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05-08-2012, 12:10 PM   #46
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QuoteOriginally posted by joe.penn Quote
I think you have completely missed the point - there was never anything in my post that pointed to that. An image produced that is not consistent across the frame as should be (landscapes can fall in this also) will not win any awards, and that is based on the equipment - you may have produced the photograph to the best you could but that doesn't make up for the shortcomings of the lens itself.

Really bad trending stuff that is seen quite often here on the forums:

- Why worry about chromatic aberration when it can be fixed with a mouse click in LR
- I don't need to worry about framing this scene perfectly, as long as I am somewhat close I can crop it in
- I am not worried about the sharpness of that lens, I will sharpen in post
- I am not worried about a proper exposure, hell I will fix it in LR

Every thing noted above is bad with cropping being the least of the evil's (this is where MFT really comes into play). In short, the image produced is also dependent on the equipment you are using so I am not sure where this would be or sound troubling. I do understand that corners can be cut and a lot of this stuff is somewhat mute when it comes to certain things like wall prints and digital display(ing) but there are plenty of areas where these shortcomings make a huge impact and this is why a lot of photogs pay the big money for higher end lenses and this goes for all brands...
Excuse me if I am taking this the wrong way, but I think what you have written is a bit unfair.
The majority of the people on this board are people that don't earn their living as a photographer. That is why we live with the cheaper gear and fix as much as we can in PP...because we cant justify the $$$ for lenses that don't have CA, sharp corners, etc.
In your line of work where the gear used can make or break you, of course you want th very best.
But in amateurland, where i live, I just try to bandaid poor lens quality as much as possible because I cant afford the top notch stuff.

Edited:
But I will add that getting proper exposure during at the time of the shoot and proper framing is something that people with the cheapest of gear should try to accomplish.

05-08-2012, 12:28 PM   #47
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@cali92rs

I don't make my living either as a photographer, I would go broke and really really quick. But this isn't about cheap gear or anything else - my response was in direct response to laurens about "who care about corner sharpness" (well, that was shortened), a lot of people do including a lot who make their living as a photographer, the only reason why I do is because of the industry when I was on the purchasing/marketing side of things - wasn't trying to be unfair or anything, I even use cheap glass..
05-08-2012, 12:46 PM   #48
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Ya, right, only you care about edge sharpness. Now I get it. Thanks for clarifying your thought on this. But wait, croppping unsharp edges would be a crime for you, because cropping is also a crime. You must hate APS-c with full frame lenses , all those unsharp edges are cropped without cropping so to speak. The ultimate cheat. That might turn a so , so lens into a great lens no? Oh ya and spending money for expensive lenses means you care more about edge sharpness than others. Ya, you have a few gems here.

QuoteQuote:
In short, the image produced is also dependent on the equipment you are using so I am not sure where this would be or sound troubling.
You fail to make a link between the value of the equipment used in 3D photography and MTF which as far as I can tell is pretty much a 2D system. Everyone agrees that you have to have the right equipment. The question then becomes, how do you determine what is the right equipment. You've suggested high MTF numbers and price. MY answer is it's more than MTF, and it's certainly more than price. In my view you're over simplifying a complicated issue. And my efforts in this thread have been to try and bring out other parameters to the front, such as the rendition of out of focus areas.

But just to be clear, you don;t care about edge quality more than I do. You don't spend more time pixel peeping than I do. There is nothing about this conversation that should be about me and you anyway. The question is, of what relevance is a 2D test of like MTF in the 3D world? IN this case we have a lens with some pretty terrible MTF numbers that has produced some pretty spectacular images. I was trying to come up with an explanation as to how that was possible. ANd please, spare me the "I'm the pixel peeping expert" stuff... I don't judge by any kind of reputation. I judge solely on quality of work.

I don't dispute MTF is good for evaluating flat image renditions. You've yet to convince me it's worth much evaluating lenses for use in a 3D enviroment. But hey, I'm open to arguments technical arguemnts or examples. I don't care whether I'm proved right or wrong. I'm just looking for info. And trying to understand how my 21 ltd rated 1.5 out of 5 with terrible MTF numbers takes such great images.

All you have to say here is, from your long experience pixel peeping, lenses with great MTF numbers across the frame produce better across the frame sharpness in rendering 3D scenes. Now, that at least for me, would be the kind of statement I would make note of.


From my 1.5 out of 5 rated 21 ltd. It's not MTF ( 2D )sharp, but I like it's 3D rendering ability.


Last edited by normhead; 05-08-2012 at 01:04 PM.
05-08-2012, 01:10 PM   #49
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QuoteOriginally posted by joe.penn Quote
@cali92rs

I don't make my living either as a photographer, I would go broke and really really quick. But this isn't about cheap gear or anything else - my response was in direct response to laurens about "who care about corner sharpness" (well, that was shortened), a lot of people do including a lot who make their living as a photographer, the only reason why I do is because of the industry when I was on the purchasing/marketing side of things - wasn't trying to be unfair or anything, I even use cheap glass..
No, I never said "who cares about sharpness". I said who cares about the 10-20% I never use in a given image - especially at the edges. Very few pros use their entire image. Very few amateurs do either. Name one time any image was looked at and someone went to the extreme corner and said "Gee, it's not sharp out here". If the edges of something *are* important, you make sure your zoom/focal lenth is appropriate. It's real life, not measurebation. Just like sex is different from masturbation...unless all you ever do is master...er...measurebate.

05-08-2012, 03:22 PM   #50
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QuoteOriginally posted by LaurenOE Quote
No, I never said "who cares about sharpness"
Neither did I -> As Noted my response was in direct response to laurens about "who care about corner sharpness" (well, that was shortened)

You did however in your post mention:
QuoteQuote:
In ANY photograph I take, I have never used the 10-20% around the periphery of any given image. No one cares aesthetically what is at the extreme edges of a photograph
Hence, Edge Sharpness

And:
QuoteQuote:
the center/color/sharpness are what matter to me in a lens
Hence, Not Worried About Corner Sharpness

And:
QuoteQuote:
No one cares aesthetically what is at the extreme edges of a photograph
With the above quoted was what I directly quoted, and well really to sum it all up:

QuoteQuote:
my response was in direct response to laurens about "who care about corner sharpness"
Sounds pretty dead on or did I misinterpret something?

QuoteOriginally posted by LaurenOE Quote
Name one time any image was looked at and someone went to the extreme corner and said "Gee, it's not sharp out here".
I can probably look back into some old printing contracts that are boxed up and give you quite a few, but I do remember one back when we printed yearly the Thelonious Monk International Jazz Festival Magazine (the particular one was either '98 or '99), I remember this one clearly as it was an article about Bill Cosby and the start page for the article was a full page spread - during the press inspection there was a big inconsistency across the photo, beautifully printed but clarity across the page shifted and shifted pretty quick from about 15% on the left into the spine - after going through hours upon hours re-shooting negatives and burning plates and looking for registration issues, it was found that the photograph itself was the issue.

Wonder how many of the millions upon millions of stock photography out there that is shunned because of IQ inconsistencies every minute of every day - I can guarantee one thing that is certain fact, if anyone on this forum was tasked with purchasing big ticket photography for national publications or high end print work from places like Getty or the alike you will definitely be concerned with edges then because it is your money purchasing the product.



@normhead

APS-C vs FF lens cropping at the sensor:
I am not technical on this and do not know the actual internal methods of it but as I understand it there is somewhat of a difference between sensor cropped and post cropped, I believe the difference is the sensor or internal algorithm is actually pixel optimized for this which in return yields near (or even) loss'less IQ. [again, I have like zero knowledge on this and only noting what I have read in the past]

QuoteOriginally posted by normhead Quote
Oh ya and spending money for expensive lenses means you care more about edge sharpness than others. Ya, you have a few gems here.
Well, not really - my kit is pretty specific and detailed:


Sigma 70~200 OS FLD (Recently Purchased After Couple Months of Pondering)
This lens was specifically purchased for Sports and [Nighttime] | [Indoor] Concerts. What a Juggernaut of a lens this thing is even wide open this thing is insanely good.

DA*50~135mm (Purchased Used From Member Here)
This lens was specifically purchased for [Nighttime] | [Outdoor Bad Weather] | [Indoor] Concerts, I have however used it for a few other things.

Sigma 15~30mm
This may be my best gem - what an absolute killer performer this thing is.

Tamron 28~75mm
Pretty good lens, lacks many features but a good one to have.

I also have a couple of macros and some primes. None of my lenses were expensive, the 70~200 tops the chart at $1300 but that was an absolute must have lens for my kit.

QuoteOriginally posted by normhead Quote
But wait, croppping unsharp edges would be a crime for you, because cropping is also a crime.
It's not crime, it does however create issues depending on the presentation medium - example:

- I need a photo for a national ad, my photo will be part of an overall ad that covers a half page horizontal block.
- The photo will be the main visual of the ad and will have a page and a spine bleed.
- The photo must be supplied at 8.965" width by 5.625 inches high at 300ppi.

Shooting the above with a K5 (and a consumer grade lens), this would be using the entire image as outputted by the K5 (4928x3264 <- No Enlargement @ 300ppi -> 8.965" x 5.938"). Those dimensions are directly from the camera.

Lets say you crop out 50% of the original photo, the photo must be converted and enlarged to twice it's supplied size - the image has pretty much become a pixelated mess at this point and would be hard pressed to use in even newsprint. This is where higher resolving/resolution lenses can be somewhat of a god send and can help with cropping considerably - the example yielded an unusable photo because of shooting with a consumer grade lens, a pro grade lens with it's resolving power would have at least got it to newsprint.

QuoteOriginally posted by normhead Quote
I don't dispute MTF is good for evaluating flat image renditions. You've yet to convince me it's worth much evaluating lenses for use in a 3D enviroment. But hey, I'm open to arguments technical arguemnts or examples. I don't care whether I'm proved right or wrong. I'm just looking for info. And trying to understand how my 21 ltd rated 1.5 out of 5 with terrible MTF numbers takes such great images.
I reference MFT specifically for resolution and nothing else - a high(er) resolution chart for a particular lens vs another manufacturers MFT chart for the comparable lens is just how I judge before purchasing (and considering the application at which I will be using it for). For your 21ltd, I am not sure of the numbers vs great images MFT confusion, I just don't know about that - could it be specifically it's resolution? Have you compared 90% crops of the same framing against another lens? I would think that may reveal something.

QuoteOriginally posted by normhead Quote
All you have to say here is, from your long experience pixel peeping, lenses with great MTF numbers across the frame produce better across the frame sharpness in rendering 3D scenes. Now, that at least for me, would be the kind of statement I would make note of.
I can't say that as I never have compared images in that way and also my earlier posts were directed specifically at edge (or corner) sharpness which could also be an issue with some high resolving lenses as it is with some consumer grade lenses.

QuoteOriginally posted by normhead Quote
From my 1.5 out of 5 rated 21 ltd. It's not MTF ( 2D )sharp, but I like it's 3D rendering ability.
Awesome pic just like your others!
05-09-2012, 08:59 AM   #51
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In the 3D world, the lens is actually decent. High contrast gives the impression of higher resolution and sharpness. However at 100mm+ the image does suffer comparing to other lengths. The good news is that the problem has been solved - by throwing money at it, of course. Found a NIB DFA 100WR locally for about the cost before the price increase - totally worth the money! 18-135 for rainy day snapshot (with DXO fix) and DFA100WR when absolute quality is required.

135mm f8.0



18mm f8.0


Last edited by chesebert; 05-09-2012 at 09:46 AM.
05-09-2012, 09:45 AM   #52
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QuoteOriginally posted by chesebert Quote
In the 3D world, the lens is actually decent. High contrast gives the impression of higher resolution and sharpness.
I agree. Sharpness is a combination of resolution and contrast. That's the reason that Photozone and DXO, who only measure resolution, disagree on lens quality vs. some other sites like PopPhoto, where contrast is also considered. Pentax lenses often excel at contrast and flare resistance, which is appreciated by users and ignored by MTF numbers. People seem to disrespect PopPhoto, but generally I find their Subjective Quality Factor (SQF) results correspond better to my opinions of lenses than those from DXO or Photozone.

Last edited by audiobomber; 05-09-2012 at 12:00 PM.
05-09-2012, 11:31 AM   #53
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Maybe I'm missing something. This is a zoom lens. Not even a * series zoom lens. I know when I mount a zoom, it's going to be a compromise. I also know the sensor on these cameras allows a lot of cropping - sorry if that's a cheat, but even in the film days we cropped images for composition. Photography and processing must go hand-in-hand.

The 18-135 is pretty nice, I wanted a weather-resistant lens and now I have one. The 16-45 might be sharper and brighter, but I'm satisifed with the 18-135. It focuses very quickly and as far as I can see, quite accurately.

Is it a macro lens?



Clearly not the equal of the FA100.


But then, I don't really expect it to be.

05-10-2012, 04:50 PM   #54
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well,after reading all the discussions on this Forum regarding Pentax DA 18-135 , I finally purchased one.I need a wheather resistant / walk around lens that focuses quickly and accurately , a friend with a K-5 has this lens and I had a play around with it and all I can say from my experience I was impressed. IQ seemed to be very reasonable at different FL.
05-11-2012, 01:55 AM   #55
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The OP says "objectively, this is a bad lens" - and if you read the Photozone review, then that is probably true- at least it is a "less good lens" I have used some a lot worse ( F35-135, Sigma 28-105 F2.8 to name two, awfully soft all over, halo, etc) Subjectively, a lot of people like the lens and do not find the IQ objectionable if used in the right context, not for shooting brick walls, which may also be down to sample variation too as well as differing expectations.

Personally,I bought an 18-135 recently, not without some trepidation. I got the chance to get one at a reasonable price (although it was only 20 cheaper than the DA 70 I also got, that's my LBA for this year sorted) and knew I could always return it or sell it if it proved to be a disaster. Actually I find it very useful, I sold my 18-250 Tamron to help pay for the new lens and do not regret it. Here in the UK it has rained solidly for about 5 weeks, horrible fine rain as well as downpours, so WR is key. The 18-135 produces good contrast, I have not found it particularly soft except at extreme corners, edges seem fine for the sort of pictures I take mostly at F6.3-F8. Lens swapping much reduced,even the sharpest lens in the world is useless for producing images if it is not actually on your camera.

So to the first point of the OP, I would say no, this is not a bad lens, it is not the finest Pentax have ever produced, but it is a solid middle order batsman, able to knock off a decent few runs and capable of the odd century when needed.

As to the second point of the original post, how can I hand on heart recommend this lens? Well I wouldn't advise selling your DA* zooms or FA Ltd to fund it, but as a WR walk around it does what it says on the tin, I have the WR 18-55 and my 18-135 is better, certainly appears sharper, although this might just be the contrast, certainly handles better, the motor driven focussing is a great improvement.
I had the Tamron 18-250 and find the 18-135 suits me better and is better built, so as a one lens solution for day to day use, yes, I could recommend this lens. If someone wanted a low light solution, or a decent macro lens or a lens for product shots in the studio, then this is not the lens for them
05-11-2012, 04:21 AM   #56
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QuoteOriginally posted by TER-OR Quote
Maybe I'm missing something. This is a zoom lens. Not even a * series zoom lens. I know when I mount a zoom, it's going to be a compromise.
Exactly! And if you're using an all-in-one zoom it's going to be even more of a compromise! All this talk about edge sharpness on big budget shoots is kinda crazy. That's not what the 18-135 was designed for.
05-11-2012, 11:01 PM   #57
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Would be so cool if any of you guys in possession of 18-135, posted some portraits made at longer ends.
05-11-2012, 11:15 PM   #58
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135mm


135mm



135mm

05-11-2012, 11:23 PM   #59
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looks soft even downsized; I think DXO might be able to fix that up, if just a little.
05-12-2012, 12:20 AM   #60
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Thanks! Well, colors are not bad at all, but overall sharpness looks worse than old DA18-55. This lens should be cheaper definitely.
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