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Thread: 3 Nikon mount lenses @ 18mm (for Guy)

  1. #51
    Paul.R.Lindqvist
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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by fotografz View Post
    IMHO this needs a in-studio test using a test target ... I find it hard to believe there would be such a huge margin of manual focus error @ f/5.6 or smaller... especially using the 10X Live View ... it also needs an electronic release with a squared up, leveled and locked down camera stand.

    Like I mentioned, my test for distortion was for Guy's purposes, where f-stop is mostly irrevelant ... but for center, edge-to-edge or corner sharpness, a different type of test is warranted.
    I was refering to my first "test" test targets wouldnt make a diffrence at all. And the test was repated just in case my mf with the 14-24/2,8 had affected the end result. I used a heavy duty studio tripod , along with a Manfrotto 468 ballhead wich both are overkill for the setup, and offcourse cable release.

    Offcourse i do appreaciate a lab test , and are looking forward to see some. But also find "real" world "tests" to be of value aswell. (such as a outdoor scene shot at infinity)


    Kindest
    Last edited by Paul.R.Lindqvist; 24th August 2008 at 05:16.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by Paul.R.Lindqvist View Post
    I was refering to my first "test" test targets wouldnt make a diffrence at all. And the test was repated just in case my mf with the 14-24/2,8 had affected the end result. I used a heavy duty studio tripod , along with a Manfrotto 468 ballhead wich both are overkill for the setup, and offcourse cable release.

    Offcourse i do appreaciate a lab test , and are looking forward to see some. But also find "real" world "tests" to be of value aswell. (such as a outdoor scene shot at infinity)


    Kindest
    HI Paul
    Please don't take offence, but what worries me here is that if I hadn't chimed in we would have a set of tests which clearly showed that the Zeiss 18mm cleaned up in terms of corner performance, and that at 18mm the Nikon was absolute pants. I still think that the first tests are thoroughly unrepresentative of what I'm seeing with my 14-24.

    I agree that 'real' world tests are useful, but, having been the victim of several (apparently well informed) people's lens recommendations over the last month or so, it is my fervent belief that you should be very very careful of putting test results which result in any sort of conclusion.

    Putting up unrepresentative results is not good for the manufacturer of the lens, or the end user who is thinking of buying it.

    Of course, we all know that the internet is full of 'unreliable evidence' and would be fools to trust things too closely, but in this case your described methodology and devastating results might easily have made people come to the incorrect, and possibly very expensive, conclusion.

    Sorry to be so blunt, but that's the way I see it.
    Last edited by jonoslack; 24th August 2008 at 05:45.

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  3. #53
    Oxide Blu
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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by jonoslack View Post

    ... I've had supper and a couple of glasses of wine.
    Well, there's your problem right there. I found that if I drink the whole bottle everything is equally out of focus and distorted with swirling colors and eyeball abrasions and whatever ... and I swear it all looks good.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by Oxide Blu View Post
    Well, there's your problem right there. I found that if I drink the whole bottle everything is equally out of focus and distorted with swirling colors and eyeball abrasions and whatever ... and I swear it all looks good.

    Ah, but that was then . . . and this is now!

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  5. #55
    Paul.R.Lindqvist
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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by jonoslack View Post
    HI Paul
    Please don't take offence, but what worries me here is that if I hadn't chimed in we would have a set of tests which clearly showed that the Zeiss 18mm cleaned up in terms of corner performance, and that at 18mm the Nikon was absolute pants. I still think that the first tests are thoroughly unrepresentative of what I'm seeing with my 14-24.

    I agree that 'real' world tests are useful, but, having been the victim of several (apparently well informed) people's lens recommendations over the last month or so, it is my fervent belief that you should be very very careful of putting test results which result in any sort of conclusion.

    Putting up unrepresentative results is not good for the manufacturer of the lens, or the end user who is thinking of buying it.

    Of course, we all know that the internet is full of 'unreliable evidence' and would be fools to trust things too closely, but in this case your described methodology and devastating results might easily have made people come to the incorrect, and possibly very expensive, conclusion.

    Sorry to be so blunt, but that's the way I see it.
    No offence taken,you offcourse entitled to your opinion, regarding my lens being off or any test being missrepresentative.

    The reason i repeated the second test had nothing to do with you chiming in, i analyzed the 3 sets of images and saw a inconsistent result both in the center and in the corner of the 14-24 primarily. Wich led me to belive my focusing was off, wich it was for the second test.

    Ill trust my eyes, and my experience more then anything else, thus im not afraid nor will i stop drawing any conclusion based on them.

    I couldnt care less about the manufacturer i dont work for any of them.

    Ill make sure to not post any more "tests" here though.

    Kindest

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by Paul.R.Lindqvist View Post
    No offence taken,you offcourse entitled to your opinion, regarding my lens being off or any test being missrepresentative.
    Well, if you had looked at this thread last night - and again this morning, you would have seen perfectly clearly that my 'opinions' were, in fact, fact. Now you've redone the tests it simply looks like I'm splitting hairs and arguing about nothing.
    I'm glad you didn't take offense though

    Quote Originally Posted by Paul.R.Lindqvist View Post
    The reason i repeated the second test had nothing to do with you chiming in,


    Quote Originally Posted by Paul.R.Lindqvist View Post
    Ill trust my eyes, and my experience more then anything else, thus im not afraid nor will i stop drawing any conclusion based on them.
    and nor should you, but perhaps it's worth pausing very hard before postulating those conclusions as 'facts'

    Quote Originally Posted by Paul.R.Lindqvist View Post
    I couldnt care less about the manufacturer i dont work for any of them.
    Well - okay - but I don't like to see anybody being done down on the basis of unreliable evidence. However big or small the may be

    Quote Originally Posted by Paul.R.Lindqvist View Post
    Ill make sure to not post any more "tests" here though.

    Kindest
    Don't take any notice of me Paul - I'm just a geezer around here, not particularly knowledgeable and certainly not representative.

    I hope you won't make any decisions on the basis of anything I say
    Last edited by jonoslack; 24th August 2008 at 06:24.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Morning folks . Not had my second expresso yet but let's not get to overboard . Tests are tests and always subject to questions . Reason I hate doing them sometimes. But I look at them as just part of a puzzle to making a purchase. Be it we agree or not will always come up but last thing I want around here is bad feelings between members and folks not wanting to post or worse yet leave the forum. I'm married if the day comes I agree with my wife 100 percent of the time just put a gun to my head and pull the trigger. It will never happen that I agree with her but i still love her. Let's sort of take that approach here if you will. You guy's are a big part of this place and we may not always agree and that would be boring as hell but lively debate is good. I'm not going to make any admin decisions and lock the thread or anything like that . Let's just have fun. I do appreciate the PM's too me and that is how this forum should work but let's see what the day brings. Besides it is the closing ceremonies of the Olympics and let's not kill the good mojo of the day.
    Photography is all about experimentation and without it you will never learn art.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by Guy Mancuso View Post
    Besides it is the closing ceremonies of the Olympics and let's not kill the good mojo of the day.


    How do you come up with stuff like that, Guy?

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Wait till the second cup of espresso.
    Photography is all about experimentation and without it you will never learn art.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by Guy Mancuso View Post
    Olympics and let's not kill the good mojo of the day.


    You'll need at least two cups to be able to watch our Boris take the wotsit from the Chinese. Probably a lot more!

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  11. #61
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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Lens testing in general is a nightmare, and why I stopped posting my own results several years back. No matter how you structure your test, you will have great difficulty looking at multiple variables in a single test. THus it takes several controlled comparisons and most of us don't really want to spend that kind of time performing them.

    Here is what I have gleaned from years of doing lens tests:

    1) Resolution testing. The ONLY way you can compare resolution is to shoot resolution targets that generate empirical evidence of actual lines/mm resolved. You can have situations where lens A looks softer than lens B across the image, yet lens A discriminates more lines/mm than B. Better if the test chart has resolution grids in the three RGB color channels in addition to black, and has them displayed vertically and sagittally as well as horizontally. (Here is where a real version of the USAF optical test target can help a lot.) You will be surprised at how many lenses render some colors better than others or how different an individual lens can be on sagittal resolution relative to horizontal...

    2) Distortion testing. A NIGHTMARE! I used to use a building in my neighborhood that had lots of vertical and horizontal structural components like windows and beams --- NOT bricks! With this, I got far enough away in the parking lot, then leveled and squared the camera as it is easier to evaluate from a distance where being off becomes more visible and thus avoidable. Mark your position in the parking lot for future tests.

    3) Then you have to triple check that you have the proper lens matched to the image --- easy with EXIF, but when testing a bunch of different third party lenses via adapters, it can get arduous to keep every thing organized.

    Corollary to 1) And from my experience, you will almost always choose to own lens B in the above situation #1 even though it registers less resolution, so spending time on the rest of the testing is pointless anyway What I do now is simpler: I take each lens under consideration and shoot normally with it, exposing various subjects of various colors at various distances and various apertures. I then scrutinize the images initially and make my final decisions based on my partially empirical yet often mostly SUBJECTIVE experiential appraisal of what I see on my monitor: if I like what I see I keep the lens, if I don't I return it.

    Now to the discussion in the above posts, via a PS on corner resolution testing on wideangles: It is almost always an exercise in futility due to one simple optical phenomenon: curvature of field. An example is the 28/f1.8 Canon. I tested that lens early on, having shot it on my standard flat test target and pronounced it as horrible in the corners to the point I considered it unusable. A few years later, I obtained one as part of a bulk gear purchase. I was going to sell it immediately, but then tested it per my revised "shoot it" test as described above. What I learned was eye-opening: It was stunningly sharp in the corners, just at a distance significantly closer than where the center of the lens was focused due to significant curvature of field! (In that case, if I focused the center at 10 meters, the corners were crisp at 2 meters, even wide open.) Moreover, I discovered for my style of shooting, this was actually a positive trait: with the lens angled down slightly, foreground elements through the mid-range elements I had focused on could be held in good focus at wide open apertures -- this can a superb "characteristic" for street and landscape shooting if and when exploited, and was a significant "ah-ha!" for me. (FWIW, when I sold off the bulk of my Canon gear to help fund the medium format purchase, I kept two lenses -- a particularly good example of the 50/1.4 and that 28/1.8 .)

    Finally, please note that curvature of field and rectilinear distortion are almost always battling elements of wideangle lens design -- you cannot have both, so lens designers have to choose one in favor of the other; if the design favors low distortion, it will likely have higher curvature of field; if the design favors flatness of field, it will likely have greater linear distortion.


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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Shades of Sean Reid!

    Two great minds that think alike

    Woody

  13. #63
    asabet
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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Thanks Jack! As a sometimes tester and hopeless pixel peeper, there's a lot there to think about.

    The first thing I thought of in Paul's test was field curvature. Maybe that's in part because I had that same Canon 28/1.8 .

    Since it's impossible to know that AF or manual focusing systems are in perfect alignment, focus bracketing is always a good thing in lens testing and has the added benefit of bringing out issues related to field curvature.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Hi Jack
    Like you, I stopped posting things like this a long time ago (at best you get ignored!).

    Still, the problem here is that lots of us want to know how good this new Zeiss lens is - so a comparison is valuable . . . . . or not, as it would seem.

    I feel a little sorry for Paul, and a little guilty for having been so much on the case. The trouble is that if you post these comparisons, at least in this case, you may be influencing people spending literally thousands of dollars.

    IMHO by drawing conclusions you make yourself responsible under such circumstances.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    I think that's a good point Jono, and at the end of the day I think it is up to an individual to decide if the review they're reading is credible... Without reviews, we have no data, with reviews we have suspect data unless we do the test ourselves. After time, a reviewer then gains (or loses) credibility --- and in either event, the process is not enjoyable

    From MY point of view, I usually posted my reviews with appropriate disclaimers, stating only what I saw in the images, then encouraged folks to look closely and decide for themselves --- the last thing I wanted was folks blaming me for an expensive and poor choice!
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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    FYI for anyone interested - Lloyd Chambers on 18ZF vs 14-24G, specifically the ZF's flare issue. Has a mouse-over comparing 18 and 14-24G

    http://diglloyd.com/diglloyd/blog.html

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by robmac View Post
    FYI for anyone interested - Lloyd Chambers on 18ZF vs 14-24G, specifically the ZF's flare issue. Has a mouse-over comparing 18 and 14-24G

    http://diglloyd.com/diglloyd/blog.html
    I don't have an issue with doing distortion tests if nothing changes but the lenses. It's all relative. mulltiple images can be loaded and toggled to get an overall impression.

    I found exactly the same odd flare issue as Chambers did with the 18mm when shooting directly into the sun. I also shot a few where it was greatly dimminished.

    I also have shot enough with both lenses to know the value of both in the real world ... and user tests can be valuable in at least indicating that value and flagging potential issues or strengths. And others challenging any opinion can bring more info to the table.

    From there it is up to a potential buyer to look deeper.

    The ZF18 is a nice addition mostly because it has similar color and feel to other ZFs ... a consistancy I value where others may not care. It's other chief attribute is that it is small.

    I rarely shoot landscapes and almost never shoot directly into the sun ... which renders one of it's flaws down the list of things on my consideration list.

    BTW, I do not see this lens as a replacement for the 14-24 in any way shape or form ... but when grabbing a few lenses for a trip or some casual shooting, the last one I'd grab is the 14-24 ... so the ZF18 is way,way, way better than nothing.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by Jack Flesher View Post
    I think that's a good point Jono, and at the end of the day I think it is up to an individual to decide if the review they're reading is credible... Without reviews, we have no data, with reviews we have suspect data unless we do the test ourselves. After time, a reviewer then gains (or loses) credibility --- and in either event, the process is not enjoyable

    From MY point of view, I usually posted my reviews with appropriate disclaimers, stating only what I saw in the images, then encouraged folks to look closely and decide for themselves --- the last thing I wanted was folks blaming me for an expensive and poor choice!
    Yes - exactly!

    I've certainly learned quite a bit from this experience. As you said, (and Marc above) the only real way to evaluate a lens is with respect to your own use, and that may be of limited use to others.

    I've been re-evaluating my ZF 25 - which I have both loved (sparkling centre, fun close ups, good bokeh) and hated (soft corners, vignetting). What I've discovered is that the soft corners are indeed to do with a convex focus plane - extremely so! However, it has shown me that for landscape work, focusing a little in front of the subject (or backing off from infinity) and using a smaller aperture will pretty much alleviate the problem without having much effect on the overall sharpness.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    One of the 'characteristics' of the 25 is it's field curvature apparently - exacerbated at close distances by the lack of a floating element (as in the 28/2). The center sharpness is something else however...

    Another tool for the toolbox as it were.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by jonoslack View Post
    Yes - exactly!

    I've certainly learned quite a bit from this experience. As you said, (and Marc above) the only real way to evaluate a lens is with respect to your own use, and that may be of limited use to others.

    I've been re-evaluating my ZF 25 - which I have both loved (sparkling centre, fun close ups, good bokeh) and hated (soft corners, vignetting). What I've discovered is that the soft corners are indeed to do with a convex focus plane - extremely so! However, it has shown me that for landscape work, focusing a little in front of the subject (or backing off from infinity) and using a smaller aperture will pretty much alleviate the problem without having much effect on the overall sharpness.
    And according to Mr. Chambers, the somewhat maligned 25 has superior flare control ... which is of value for me when shooting weddings indoors at a reception with strong points of light or back lighting present in the image.

    "Horses for courses" takes on even more meaning as you detail your specific needs as it relates to specific attributes.

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    Re: 3 Nikon mount lenses @ 18mm (for Guy)

    Quote Originally Posted by fotografz View Post
    And according to Mr. Chambers, the somewhat maligned 25 has superior flare control ... which is of value for me when shooting weddings indoors at a reception with strong points of light or back lighting present in the image.

    "Horses for courses" takes on even more meaning as you detail your specific needs as it relates to specific attributes.
    Hi Marc
    I haven't paid for Mr Chambers reviews, although I suppose I might. I'm afraid I have a very low concentration span!

    You're right about 'horses for courses'. I'm struggling at the moment trying to decide what to take on our annual two week 'chill out' in Crete - Last year I took the M8 and some lenses, and this year, although I'll take an M8, I plan to use an SLR as a primary setup. There's lots of steep walking, so the 14-24 really is a bit big. Now I've 'rediscovered' my 25mm I'm beginning to wonder about the ZF 18 as a companion.

    Oh well, one should enjoy these decisions - all part of the fun of a holiday!

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