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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 05 Nov 2010 (Friday) 15:36
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Tamron Lens Phenomenon

 
vishnu
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Dec 01, 2010 10:56 |  #46

Cross type sensors are more accurate and will focus faster, right?


Learning to artistically capture the world through my lens.

  
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RDKirk
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Dec 01, 2010 11:08 |  #47

vishnu wrote in post #11376140 (external link)
Cross type sensors are more accurate and will focus faster, right?

Not necessarily. Each rectangular mark on the viewscreen represents the viewpoint of of two parallel rows of pixels (an array) that "see" a ray of light from offset points (like your two eyes). They only see lines of contrast that run perpendicular to the orientation of the rectangular mark--either horizontal only or vertical only.

The cross type "sensor" (the square marks on the viewscreen) represent two sets of the same kind of arrays--but set perpendicularly. So that point on the view screen is being seen by sensors that detect linear contrast both horizontally and vertically.

However--each sensor array itself is no "better" than the points where there are arrays oriented in only one direction. Because they are sensitive to linear contrast in two directions, they are more likely to focus on more types of subjects if conditions are otherwise appropriate, but if the light is too dim or the subject lacks a linear contrast, then either type of sensor is equally ineffective.

When you mount an f/2.8 or faster lens on the camera, it switches the system to its "high precision" algorithm--which turns on additional sensor arrays to provide more data. These additional sensor arrays are normally unidirectional themselves, adding more data in only one direction.


TANSTAAFL--The Only Unbreakable Rule in Photography

  
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Steve-R
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Dec 01, 2010 16:22 |  #48

Just to clarify, most cross-type sensors do not have the additional f/2.8 (high precision) sensors. For example, on the 40D, only the center point has the additional f/2.8 sensor arrays (and they are arranged in an X-orientation).


Steve

Canon 70D,
10-22, 28-105, 70-300 f/4-5.6, 100 f/2.8
Tamron 17-50 f/2.8, Tokina 10-17 Fisheye, Tokina 35 f/2.8

  
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vishnu
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Dec 02, 2010 15:26 |  #49

Thanks for the detailed response guys. Looks like I am not loosing much as I use center point and recompose usually. For critical focus, I use manual focus in live view.


Learning to artistically capture the world through my lens.

  
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msgnighty
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Dec 21, 2010 07:45 as a reply to  @ vishnu's post |  #50

The problem is solved!!!

if you have this problem - just contact the tamron support - they will ask you to send them your lens to repair the AF-module

actually they will change the Lens-ID from 37 to 137. this will solve the problem and the lens will focus as it's supposed to do with cross type sensors!




  
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T-Fish
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Jul 11, 2011 11:45 |  #51

Sorry to dig this up from the grave, but how does a person test to see if their lens is working properly?

And I might need great detail, I'm somewhat 'green' when it comes to terminology. :)




  
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vickylou
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Jul 11, 2011 14:03 |  #52

Same here I just bought a used 17-50 vc for my 60d. What is the best way to check?


Canon 60D; Canon 10-18 IS STM; Tamron 17-50 VC; Canon 100mm F2.8L macro; Tamron 60mm F2 macro; Tamron 70-300 VC USD; Canon 430ex II; Yongnuo 565ex; Manfrotto 190 classic; Manfrotto 488RC2; Hama Rexton 150; Manfrotto backpack & Eager to learn :)

  
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vickylou
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Jul 12, 2011 12:07 |  #53

So any more news on this issue?


Canon 60D; Canon 10-18 IS STM; Tamron 17-50 VC; Canon 100mm F2.8L macro; Tamron 60mm F2 macro; Tamron 70-300 VC USD; Canon 430ex II; Yongnuo 565ex; Manfrotto 190 classic; Manfrotto 488RC2; Hama Rexton 150; Manfrotto backpack & Eager to learn :)

  
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msgnighty
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Jul 12, 2011 13:14 |  #54

https://photography-on-the.net …p?p=11241614&po​stcount=21

way to check it :)




  
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WilsonC
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Jul 12, 2011 13:16 |  #55

Opps...read the post above wrong...but I'll leave this here for those interested, and don't already know this

To check your LensID
Download exiftool and the exiftool gui. (There should be instructions on how to set it up).

http://freeweb.siol.ne​t …foto/exif/exift​oolgui.htm (external link)

Take a photo, and download it to your computer. Open Exiftool GUI and browse to the file (can be a cr2), click on the file. In the "option" menus set "Show tag values as Numbers". On the right hand side click the "Maker" button. Look under the "LensType" value...if it says 37 then your lens is affected. After being sent to Tamron repair the problem it should say "137".


Christopher
50D | 450D | 50mm 1.4 | Tamron 70-200mm 2.8 | Tamron 10-24mm | Sigma APO Macro 70-300mm |18-55mm IS | 430EXII

  
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vickylou
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Jul 12, 2011 14:50 |  #56

msgnighty wrote in post #11241614 (external link)
oh great - i have an account here ;)


ok - hey everyone - i am the guy who wrote the text quoted by CR - so i try to give you a few more details


first of all - tamron europe replied to my mail, that they were able to reproduce the problem, they also replied this to several other guys who wrote mails to them regarding this issue - so this whole thing is confirmed by tamron europe! (took about 4 weeks for them to reply)


ok - as you can read in the text, the lenses mentioned aren't using the outer cross-type sensors as they should use them - they are only work like they would on a body like the 400/450/500/550D - this was tested on several 40Ds and 50Ds on the forums and i was able to confirm this problem with the 60D as well (first thing i checked when i was able to use this cam during a weekend) - there were several ways to check and reproduce this problem - the easiest way is to just open you photoshop (or whatever you like to use) - get a white background and draw a black line - the center sensor will focus the line in every direction - the outer sensors wont focus depending on the direction of the camera - i made the picture that you can see on the bottom of the post - green lines are focused correctly - red lines are not focused

the same thing happens if u use a black line on a white sheet of paper - or if you put something like a belt on your wall and use this as your black line


when it comes to the 7D it's a bit more complicated due to the amount of sensors - but in the end it's the same - not every sensor is working as it's supposed to

the problem was confirmed by several users on our forums - the problem is confirmed by tamron europe - the problem is confirmed with the lenses mentioned in the text (i tested the 17-50 vc, the 60 macro and the 70-200 for example)

the 17-50 non-vc does not have this problem!


would be glad if some of you could check this as well :)

So I drew a black line on paper, landscape and the three focus points along the line lit up but none of the others?


Canon 60D; Canon 10-18 IS STM; Tamron 17-50 VC; Canon 100mm F2.8L macro; Tamron 60mm F2 macro; Tamron 70-300 VC USD; Canon 430ex II; Yongnuo 565ex; Manfrotto 190 classic; Manfrotto 488RC2; Hama Rexton 150; Manfrotto backpack & Eager to learn :)

  
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lar55
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Jul 12, 2011 18:07 |  #57

vickylou wrote in post #12746811 (external link)
So I drew a black line on paper, landscape and the three focus points along the line lit up but none of the others?

Here is how I understand it. My camera (60D) has 9 sensors, all cross-type.

I drew a black line on paper, taped it to a wall, set camera to automatic focus point selection. Point the camera so the line is under the top-most sensor row (1 sensor) and half-press the shutter. The top point should light up. Now move the camera up so the next sensor row down (which has 2 sensors) is over the line. Again, half-press, those 2 sensors should light up. Repeat for the 3rd row (3 sensors), 4th, and 5th rows. Each sensor should light up when it is over the black line.

Now turn the camera (or paper) 90 degrees and repeat the whole thing.

Each sensor should light up when the line is under it (provided you aren't closer than your lens can focus), both when the line is horizontal and vertical. This means each sensor is detecting both vertical and horizontal lines.

I did this with a Tamron lens which is not one of the affected ones, but I could not get my bottom-most sensor to fire for horizontal lines, or my right-most sensor to fire for vertical lines. The other ones did work, but sometimes it took a few tries. Sometimes one of the focus points will fire even if it is over blank paper (or wall) for some reason.




  
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vickylou
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Jul 14, 2011 03:56 |  #58

WilsonC wrote in post #12746287 (external link)
Opps...read the post above wrong...but I'll leave this here for those interested, and don't already know this

To check your LensID
Download exiftool and the exiftool gui. (There should be instructions on how to set it up).

http://freeweb.siol.ne​t …foto/exif/exift​oolgui.htm (external link)

Take a photo, and download it to your computer. Open Exiftool GUI and browse to the file (can be a cr2), click on the file. In the "option" menus set "Show tag values as Numbers". On the right hand side click the "Maker" button. Look under the "LensType" value...if it says 37 then your lens is affected. After being sent to Tamron repair the problem it should say "137".

Cannot seem to get this to work, is there a simpler program for non IT buffs?


Canon 60D; Canon 10-18 IS STM; Tamron 17-50 VC; Canon 100mm F2.8L macro; Tamron 60mm F2 macro; Tamron 70-300 VC USD; Canon 430ex II; Yongnuo 565ex; Manfrotto 190 classic; Manfrotto 488RC2; Hama Rexton 150; Manfrotto backpack & Eager to learn :)

  
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vickylou
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Jul 14, 2011 04:03 |  #59

vickylou wrote in post #12755893 (external link)
Cannot seem to get this to work, is there a simpler program for non IT buffs?

Ok working! my lens ID is sigma 17-50 2.8 OS HSM, is this good? I managed to to get the lens ID number and it is 137?

Also I checked by drawing the black line of a white piece of paper and all points seem to work except the bottom point in both portrait and landscape.


Canon 60D; Canon 10-18 IS STM; Tamron 17-50 VC; Canon 100mm F2.8L macro; Tamron 60mm F2 macro; Tamron 70-300 VC USD; Canon 430ex II; Yongnuo 565ex; Manfrotto 190 classic; Manfrotto 488RC2; Hama Rexton 150; Manfrotto backpack & Eager to learn :)

  
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lar55
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Jul 14, 2011 15:20 |  #60

vickylou wrote in post #12755906 (external link)
Ok working! my lens ID is sigma 17-50 2.8 OS HSM, is this good? I managed to to get the lens ID number and it is 137?

Also I checked by drawing the black line of a white piece of paper and all points seem to work except the bottom point in both portrait and landscape.

Yes, 137 is a good lens ID. That is, it is not one of the "black-listed" lens IDs Canon programmed into the camera such that if a lens reporting this ID is mounted, the camera will downgrade the cross-type outer sensors into linear sensors.

Your bottom-most auto-focus sensor does not work on a black line at all, either orientation? Does it work for other targets, such as something with texture?




  
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