013 at 11:48 PM
 

Search in Used Dept. 



deepbluejh
Offline
• • • • •
Upload & Sell: Off
p.1 #11 · Need some help from expertise


Imagemaster wrote:
Why would you expect the camera to know what you want it to focus on in that scene? If you had used spot focus on just the bird, there would not be all those other focus points trying to focus on something with more contrast than the bird.


Exactly right.

The picture is correctly focused. The issue is that the camera focused on something different than you wanted it to focus on. The solution is to use spot focus on the portion of the bird that you want in focus.



Mar 24, 2013 at 11:52 PM
robinlee
Offline
• •
Upload & Sell: Off
p.1 #12 · Need some help from expertise


Hi Petkal, I use center point focusing with 8 point expandable and the target is on the head of the little bird. I can see the tail and cone are being in focus it should be front

Hi Imagemaster, I use center point focusing not the whole 61 point AF



Mar 24, 2013 at 11:54 PM
johnip
Offline
• • •
Upload & Sell: Off
p.1 #13 · Need some help from expertise


Looks to me like it picked the bottom left point of the expanded center section or the one under his head. Looks like it may be a little front focused as well. Try it again with single point or spot focus when dealing with something small that isn't in the air.


Mar 25, 2013 at 12:01 AM
veroman
Online
• • • •
Upload & Sell: On
p.1 #14 · Need some help from expertise


Appears to be focused on the bird's right wing rather than the eye or beak. On my monitor, it's the wing that's the sharpest part of the bird. Is that what you wanted?
- Steve



Mar 25, 2013 at 12:05 AM
PetKal
Offline
• • • • • • •
Upload & Sell: On
p.1 #15 · Need some help from expertise


robinlee wrote:
Hi Petkal, I use center point focusing with 8 point expandable and the target is on the head of the little bird. I can see the tail and cone are being in focus it should be front



That is where the problem usually arises. The center AF point locks focus first on the intended place. After that, the surrounding AF points are "free to drift" around, and more often than not they will focus on the closest detail with enough contrast. The net effect of such expansion is lack of precision AF.
(Obviously, there are some other significant benefits of AF expansion, but precision pin-point AF is not one of them.)



Mar 25, 2013 at 01:53 AM
BrianO
Offline
• • • • •
Upload & Sell: On
p.1 #16 · Need some help from expertise


PetKal wrote:
It's backfocused...


How do you figure? It looks slightly frontfocused to me, if using the bird's eye as the focus point.

However, I think it might have locked focused on something other than the eye:







Mar 25, 2013 at 04:11 AM
PetKal
Offline
• • • • • • •
Upload & Sell: On
p.1 #17 · Need some help from expertise


Sorry, focus is placed on the back of the bird but it is front focused....good catch.


Mar 25, 2013 at 04:28 AM
Imagemaster
Offline
• • • • • • •
Upload & Sell: On
p.1 #18 · Need some help from expertise


robinlee wrote:
Hi Imagemaster, I use center point focusing not the whole 61 point AF


You are missing the point. You said Taken with 5D3 + EF500mm center point focusing + 8 point expandable.

That is not the same as centre-point only, nor is it the same as spot AF. What is the point of having any focus points on something other than the subject? Do not leave it up to a bunch of focus points to decide what to focus on when you can let fewer focus points do it more accurately.



Mar 25, 2013 at 04:54 AM
robinlee
Offline
• •
Upload & Sell: Off
p.1 #19 · Need some help from expertise


Thanks all, I have quickly done some MA using DotTune method and it needs about +10 on average so it is confirmed to be front focused (thank you johnip, veroman and BrianO). I will test out hopefully today and using only 1 focus point if the weather permits.

Petkal/Imagemaster: do you just use single point focusing for birding?

Edit: DonTune method.

Regards,
Robin


Edited on Mar 25, 2013 at 12:32 PM · View previous versions



Mar 25, 2013 at 07:08 AM
darryn patch
Offline
• • • •
Upload & Sell: Off
p.1 #20 · Need some help from expertise


I might be wrong but with 1D series cameras from memory if you shot with a tele photo and shot centre point it automatically expands the AF points??

Is that a function that is now in the 5DIII??

I haven't shot for over 4 years so my memory may be wrong?



Mar 25, 2013 at 10:41 AM
1
       2       end




FM Forums | Canon Forum | Join Upload & Sell

1
       2       end
    
 

You are not logged in. Login or Register

Username   Password    Retrive password