EF 24-105mm f/4L Soft and Hazy

[wilmark]

I have the above lens that is very soft and hazy - but i cannot see any dust or mold. I think i want to try to tear it down and see if i can do anything with it.  Like this guy is doing here: 

https://www.youtube.com/watch?v=bdShwMk-LDc

But he says that the "Axis Test" showed poor results early in the video. I gather that some of the elements are misaligned causing the blurriness. I'd like to confirm that it is indeed an axis problem. Any idea what exactly is an axis test? What charts are used? Is it the same as a lens calibration test?

[Anonymous]

Try removing the polarizing filter and make sure the lens hood is not installed crooked. That haze looks like some sort of reflection to me.

[wilmark]

Thanks - ill try this. 

[amfoto1]

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@wilmark wrote:

Yes i have a Hoya polarizing filter that remains on - and the hood never comes off. 

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Hoya makes some six or seven different qualities of polarizing filters, ranging from very good to utter crap. It is probably the filter is causing the problem you are seeing and I'm guessing it's not one of their better, multi-coated ones (such as their "HD3" or "NXT Plus").

While a quality circular polarizer is one of the most useful filters with digital photography, there is no way one should "remain on". There are many situations where the filter can help... but there are also many where it will be more of a problem.

A C-Pol cuts 1.5 to 2.25 stops of light, forcing you to use higher ISO and/or slower shutter speeds. When shooting in marginal lighting conditions, the filter is just hampering you unnecessarily.

There also are times when a C-Pol is effective and times when it's not. The polarization effect is greatest  at 90 degrees from the light source, tapering off to nothing at 0 or 180 degrees. So shooting a scene midday with the sun right above your  head might give a fairly strong filter effect. But pointed directly at a sunrise or sunset, or pointed directly away from a sunrise or sunset, the filter does nothing but potentially cause flare.Here is an example where the sun was high and a bit behind me, so the effects of the filter deepening the blue of the sky and the green of the water was fairly strong (in fact I dialed it back a bit, so the reflections of the boats in the water wouldn't completely disappear)

:

In addition, because of the variation in the polarization effect, you can get uneven look in broad, plain expanses, such as the blue sky in the image below:

The sun is low and off to the left in this image, so the filter's effect is stronger on the right hand side of the image. It was a plain blue sky, so I didn't mind the difference in this case. But I could have gotten a more even sky without the filter.

Here's an example where clouds in the sky tend to "hide" a similar uneven effect from a C-Pol... this time with the sun low and to the right:

C-Pol filters reduce reflections... but sometimes the reflection IS the image! The last thing I wanted for the shot below was to reduce the reflection of the sunset off the water or the wet sand and rocks (not to mention, directly shooting a sunset would mean no polarizing effect in the middle of the image), so I didn't use any filter at all:

A C-Pol can be helpful for portraits, too... if a subject wears eyeglasses or has "shiney" skin.

But a C-Pol should not be left on all the time. If you try to photograph a rainbow, a C-Pol will make it disappear! As you can tell, I don't hesitate to use a C-Pol... It's by far my most used filter, ever since I switch from film to digital 20 years ago. HOWEVER, I probably only use one 10 or 15% of the time. I would never let one "remain on" my lens all the time!

Try some shots without the filter (and with the lens hood properly installed) to see if you have less flare issues.

There is another possibility... a dirty sensor in your camera. That also can cause problems like you're seeing. And, yes, it can be problems with the lens itself. But both of these are far less likely than the filter.

***********

Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2), EOS M5, some other cameras, various lenses & accessories
FLICKR

[Waddizzle]

If you sent it to Canon for a repair and it came back with a performance issue, then I have to ask whether or not have you tried to contact Canon.  Any repair should be covered under a repair warranty.  

I think you need to talk to Canon Support, not social media.

[wilmark]

Hi - i did some trial shots - with the filter/hood on and off and with the same filter on my 70-200 for reference, both Wide and Zoomed.

First i made a mistake about the filter - its a simple UV filter like this one https://www.amazon.com/Hoya-Digital-Frame-Multi-Coated-Filter/dp/B002L60TTI?th=1

The photos were generated using Print from Lightroom because i can figure out no other way to put either the file name or other keywords on the photo - amazing that this cant be done in 2023. I ill appreciate any feedback - the Hooded + no Filter seems just slightly better. (Forgive the quality - trying to make the image small and i suspect that using "Print" also has issues)

I see

[Anonymous]

I see a slight improvement without the filter. Is the front and rear element of the lens perfectly clean with no smudges or fingerprints?

[wilmark]

Yes its all clean. The 70-200 is way cleaner and lacks any haze, all the 24-105's have this haze on it. The latter is wide open at 4, while the former is 2.8. 

[wilmark]

I explained why this became a problem in one of my other posts here. Im not blaming canon, I realized the problem with the repair too long after the repair. My question/post is fairly specific - its about testing a lens to see if there is an Axis or alignment problem. Sending it back to canon will mean at least 400$ + shipping and Duties when the camera enters back my country and i still might not fix it, and i dont consider this feasible at this point. Which is why i contemplated this. 

[Anonymous]

With clean front and rear lens elements and no filter installed, there would appear to be some problem with the lens. I would recommend getting it serviced.

[ebiggs1]

My advice as my associates have indicated don't take the lens apart. There is nothing you can do at home to repair anything related to alignment issues or decentered. Now if you just want to run the percentages or chances keep these in mind. It is highly unlikely that Canon returned a faulty lens. Not impossible but surely way improbable. Secondly, it is very highly likely the UV filter is causing the issues. Discard it today. Keep the hood always. Lastly and I know, most untasteful, is the fact 90% of all OOF and/or any focus issue is user caused and not do to gear.

Someone mentioned, "Is the front and rear element of the lens perfectly clean with no smudges or fingerprints?"

This, too , is not the cause unless it is really smudged to be obliviously noticeable. These parts of the lens are OOF to the camera sensor and generally will not effect the picture. Since light is everywhere and not simple straight lines it will pass such imperfections. I have seen font elements that were cracked that did not show up in the photo.

Try the test KVB suggest