D80, different lenses, different "correct" exposures, but one lens always darker

[jrichardson]

<p >Hi, new here, hope this is the right place. I am new to DSLR cameras, and only have experience using point and shoot cameras set to auto.</p>

<p > </p>

<p >I recently bought a used D80 from a friend. Came with SB600 flash and Nikkor 50mm 1.4 prime lens. I ordered a new Nikkor 18-105 3.5/5.6 lens from B&H. </p>

<p > </p>

<p >I borrowed the camera for about a month before I bought it. Took great pics, which is why I bought it. I just received the 18-105 lens last week. Almost all of my pictures using the 18-105 lens come out underexposed and dark. I did a few tests using the flash and not using the flash. I set the 18-105 lens to 50mm, and took a picture of an object with both lenses. Most of the time, the aperture and shutter speed were the same (ISO never changed during the tests). Regardless, the exposure meter in the viewfinder would show a correct exposure (no bars to the right or left of center on the meter). Every time, the picture taken with the 18-105 comes out noticeably darker. Dark enough that I don’t even like the picture.</p>

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<p >In my tests, nothing changed between pictures other than the lens (that I am aware of). Is this normal? Shouldn’t a TTL meter account for any lens differences and note so accordingly on the meter display?</p>

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<p >The tests I performed were done on Auto and Manual. Both set of tests give the same results: a dark picture from the 18-105 lens. My wife will be using this camera pretty much on Auto only, which is why I tested on that setting. I have started using manual for just about everything.</p>

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<p >Any help is appreciated. Thanks.</p>

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<p >Jason</p>

<p > </p>

[photo5]

<p>Without being able to look at an example, there isn't much I can comment on. However, I do remember owning the 50mm f1.4 AF-D and I felt that lens created photos that were overexposed (don't have one anymore, I much prefer the f1.8). If you can post an example of your underexposed photos, that would be helpful.</p>

[monika_epsefass]

<p>Same f setting, same time values?</p>

<p>I have the 50/1.4 too (great lens!), but agree with what Dave says. Often, I feel like I have to underexpose by a tad bit during postprocessing. It may be just the opposite, then - the 50/1.4 being extremely light collecting. You want to try yet another lens, for comparison. Try to use the most similar settings when testing, though.</p>

[jrichardson]

<p>Thanks for the responses. Here are links to 2 pictures that I took. Both set to 50mm, exposure meter indicated a correct exposure (ISO, shutter speed, and aperture happened to be the same for each picture). No flash used.<br /><a href="http://www.burrowspestcontrol.com/jason/DSC_0239.JPG">http://www.burrowspestcontrol.com/jason/DSC_0239.JPG</a><br /><a href="http://www.burrowspestcontrol.com/jason/DSC_0240.JPG">http://www.burrowspestcontrol.com/jason/DSC_0240.JPG</a></p>

<p>Here are 2 more, using the flash.<br>

<a href="http://www.burrowspestcontrol.com/jason/DSC_0165.JPG" target="_blank">www.burrowspestcontrol.com/jason/DSC_0165.JPG</a><br>

<a href="http://www.burrowspestcontrol.com/jason/DSC_0166.JPG" target="_blank">www.burrowspestcontrol.com/jason/DSC_0166.JPG</a> <a href="http://www.burrowspestcontrol.com/jason/D"></a></p>

[andreas_manessinger]

This happens. Ken Rockwell blames it on incorrect aperture openings, i.e. the opening is not exactly as wide as the aperture reported to the camera would indicate. It happens with my Sigma 30/1.4 (needs -0.3EV on all apertures), on other lenses it seems to depend on the selected aperture as well. Ken's explanation seems plausible to me.

 

Simply check the histogram and use +/- for exposure compensation. It should not depend upon the absolute exposure value, thus you can set it for the lens and just leave it at that.

[elmroc]

<p>One thing that is strange in your exif data is the fact that the the 2 darker photos, it shows that your maximum aperture vale is 4.92. And thephotos that look properly exposed, show the max aperture value of 1.41.<br>

I'm not certain what this means, only that it shows a variation.</p>

[jrichardson]

<p>Hi John, I noticed that too. I don't know much about EXIF data, I just started looking at it yesterday. I took it to mean that at the set focal length (50mm for both lenses) the max aperture available was the number given. The max aperture on the 18-105 3.5/5.6 at 50mm is 4.92 since the max aperture changes with focal length. Obviously the max aperture for the 1.4 prime is 1.4. Is that correct about the max aperture EXIF data?<br /><br />Andreas, is there an article from Mr. Rockwell I can read about the aperture? It makes sense, since the aperture isn't actually adjusted until the picture is taken. I did not notice a way to adjust exposure compensation in Auto mode. That's all my wife is going to use to take pictures of our twin babies, so I need a solution for the Auto setting.</p>

[hans_janssen]

<p>I think the 5.6 on the 18-105 is something like 6,4 or so, so there comes less light into the cam. Try find another 18-105 and do same test and draw your conclusion or send it back right away.</p>

[ted_raper1]

<p>Try also the same experiment with the camera set in Auto (Program) mode and let the D80 make what it thinks is the correct exposure and see what happens. If the 18-105 is still underexposing, you may have a lens issue. I had an 18-105 for a while and mine never had issues like that.</p>

[photo5]

<p>They both look under to me, how did you meter this scene? Hans is right, the 18-105mm is not a constant aperture lens, so at 50mm the f5.6 setting is probably 6.4 or so. Oh, I see your D80 has almost 30k shutter actuations.</p>

[Michael R Freeman]

<blockquote>

<p>"... the 18-105mm is not a constant aperture lens, so at 50mm the f5.6 setting is probably 6.4"</p>

</blockquote>

<p>No, that is not true. Although it is a variable aperture lens, if the aperture is set to f/5.6 via the command dial, then the lens will stop down to a true f/5.6 (within tolerances) when the shutter is released. This is a G lens, so unlike a variable aperture lens that sets f/stop via the hard physical stop of an aperture ring (assuming the camera is set to control aperture via the ring), f/5.6 does give you f/5.6.</p>

<p>However, it is certainly possible that the mechanical components of the aperture stopdown mechanism in this lens are incorrectly adjusted, and the opening at the f/5.6 stopdown lever position (controlled by the camera) is not giving a true f/5.6 opening.</p>

<p>Take a photo of an evenly lit blank wall using the two lenses in aperture priority mode, without flash. Same ISO, same lighting, same aperture. See what you get.</p>

[photo5]

<p>I would have to see it to believe it. All variable aperture zooms that I've used will not give a true f5.6 at both ends of the range. I don't think they are sophisticated enough to give a true f5.6 throughout the zoom range if set to that. It's going to vary depending on the focal length selected. We're talking cheap consumer zooms here, not pro zooms. If you were to do that test, I'm sure the exposure would be darker at 105mm vs. 18mm. I don't have that lens here (nor do I have any G zoom lenses), so I can't do that test.</p>

[Michael R Freeman]

<blockquote>

<p>I would have to see it to believe it.</p>

</blockquote>

<p>Dave - the way the aperture is physically closed when the shutter opens is different with G lenses (all CPU lenses in fact) on modern bodies than with traditional lenses on older bodies. It has nothing to do with pro vs. consumer, or G vs. D, etc.</p>

<p>Of course the aperture will vary as the lens is zoomed when aperture value is set to the MAXIMUM aperture on the WIDE end. But at values equal to or smaller than the maximum aperture at the long end, the camera is able to adjust and keep the lens aperture value constant as the lens is zoomed. In fact, some cameras can be set as such via custom function when in aperture priority or manual exposure modes. If you set the aperture value to f/8 at the long end of a zoom, the aperture value does not get wider as you zoom to the wide end. And vice versa. The 18~105 is capable of f/5.6 at 50mm. so if you tell it to set the aperture to f/5.6 with the body command dial, then f/5.6 will result at stopdown.</p>

<p>You can choose to believe it or not, but when the aperture opening at the instant of exposure is set via the body controlled stopdown lever (infinitely variable), stopdown action is different than when the aperture opening is controlled via a hard physical stop of an aperture ring (stopdown lever always stops at the same position).</p>

[jrichardson]

<p>Mr Freeman,<br>

I took 2 pictures of a blank wall in aperture mode. Aperture 5.6 for both, ISO 400 for both, no flash, 50mm for both (actually the variable zoom lens shows 52mm, so I was a tad offwhen I zoomed in). Same results. The variable zoom lens picture is darker.<br>

<a rel="nofollow" href="http://www.burrowspestcontrol.com/jason/DSC_0252.JPG" target="_blank">http://www.burrowspestcontrol.com/jason/DSC_0252.JPG</a><br>

<a rel="nofollow" href="http://www.burrowspestcontrol.com/jason/DSC_0253.JPG" target="_blank">http://www.burrowspestcontrol.com/jason/DSC_0253.JPG</a></p>

[Michael R Freeman]

<p>Something is amiss, because the darker image has a 1/2 stop slower shutter speed (1/90 vs. 1/125). Setting aside that the fact that both should give the same shutter speed in A mode if the lighting is constant, one would expect the 1/90 image to be lighter, not darker.</p>

<p>Try again, but this time in full manual mode. Same f/5.6 aperture for both lenses, and the same shutter speed. If the images are not the same density, then something is a) wrong with the body, or b) one of the lenses is not within tolerances.</p>

[pete_s.]

<p>There are two things going on. First there is some variance in exposure between lenses because the mechanics is never perfect. I believe it can be adjusted by Nikon service. There is also some variance from shot to shot when using the same aperture, shutter speed and iso.<br>

<br /> Secondly, the zoom lens is suffering from vignetting as most slow aperture zooms do. Comparing the two last pictures you posted the difference in the center is that it's about 54% brightness in the center for the 50mm and 50% for the zoom. That difference is normal given that the exposure wasn't exactly the same.<br /> The corners however are much darker on the zoom but that is vignetting and should be expected. If you would have shot at f/16 the vignetting would have been less.</p>

<p> </p><div></div>

[pete_s.]

<p>PS. I think you should try a third lens and then all three lenses on another camera. Just shoot something grey in manual mode and compare them all. I think your zoom might need to be adjusted by Nikon but it could also be your 50mm.</p>

<p>Realize that the camera measures the light with the aperture fully open then it mechanically stops down (smaller opening) to your selected aperture to take the picture. If the mechanics is not perfect the aperture of the lens will not be what the camera intended.</p>

[jrichardson]

<p>Thank you all for your help. I will try what other tests I can tomorrow. I don't have access to another body or lens right now. I will say that while I was borrowing the camera, I had 2 other lenses (that I did not buy): a 18-200 made by Quantaray (sp?) and a 24-80 (I think) Tokina 2.8. I never did any tests like this when I was borrowing the camera, but I never had any pictures turn out underexposed like I have with the new 18-105 lens. The friend moved to Canon, so she sold her other lenses that I didn't buy.<br>

Unfortunately, based on B&H's website, I don't think I can return the lens for another one. I filled out my warranty card already (since it said I had to do so within 7 days of purchase), and it looks like I need a blank one for the lens to be able to send it back. I meant to call B&H today, but forgot. Now they are closed for a week or 2. I like the lens, so I guess if, after further testing, it looks to be the lens, I will call Nikon and see what they will do.</p>