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07-09-2008, 12:53 AM   #1
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yet another how is my lens thread

sorry to make another one of these. i feel like we should be forum-ing (talking) about more substantial topics. but this isn't about a DA* 16-50! and this is MY lens!

i just got a DA 12-24 on the weekend, BIG purchase, and only have a 7-day return period, so i want to make sure what i have is good. so some third-party opinions (from you) would be amazing, wonderful, greatly appreciated .

short story: it looks like the right side is softer/more blurry in some of the test pics i made. they were not scientifically done - no tripod, no aligning the lens with a mirror, etc. but at 12mm the depth of field, even @ f4, focused to only 6' extends from 3' to infinity, so i don't think dof should be an issue (?).

here are two pictures, with left and right side crops (k10d, RAW, no sharpening at all, no NR, only correct CA, exposure a little):

shot 1, crops highlighted:


Left side:


Right side:


image 2, crops highlighted:


Left Side:


Right side:


opinions please! what do you think? am i imagining things, no big issue, or bring it back immediately? i only have a couple days to decide.


p.s. i wanted to try both the 14mm 2.8 and the 16-50 but adorama was sold out.

pps. they had a k50 1.2 listed online when i left that i wanted to try also, but it was sold by the time i got to the store!

ppps. anybody know why the html code from flickr for posting an image doesn't work on here? "the community guidelines specify that if you post a Flickr photo on an external website, the photo must link back to its photo page." i had to make the images link back manually. maybe some setting can be changed on the forum?
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07-09-2008, 01:05 AM   #2
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QuoteOriginally posted by architorture Quote

Left Side:


Right side:


~
Seems to me the sharpness or the lack thereof is the same (re brickwall)

Daniel
07-09-2008, 02:03 AM   #3
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First of all, your pictures look terribly underexposed, so it makes it hard to ascertain detail. Secondly, are you shooting hand held or on a tripod? What were the exposure settings and the focus point?

Frankly until you can eliminate potential variables such as focus point and camera shake and whether you were shooting perpendicular to the wall, I'd go along with danielchtong's observation.
07-09-2008, 11:39 AM   #4
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danielchtong:
thanks for the opinion. what about the first image though, you don't think the"24 hr. P" part looks odd compared to the other side of the frame?



QuoteOriginally posted by creampuff Quote
First of all, your pictures look terribly underexposed, so it makes it hard to ascertain detail. Secondly, are you shooting hand held or on a tripod? What were the exposure settings and the focus point?

Frankly until you can eliminate potential variables such as focus point and camera shake and whether you were shooting perpendicular to the wall, I'd go along with danielchtong's observation.
are you referring to the overall views? those have a 50% opacity layer of black over them with squares taken-out to show where the crops came from. the crops show the actual exposure - if you're saying those are too dark ok, but the sky was blown out.

to your second point - i mentioned all that already. and the exif is in the files, too. i was well past even 2x the focal length for shutter speed. the first shot is 24mm, f4, 1/200s. the second shot is 12mm, f5.6, 1/50s.

and even if there is variation from one picture to the next, i don't see how that makes it impossible to judge them. i'm comparing one part of one picture to another part from the same one.

07-09-2008, 12:16 PM   #5
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Hi,


What I would do is to take a photo with say the 24 hour sign on right hand side of the image and then another with it on the left hand side.

That way you will be comparing the same thing and should make your analysis a bit easier.
07-09-2008, 12:19 PM   #6
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Just out of curiosity, how does a center section look? You can tell how much things fall apart at the edge by comparison. If the center isn't all that much better, then that's how this particular lens is.

The question then is, does the lens make photos that make sense to you, without the pixel peeping?

Of course, when someone with the same lens takes a look, they might be able to say, Yep, that's like mine or Nope, mine's worse I mean more betterer..
07-09-2008, 07:53 PM   #7
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QuoteQuote:

Of course, when someone with the same lens takes a look, they might be able to say, Yep, that's like mine or Nope, mine's worse I mean more betterer..
Just about every agrees the 12-24 is a very sharp lens, but I don't see it in that shot, sorry.
07-09-2008, 08:02 PM   #8
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I'm with Daniel on this one. First I'd want the typical brick wall shot properly exposed. Camera perfectly parallel to the wall and about 10 feet back. Set up on a tripod and no SR with 2 second MLU.

The a second shot maybe 30 feet back of the same thing.
Then check the center against the sides crops.
The shots above just have too many variables that could cause issues.

07-09-2008, 11:43 PM   #9
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so if i'm setting up a more controlled shot, it would be easier/take less time if i did it inside. does it make a difference (in terms of negatively affecting the usefulness) if the tests are done from close range - say 10-12 feet rather than say 30-60+feet? my house is only so large inside

i know tips for lens testing say 1:50 or 1:100 magnification ratio (i.e. 50x focal length), but that's always in relation to actually measuring resolution via software like imatest. though i guess since the 12-24 focal length is so short i'm ok anyway?

thanks again for everybody's help!
07-10-2008, 12:40 AM   #10
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Inside under those circumstances is fine. The typical brick wall shot is suggested since the brick has a lot of texture and so sharpness (or lack of it) is easily seen.
07-11-2008, 04:04 PM   #11
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How do you reckon we know when we are perfectly parallel to a wall? Isn't it more likely we think we are, then we find differences on the sides, and go return a perfectly ok lens?
The only way we could rule this out is if we could rotate around the lens axis.
If the softness goes from one side to the other side, it would be the lens, if it stays on the same side, it's the camera to wall alignment. But who has such a setup?
07-11-2008, 04:07 PM   #12
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yes it is very good, and you are pixel peeping too much.
07-11-2008, 09:20 PM   #13
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Threads like these wouldn't exist if we still picked up our 4x6 and from those picked the 8x10 or 11x14 we wanted. Instead of 100% views on large LCDs. even 50% views help restore sanity
07-11-2008, 09:51 PM   #14
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did you use tripod for the shot? I don't understand why you're focusing more the left and right side of the images instead of center.
07-11-2008, 11:23 PM   #15
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QuoteOriginally posted by Shashinki Quote
yes it is very good, and you are pixel peeping too much.
ha! now that's an answer!

Paul, i did not use a tripod, as i mentioned in the OP.

FWIW, i did attempt a more scientific test yesterday inside with the 12-24 and my fa35-2: tripod, two strobe units, 2sec timer w/ mlu, manual focus, focus bracketing, testing 5.6degree rotated squares in 5 spots across the frame with the program quickmtf, aligning the optical axis of the lens with a mirror on the wall...

unfortunately, that last part was not successful at all, and as i looked through the images it seemed pretty obvious that the lens was not perpendicular to the wall.

thanks for everybody's opinion. it's now past the return period, so unless somebody offers me $685+nys tax, the lens is mine!

here's a picture i took today with the lens @12mm, corrected w/ hugin for distortion (barrel and perspective); a parting shot (pun):


100% crop from a DIFFERENT picture (@24mm, the supposed weak spot of the 12-24):


have a great weekend everybody! one week till batman...
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