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12-30-2008, 02:52 PM   #1
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help... second opinion on my 16-50?

I've been doing some testing on my new DA*16-50, and I'm a little concerned. It front-focuses a little bit, but I'm on the fence about whether or not to send it in for an exchange just based on that.

However, the vignetting seems a little excessive to me. There is vignetting visible at the wide end even at f8, and it's quite pronounced at f4 and lower. Corner softness also seems a little excessive under f4, but I'd really like a second opinion.

Thanks in advance!

Thumbnails go to full size image:
16mm f/2.8


50mm f/2.8



16mm f/4


50mm f/4



16mm f/8


50mm f/8


12-31-2008, 02:57 AM   #2
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Anybody? I know people are probably sick of these threads at this point, but I have essentially one day to decide whether I should try to exchange with B&H or if the vignetting and corners are within reasonable tolerances for this lens and I should keep it, and I'd really appreciate any opinions.

The focusing issues I can deal with, or send in to Pentax. Thanks to anyone who takes a look!
12-31-2008, 04:28 AM   #3
RaduA
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QuoteOriginally posted by yenemy Quote
I've been doing some testing on my new DA*16-50, and I'm a little concerned. It front-focuses a little bit, but I'm on the fence about whether or not to send it in for an exchange just based on that.

However, the vignetting seems a little excessive to me. There is vignetting visible at the wide end even at f8, and it's quite pronounced at f4 and lower. Corner softness also seems a little excessive under f4, but I'd really like a second opinion.

Thanks in advance!
IMO, this is not the best lens to shoot walls with since it has some optical curvature, hence the fuzziness of the corners. Also I find the pictures underexposed (look at the histogram) and the light uneven so a even further difficult scene to pose.
All in all after some levels in photoshop I'll say the vignette is not bad, all the picture is underexposed and that agravates what you percieve as vignette.

I hope it helps.
Radu
12-31-2008, 12:19 PM   #4
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Thanks, Radu. Yeah, I tend to underexpose my shots a lot. Not sure why, I might have my LCD and monitors gained up a little too much. Good point about it affecting my perception of the vignette, that's definitely a factor.

I did the brick wall as I've seen/heard that to be a standard sharpness/lens test.

12-31-2008, 12:58 PM   #5
RaduA
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QuoteOriginally posted by yenemy Quote
Thanks, Radu. Yeah, I tend to underexpose my shots a lot. Not sure why, I might have my LCD and monitors gained up a little too much. Good point about it affecting my perception of the vignette, that's definitely a factor.

I did the brick wall as I've seen/heard that to be a standard sharpness/lens test.
Yenemy,

Like I said this lens and many others have an optical curvature that will make corners fuzzy. Other lenses (such as macros and tele ones) tend to have a planar field that makes them more apt for this wall test.

I took one picture in PS and the histogram shows massive underexposure. If you have an image editor (Photoshop or an equivalent) just adjust this and the whole picture will change pretty dramatically. I still don't think your lens acts unusually!

Regards,
Radu

Last edited by RaduA; 05-14-2009 at 07:03 AM.
01-02-2009, 03:42 AM   #6
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QuoteOriginally posted by yenemy Quote
I did the brick wall as I've seen/heard that to be a standard sharpness/lens test.
Yenemy,

The brick wall is not a standard sharpness/lens test as far as I know.

For vignetting you'd better shoot a blue sky and see how much the corners darken in comparison of the center of the image. There is no way to tell how much the colours of the individual bricks differ now.
Also, it is very hard to align your camera with the plain of the wall.
At last, brick walls tend to be not a 100% even surface.
The pin cushion effect you are seeing is not depending upon diafragma.

If the sharpness of the lens is good enough (and I'd find a different setup to test that), straightning the lines and compensating the vignetting can easliy be corrected by in postprocessing with Bibble Pro and the likes.

Succes,

- Bert
01-03-2009, 04:15 AM   #7
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Thanks for the help guys. I did some random shooting around town, and I've decided I'm happy with the lens' performance, except for the front focusing which is admittedly only noticeable on close-ups. I may pack it off to Pentax warranty repair, we'll see how it goes.

Now the next challenge is how to "uglify" my K10D and 16-50 for my backpacking trip to Asia so it doesn't get stolen!
01-03-2009, 05:54 AM   #8
RaduA
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QuoteOriginally posted by yenemy Quote
Thanks for the help guys. I did some random shooting around town, and I've decided I'm happy with the lens' performance, except for the front focusing which is admittedly only noticeable on close-ups. I may pack it off to Pentax warranty repair, we'll see how it goes.

Now the next challenge is how to "uglify" my K10D and 16-50 for my backpacking trip to Asia so it doesn't get stolen!
You're welcome and have a nice and safe trip!

Radu

01-04-2009, 03:14 PM   #9
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Where in Asia are you going?

I took my K10D with the not-so-impressive Kit Lenses through Thailand and China last year, and no one even looked at me funny...

They're pretty serious about crime over there, and basically every tourist has a giant digital camera, so you won't stick out too much (plus no one's heard of a Pentax! They're far more likely to go for a N*kon or C*nnon!)
01-04-2009, 10:15 PM   #10
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QuoteOriginally posted by yenemy Quote
Thanks for the help guys. I did some random shooting around town, and I've decided I'm happy with the lens' performance, except for the front focusing which is admittedly only noticeable on close-ups. I may pack it off to Pentax warranty repair, we'll see how it goes.

Now the next challenge is how to "uglify" my K10D and 16-50 for my backpacking trip to Asia so it doesn't get stolen!
I wouldn't be too concerned with uglifying the camera and lens itself. You're significantly less likely to be mugged in most of Asia than the most of the US.

Your camera bag, on the other hand, needs to be damn ugly or at least inconspicuous.
01-04-2009, 11:34 PM   #11
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QuoteOriginally posted by Hannican Quote
Where in Asia are you going?

I took my K10D with the not-so-impressive Kit Lenses through Thailand and China last year, and no one even looked at me funny...

They're pretty serious about crime over there, and basically every tourist has a giant digital camera, so you won't stick out too much (plus no one's heard of a Pentax! They're far more likely to go for a N*kon or C*nnon!)
Believe me, they are not going to mug you, but they will attempt to steal it from your room, anywhere they get a chance.

try an old beat up napsack with a real smaller camera bag inside with some dirty old socks etc, they'll pass it up every time.
01-05-2009, 04:18 PM   #12
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QuoteOriginally posted by yenemy Quote
Thanks for the help guys. I did some random shooting around town, and I've decided I'm happy with the lens' performance, except for the front focusing which is admittedly only noticeable on close-ups.

Now you're properly testing the lens. In my opinion, there's no need to look for problems with your gear if you're happy with how it works in the real world.

I must admit I almost gave into the hype on the 16-50 and started to shoot some brick walls. Then I just stopped, banged my head against said brick wall a few times, and then went out and shot with the lens. I'm happy with the shots I get, so it's a keeper.
01-07-2009, 02:34 AM   #13
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Wow, I forgot about this thread for a few days, and I come back to responses, hehe.

Appears there's some curiosity about my trip, so some details: Right now my trip is going to be ~2 weeks in China in early April -- along the Great Wall -- and 2 or 3 months after that touring various places.

I'll be travelling pretty light; I'll have this pack -- yeah, it looks like an expensive pack, so that worries me a little too. Stuffed in it will be the normal semi-roughing-it essentials, along with a notepad+pen, Eee PC, and K10d. Might take my UltraPod as well, but I don't think it'll deal with that body+lens combination very well.

I'm only taking the 16-50 with me. I considered bringing the Sigma 10-20 and Tamron 90mm macro as well, but so far I think I'd rather concentrate on the journey rather than photography this time -- it's a soul-seeking kind of trip


Hannican:
That's great to hear, thanks. I keep hearing things to the same effect, but I'm kind of a paranoid traveler and need to be reminded often There's no set plan yet, but the list of "wants" so far are: China, Thailand, Laos, Vietnam, Cambodia, Hong Kong, Taiwan, and Japan. That list will have to get trimmed down... just have to figure out which ones. Mongolia's a maybe as well. If I get really crazy, I may even give in and pop over to India for another month or two.


Kranrev and Torphoto:
The camera bag I have is a small LowePro AW -- just big enough to hold the K10D with 16-50 attached, and some extras -- SD cards, extra battery, and lenspen. I'm going to take my Canon P&S as well, so some days I'll probably have to just wrap the K10D in dirty clothes and stuff it in my pack or find somewhere secure to keep it.

When I do go out with the K10D, it'll be on a neckstrap around my neck, or strapped to my hand. When I'm chugging along a road or trail on foot, it will probably be hanging around my neck or stuffed in the pack.


rfortson:
Thanks. I'm pretty geeky, so it's tough for me not to get caught up in the numbers and constant scrutiny of my purchases. I guess the justification is, if I know my gear is good, then I have eliminated all of those variables of error. So, the poor results I get can only be blamed on me.

Or the corollary; if I can convince myself there's something wrong with my gear, then the poor results aren't my fault

The fair argument is that we deserve an "as promised" product for our hard-earned cash, but I do get carried away sometimes. Either way, I'm happy with the copy I have.
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