Advise needed: My 70-200mm IS F4 is soft! Pics inside
- Thread starter yanyanyan881
- Start date
Canon replaced a new one for me. And test results show at F4, its only a little bit sharper. Still front/back focus from f5.6 to f8.0 The canon man said he did his own focus test and found it to be spot on. I just accept the new lens as i think this is the way it is.
Since today got a bit of mood, oblige....ignore the white balance. I am using fluorecent light and AWB. Just a quick test so too lazy to amend WB.
1.5m away, manual focus using liveview x10
70mm 1:1 vs 135mm 1:2 @ f4
70mm 1:1 vs 135mm 1:2 @ f8
100mm 1:1 vs 200mm 1:2 @f4
100mm 1:1 vs 200mm 1:2 @f8
You can see this lens is sharp from 70-135 from f4- f8 and can even crop to 2x focal length. It is very very slightly soft at 200mm but it is still very consistent throughout its entire FL and aperture. You would not notice the softness at 200mm unless you pixel peep at this level. If this is not as good as prime, it must be pretty near.
Last edited:
Then could it be your camera that needs to be calibrated ? Maybe they will change your camera too. Give it a try
I am surprise that CSC did not try to troubleshoot further to resolve the issue. Maybe you are happy that they replace your lens and let them off.
Last edited:
Then could it be your camera that needs to be calibrated ? Maybe they will change your camera too. Give it a try
I am surprise that CSC did not try to troubleshoot further to resolve the issue. Maybe you are happy that they replace your lens and let them off.
Actually this is not the 1st time
When owning 70-200 f2.8 L Non IS, I found a dirt inside my lens (I own this lens on 1st hand; new - under warranty). It's bigger than usual dust, so I asks CSC to do checking (I'm afraid of fungus). They are checking and told me that there are bubbles not fungus nor dusts (The bubbles maybe comes from the unproper coating - my own thinking). I asks them can they do something about this, can they remove it? Their answer make me off. They said common sense like "This is no impact on IQ", and more they said "Maybe things become worse once they open it (lens)". How came they has no confident about what they are doing...
Actually, bubbles are common. In the old days, people look for bubbles in lenses, and if they found a bubble, they will buy the lens, knowing that it is a good quality glass.
Bubbles in optical glass is fine.
actually I agree with Canon on this. Seriously can you see ANY degradation of the pics from the bubble??
if not, why you want to fix it? opening the lens is not easy I think.... I am sure the lab in the lens manufacturing place is cleaner and more professional than CSC singapore. You sound like the kind who is very particular about the "cleanliness" of your lens so what happen if some dust got it???
Last edited:
well, if you in my position you must in this kind of 'panic'
As I said, the bubbles is bigger than dusts, and it's easily spotted when you look through inner element... (I always blame myself cannot see this when buy it)
And there are not only 1-2 of them, there are many, to many until panicking me since I thought the lens got fungus
When I told my buyer (which is my ex classmate) regarding this issue, the buyer thought maybe the lens drop to the water before, and that's are residue of water, but confirm the purchase since it still under warranty. I only able to secure 1.2k for 7 month old lens (which that time I bought around 1.7k)
Yanyanyan881, I think my lens is like yours. It is softish at f/4 near the highest magnifications that the lens is capable of. But, only near these highest magnifications -- that is BOTH near 200mm focal length and near its minimum focus TOGETHER. If I photograph at 200mm from 2.5 metres or so away, it's fine.
I really learnt something from your tests. You clearly demonstrated that considerable focus shift occurs when this lens is stopped down at highish magnifications. So, now I've found that so long as I stop down to around f/11 (to reduce spherical aberration) and refocus at this taking aperture (to get around the focus shift), I can get very sharp photos right up to 200mm focal length and minimum focus. This is OK with static subjects.
I really learnt something from your tests. You clearly demonstrated that considerable focus shift occurs when this lens is stopped down at highish magnifications. So, now I've found that so long as I stop down to around f/11 (to reduce spherical aberration) and refocus at this taking aperture (to get around the focus shift), I can get very sharp photos right up to 200mm focal length and minimum focus. This is OK with static subjects.
I did some AF tests today. My results are at f8, the AF does seems to back focus a weeny bit but nothing like TS's tests. In fact they looked pretty spot on. Maybe the magnification and inclination of the shot are different from TS's tests so it does not appear that back focus in my tests. I still have to say this is a remarkable lens.
200mm, 45 degrees incline, 1.5m away. focus on the lines of words at 0.
f4
f5.6
f8
200mm, 45 degrees incline, 1.5m away. focus on the lines of words at 0.
f4
f5.6
f8
Last edited:
I'm not sure if it has any impact on the MFD, have yet to read the physics part of optics with regards to that.
But I must say that my 70-200 f/2.8 non IS was way sharper when I used it on my friend's full frame compared to my APS-C body. I'm not sure why, but I believe is the resolving power of the lens. By taking the "middle" of the lens and blowing it up, the sensor out-resolved the lens, thus resulting in the image looking soft.
It's just my theory, feel free to correct me in case I'm wrong
I think your scenario is not so much of lens resolving strength. It is simply you are handling a longer focal length and hence more difficult to keep it shake free. 200mm on APS-C is 320mm.
-----
I am just wondering if MFD is also multiplied by cropped factor. If it is not, then it is effectively 320mm at 1.2m MFD. Any inaccuracy in focusing would have been magnified. Maybe this is a reason for APS-C to stick to EF-S lenses since EF lenses are optimized for FF. I wonder if any APS-H users can try and see if there is any AF inaccuracy.
Last edited:
Similar threads
