Advise needed: My 70-200mm IS F4 is soft! Pics inside

[yanyanyan881]

but hey, the 70-200mm f4 IS is famous of having prime quality. but matching my 50mm @ 1.8 is surely not right. i know very well many lens are soft wide open. im sure this is Not the case for 70-200mm f4 IS. because i read user reviews.

even digital-picture has samples showing it is a bit sharper than 50mm both at F4. other reviews has charts showing this lens at F4-F8 is constantly sharp and unnoticeable wit naked eye. i have a tripod mount. i put it on table instead of tripod also produce same result. its very stable.

the test was bright enough. it doesnt matter because i was using manual focus.

 

[Octarine]

the test was bright enough. it doesnt matter because i was using manual focus.

:thumbsup: you win.
AF sensors perform best in proper light. Ever heard about cross-type sensors going to single type in low light? And what gives you the impression that your manual focus is more accurate than the AF sensors?
Please get a focus test chart, setup as described and let us see the results there. This torch light tinkering is crap, sorry to be that frank.

 

[ManWearPants]

I also think the test is inconclusive due to the various factors that have not been kept constant. But then hey, it's your lens. If you think it is not sharp. By all means, make a trip to CSC. BTW, if the lens is new and under warranty, CSC will not charge. Do keep us posted on the diagnosis by CSC.

Coincidentally, I used to own the f2.8IS and now the f4IS. I never felt that indoor is bright enough for the f4, despite the 4-stop IS, without requiring ISO3200 (noise) or slow shutter speed (shake). Maybe I live in a dark dark house, in a dark dark place, in a dark dark world.

 

[yanyanyan881]

:thumbsup: you win.
AF sensors perform best in proper light. Ever heard about cross-type sensors going to single type in low light? And what gives you the impression that your manual focus is more accurate than the AF sensors?
Please get a focus test chart, setup as described and let us see the results there. This torch light tinkering is crap, sorry to be that frank.

becoz i can see the result btw AF and my own MF. ill post some more test soon.

 

[yanyanyan881]

Here is the 2nd set of test.
My windows wide open. its very bright today
No wind from windows, fan off.
550D + 70-200mm IS off standing on table and very stable.
mirror lock
10 secs
Dial on M mode. 1/20 @ F4 & 1/6 @ F8
Hood on
iso 100
no filter
focusing at the word CLEAR which is at the center of the image
live view 10x when using MF
all AF are One Shot and Phase detection
what else have i miss?

1)
F4 AF

2)
F4 MF

3)
F8 AF

4)
F8 MF

5)
F8 MF while holding D-button when M-focusing

 

[yanyanyan881]

6)
EF 50mm 1.8 @ F4

Few problems i suspect.

1) There is a bit of front/back focusing because my MF is sharper than AF.

2)This lens is soft at F4. The result F4 MF shows it is not close the 50mm 1.8 @ f4. (i know 70-200 can come very close to 50mm at F4.)

3)F8 AF is blur because I believe the lens is soft at F4 which leads to inaccurate focus. (all dslr focus at largest aperture before closing it when snapping)

For those who thinks all lens are soft wide open : see this again http://the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=404&Camera=453&Sample=0&FLIComp=0&APIComp=3&LensComp=105&CameraComp=453&SampleComp=0&FLI=4&API=0

I know 70-200 F4 IS can be super sharp wide open which is the reason why I bought it at 1st.

Ill still go down to CSC tml!

 

[ManWearPants]

For those who thinks all lens are soft wide open

I think what the others meant are the lenses' optimum performance is 1-2 stops down. It is undeniable that 70-200f4 is sharp wide open but even better when stop-down

Maybe it is my eyes. Your AF shots seems "sharper" than your MF to me but you did nail the focus in (5). Anyway, that is beside the point. I think it may be front or back focusing issue which CSC can calibrate. Strange that it happened after 2 weeks? Anything happened during this 2 weeks?

I'll run some tests tonight and see how it compares.

 

[yanyanyan881]

Maybe it is my eyes. Your AF shots seems "sharper" than your MF to me. Anyway, that is beside the point. Why don't you turn IS on or try at a faster shutter speed such as 1/focal length?

I'll run some tests tonight and see how it compares.

maybe a bit sharper. the F8 shots are clear to me MF is sharper.

 

[Anthony Lee]

Your no 4 and no 5 clearly demonstrate "focus shift" in an AF lens. No 5 you held the DOF button then focus manually, so what you saw, what the lens saw was what the camera took, that's why it's so much better.

 

[Learnphotography]

Your no 4 and no 5 clearly demonstrate "focus shift" in an AF lens. No 5 you held the DOF button then focus manually, so what you saw, what the lens saw was what the camera took, that's why it's so much better.

Hi, focus shift is a defect isnt it?

 

[Anthony Lee]

Hi, focus shift is a defect isnt it?

This is inherent of all AF lenses with auto-aperture controlled by the camera body. Although some are very well corrected so much so that when stepped down, because of wider DOF, its not noticeable. All AF lenses focuses wide open but depending on what aperture you have selected, it will take the photo with the selected aperture. Normally, focus shift is more detactable in fast lenses, like the Canon EF 50f1.2 and the Zeiss ZE 85f1.4. Google "focus shift" and read more about this phenomenon.

 

[ManWearPants]

TS, don't mind I share my test results here.

This test chart is taken from 1.5m, 85mm FL, ISO400, original sample image unedited. The below comparisons are all zoomed to 1:1

AF vs MF @ f4

AF vs MF @ f8

Auto Focus on my lens does focus off by a bit. This is not obvious when viewed from far but when zoomed to 1:1, you can see the slight softness. One interesting thing to note about the AF is that it is sharper at f4 compared to f8. This finding is not conclusive as the sample size is only 2. Manual Focus gives very sharp reading. Notice that when using MF, the image of f4 and f8 exhibit identical sharpness. This shows this lens is very consistent across f4 - f8 at least

Below is proof that this 70-200 f4 IS is incredibly sharp wide open. The sharpness is just as good as a prime lens stopped down 3 stops. however, lens sharpness is just one aspect. Notice the tonal gradation of the CY85/1.4. You can see the patterns within the grey squares whereas the Canon just produces almost flat grey squares.

70-200f4 vs Contax 85/1.4 @ f4

So TS, seems like you do need to send in to CSC for calibration.

 

[Anthony Lee]

MWP,

Excellent test. When you MF did you hold down the DOF button. Actually shooting this lens at F8, whether AF or MF, there should not be any detactable difference,and also the same when the shots are taken at F4 whether AF or MF . For such a slow lens, differences should not be noticecable at normal viewing. At longer distances this lens should be perfectly sharp whether MF or AF as I owned it for about six months and shot at least 2000 images with it. Excellent lens for both crop and FF.

TS, your lens is definitely out of specs, sent it to CSC for calibration.

 

[chicklit]

TS, u dun expect a lens to be sharp at the widest aperture in this case.

most lens soft spot is 2 stops more as explained by fatigue.

But this is 'L' lens, lens should be sharp on widest open and damn sharper if step down

I think what the others meant are the lenses' optimum performance is 1-2 stops down. It is undeniable that 70-200f4 is sharp wide open but even better when stop-down

For my self, I'll give a high standard for 'L' lens. Widest open should be pleasing, 1-2 step down should be best performance. In this case of 70-200 f4 L lens, if already in f8, I'll reject this copy. Cheapo lens even sharp at f8

Strange that it happened after 2 weeks? Anything happened during this 2 weeks?

I has differ opinion. I talk to a pro wedding photographer before, and he mention he need to calibrate his 24-70 L regularly because after times, the AF will run off. I also read that sometimes AF can run off because of lot of factors (if your lens fell down maybe )

TS, your lens is definitely out of specs, sent it to CSC for calibration.

2nd that. TS has done his homework nicely.
Based on TS test I'll conclude this lens need to calibrate.

 

[sinned79]

But this is 'L' lens, lens should be sharp on widest open and damn sharper if step down

L lens not equates to sharpness only. It means they are using a better glass, better build (some with weather proof), constant aperture etc.

I personally uses 3 L lens (35mm f1.4, 135mm f2 and 17-40mm f4) myself, but they are not exactly super sharp at f1.4, f2 and f4 but are reasonably quite sharp, fyi.

 

[chicklit]

L lens not equates to sharpness only. It means they are using a better glass, better build (some with weather proof), constant aperture etc.

I personally uses 3 L lens (35mm f1.4, 135mm f2 and 17-40mm f4) myself, but they are not exactly super sharp at f1.4, f2 and f4 but are reasonably quite sharp, fyi.

Yes; completely agree, 'reasonable sharp' is more proper word

 

[fatigue]

TS mentioned that he will bring his lens today to CSC.
Maybe they will compare his lens with the same lens model which I think would give the best comparison results

Let's wait for his update...

 

[ManWearPants]

MWP,
Excellent test. When you MF did you hold down the DOF button.

No, I did not press the DoF button but liveview x10.

I also read that sometimes AF can run off because of lot of factors (if your lens fell down maybe )

TS has done his homework nicely.

Which is why I asked if something happened during these 2 weeks since TS is in NS and would not have used it much. Agreed that TS has done his homework, just the initial tests is less conclusive than the eventual one.

Let's wait for his update...

If TS managed to calibrate his AF to be tack sharp like MF, then I will be the next to go CSC So will be waiting for his update.

 

[Anthony Lee]

If TS managed to calibrate his AF to be tack sharp like MF, then I will be the next to go CSC So will be waiting for his update.

MWP, if AF can be as sharp as MF then, there is no necessity in MF. When I first changed my focusing screen to Ex-S and replaced my VF with a 1.35x magnifier, I was often twitching the MF with my EF100f2.8 macro because I could see very clearly that AF was never accurate. Try this with your AF lenses, 50mm and above, focus on a chart like the one you used, AF, hold and shoot. Within that split second before the shutter clicks you may see the focusing actually shifted when the camera takes the picture. Because of such minor shift, I could never get AF to be totally accurrate. That's the main reason I am where I am, sacrificing confort, convenience, speed and everything that AF provides for focusing accuracy.

 

[ManWearPants]

MWP, if AF can be as sharp as MF then, there is no necessity in MF. When I first changed my focusing screen to Ex-S and replaced my VF with a 1.35x magnifier, I was often twitching the MF with my EF100f2.8 macro because I could see very clearly that AF was never accurate. Try this with your AF lenses, 50mm and above, focus on a chart like the one you used, AF, hold and shoot. Within that split second before the shutter clicks you may see the focusing actually shifted when the camera takes the picture. Because of such minor shift, I could never get AF to be totally accurrate. That's the main reason I am where I am, sacrificing confort, convenience, speed and everything that AF provides for focusing accuracy.

Yes, I have to agree with you on this one. None of my AF lenses are tack sharp on AF mode. Even if they are sharp at close distances, they may not be sharp at mid or infinity. AF are more for convenience and ease of use. For those who are insistent that L lenses have to be sharp and so and so. I think the AF mechanism is vital here. You may be disappointed if you pixel peep. I wonder how the Sigma zoom lenses will fare in the AF department.