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10-09-2014, 05:53 PM   #1
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Is this normal sharpness for the SMC 40mm Limited?

I bought the used SMC 40mm Limited lens which was listed on Adorama recently, and my gut feeling is that it is way less sharp and way less contrasty than all of the other lenses I own, from the 31mm Limited way down to the 18-55mm kit lens. If you have experience with this lens, could you take a look at these example photos and tell me what you think? There are two pictures which represent the whole frame, as well as a crop of the one with the red and green tree branches showing a weird bubble-looking pattern in the green tree. These are just direct JPEG conversions of the RAW files, with no editing in Lightroom at all.

Tomorrow I'll break out my tripod and take direct comparison photos with the 31mm Limited and the kit lens.

Thanks!

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10-09-2014, 05:58 PM   #2
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Something isn't right, as the samples from this particular lens are always great. I can't even see the focal plane in the last picture.
10-09-2014, 06:09 PM   #3
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I'd suggest manually focus in liveview to make sure it isn't a mis-focusing issue.

If it helps, here is the DA 40mm XS which is the same optical formula (unsharpened jpegs converted from RAW):
F2.8 - https://farm6.staticflickr.com/5574/14925270157_4c27f27690_o.jpg
F8 - https://farm4.staticflickr.com/3919/15111822355_e0be5fbe9a_o.jpg
10-09-2014, 06:12 PM   #4
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This lens is always sharp for me. Something is very wrong.

10-09-2014, 06:19 PM   #5
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Seems soft to me (assuming focus is on). This is a shot from my copy at f2.8.

10-09-2014, 08:32 PM   #6
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QuoteOriginally posted by Outis Quote
I bought the used SMC 40mm Limited lens which was listed on Adorama recently, and my gut feeling is that it is way less sharp and way less contrasty than all of the other lenses I own, from the 31mm Limited way down to the 18-55mm kit lens. If you have experience with this lens, could you take a look at these example photos and tell me what you think? There are two pictures which represent the whole frame, as well as a crop of the one with the red and green tree branches showing a weird bubble-looking pattern in the green tree. These are just direct JPEG conversions of the RAW files, with no editing in Lightroom at all.

Tomorrow I'll break out my tripod and take direct comparison photos with the 31mm Limited and the kit lens.

Thanks!
The complete shots are too small to tell here; the third one (the detail) is not focused on this bit of the image. The bubbly things are just out-of-focus highlights - this lens is not a great bokeh-creator. Can't really tell if the lens is at fault from these samples. I have a DA40, and while I find the focal length a bit strange, it performs very solidly.

Last edited by timo; 10-09-2014 at 08:36 PM. Reason: initial brain failure
10-09-2014, 08:45 PM   #7
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This was with mine this evening. Im happy with this lens.

https://www.flickr.com/photos/125982732@N04/15489559451/
10-09-2014, 08:56 PM   #8
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That last pic clearly shows that focus was way off.

10-09-2014, 09:43 PM   #9
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The OOF highlights in the last photo look like coma to me. This is from a 24mm lens that is excellent at coma, and not very sharp:



I have never used a DA 40 but really doubt it should look like any of the OP's sample shots.
10-09-2014, 10:40 PM   #10
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Your third pic's OOF dots in the leaves tell the story -- your lens is focusing on the wrong plane. That's not to say it's missing it's focus but that it's simply focusing in the wrong place. That's why you have those OOF dots with the bright centers. It's like how a magnifying glass focuses the sun at a certain distance from the ground or an ant but doesn't if you move it closer or further. I suspect you have an element installed backwards or some missing mount shims (or too many) that are changing the lens' plane of focus. Have you ever had this lens serviced? Did you buy it used?
10-10-2014, 01:06 AM   #11
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Send it back. This is what it should be like.
10-10-2014, 05:49 AM   #12
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Oh, sorry I wasn't clearer-- the third pic is a crop of the second pic, so I may have just managed to crop an out-of-focus area.

Yeah, I bought it used. I've never had the lens serviced-- I've had it for all of two days now.
10-10-2014, 07:27 AM   #13
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focus adjust

You may want to try testing the lens for front or back focus. I don't know what f stop the photos abover were taken with but I have a lens that was underperforming and finally figured out that it was front focusing. It was more apparent at larger F stops.
10-10-2014, 08:44 AM   #14
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QuoteOriginally posted by JinDesu Quote
I'd suggest manually focus in liveview to make sure it isn't a mis-focusing issue.
Do what he says. I'll offer more details on a test routine below. This is by no means definitive and others might offer alternative or even better ways. Basically, you want to check manual first, then contrast detect, and finally phase detect autofocus.

Put the camera on a tripod, switch to manual focus, press the Info button to zoom the view to get perfect focus. Try this on a close object as well as a distant object to make sure manual focus works at all distances. Do the photos look sharp?
  • If no, then an optical problem is preventing good focus. There's not much you can do on your own to fix the problem. The lens needs servicing.
  • If yes, then start testing autofocus. Continue below.
To test autofocus, start with manual focus (or quickshift if the lens allows) and blur the image. Then press your AF button in liveview to activate contrast detect AF (CDAF). Is liveview AF giving sharp images?
  • If no, there might be a mechanical problem. Maybe the focusing motor isn't engaging or the gears in the lens are bad.
  • If yes, continue below to test phase-detect autofocus (aka PDAF).
With liveview off, AF on one of the targets above where you already got a sharp image. Is the image sharp?
  • If yes, your problem is "magically" fixed. This is good news and suggests operator error in the test photos posted at the top of this thread.
  • If no, the lens might have poorly calibrated PDAF on your camera. If it's not too far out of range you can use the camera menus to adjust the lens AF.
10-10-2014, 08:46 AM   #15
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QuoteOriginally posted by Outis Quote
Yeah, I bought it used. I've never had the lens serviced-- I've had it for all of two days now.
Surely Adorama will take it back ? You could probably get it repaired but the chances are that it will take more effort than it is worth to sort out the repair. As for front/back focus - go outside in good light and take a slanted shot of your pavement (sidewalk). Then see if anything is sharp and in focus.
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