Canon EF 35mm f/1.4 L not as sharp as 50mm 1.8 STM?

[AutumnApple]

Hi guys. In my previous question regarding getting good focus on big aperture. I mention that my camera or 35mm L lens seems to have little focus issue. As recommended, I put my camera and lens on tripod and tested with stationary subject today. 

I used 3 different cameras for the test and results were the same on all 3 either shooting through viewfinder or using liveview so I'd just post one example in here. 

Cameras were 6D and 7D, lens in tests were Canon EF 35mm 1.4 L and Canon EF 50mm STM. I used tripod, all test were set at 1/250 up to 1/640 , f/1.8 , ISO 100. Focus were set on the cross in the middle of this remote

This one is result with 50mm lens

This pic were result of 35mm lens

I did attempt to do little AMA using dotune method, +2 seems to yeild slight improvement on 35mm but still not as clear as I'd expected. What should I do next? I do notice the strange behavior (handheld tested only), for same setting, it focus better if subject is closer.

[Waddizzle]

Next time use a ruler, instead of a remote control. Angle the ruler so that it is about 30 degrees to the plane of focus.

[wq9nsc]

You 35MM looks like it is back focusing to me.  As Wadizzle noted next time use a ruler as your subject but looking at whatever is supporting our remote it looks more in focus than it should be (Look to the left side of the remote where the light isn't likely blowing out the highlight) with the 35mm.

Rodger

[AutumnApple]

Thank you, Waddizzle and Rodger. I will find a ruler and update the test. Today is pretty gloomy and dark, so I might have to wait since I donot have external light 

[ebiggs1]

One issue with how you are comparing the two lenses is the remote is not straight up and down. Not perpendicular to the lens.

Second focus adjustment in the camera does not, and can not make the lens any sharper. The lens is as sharp as it will ever be. It simply moves the critical focus point.

OK, just because there is an "L" at the end of the lens name does not mean it is a sharper lens than some other lens. The 50mil is a sharp lens in its own right. The "L" indicates a professional package while the 50mil is a general starter beginner type lens. This is not to say it isn't a good lens. It is just the goal in its design is different.

[ebiggs1]

To expand on this a bit further, in real world use can you see a difference? Almost any lens will show some issues when put to a critical test like this. For instance I bought the sharpest 50mm lens made in the Sigma 50mil Art f1.4.  I sold it in favor of the Canon ef 50mm f1.2L.  The Siggy is sharp, I mean, but the Canon 50mm is just amazing. Beautiful lens. Nothing like it.

[Waddizzle]

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@AutumnApple wrote:

Thank you, Waddizzle and Rodger. I will find a ruler and update the test. Today is pretty gloomy and dark, so I might have to wait since I donot have external light 

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If you are using a tripod, you can take test shots indoors as long as you have sufficient room.  How room you need to check AFMA using “Dot Tune” is 50x the focal length.  The problem with testing indoors is the narrow band, artificial lighting.  Testing with broad spectrum sunlight is best.

If you do not have a ruler, a tape measure stretched out on the floor, or ground, away from the camera works, too.  Just angle the camera downward so that it is at a 30-60 degrees angle to the focus point.  A 45 degree angle would be ideal.   

The whole point of angling the camera to focus on the test target is to test back or front focusing.  This cannot be observed when the test target is aligned parallel with lens’ focus plane, or straight up and down, as previously suggested.

[Waddizzle]

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@AutumnApple wrote:

Thank you, Waddizzle and Rodger. I will find a ruler and update the test. Today is pretty gloomy and dark, so I might have to wait since I donot have external light 

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BTW, many complain that the EF 50mm f/1.8 STM becomes soft wide open.  In some cases, this may be user error.  In other cases, it may be a lens that is out of adjustment.  I think there is another possible cause for the complaints, too.

I do not think the EF 50mm /f1.8 STM focuses consistently enough to bother with an AFMA adjustment. If the lens is way off, it may help, but a lens that focuses this poorly would need warranty service.  

Most consumer lenses probably fall into this category of not focusing consistently enough to make it worth the trouble to do an AFMA adjustment.  Wide open the depth of field is pretty narrow.  Also, most consumer DSLRs, specifically most Rebels, do not have AF systems that are accurate enough to make it worth adding AFMA, or even using professional grade lenses.

[AutumnApple]

Thank you everybody for suggestions. Sadly my 35mm lens had started serious focus issue after I posted this thread. All photos either handheld with fast shutter speed or on tripod are blurry like it completely missed focus and sometimes hazy like when you put a cheap scratched filter on it. Im sending it in to Canon hopefully it won't be too expensive to fix

[ebiggs1]

"Im sending it in to Canon..."

That is where it belongs.