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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 08 Sep 2010 (Wednesday) 18:18
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Focus test on Canon 100-400mm zoom lens

 
MSPSpotter
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Sep 08, 2010 18:18 |  #1

Hello,

I just received my new canon 100-400mm lens and have been testing it out for the last few hours. It seems a bit soft to me but then again, I've never owned an "L" lens previous to this so how would I know either way. :lol:

Anyway... I setup my tripod and mounted the camera at a 45 degree angle to the ground, I laid a tape measure on the garage floor and aimed at the 15 inch mark. I actually used a sharpie and put a black dot at the 15 inch mark and that's what I aimed the center focus point at. I used mirror lockup, 2 second timer with a remote cable release with IS turned off.

This is the first time doing a focus test.... are these results good? Did I perform the test properly? It seems to me the lens is focusing somewhere around the 14.5 inch mark. Maybe I'm splitting hairs here????

What do you guys think?
Thanks in advance. :)

75% crop:

IMAGE: http://www.mspphotos.com/uploads/focus.jpg



  
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Badger49456
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Sep 08, 2010 18:22 |  #2

I think you're splitting hairs! What did you shoot this at, 100 or 400mm?


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MSPSpotter
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Sep 08, 2010 18:26 as a reply to  @ Badger49456's post |  #3

Hello,

The exif data says 220mm. I wasn't sure where I should preform the test so I just zoomed in until I got the shot I was looking for.

Thanks.




  
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harcosparky
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Sep 08, 2010 18:42 |  #4

I would have done a couple of tests.

Test #1 - Center Focus Point

Test #2 - Center Focus Point - Spot Focus Mode ( this is the mode where the center focus point box has a smaller box inside of it )


From what I recall reading the actual focus sensor is slightly larger than the box that represents it.

In Spot Focus Mode the sensor is 'shrunk' to be no larger than the box.

I hope that makes sense.

EDIT: I was slightly off - in Spot Mode it shrinks but still slightly outside the box.

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NeutronBoy
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Sep 08, 2010 20:04 |  #5

Harco,

As the OP dod not mention what camera he has, will this work for all Canon DSLRs? I dont seem to recall my 40D having a spot focusing mode. I can focus with center point (it's my default setup), but not a spot focus.


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MSPSpotter
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Sep 08, 2010 20:29 as a reply to  @ NeutronBoy's post |  #6

I'm sorry I forgot to mention the camera..... I'm using a Canon Rebel XSI/450D.




  
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harcosparky
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Sep 08, 2010 21:22 as a reply to  @ MSPSpotter's post |  #7

:oops:

I forgot to ask.

My info is for the 7D only!

Sorry! :D




  
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rad ­ doc
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Sep 08, 2010 21:58 |  #8

Maybe it is slightly front focusing. Or the angle you took the image at was not 45 degrees. I would reshoot it again. I usually take 3 images to make sure they are the same.




  
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MSPSpotter
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Sep 08, 2010 22:13 |  #9

Now I'm really not sure what to think about this lens. I did a test with my EF-S 55-250 f5.6 IS NON "L" lens, wide open (5.6) at 250mm. It seemed to focus better AND was much sharper. Surly the "L" lens should give a better result in the middle at 220MM (picture above) than a cheap "kit" lens at full zoom? I'm starting to think I received a bad copy of the 100-400 lens.

You be the judge.... To me, the cheap lens seems much better.

100-400 wide open (F5.6) at 400mm

IMAGE: http://www.mspphotos.com/uploads/100-400mm%20lens%20at%20400mm%20crop.jpg

EF-S 55-250mm wide open (F5.6) at 250mm
IMAGE: http://www.mspphotos.com/uploads/55-250%20lens.....%20at250mm%20crop.jpg



  
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MSPSpotter
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Sep 08, 2010 22:21 |  #10

rad doc wrote in post #10875436 (external link)
Maybe it is slightly front focusing. Or the angle you took the image at was not 45 degrees. I would reshoot it again. I usually take 3 images to make sure they are the same.

This is the first focus test I've ever done and wasn't sure how critical it was to be exactly at 45 degrees. I used a speed square (carpenters tool) on my tripod to get the camera as close as possible to 45 degrees. With that said, I only eyeballed it so it could be a few degrees off. if so, will that cause bad results? maybe I need to skip the speed square and get out my digital angle finder on the next test. :lol:




  
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JWright
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Sep 08, 2010 22:40 as a reply to  @ MSPSpotter's post |  #11

Focus tests are all well and good, but what you really need to do is take the lens out and see how it performs in the real world. Unless all you're going to be taking pictures of is tape measures on your garage floor...


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MSPSpotter
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Sep 08, 2010 22:45 |  #12

JWright wrote in post #10875694 (external link)
Focus tests are all well and good, but what you really need to do is take the lens out and see how it performs in the real world. Unless all you're going to be taking pictures of is tape measures on your garage floor...

I took it out this afternoon and had very poor results.... that is the only reason why the tape measure came out. I was just trying to eliminate possible focus issues. I like taking pictures of aircraft landing and taking off and I got MUCH better results with my cheap lens at the airport today!




  
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crn3371
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Sep 08, 2010 23:38 |  #13

I've always felt that the 100-400 had a bit of a learning curve in order to get the most out of it. Make sure you keep the shutter speed up as the IS helps but is really only good for a couple of stops. Also, the 100-400 likes to be stopped down a bit, only shoot wide open if you have to. There also seems to be some discussion regarding how this lens reacts with UV filters on it. Many here in the forum swear that their lens was crap with a filter on it. I have a good Hoya on mine with no ill effects.




  
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MOkoFOko
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Sep 08, 2010 23:45 |  #14

You never said if you got a new copy or a used one off ebay. The pre-2006 models are pretty notorious for going soft... fairly regularly. Some wildlife photographers in another forum were complaining that they had to be sent in for calibration at least once a year.

That said, it's possible you're also doing something wrong. If you're handholding, you may be doing a poor job of it--keep in mind that the 100-400 has an older-generation IS system and won't hold up as well with low-light.

edit: I see now you said you did the first shot with a tripod at least. Was IS off? From that shot it honestly doesn't look bad. In your comparison, it's REALLY not fair to compare sharpness of 250mm to 400mm. The 100-400s are softer at the long end, which is typical. If it's new and you have a receipt, you may as well send it in for calibration just to be satisfied with it...


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MSPSpotter
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Sep 09, 2010 00:10 |  #15

MOkoFOko wrote in post #10876019 (external link)
You never said if you got a new copy or a used one off ebay. The pre-2006 models are pretty notorious for going soft... fairly regularly. Some wildlife photographers in another forum were complaining that they had to be sent in for calibration at least once a year.

That said, it's possible you're also doing something wrong. If you're handholding, you may be doing a poor job of it--keep in mind that the 100-400 has an older-generation IS system and won't hold up as well with low-light.

edit: I see now you said you did the first shot with a tripod at least. Was IS off? From that shot it honestly doesn't look bad. In your comparison, it's REALLY not fair to compare sharpness of 250mm to 400mm. The 100-400s are softer at the long end, which is typical. If it's new and you have a receipt, you may as well send it in for calibration just to be satisfied with it...

I ordered it brand new. It was manufactured in July of 2010.

When I was shooting earlier today the light was very good and the sun was directly at my back. At times I could shoot stopped down to F7.1 and still have shutter speeds between 1/1250 - 1/2000, with an ISO of 200.

I realize it isn't fair to compare two lenses at different lengths but the first picture in this thread was shot a 220mm and it's still not as sharp as the cheap lens was at full zoom. Either way you look at it..... the cheap lens was sharper at full zoom, than the "L" lens at full zoom. If that is normal, why spend the money for "L" glass?




  
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Focus test on Canon 100-400mm zoom lens
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