Double Checking a 14-24

AmericanLoonie

Greetings,

Long time reader/lurker, finally made an account; I look forward to participating more in the forum and discussions, and I thank everyone for the information I have gleamed from you all over the years. I am sure I can search through the bagillions of posts about this lens and find this information, but I simply don't have time and am hoping someone will be able to help me out. My apologies for that in advance...

I just ordered a brand new 14-24mm Nikkor and it is my first pro lens purchased at full price other than my 200-400 f4. Leaving aside focus adjustments, I have no experience testing this sort of optic but have heard stories of multiple returns until a flawless copy was finally received. I ordered mine through Amazon.ca which means I have every opportunity I want to return for a proper replacement, but it is up to me to test it properly...

My question(s) is(are) this(these): how or what process should I go about to test this lens and ensure that I have a proper copy? What are the most important things I should be looking out for other than focus accuracy–which is already questionable through the finder with this kind of lens in the first place–and dust/damage? In short, how can I make sure I have a good copy?

I'm super excited about this thing but don't have a lot of cash and really want to make sure I get my money's worth. This is on top of how crazy intimidated I am by that front element and lack of protective filter options! Maybe I should just grab a Wonder Pana and schlap a 145mm UV filter on it...

Cheers!

Nikoniser

I check lenses by printing out this chart - use Adobe Reader to open, and print in poster mode set to 160 %to get a chart big enough http://www.graphics.cornell.edu/~westin/misc/res-chart.html

You need to shoot from a tripod with mirror up/delay/remote release from the center of the chart and dead square on, base iso ( 100/64) .

You can check for decentering by checking the sharpness of the corner charts vs each other, ( I overlay crops in photoshop ) and checking the Cromatic abberation of the corners.

The 14-24 ought to *easily* resolve the central 20 lines ( as long as your printer is good enough )

Another good check is to shoot a starfield, with the camera pointed straight up, to check for corner sharpness and coma performance. However this relies on you being familer with astro photography, so the chart method is a good start.

AmericanLoonie

Many thanks for the tips, I really appreciated it. I have an Epson R2000, so I can poster-print that sucker nice and big to test the full focal range. I will do exactly what you said when she arrives next Wednesday (why did I chose such a slow shipping method?!) and hope for the best. Shooting a star field would be an option if we had stars where I live... sadly not a luxury I enjoy in the (sh)city.

Pistnbroke

Testing wide lenses is difficult,setting the fine focus adjust particularly so. I would put it opposite and photograph a brick wall and then examine the sand grains in the mortar on your computer screen at say 200% . This will show up any de centering issue as these are usually severe . Dont go looking for problems .use it for the purpose you bought it for and see if you are happy. Remember if you halve the focal length and take a photo from the same point you need 4x the pixels to maintain the IQ ( Square law) Wide lenses are demanding on sensors.

Ironheart

Also if you are not perfectly perpendicular to the wall or test chart you will think your corners are bad when they are not. Measure out two lines from the target at least 6' apart and draw a line connecting them. This should be exactly parallel to the wall. Check the diagonals to be sure, as they should be equal length as well. High-school geometry

AmericanLoonie

Pistnbroke: Another good idea, I will find a wall that should work. When you say a corner comparison @ 200% will show decentering, do you mean to say that the corners should all be equal in regard to IQ? I know nothing of these things, but wouldn't a better test be to frame a shot of the wall and take four photos, rotating the camera 90º radially from the center of the camera lens after each? You could then chop the entire frame into quarters and overlay to test the entire image? I guess it wouldn't be the easiest test to do precisely, but it would be doable with the right rig and plates... Contrary to how crazy my thought process may sound, I am not looking for errors/flaws as much as I don't want to find them in a few months. I have been using a beat up 20-35mm on my D800, and I'm scared I will be so blown away that I'll be blind to any smaller issues!

Ironheart: For sure. If you really want to be precise in that regard, the iPhone's level and compass is a great and convenient tool to make sure you are on point. Pick your planes, schlap your phone on 'em, and rock that high school geometry.

Speaking of schlapping... I used the $500 I saved and bought the Wonderpana system. Shipping was updated and she arrives on Monday. I haven't been sleeping much, and I only regret not saving (a lot) longer for the 15mm Zeiss a little bit...

Pistnbroke

If you have de centering ,,try at f8 as well as wide open you will tell straight away as the centre will not be the sharpest part...sharp part will be off to one side.
As for the 15mm Zeiss you will not better the Samyang 14mm

AmericanLoonie

Got it. I have found a few walls that may work, but the only brick wall I have found near me is in a back parking lot in a more shady part of town; it's not the best testing area, to say the least...

For now, I created a really nice poster of the ISO 12233 pdf using four custom-cut, 13"x24" satin sheets, printed with photo black ink on the slowest highest quality setting. The final cut and assembled poster is just over 22.5" x 37" and looks great. I don't have perfect definition between lines at 20x, but enough to accurately assess sharpness for sure. If you print with matte black ink on the right paper, I am sure better definition could be achieved–at the expensive of durability/risk of smudging, which would certainly be annoying as there is so much black around those edges. There are also the obvious lines from merging pages, but these can be used as further means for assessment.

If you have a 13" wide printer and would like my prepress pdf of the ISO 12233 chart for that page size with crop marks, feel free to shoot me a message. In the mean time, I am anxiously waiting by the door (like a dog) for the lens to arrive while an incredible Fall day passes me by.

autofocus

Hopefully by now you've had a chance to shoot your new lens. I love my 14-24mm. I'll put it up against primes in that range any day. At 2.8 it's fantastic and from f4 to f8 it's incredible. Yes, I lose a stop or two to the primes but with todays cameras that isn't as big a deal. It's not a lens I use all the time but when I want something in that focal length it performs. Get out there and enjoy it. Your photos will tell you whether it's right or not.

AmericanLoonie

I have indeed! Sadly the weather went straight downhill the day after I picked up the lens. I was able to get outside and take a couple quick hand-held snaps the evening I received it, but man oh man am I inexperienced at 14mm! This merge was the only thing I got that was worth anything:



I ran tests like crazy on the lens, with my best and most consistent results coming by laying the ISO poster on the ground and leveling out my camera in live view tethered to my PC. A combo of an actual level and using the grid got me as close to perpendicular as possible. While I still need to set up the rig to test at 14mm (tripod was casting shadows so close to the poster), the thing is incredibly sharp. The left corners are a tiny bit better than the right corners, top left being the best, but I did achieve a test or two where that was not noticeable. It is certainly possible that my lens face was not parallel with the poster, as even the smallest deviation could cause such results.

All in all I am so pleased I picked up this lens; I can't wait to get it back out in the field and see how 14mm can push my work. Many thanks to you all for the tips, though I still need to try it out on a brick wall...

haroldp

14mm at f2.8 in antelope canyon was magic.