p.3 #2 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
Beni wrote:
CA is nothing to do with calibration as far as I know, the 85mm does have a lot wide open but that is its only fault wide open and that is very good.
I agree but on a second inspection of the original size image, there is also purple fringing in the edge timber in the centre of the shot. I'm not saying it's a calibration issue, unless the sensor is actually over sharp but rather that it could be some sort of moire pattern causing it. I don't believe that lens has CA throughout.
p.3 #3 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
I have not posted in order to argue about testing methodology. I am convinced (after checking three 70-200 f/4.0 L IS lenses) that this particular design suffers from a "sharpness" problems at focal length > 180 mm and close to MFD. I believe that quite a few people experienced the same issue.
I am wondering if you can spot an 200 mm, close to MFD image :-)
I almost decided ((still thinking) to keep the lens and use it at 135 mm (and less) for most of my photography and at >160 mm, only if focusing distance is more than 7 feet. By the way, it is better to stop down my copy to f/5.6 when using it at 200 mm even at longer focusing distances.
p.3 #5 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
I've got this lens a couple of days ago. No it's not as sharp at MFD as it is at let's say 4 meters. My copy seems to be equally sharp between f4 - f8, which makes me happy. It is OK for shots at MFD, but softer. Would I use it for close up photography - no because I use a 100 macro for it.
In the macro forum there are suggestions that if you put closeup filter (500D) on it then at the same distance (1.2m) your lens will focus at it's near infinity setting, and that the results are great.
I think most people don't shout about this problem, because they just don't notice it too often. 1.2 m at 200mm is a pretty specific working distance after all.
p.3 #6 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
jahoo said: In the macro forum there are suggestions that if you put closeup filter (500D) on it then at the same distance (1.2m) your lens will focus at it's near infinity setting, and that the results are great.
p.3 #7 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
I returned my 2nd copy of this lens and went to another store and got the 70-300 IS for around half the price.
Just to confirm that I am not totally mad I did the same backfocus test immediately and can confirm that the new lens does not backfocus at all.
Performance seems similar - obviously non-constant aperture, no full time manual focus are downers but there's a bit more range and it's a lot lot cheaper.
Anyway, I just hated the backfocus because I knew that taking pictures of kids close up at 200mm I would miss a lot (maybe most) of the time.
And for me that was the deal breaker and I gave up with the 70-200mm f4 IS.....
These are "average" shots (a few taken). The results are very preliminary and the test is "quick and dirty" but I think that if true, this finding is very interesting or even shocking. Can anyone explain it?
He says:
all the tests with the camera on a tripod gave good results regardless of the IS engaged or not
all the tests with the IS engaged with 2 sec delay gave good results
many of the tests with the IS ON with less than 2 sec. delay gave bad results pushing the focus in the back (most of the time) or pushing the focus who knows where (sometimes).
The IS needs more time to settle when shooting at 200mm targets close to the MFD. More time than normally required.
It's not normal and I still believe that Canon should address the issue.
Usually a second will be enough to shoot with the IS engaged, but not so at 200mm in general and in particular when the target is close to the minimum focus distance allowed by the lens.
note: by the end of the tests I was able to shoot 16 pictures in a row with the IS engaged at F4 with very good results: all at the MFD: giving the IS 3 or 4 seconds to settle.
owners of the lens please verify my findings. I'd like to see if my theory is confirmed so I can address the Canon USA support with more facts.
p.3 #10 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
I don't know what your exif's are, however with that level of magnification due to the closeness of the subject and the focal length, could it be that the IS is just not good enough for you to keep it razor sharp? That would explain why the shorter focal lengths are working for you. I'm afraid I can't give credence to your findings based on handheld testing even with such a good IS, I doubt canon will either.
p.3 #11 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
Beni:I'm afraid I can't give credence to your findings based on handheld testing even with such a good IS,
First of all, I am within the specs of the lens and in all my previous tests my shutter speed was higher than 1/320 s for 200 mm shots.
What is more important though is that it appears to be a problem with how IS works (on this lens?) at 200 mm and MFD. There have been tests that show that images with IS on (and running for a sec or two) are suffering from "softness" more than when IS is off.
Why would IS be a problem, do you think (and only at MFD and 200 mm)?
p.3 #15 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
The more the magnification the more stability you need. What I am saying is that at 200mm even with IS you might not be able to get enough stability. Not that there is anything wrong with the IS, just that it is having to work far harder to provide no handshake effect at that magnification. It's like trying to say that you can handhold a 24-105L at low shutter speeds with IS so why can't you handhold a 600mm!
The 1/focal length rule for handholding does not apply to macro photography by a long stretch. Many say that it is actually double the rule for long lenses anyway. So if we say that you could need a 1/400 for critical high resolution sharpness with a normal subject, but at high magnification that itself could double then you have already passed the 4 stop allowance that IS gives. 1/320 does not impress me I'm afraid. Why do you refuse to use a tripod to test whether you are the weak link or the lens?
p.3 #16 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
Beni: 1/320 does not impress me I'm afraid. Why do you refuse to use a tripod to test whether you are the weak link or the lens?
It is not about stubbornly sticking to "no tripod" rule but I want to see how the lens performs when hand held. If I intended to use tripod, I would not have bought this lens.
In other words, I am not testing the optics of this lens - I am testing the whole lens. Even if it works perfectly on a tripod, that would not be the most important part of the whole exercise.
What would you say to my recent finding that with IS on "sharpness" at 200 mm and MFD is worse than with IS off? I could never (hundreds of shots) get anything even close to the one above (I am not saying that it is great), with IS on. Is IS working overcompensating at MFD?
Once again: why does IS on this lens seem to make things worse than better at MFD?
p.3 #17 · EF 70-200 f/4.0 L IS - sharpness question - IS problem?
I'm not having any problems getting sharp shots at 200mm and MFD with IS on with this lens HH.
As Beni has pointed out you need to test your lens on a tripod to take you out of the equation. If it is sharp under these circumstance then your the problem and your inability to HH this lens for optimum performance.
Any conjecture on your part that it is IS or anything else is useless until you tighten the variables of your test and eliminate the human error factor.
Putting it on a tripod doesn't just test the optics if the problem is you weaving to and frow, in and out of the focus plane trying to HH it. As many have told you the DOF is very thin at 200mm and MFD on this lens.
If you really want to evaluate this lens performance properly then use a tripod and cable release for your test. You can also dial in the MFD alot better with a stable platform.
I know because I have done the test. I wanted to know if the 70-200 f/4L IS with and without a TC @ 200mm and its MFD would give me a tighter FOV than the 300 f/4L IS @ MFD. Based on the reported shorter MFD of the 70-200 vs the 300 I figured it would work better for me with flower shots.
