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04-18-2014, 09:26 AM   #1
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DA 40mm f2.8 flare problem?

Hey fellow Pentaxians,

I bought the 40 Limited recently and received it earlier this week. I was extremely excited to get my first Limited so I have since been testing it, but I've come upon what appears to me to be a problem (with the coating?). This thing ghosts like crazy in any situation where the source of light isn't behind me. I'm using the hood, so I don't think it's that. Is this common for this lens? All my outdoor images are really low contrast and require a lot of work. My DA 35 f2.4 seems superior to this lens in all but build quality. I bought it used, so is it possible the coating was rubbed off or something?

Thanks.

04-18-2014, 09:40 AM   #2
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It might have a haze inside that isn't visible at first glance. Exactly the same problem I have with my K 50mm 1.4 and learned that recently when I looked through it against some torch light. What that haziness does is precisely what you've described - lack of contrast in well lit situation. I would check it and then contact the seller.
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04-18-2014, 09:45 AM   #3
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QuoteOriginally posted by manntax Quote
It might have a haze inside that isn't visible at first glance. Exactly the same problem I have with my K 50mm 1.4 and learned that recently when I looked through it against some torch light. What that haziness does is precisely what you've described - lack of contrast in well lit situation. I would check it and then contact the seller.
--manntax
Thanks for the reply.

What exactly would I be looking for? I held the blades open and shined a light through and saw dust. What else should I be looking for?
04-18-2014, 10:10 AM   #4
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I'm assuming there's no UV filter or anything on it that might be causing a problem. So take it off the camera, use your finger to open up the aperture blades, and shine a flashlight through it, in both directions… see what it looks like inside - dust, etc… then check it from angles. The coating should be reducing reflections, so it shouldn't be too shiny, but if the coating has been damaged it should be obvious. Some people are a little too vigorous in their cleaning. Might be a problem with the rear element, too, not just the front. That lens has such tiny elements (at least, my 40xs does and I think they're the same) that it might be difficult to keep clean properly. I've had a few pairs of glasses where I damaged the antireflective coating. I'm more careful with lenses. (and the last pair of glasses I bought I opted for mineral glass, no coatings at all (UV protection is built in somehow).

---------- Post added 04-18-14 at 01:13 PM ----------

QuoteOriginally posted by bsamcash Quote
Thanks for the reply.

What exactly would I be looking for? I held the blades open and shined a light through and saw dust. What else should I be looking for?
Though much of what he posts is questionable, this one is pretty solid.
The Flashlight Test

04-18-2014, 10:23 AM   #5
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QuoteOriginally posted by narual Quote
Though much of what he posts is questionable, this one is pretty solid.
The Flashlight Test
Thanks a lot. I'm not a huge Rockwell hater like many others. I have no problem taking his advice for things like this.

After inspecting the lens and blinding myself the first few tries, I can say to looks perfect to me. So what other options do I have? Should I get a tiny UV filter to screw on the inside of the hood, or should I just return the lens? I won the lens on eBay for $200, and I'm sure I will not find it again for that price any time soon, so I want to solve the problem by keeping the lens.

Thanks again.
04-18-2014, 10:38 AM   #6
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Yeah that's not normal. I'd return the lens. My DA 40 Limited is my second most flare resistant lens - it should not be doing that.
04-18-2014, 10:57 AM   #7
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QuoteOriginally posted by miltona580 Quote
Yeah that's not normal. I'd return the lens. My DA 40 Limited is my second most flare resistant lens - it should not be doing that.
That's unfortunate because the indoor shots, especially the portraits, are gorgeous and three-dimensional.

Last edited by bsamcash; 04-18-2014 at 11:03 AM.
04-18-2014, 10:58 AM   #8
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I have had mixed luck with the DA 40 limited. First copy was stellar for close ups but very poor on landscapes. Returned it. Second had 2 dust specks that reproduced. Returned it too. I have heard but don't know for sure that the limited number of elements in this lens results in small faults having big effects. I'm not sure that is correct but thought I would mention it.

---------- Post added 04-18-14 at 02:00 PM ----------

If you are getting dimensionality indoors, I would keep it for $200 and just make it your indoor lens.

04-18-2014, 11:06 AM   #9
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QuoteOriginally posted by kharry2012 Quote
I have had mixed luck with the DA 40 limited. First copy was stellar for close ups but very poor on landscapes. Returned it. Second had 2 dust specks that reproduced. Returned it too. I have heard but don't know for sure that the limited number of elements in this lens results in small faults having big effects. I'm not sure that is correct but thought I would mention it.

That's a good point.

---------- Post added 04-18-14 at 02:00 PM ----------

If you are getting dimensionality indoors, I would keep it for $200 and just make it your indoor lens.
Another good point.

I may just order another one to compare and return the worse one.
04-18-2014, 11:14 AM   #10
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I'd put a good quality polarizing filter on it when you're outdoors -- see if that fixes the problem you're seeing. A UV filter won't help anything -- I was saying a UV filter might be adding to the problem if you had one on there (at least, a cheap one).

I don't think i've ever actually used my XS outdoors in daylight. I mostly throw it on there when I'm going to hang out with friends and want to snap photos of them, which is usually indoors or in the evening or both. Now that spring is starting to show up, I'll probably use it outdoors in the light more. Hope I get better results than you're experiencing
04-18-2014, 11:53 AM   #11
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QuoteOriginally posted by narual Quote
I'd put a good quality polarizing filter on it when you're outdoors -- see if that fixes the problem you're seeing.
Any recommendations?
04-18-2014, 12:11 PM   #12
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Hey, my DA 40mm XS (similar if not same optical design) is not quite perfect wide open. At f2.8 it has a tendency to fringe. Overall I also find the DA 40mm XS to be more of a "purple" lens, while the DA 35mm f2.4 is more of a "green" lens. Some people are surprised when I say that, and I may be completely wrong about this. But this is what I feel about my particular lenses. There is a difference between different lenses and even variance between the individual lens copies. What I would suggest with the 40mm is to try stopping it down more, its a stellar lens from f3.5 onward, and I like its FoV and overall rendering more than my DA 35mm.
Also, feel free to post a photo or two, so we can see how bad it is. If you feel the lens is unusable or are unhappy with it, I would suggest you try returning it. Or at least go to a store and try another copy on your camera, to see if that one is noticeably better.
04-18-2014, 12:58 PM   #13
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QuoteOriginally posted by bsamcash Quote
Any recommendations?
B+W MRC if you can afford it.

There's a decent article here where someone did a comparison of a bunch of CPL filters a while back.
Polarizing filters test - Results and summary - Lenstip.com
04-19-2014, 08:12 AM   #14
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My guess is you have something on one of the elements. Maybe the last owner was a smoker. My 40 is nearly invincible with respect to flare:

Sun in the frame:




Strong cross-light



This shot is the worst flare I have ever gotten out of it. There is the green blob of reflection from the sensor, and just a little haze.
04-19-2014, 08:56 AM   #15
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Just to echo what others say, the DA 40 limited will flare some with direct light, but it should be pretty resistant to flare. Nothing like the DA 15 limited, but pretty good none the less.


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