Nikkor 24-70mm issue

[dbose]

I had However, after using it for the last few months, I am still not 100% happy with the lens. I still have issues with soft focus. Using all the basic rules such as using single focus, focusing on the eyes, using a narrow DOF like 5.6 (as opposed to a very shallow DOF like 2.8) still does not seem to bring out those crisp, sharp images. I am starting to think that there may be some issues with the lens itself. Is there a way to ensure that the lens is absolutely not faulty? I bought it over the INTERNET but do have warranty on it for 12 months.

How do I ensure that the lens is not faulty? :(:(

[ronaldhw]

can you post some images that is not sharp, along with the shutter speed and aperture information?

Have you done some back/front focus testing? have you tried to fine tune the auto focus in your camera?

My 24-70 is sharp, and razor sharp when I use -3 from the AF fine tune.

[dbose]

can you post some images that is not sharp, along with the shutter speed and aperture information?

Have you done some back/front focus testing? have you tried to fine tune the auto focus in your camera?

My 24-70 is sharp, and razor sharp when I use -3 from the AF fine tune.

I will post some shots that I think have issues - in the mean time how exactly do you do back/front focus testing? Also how do I fine tune the auto focus in camera? I use a Nikon D90 (is it possible that using a FX lens on a DX body could have issues)?

[ronaldhw]

there should be no problem using the FX lens in DX body.

it's not possible to do AF fine tuning with D90. but the AF fine tune won't help much if the lens AF is faulty.

you can read the focus test here http://focustestchart.com/chart.html

post the result from the focus test here too.

[kiwi]

Tripod mount
Use flash on 1/200s f/4
Shoot at a beer can 20 feet away
Drink beer

Report

(I'm happy to test it for you, I have one myself, just provide the beer)

Yours quite ntp so I'm going to guess user error but you never know

Where in Brisbane are you ?

[mongo]

What Kiwi said to try (although Mongo does not need the beer). Also do NOT rely on the auto focus when testing. Do one using AF and at least several others NOT using AF (use manual focus). That will at least eliminate any camera/focus issues

PS Just because it may be new does not mean if may not have a problem

[kiwi]

Yip, and d90 has fine tuning too I think

But to reiterate it's possible the lens is out

[Wayne]

Mine is like a razor with no fine tune and that is on 2 FX bodies. These are not known to have too many issues from factory, but you could need to get it calibrated.

You have to follow the advice above to eliminate user error first.

[dbose]

Hi Kiwi/Mongo - I'd be happy if turns out to be a user error (at least I can fix it). I am worried that the mens may be faulty and as I bought it over the internet (for the first time) I am even more worried.

Kiwi I live on the western suburbs near Mt. Omeney. I am on holidays gthis week so could come and see you - I'd be more than happy if you could test it out for me and even show me any faults to rectify (oh I am more than happy to bring the beer - a good way to have a drink together...)

[kiwi]

Hmm, I'm Albany creek, I do work in the valley though so one day next week could catch up for lunch and do some quick testing if you still think there's a problem, my phone numbers on my website

[dbose]

Hmm, I'm Albany creek, I do work in the valley though so one day next week could catch up for lunch and do some quick testing if you still think there's a problem, my phone numbers on my website

That'd be very kind of you Kiwi. I work in the city and can easily come and see you next week. I'll call you early next week.

[kiwi]

No worries. Try the tests first though eh

[dbose]

No worries. Try the tests first though eh

Yep will do...

[dbose]

Hi Kiwi I did the test (not set up quite with a beer can). I did not have exactly 20 feet but was about 15 feet away from the red flower vase (which was my point of focus for all 3 shots). The first was taken with AF (changed the settings in the menu to set the AF-area mode to be Dynamic Area). The second was also taken with AF this time chaning the AF-Area to Single Point. the last one was taken with manual focus. All 3 was focused (middle focus point) at the middle of the red flower vase at F4 at 1/200 with external flash and tripod mounted.

I think all of them are soft focused (the first one being the worst with AF and Dynamic area).

[dbose]

Ok here are 2 more with my old 18-105 DX - the first with AF (single area) and the second with manual focus at 30mm and everything lese the same.

[kiwi]

Too small an object too far away. Try 5 feet

[dbose]

Too small an object too far away. Try 5 feet

Will do today and repost. The only thing is when I zoom in to the vase it looks quite soft. The shots are large format so would have imagined that they would not pixilise on a bit of zoom.

[kiwi]

Dont use the vase, not enough contrast - use something like a cereal box at 45% angle to camera, focus half way along the box half way up on a particular letter, try to fill the frame from about 5 feet away at 70mm and f/8 using 1/200s tripod mount flash

[farmer_rob]

If the lens is OK, then there should be some point in sharp focus.

I'd guess there are three possibilities:
a) User error - we all make them - Lens OK
b) Front or back focus (it focuses, but not exactly where you want) - factory adjustment or camera adjustment with "fine-tune" - minor issue
c) A sharp point of focus does not exist - warranty claim - major issue.

To distinguish, you need to give the camera a chance to show that there can be a point in sharp focus. Most lens tests involve a set of similar objects in a row receding away from the camera, so that something will be in focus. From your test images, it is impossible to see if any point in the frame is in focus. (A cheap and quick method I use is shots of a grassy lawn - some of the lawn will be in sharp focus.) Don't forget to use an open aperture (eg f4 or lower.)

BTW, are you shooting jpeg or RAW? If RAW, you need to be doing PP to add sharpening. If JPEG, check the sharpness settings in the camera.

[farmer_rob]

Kiwi, are you sure about f/8? I would have used f/5.6 or f/4 to give more definite OOF areas. (Or used a range of apertures:p)

[Wayne]

Use a ruler and shoot almost parallel along it, say focus on the 15cm mark of a 30cm ruler at say 2m from the camera at various fstop settings. This makes identifying front or back focus easy.

[kiwi]

Kiwi, are you sure about f/8? I would have used f/5.6 or f/4 to give more definite OOF areas. (Or used a range of apertures:p)

Yeah, good point, use 2.8 through to 8 on the object. Waynes ruler is a good idea too. Just get something that has good doF markings and get close enough to fill say 1/4 of 1/2 frame with it

[swifty]

Hi DJ,
I don't want to confuse you further but there are a few more points to consider after you've determined whether your 24-70 is focussing properly.
Assuming the focus is OK, there are a few quirks with this lens that might explain some of the lack of sharpness issue.
Firstly there is noticeable field curvature at 24mm. Since you use DX, the effect is less but I definitely could detect it when I use to have this lens and used it on an S5 (also DX camera). It basically means if you're focussing on a flat object, say in the middle, even if the middle is in focus, the corners might not be (not that the corners arn't sharp). Problem goes as you stop down.
24mm is not the lens' strong point. It really shines in the mid to long focal lengths, at least on my copy.
As with all lenses, the sweet spot for sharpness is usually a few stops from maximum but although this is still true for the 24-70mm, I certainly had no problems with sharpness at 2.8 which was where I used it most.
But as others have mentioned, regardless of all these 'issues,' if the lens is not a dud, there should be at least one point in the photo (not necessarily where you AF) that should show good sharpness and the tests the other forum members have suggested should show you whether there are focus problems, that should be eliminated first.

[dbose]

Thanks guys - I will use the ruler and try and shoot at F2.8 through to F8 and see what the results come up. I'll post them in this thread. I do shoot RAW so will use cs5 to sharpen the images.

Kiwi, after all of these I still think it'd be good if I could meet you next week for a quick test - if that's still ok with you.

[kiwi]

Yip. Shoot these tests using jpeg too

[Wayne]

A note.

When shooting these tests, shoot jpeg if you like , but make sure the incamera settings are 0 for sharpness. I prefer to shoot tests raw and simply convert them to full size tiff for examination. That way you can see raw data that has no sharpening applied and it not only determines spot on focus but whether or not your sample of the lens is a sharp or soft copy.

[dieselpower]

Yip, and d90 has fine tuning too I think

Definitely doesn't have it - not in software anyway.

The AF system in the D90 is based on mirror refraction. If the AF sensor is a slightly different distance to the image sensor, then what the AF system reports as in focus and what the sensor grabs are completely different things.

I had issues with my D90 back focusing when I first got it and had to take it to Andersen's at Capalaba to get it re-calibrated (under warranty). It was way, way out was their diagnosis when they gave it back. I was noticing it with ALL lenses, not just one particular one (though my 50mm/f1.8 was the worst).

I used focus charts to test - basically grids on paper, with a target to focus at. I did multiple tests - using AF, manual focus using my eye to tell me when it was right, manual using the indicator in the view finder and live view. Live view got it right 100% of the time (it focuses using the image sensor, not the AF sensor) as did using my eye. The AF system and the indicator in the view finder were both out (the indicator while manually focusing relies on the AF sensor for its information).

Here's what I'd do for a quick, easy test -

Set the camera up on a tripod, or make it so it will not move
Turn off vibration reduction on your lens
Grab a series of batteries and line them up getting progressively further away from the camera, or use a ruler and shoot it at a 45 degree angle.
Fill the frame with the batteries/ruler and make note of where you focus using single point AF and your center focus point
Take a test photo letting the camera AF
Take a test photo manual focussing but using the focus indicator in the view finder
Take a test photo manual focusing, ignoring the viewfinder indicator
Take a test photo using live view
Try with several different apertures to eliminate lens softness
Compare results in your computer

It can't hurt to do this with all your lenses to compare the results. If it's front focusing, you'll see the point that is in focus is in front of where you anticipated. If it's back focusing, the point in focus will be behind where you anticipated. Hopefully, it's neither! If it's an AF calibration issue, you should see the auto focused shots are out, the ones with the focus indicator are out, the one where you focused to what you could see (provided your eyesight is good!) should be ok, and the liveview should be spot on.

If you see that it's out with the AF and the focus indicator on all your lenses, then it's an AF calibration issue and will need to go to Nikon for calibration. From what I've read and heard it's a relatively common problem.

What this setup achieves - stops camera movement and eliminates user technique problems. Basically provides a controlled test environment :)

This may show up the problem, or it may not, but it's something to test and only takes about 10 mins.

[dbose]

Ok here are the retests. I used a flat book. The camera was set up at 45 degrees on a tripod. There are 8 images. The first 4 were using AF (starting from F2.8, F4, F5.6 and F8) with 1/200 th shutter speed and external flash. The next 4 were with manual focus and same settings. All shots were aimed at the middle part of the writing. Other settings were ISO 200 taken in RAW and then sharpened using cs5 and saved in jpg. I can see the sharp bits but still think the images are a bit noisy (?) or could have bee shaper?

[kiwi]

the books dont look perpendicular to the camera ?

[dbose]

The next 4 with manual focus...

[dbose]

the books dont look perpendicular to the camera ?

Yeah you are right - setting it up was difficult and I did it quickly (kids screaming behind my ears)...will try out again...but would these give some of idea regarding the lens? I am back at work from tomorrow and will call you to see if we can meet sometime.

[kiwi]

not much help sorry, tests have to be done properly to form any conclusion. just call at some stage, no worries.

[Wayne]

I think they are too underexposed to really see the point of focus properly.

I suggest the ruler, it really does make this test very easy.

Set the strobe to iTTL so that you gain correct exposure.