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Author Topic: Nikon 24mm-70mm lens abberation at long exposure  (Read 13041 times)
Dustbak
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« Reply #40 on: October 19, 2009, 03:05:38 PM »
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Quote from: duraace
Could you confirm the settings for these shots?  Focal length, especially?


image 1)
Focal length 50mm
ISO100
4minutes (240sec) exposure
f11
NR on

image 2)
Focal length 50mm
ISO200
64minutes (3840sec) exposure
f8
NR off!
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rethmeier
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« Reply #41 on: October 19, 2009, 03:33:11 PM »
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Dustbak,
was the sun hitting the camera and lens?
The problem is I think and others have said this,that light is seeping in from the outside of the lens.
Not trough the front.
As soon as I'm getting my ND filters,I'll try it myself.

Cheers,

Willem.
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Willem Rethmeier
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Dustbak
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« Reply #42 on: October 19, 2009, 04:27:14 PM »
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I took this around 4PM with the sun on the side (left side) of the lens. Not much sun since I was shooting from the floor of my space through the doors (so I could stay in and remain warm ). I can repeat it one of this days with the sun directly hitting the equipment but if there is a real leak it would have been apparent after exposing for over an hour.
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rethmeier
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« Reply #43 on: October 19, 2009, 04:33:27 PM »
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Dustbak,
leuke dakpannetjes!
It's obvious now that the problems is with light entering trough the side of the lens.
In direct sunlight only.
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Willem Rethmeier
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duraace
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« Reply #44 on: October 19, 2009, 04:34:18 PM »
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Quote from: Dustbak
I took this around 4PM with the sun on the side (left side) of the lens. Not much sun since I was shooting from the floor of my space through the doors (so I could stay in and remain warm ). I can repeat it one of this days with the sun directly hitting the equipment but if there is a real leak it would have been apparent after exposing for over an hour.

I'm encouraged by this. Looks like a case of a bad batch. I will try do a test with a new one, from a local store.
What was the camera?
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NashvilleMike
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« Reply #45 on: October 19, 2009, 06:53:45 PM »
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I've reproduced the problem to some extent and I think I've determined the cause and a solution.

Details:

First off, I don't have a 10 stop ND filter - sorry guys, I'm not dropping 100$ just to do this test and then watch the filter collect dust on the shelf since I have absolutely zero use for such a thing, but I do have a lens cap....

I have always thought the problem might be a light leak, so my test setup was as follows:

D300 on tripod/ballhead, set in landscape position
24-70/2.8 lens set at F/9 and 50mm
ISO 125
long NR set to "on"
Shutter set to bulb
remote release timed exposure of 4 minutes

Instead of a 10 stop ND, I put the lens cap on the lens and put the lens hood on the lens as I normally would.

Took a 250 w/s Dynalite strobe I had lying around, mounted it so the unit aimed down at approximately 40 degrees straight on into the lens/camera.
Center of flash tube was 3 feet from focal plane of lens/body.
Set the monolite at 250 w/s and turned the modeling light on full.
Ambient light reading at that distance for that ISO was 1/250 at F/16, which emulates strong daylight.
In addition, during the 4 minute exposure I fired the strobe at full power (250 w/s) 30 (yes, thirty) times, which I do believe is considerably brighter than any daylight exposure you're ever likely to encounter on this planet.

My first frame showed a narrow horizontal area along the top left edge of light leak/flare - from the left edge to maybe 1/4 to 1/3 inwards. Not very tall, perhaps 3/8 of an inch on the back LCD screen. The rest of the frame was pitch black.

I then redid the test with just the ambient light from the modeling light (did not hit the strobe 30 times at full power) and got a weaker version of the above.

I then covered the lens barrel with a dark washcloth and repeated the first test (4 minutes ambient, 30 hits with the strobe): result: pure black frame.

Then I removed the dark washcloth and covered the plastic cover over the distance display on the top of the lens barrel with a double folded piece of gaffers tape and redid the same test (4 minutes ambient, 30 hits with the strobe). Result: no flare, pure black frame.

Obviously while I can't exactly reproduce the ND filter scenario, I'm deducing that there is a light leak around that plastic distance display in these conditions that's causing the problem.

While nothing I say will make the 24-70 haters ever like this lens, I would say if you want to do this sort of long exposure/daylight shooting, I'm betting a double layer of black masking tape over the plastic distance scale would solve the problem.

Hope this helps....
(and perhaps someone can also verify my test to see if they come up with the same thing)

-m

ps: I apologize for not providing samples: I don't have a hosting site at the moment.
« Last Edit: October 19, 2009, 06:55:40 PM by NashvilleMike » Logged
rethmeier
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« Reply #46 on: October 19, 2009, 07:26:27 PM »
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Looks like you've solved the problem NashvilleMike!
Well done!

All we need is to cover the distance scale,which I never look at anyway.

Phew,

Best Willem.
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Willem Rethmeier
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duraace
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« Reply #47 on: October 19, 2009, 07:51:50 PM »
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Quote from: NashvilleMike
I've reproduced the problem to some extent and I think I've determined the cause and a solution.

Details:

First off, I don't have a 10 stop ND filter - sorry guys, I'm not dropping 100$ just to do this test and then watch the filter collect dust on the shelf since I have absolutely zero use for such a thing, but I do have a lens cap....

I have always thought the problem might be a light leak, so my test setup was as follows:

D300 on tripod/ballhead, set in landscape position
24-70/2.8 lens set at F/9 and 50mm
ISO 125
long NR set to "on"
Shutter set to bulb
remote release timed exposure of 4 minutes

Instead of a 10 stop ND, I put the lens cap on the lens and put the lens hood on the lens as I normally would.

Took a 250 w/s Dynalite strobe I had lying around, mounted it so the unit aimed down at approximately 40 degrees straight on into the lens/camera.
Center of flash tube was 3 feet from focal plane of lens/body.
Set the monolite at 250 w/s and turned the modeling light on full.
Ambient light reading at that distance for that ISO was 1/250 at F/16, which emulates strong daylight.
In addition, during the 4 minute exposure I fired the strobe at full power (250 w/s) 30 (yes, thirty) times, which I do believe is considerably brighter than any daylight exposure you're ever likely to encounter on this planet.

My first frame showed a narrow horizontal area along the top left edge of light leak/flare - from the left edge to maybe 1/4 to 1/3 inwards. Not very tall, perhaps 3/8 of an inch on the back LCD screen. The rest of the frame was pitch black.

I then redid the test with just the ambient light from the modeling light (did not hit the strobe 30 times at full power) and got a weaker version of the above.

I then covered the lens barrel with a dark washcloth and repeated the first test (4 minutes ambient, 30 hits with the strobe): result: pure black frame.

Then I removed the dark washcloth and covered the plastic cover over the distance display on the top of the lens barrel with a double folded piece of gaffers tape and redid the same test (4 minutes ambient, 30 hits with the strobe). Result: no flare, pure black frame.

Obviously while I can't exactly reproduce the ND filter scenario, I'm deducing that there is a light leak around that plastic distance display in these conditions that's causing the problem.

While nothing I say will make the 24-70 haters ever like this lens, I would say if you want to do this sort of long exposure/daylight shooting, I'm betting a double layer of black masking tape over the plastic distance scale would solve the problem.

Hope this helps....
(and perhaps someone can also verify my test to see if they come up with the same thing)

-m

ps: I apologize for not providing samples: I don't have a hosting site at the moment.


Apparently the problem doesn't show up at the extreme lengths (i.e. 24mm and 70mm).  Does this make sense given your deduction re: the plastic distance display leak?  The same test at those settings would be interesting.  Are the frames still pure black?
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rethmeier
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« Reply #48 on: October 19, 2009, 07:56:21 PM »
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I suspect that the difference in settings like 24 or at 70,the internal movements will not reproduce the same.That's why the issue is only at midrange at 50.
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Willem Rethmeier
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JeffKohn
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« Reply #49 on: October 19, 2009, 07:57:35 PM »
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Quote from: rethmeier
I suspect that the difference in settings like 24 or at 70,the internal movements will not reproduce the same.That's why the issue is only at midrange at 50.
I agree. The 24-70 has an 'inner barrel' that extends/retracts depending on the focal length, so it could be that it depends on the internal position of various elements of the lens.
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NashvilleMike
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« Reply #50 on: October 19, 2009, 08:06:54 PM »
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Quote from: duraace
Apparently the problem doesn't show up at the extreme lengths (i.e. 24mm and 70mm).  Does this make sense given your deduction re: the plastic distance display leak?  The same test at those settings would be interesting.  Are the frames still pure black?

I accidentally ran the test first at slightly less than 28mm before remembering that you had experienced the problem at 50mm, and at that slightly less than 28mm setting, no, I did not have the flare problem with the lens barrel uncovered. I didn't check at 70mm. I've got to move on to other things (have a ton of stuff in the retouching/post processing queue that needs to be addressed) so my testing for the week is complete; hopefully I've given other folks enough that they can continue and confirm or deny my results if they wish. I'm reasonably comfortable saying that the plastic window is the culprit.

The 24-70 zoom does have a set of elements internally that move back and forth depending on focal length and it's in the middle focal length ranges that something appears to be "in the middle of things" in terms of where that moving group is, and I suspect that's why we're only seeing it in the middle focal length ranges.

-m
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Downtown
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« Reply #51 on: October 19, 2009, 09:01:05 PM »
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Quote from: duraace
Apparently the problem doesn't show up at the extreme lengths (i.e. 24mm and 70mm).  Does this make sense given your deduction re: the plastic distance display leak?  The same test at those settings would be interesting.  Are the frames still pure black?


What a team effort! A special thanks to Nasville Mike for coming up with the apparent fix and Duraace for stepping up and telling everyone of the problem! I myself ran tests late today as suggested by members who were reading this thread. I set up my camera as I did previously changing nothing but the focal lengths to see where the problem is most evident. With lens cap on the same problem persisted at  40 - 42mm as evidenced below. If someone has more time than me I'm sure they can find out if it's from 40 - 50mm or Huh. After reading Nashville Mike's latest CSI detective work I went back out and tried the same test shots again this time wrapping black electricians tape around the M/A / M area and the plastic distance finder. The result ...............no flare or sign of problem! Now if you don't remember I complained to Nikon Canada and had a service rep  put me through the grinder emailing him test shots and explaining exactly what I was doing only to be told he had no idea what was wrong. Encouraged by members who thought that Nikon in fact should replace or repair these lenses I pulled out the case that the lens originally came in (along with reciept) and printed out test examples of the shots showing the problem and was ready to send it off to the repair centre in Richmond B.C. That being said do you think this is an isolated problem or an inherent problem to the 24 - 70 lens? My current thoughts now are that rather than send my lens away for 2 weeks I'll just carry a .99 cent roll of electricians tape as a quick fix and think of CSI Nashville Mike while I wait out my long exposure!



Cheers!
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rethmeier
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« Reply #52 on: October 20, 2009, 01:06:16 AM »
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Excellent test Downtown!
Looks like we found a solution for the problem.

Now shall we test the 14-24 and the new 70-200 as well?
Or any other Nikon Zoom for that matter?

The 14-24 @19 and the 70-200 @ 135 ?

I guess the issue is that all these zooms were designed for normal use,like max 30 secs and average day use at 125th of higher.

« Last Edit: October 20, 2009, 01:12:47 AM by rethmeier » Logged

Willem Rethmeier
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Rob C
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« Reply #53 on: October 20, 2009, 02:52:26 AM »
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Quote from: rethmeier
Excellent test Downtown!
Looks like we found a solution for the problem.

Now shall we test the 14-24 and the new 70-200 as well?
Or any other Nikon Zoom for that matter?

The 14-24 @19 and the 70-200 @ 135 ?

I guess the issue is that all these zooms were designed for normal use,like max 30 secs and average day use at 125th of higher.




That might be a useful point of view to hand to Nikon Inc. for their Defense Department, but hardly washes with anybody who has bought the thing. That Nkon can market a lens with a built-in light leak is beyond belief.

Just as bad was the lousy definition at the side of the frame at the wide end on the sample that I had bought.

As for abandoning depth of field scales...

I don't think it's a matter of 'haters' as someone wrote, but of annoyed and very disappointed career-long Nikonistas!

Rob C
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Slough
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« Reply #54 on: October 20, 2009, 03:51:02 AM »
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Quote from: Downtown
What a team effort! A special thanks to Nasville Mike for coming up with the apparent fix and Duraace for stepping up and telling everyone of the problem!

I seem to recall both suggesting the probable cause (light leakage from the side) and a possible fix i.e. a sleeve. I am slightly surprised that the lens is not adequately baffled.
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rethmeier
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« Reply #55 on: October 20, 2009, 04:14:09 AM »
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Rob C!
Chill baby CHILL!
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Willem Rethmeier
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rethmeier
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« Reply #56 on: October 20, 2009, 04:22:17 AM »
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Again,
I can't believe all this!
I'm sure we can find faults with every piece of gear we own under extreme conditions.

If I was a lens designer for Nikon and designing a zoom lens,I would design it for an alternative for a prime.

Maybe RobC should become a lens designer(LOL)
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Willem Rethmeier
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Rob C
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« Reply #57 on: October 20, 2009, 09:38:21 AM »
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Quote from: rethmeier
Maybe RobC should become a lens designer(LOL)




What a ridiculous stance! So you should be a pilot ever time you fly; be a doctor every time you need to pop a pill... right?

What you are saying, then, is that lousy design and/or product control is an acceptable thing, nay, possibly even a policy for such expensive goods?

Trouble is, the more that people express this view then the more the manufacturers become aware that they can get away with it. Thanks for your help to photographers at large!

Rob C
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duraace
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« Reply #58 on: October 20, 2009, 11:27:54 AM »
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Quote from: Rob C
What a ridiculous stance! So you should be a pilot ever time you fly; be a doctor every time you need to pop a pill... right?

What you are saying, then, is that lousy design and/or product control is an acceptable thing, nay, possibly even a policy for such expensive goods?

Trouble is, the more that people express this view then the more the manufacturers become aware that they can get away with it. Thanks for your help to photographers at large!

Rob C

Being relatively new to photography, I'm curious to know whether long exposure techniques are a new practice, or have lenses been expected to do this since the film days? My guess is that the abberation with the 24-70 lens is limited to that lens only. It would be really interesting to know if it is present in the 70-200? Anyone?
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NashvilleMike
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« Reply #59 on: October 20, 2009, 12:14:59 PM »
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Quote from: duraace
Being relatively new to photography, I'm curious to know whether long exposure techniques are a new practice, or have lenses been expected to do this since the film days? My guess is that the abberation with the 24-70 lens is limited to that lens only. It would be really interesting to know if it is present in the 70-200? Anyone?

I go back a few decades in photography and while I've heard of this technique for a while, I've never personally known anyone who practiced it nor have I done so myself so I can't speak as to how popular or how much it is practiced amongst the spectrum of photographic styles.

You've definitely discovered a design defect - and I'd call it a defect more than an abberation (an abberation is typically thought of as a result of an optical design decision, not a manufacturing snafu); the question is whether it's of a magnitude that Nikon would ever redesign the lens (and whether they'd even know about it - they're not cruising the forums when they make design decisions), and as I've stated before, I don't think it's a deal killer being it doesn't impact the vast majority of usage the lens is intended for.

As for other lenses - good question. I sold off my 70-200 recently, but if I get some other things knocked off my to-do list, I might try it on some of the other newer Nikon 'G' lenses I've got kicking around.

-m
« Last Edit: October 20, 2009, 01:13:16 PM by NashvilleMike » Logged
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