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Thread started 14 Jan 2014 (Tuesday) 07:48
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70D focus issue & blurred pictures

 
ddk2001
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Aug 28, 2014 12:35 as a reply to  @ post 17120042 |  #1261

So . . . . . . . . .

My refurbished 70d arrived today. I spend most of my time shooting my kids' sports with my 70-300L. Should I even bother testing this thing? Or - just go shoot?

Wait - I don't have any lens faster than 2.8. So - I can't test it anyway - right?

:rolleyes:




  
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Scoobert
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Aug 28, 2014 15:15 |  #1262

ddk2001 wrote in post #17122847 (external link)
So . . . . . . . . .

My refurbished 70d arrived today. I spend most of my time shooting my kids' sports with my 70-300L. Should I even bother testing this thing? Or - just go shoot?

Wait - I don't have any lens faster than 2.8. So - I can't test it anyway - right?

:rolleyes:

Nope, you need a 2.8 or faster lens to test the center point focus.




  
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Molybdo42
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Aug 28, 2014 16:37 |  #1263

Good news ! I received my 70D back, this time, after the third trip, Canon replaced the camera with another one. I'm still testing it, at the moment I can only say that I get almost the same results as NebrGuy.

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Despite having a better AF alignment, I still get some missed shoots with my 18-35 Sigma lens. I still wish that the red square was a little bit more centered. The 18-35 does seem to be very sensitive to misaligned AF sensor, my other Sigma lens (the old 35mm f/1.4) seems to cause less issue. I'll need to check if theres not an issue with my 18-35mm and will try doing some MFA. I only did some quick tests, will do further testing during the week-end...

Nevertheless, this camera is much better than the previous one. I'll try to identify the scenario where focus is random, not sure if I'm going to send it back for a fourth time.

Scoobert wrote in post #17123146 (external link)
Nope, you need a 2.8 or faster lens to test the center point focus.

No the test should work with both fast and slow lens (see my post above, I compared NebrGuy focus sensitive area with both fast and slow lens... they match). I will confirm that on my camera during this week-end.
But a fast lens is still needed to show to Canon's technicians that there is a focus issue. If Canon technicians hear about misaligned sensitive AF area, they'll check the camera for parallax issue in the viewfinder, that won't fix the camera.

ddk2001 wrote in post #17122847 (external link)
=ddk2001 ;17122847]So . . . . . . . . .

My refurbished 70d arrived today. I spend most of my time shooting my kids' sports with my 70-300L. Should I even bother testing this thing? Or - just go shoot?

Wait - I don't have any lens faster than 2.8. So - I can't test it anyway - right?

The test is still useful even if you don't have a focus issue, because you'll know in advance where to aim the camera to be 99% percent sure to get what you want in sharp focus. You also don't want to discover that after your warranty has expired...

Here is an example showing why this test is useful :
My 60D leftmost focus point is a bit misaligned, I definitely noticed that when taking some pictures (see my post above). At first, I didn't do the AF sensor coverage measurement (because, as my 70D was a mess, I bought the 60D the day before snapping some pictures). Thankfully I knew some misalignment issue could cause what I observed during shoot. So I was able to change my aiming to get always sharp focus where I wanted.

But unlike the 60D, and the 7D, on the 70D, most of the focus marks are less than half covered by the sensing AF element, that also seems true even on perfectly working cameras (Canon must have crippled the AF sensor...).
That incomplete coverage is definitely something you want to know, otherwise you can get lots of blurry pictures for no apparent reason. Imagine your kid running while being aligned in the right half of focus point N°3 or 14... you would have focused on the background !

Good news is that if your centerpoint seems as "well" aligned as mine and NebrGuy, there's a good chance that your camera will give identical results. So no need to do all 19 focus points.




  
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Scoobert
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Aug 28, 2014 17:15 as a reply to  @ Molybdo42's post |  #1264

Awesome news Moly !!!!




  
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ddk2001
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Aug 28, 2014 17:17 |  #1265

Molybdo42 wrote in post #17123283 (external link)
No the test should work with both fast and slow lens (see my post above, I compared NebrGuy focus sensitive area with both fast and slow lens... they match). I will confirm that on my camera during this week-end.
But a fast lens is still needed to show to Canon's technicians that there is a focus issue. If Canon technicians hear about misaligned sensitive AF area, they'll check the camera for parallax issue in the viewfinder, that won't fix the camera.

The test is still useful even if you don't have a focus issue, because you'll know in advance where to aim the camera to be 99% percent sure to get what you want in sharp focus. You also don't want to discover that after your warranty has expired...

So . . . are you looking for more samples from 70ds? If so - I'll try it. I do have a couple of questions about your test. 1) the mirror on the (computer?) screen - is the purpose of the mirror to simply make certain the computer screen is square to the camera (no deflection)? 2) when looking in live view, compared to the focus points - how big (or small) should the rectangle be? Roughly how far from the computer screen should the camera/tripod be?

I'm new at this - so be patient . . . . hope those questions make sense.

For a lens - I can either use my EF 70-300 f/4-5.6L IS USM, EF-S 55-250mm F4-5.6 IS STM, or 18-55mm 3.5-5.6 IS STM

Let me know - PM me if you'd rather.

Thanks !




  
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NebrGuy
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Aug 28, 2014 19:05 |  #1266

Molybdo42 wrote in post #17123283 (external link)
The test is still useful even if you don't have a focus issue, because you'll know in advance where to aim the camera to be 99% percent sure to get what you want in sharp focus.

This is why I'm glad I did it. It is huge to realize that the on-screen focal points 1 & 19 are only slightly covering the actual focus area or that only about 1/4 of the area is covered by 2 & 16 is significant. Recognizing that should help improve (I hope) the quality of photos.

One thing that does bother me with the test results is how 1 and 3 are almost covering the same identical area, leaving large portions of what you think is a focal area uncovered.

Robert


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Molybdo42
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Aug 29, 2014 02:10 |  #1267

ddk2001 wrote in post #17123353 (external link)
So . . . are you looking for more samples from 70ds? If so - I'll try it. I do have a couple of questions about your test. 1) the mirror on the (computer?) screen - is the purpose of the mirror to simply make certain the computer screen is square to the camera (no deflection)? 2) when looking in live view, compared to the focus points - how big (or small) should the rectangle be? Roughly how far from the computer screen should the camera/tripod be?

I'm new at this - so be patient . . . . hope those questions make sense.

For a lens - I can either use my EF 70-300 f/4-5.6L IS USM, EF-S 55-250mm F4-5.6 IS STM, or 18-55mm 3.5-5.6 IS STM

Let me know - PM me if you'd rather.

Thanks !

1) The mirror on the computer screen isn't a required step. The camera should only focus on a single point : the black/white edge; there's no depth of field issue. The only thing to check is the sharpness of the black/white edge where the camera focused. But do try to be as parallel as you can to the screen (eyeball it). Holding a mirror flat against the LCD is a huge help but it's not necessary (NebrGuy did it without mirror).
If you use a mirror, don't forget to use 3M magic tape (use that brand only not some supermarket knockoff), because this tape leaves no residue on the screen. The tape on the LCD screen is only last resort thing if you can't hold the mirror on the screen while doing adjustments. When finished peel the tape very slowly and be careful not to damage your screen with any sharp edges of the mirror (that happened to me, thankfully it's barely visible). Like I said only last resort thing.

2) The distance shouldn't be important, I've tested that on my 60D with targets at 200 meters and 50cm, I saw no difference. Place yourself far enough from the screen to be able to focus and close enough to be able to use your mouse. But be careful and check that the camera can't focus on the white or black pixels at the distance you're at and with the lens you're using ! Ex : a glossy screen in a well lit room can be problematic !

At first, to see if you understood the steps, I'm going to ask you to map only the centerfocus point :
- twice with your 18-55mm 3.5-5.6 IS STM (to remove any operator error)
- once with your EF-S 55-250mm F4-5.6 IS STM (in case there's a problem with the lens)

You can choose any focal length you want.

Pay attention to your exposure settings to avoid flickering and to give me properly exposed pictures. Use the Liveview histogram, you'll see two spikes for black and white, adjust the exposure to get them as far as possible from each other in both end of the histogram.

Send the pictures via wikisend.com

Let's continue the discussion in PM, after I will post the result on the forum.




  
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Frodge
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Aug 29, 2014 05:12 |  #1268

So what is the final assessment? This is normal behavior?


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Molybdo42
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Aug 29, 2014 05:59 |  #1269

Frodge wrote in post #17124047 (external link)
So what is the final assessment? This is normal behavior?

This is definitely not what I expected, so I wouldn't call this "normal". But the camera seems to work, so maybe all 70D are like that !
I'll confirm that my sample works this week-end (if I have enough time).

There's a possibility that the 70D uses the "spot focus" mode of the 7D, giving us much smaller focus sensitive area, thus smaller focus points not covering the entire marks. But I'll need to have the same measurement done on a 7D (with spot focus and normal focus) to confirm this.

@NebrGuy :
It's normal to have a wide area not covered by the focus system between N°3-6 and N°14-17 (but in my opinion, it's not normal that only half the mark is covered, yet the 70D works). I think the focus assembly uses a set of three field lens, separating the focus sensitive areas in three main groups. The AF chip of a 7D is also organized similarly :

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Look at this measurement done on a 7D (not in spot AF) notice the gap between three main groups :
IMAGE: http://www.aerien.ch/IM/7d_focus_points.gif



  
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Jiggo0109
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Sep 03, 2014 05:37 |  #1270

My 70d is faulty and this is what I found...

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AF fails if I place the line at the exact focusing points (in red). When I first used my 70D, I really felt there is a problem. Keeper rate is very low especially on the right side AF points. Right AF points (starting from the middle) are really way off. Looking at molyb's af points (defective unit), I assume (just assuming) that we have the same problem. My camera is bound to Canon this week.

By the way, I tried this test in different locations and time of the day. All gave me the same results.



  
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Molybdo42
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Sep 03, 2014 10:42 |  #1271

Jiggo0109 wrote in post #17132978 (external link)
My 70d is faulty and this is what I found...
AF fails if I place the line at the exact focusing points (in red). When I first used my 70D, I really felt there is a problem. Keeper rate is very low especially on the right side AF points. Right AF points (starting from the middle) are really way off. Looking at molyb's af points (defective unit), I assume (just assuming) that we have the same problem. My camera is bound to Canon this week.

By the way, I tried this test in different locations and time of the day. All gave me the same results.

No this is normal, the focus points N°5, 6, 7, 13, 14 and 15 are supposed to overlap with focus points N°8, 9, 10, 11, 12.
What's not is if all AF sensitive areas are decentered. You'll have your answer if you check the position of the center AF point only. But before doing it wait a moment, I think I've made a mistake in the measurement protocol and I will have to modify it slightly in order to obtain better results.

This picture shows how a normal 7D (not 70D) should react :

IMAGE: http://www.aerien.ch/IM/7d_focus_points.gif

My 70D is almost similar, only difference : the areas are smaller and do not cover the entire viewfinder's rectangles (as well as being slightly shifted upwards). But maybe that on all 70D the smaller coverage is normal. We do not know, Canon might have modified the AF sensor to compensate for the lack of spot focus mode on the 70D.



  
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Jiggo0109
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Sep 03, 2014 19:18 |  #1272

Molybdo42 wrote in post #17133373 (external link)
No this is normal, the focus points N°5, 6, 7, 13, 14 and 15 are supposed to overlap with focus points N°8, 9, 10, 11, 12.
What's not is if all AF sensitive areas are decentered. You'll have your answer if you check the position of the center AF point only. But before doing it wait a moment, I think I've made a mistake in the measurement protocol and I will have to modify it slightly in order to obtain better results.

This picture shows how a normal 7D (not 70D) should react :

[GIFS ARE NOT RENDERED IN QUOTES]

My 70D is almost similar, only difference : the areas are smaller and do not cover the entire viewfinder's rectangles (as well as being slightly shifted upwards). But maybe that on all 70D the smaller coverage is normal. We do not know, Canon might have modified the AF sensor to compensate for the lack of spot focus mode on the 70D.

Thanks molyb, but if I focus the line using points 13,14 and 15 it fails. It doesn't lock on, locking starts at their left sides of the boxes, at about 1/8 of each box area to the left, upto the middle points. With regards to the mid point, it does lock on the center and adjacent left space (between 6 and mid point) and fails at the adjacent space to the right (between mid point and 14). Decentered?




  
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moltengold
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Sep 03, 2014 20:34 |  #1273

Frodge wrote in post #17124047 (external link)
So what is the final assessment? This is normal behavior?

+ 1
is it good or bad in focus ?
i want to know


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LisBerry
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Sep 03, 2014 21:12 |  #1274

Don't remember everything I did so I won't try and list it out.

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NickiRasgo
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Sep 07, 2014 21:54 |  #1275

Hi. I'm planning to buy this coming December. Just want to ask if the AF issue still present? I want to complement it with my 6D but I'm having hesitation right now if I'll get a 70D.




  
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