My lens doent look sharp

D

DDirector

Veteran
I have my Canon 17-55 f/2.8 IS lens and looking back at my footage, the lens doesnt look very sharp. Even shooting at f/4.0 or f/5.6
I don't know if its my monitor that isn't displaying the image to the best quality or what, but I doubt it.

What I have a feeling is that when I was cleaning the inside of the lens, I might have adjusted something and the focus was thrown off...
Is there a way to check if the focus is good, and the quality of the sharpness?

Its my main go-to lens, and it isn't really impressing me much.
With such a high quality camera I have, it seem to be lacking the image detail I should be getting.


Posting the picture will probably turn out to be a waste of time as it will probably compress the image and it may not look that bad. I can tell something is off about it.
 
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I use the Canon 17 - 55 EFS lens all the time on my C300. Requires regular cleaning but should be very sharp. Push the lens to 55mm, frame up a focus chart - actually anything with lots of small lines etc will be ok for this purpose - make sure its something perfectly flat with lots of intersecting lines. SO, farm that up. Use the focus hook to measure distance to chart / image....Actually the markings on the lens are a little broad so measure from focus hook and ensure its exactly say 2 feet from the image. Set the lens focus point to 2feet.

Record or watch on large monitor to verify if its soft or not. That should be pretty close to verifying though the focus marks on this lens aren't super accurate.
 
Noel Evans said:
I use the Canon 17 - 55 EFS lens all the time on my C300. Requires regular cleaning but should be very sharp. Push the lens to 55mm, frame up a focus chart - actually anything with lots of small lines etc will be ok for this purpose - make sure its something perfectly flat with lots of intersecting lines. SO, farm that up. Use the focus hook to measure distance to chart / image....Actually the markings on the lens are a little broad so measure from focus hook and ensure its exactly say 2 feet from the image. Set the lens focus point to 2feet.

Record or watch on large monitor to verify if its soft or not. That should be pretty close to verifying though the focus marks on this lens aren't super accurate.
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I have other lenses, I feel this one is the least sharpest.

Its very hard to tell if its off or not.
Looking at my test from 5ft. When I set the focus line in the middle of the #5' on my lens it seems to be just off. When i adjust it manually, I have to move the focus like half of a millimeter in the direction towards infinity. Its almost impossible to tell if its off or not on these lenses. The focus is on the right edge of the printed #5... if that makes sense? But barely a difference at all.
It shouldn't really make a difference at all really.

Whether its focused or not, it still seems kinda soft. I havent compared it to other same lenses, so I cant compare how much if it is any much softer than the other ones.
 
I would not be trusting any non cine lens to be accurate to lens datum.

Even cine lenses get tested to measure and eye focus.

I havent compared it to other same lenses, so I cant compare how much if it is any much softer than the other ones.
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Why not? Do a standard lens test on all of them...especially the one you consider has an issue.

Not sure what you are expecting from this post. We cant see what you are... and you have not run any tests!


My guess...its soft ( perception is everything)..and you opening it up to clean it or what ever...caused it.
 
Is it you selling the set of Contax primes - some of the sharpest lenses ever?

You took it apart?- hmm well Id say you put something out of alignment!

S
 
On stills lenses, focus markings are useless. Use your eyes for focusing. The best method is to use the zoom-in focusing aid (not zoom, focus, zoom, which would only work on parfocal lenses, but the button that gives you 10x digital magnification). If you can't get good sharpness that way (compared with other zooms, not with primes), there's something wrong with your lens.

I may be a bit OCD, but I always thought that knowing my gear inside out would help me be a better shooter. So, in the case of my lenses, I tested all of them to see exactly how sharp they are at each aperture, how good bokeh is on each one, etc. I carry a note on my phone that reads something like: "35mm: sharp in the center from f/2.8, in the corners from f/3.5", and so on for every lens I have. I also spent a day putting accurate focus marks on all my lenses (this won't work with modern lenses with no hard stops).
 
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Did you really take it apart? I've got plenty of proper tools, and am pretty practical, but dismantling a lens? I watched a guy do this once. His workshop was spotless, the working surface covered in a white cotton cover, he wore cotton gloves (or at least white fabric type) and he had huge anglepoise magnifying lenses and lights. The lens he was dismantling was a Fuji B4 mount, and the number of parts just to get to the rear elements was amazing.

Fascinating, but I know I'd not even think about it myself. It could be that you accidentally put pool from your fingers on one of the inner lens surfaces, softening the image.
 
paulears said:
Did you really take it apart?
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I would put ??? after that... I've never taken a 35mm lens 'apart' to clean it... If I felt a great need I'd send it out to service, with the expectation that it would come back 'better', and would tested to see if it was 'better'...

On the other hand, cleaning the back elements I've done 'rarely'... since the Wife and I have tended to use zoom lenses for the Wedding work, and perhaps only changed lenses on the Hasselblad 'in the field'...

Ok, on 4x5 cameras I would change the lens on the camera which required one to take the back element off the lensboard/shutter, and likewise for the front element, and with a can of air blowing things off to try to mitigate dust... and usually never 'on location'...
 
DDirector said:
...What I have a feeling is that when I was cleaning the inside of the lens, I might have adjusted something and the focus was thrown off...
Is there a way to check if the focus is good, and the quality of the sharpness?

Its my main go-to lens, and it isn't really impressing me much.
With such a high quality camera I have, it seem to be lacking the image detail I should be getting.
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First, you said this was your go-to lens, so I assume you have had plenty of experience with it (especially with your monitor/camera setup) and therefore I trust your new observation (regarding loss of sharpness) is an accurate one.

Second, that leaves you with two options. 1) Send it away for repair or 2) Buy a new one.

Third, most anyone who opens a lens up and takes it apart is, with few exceptions, asking for more trouble than it's really worth. Those exceptions include those who have some basic training/knowledge in the matter or do it professionally. Otherwise one risks disturbing the delicate and precise nature of elements, lens groupings, etc. Long exposure to heavy vibrations are sometimes enough to misaligned an element, so we are talking about some rather precise optics at play.

I take photography lenses apart when I 'retire' them from service. I like to see how they work and I'm always willing to lose those that I dismantle and I always do.

A misaligned lens element can present many issues but if I were you and I was still not sure if that is what really occurred I would look for the following:

1) Does sharpness vary greatly over the zoom range? Does it get significantly worse from one end of the range to the other?
2) Does sharpness vary from one area of the image to another? For instance, does the top vary greatly from the bottom, or does the left vary greatly from the right?, etc
3) Do you see an increase in CA or any other aberrations? (Blue, Magenta, or Green fringing)

because photography lenses do not have accurate witness marks, judging anything by those would not be efficient unless drastically off (like if 2' was in focus when the lens said infinity)


Good luck.





Picard-facepalm.jpg
 
I've cleaned this lens before. Its just removing the front glass. Its not that big of a deal opening it up.
There are YouTube video tutorials of how to do it too.
I'm not saying this is the cause though.

I have not noticed any big changes. Not additional CA or colours, or varying focus.
I wasn't all TOO impressed when I got the lens in the first place. But it was not that bad. I just find it a little more noticeable with the C300.


Again, I'm not sure if this is the cause, but if it was something that happened during cleaning, is there a way I can clean it?
Taking it out to get it serviced is not really an option for me
 
Taking it out to get it serviced is not really an option for me
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Apart from retiring the lens...I would have thought that is the only option if you want a lens that you can use and trust professionally.

Show us a frame grab from a test.
 
Shooter said:
Apart from retiring the lens...I would have thought that is the only option if you want a lens that you can use and trust professionally.
Show us a frame grab from a test.[/COLOR]
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I just have gigs going on regularly now and I cant send it out and wait over a month for it to be 'cleaned'. If it could be done in a day, that would be fine...
I'm out on a shoot for a week now, so I cant post any frame grabs. I'm on my phone.
 
You are shooting with a lens that you have no confidence in!

Could be a career changing decision. :undecided
 
DDirector said:
I just have gigs going on regularly now and I cant send it out and wait over a month for it to be 'cleaned'. If it could be done in a day, that would be fine...
I'm out on a shoot for a week now, so I cant post any frame grabs. I'm on my phone.
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You are out for a shoot for a week and are shooting with a soft lens?.... Go rent that lens for a week for $90 and get yours fixed. I hope your client isn't a weekend shooter and ends up on this forum!
 
Looking at your lens list you have coverage so you don't even need to rent , just use your others. All of them are better than your 17-55 if its soft!
 
I had done the mistake of opening a manual focus lens in 1995 due to curiosity and it was a costly mistake. These are sophisticated equipment and it is better done by a trained and equipped technician.

On another note, If a cinematographer can do a technician's job as well as he/she does, then one should also expect the technician to shoot professionally and take our assignments.

No point in trying to use a lens that is less than optimal and later get a bad name. Producers have an elephantine memory.
 
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