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Author Topic: Nikkor 14-24/2.8  (Read 7049 times)
Ray
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« on: October 26, 2008, 08:24:06 AM »
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I waited 8 months to receive the Nikon/Canon adapter from Mark Welsh, after placing my order in February this year. That's almost the time of the gestation period of the human foetus, so one might consider this adapter to be a premature baby.

I had a bit of trouble fitting the adapter to the Nikkor lens because a couple of miniscule screws had to be turned which I couldn't see with my normal reading glasses. I had to fit a jewelers' magnifying glass to my forehead and then locate a screwdriver small enough to fit.

The lens does not autofocus, understandably, but autoexposure does work in aperture prioroity mode. Unfortunately, selection of aperture is mostly guesswork. There are 3 marks on the adapter which signify F2.8, F8 and F16. The lens turns on the adapter across these marks, but there's no EXIF information in ACR regarding aperture, just shutter speed and ISO.

Another quirky thing which is a bit worrying is the inability of the camera to be completely switched off when the Nikkor lens is attached. The red 'activity' light on the 5D continues to flash at a rate of about one flash every 1.5 seconds, as though to indicate that a foreign object is attached to the camera and that something may be wrong.

I imagine that maybe the battery would run flat if the camera was unused for a few weeks.

I intend to compare this lens with my Sigma 15-30 and examine corner resolution. But I haven't got around to this, yet. However, this morning I had to arise early to take my partner to the airport, and for the first time in a long time, saw the sun rise over the Brisbane river as I was brewing my morning coffee. (I usually get to bed late as a result of trying to communicate with strangers on the other side of the globe.)

I grabbed my 5D with Nikkor lens already attached, and took the following shot, directly into the rising sun. I'm very impressed with the absence of flare. A shot like this with the Sigma would have produced great elliptical blobs of red.

I don't see any significant signs of flare in this shot. Do you?

[attachment=9187:7049.jpg]

14mm, 1/125th, ISO 100.
« Last Edit: October 26, 2008, 08:27:25 AM by Ray » Logged
francois
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« Reply #1 on: October 26, 2008, 01:21:22 PM »
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I don't see any flare in your photo.
I hope to read your comments once you have spent more time with your 5D/14-24.
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Francois
Andy M
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« Reply #2 on: October 26, 2008, 03:34:45 PM »
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That shot appears extremely soft in the corners, with possible CA?

Maybe crops would give a better representation?
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BernardLanguillier
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« Reply #3 on: October 26, 2008, 08:00:58 PM »
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Ray,

This is a pretty easy situation flarewise, most of the sun is behind the trees.

The 14-24 does flare to some extend when the sun is directly in the image with nothing to hide it.

Cheers,
Bernard
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Ray
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« Reply #4 on: October 27, 2008, 02:09:22 AM »
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Quote from: BernardLanguillier
Ray,

This is a pretty easy situation flarewise, most of the sun is behind the trees.

The 14-24 does flare to some extend when the sun is directly in the image with nothing to hide it.

Cheers,
Bernard

Bernard,
The Sigma flares when the sun isn't even in the image. I've been searching for an upgrade to the Sigma 15-30 for a long time. The obvious candidate was the Canon 16-35, but I've heard conflicting reports on this lens. In any case, the Canon 16-35 was the alternative lens I compared with the Sigma in the store before choosing the Sigma, but using the cropped format D60 for the comparison. Edge performance on a full frame was not a consideration at the time. The prevailing wisdom at that time was that FF 35mm would always remain an expensive item for the professional. That was a long time before the introduction of the 5D, which upset the apple cart.
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Ray
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« Reply #5 on: October 27, 2008, 03:52:46 AM »
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I'm completely staggered by how much better corner performance is, with the Nikkor 14-24 at 14mm, compared with the Sigma 15-30 at 15mm.

I always knew that the Sigma was rather poor in the corners, but seeing a comparison with the Nikkor is just ridiculous. Both lenses produce equally sharp results in the centre of the frame, within an image circle of about 24mm diameter, but stray outside that image circle and the Nikkor becomes increasingly better, to the point where, in the extreme corners it's so much better that comparing chalk with cheese becomes an inadequate metaphor. We need a new metaphor. How about, comparing diamonds with jelly?

Sometimes the focal length markings on lenses are not accurate. I get the impression that the Sigma at 15mm is accurate because it's noticeably wider on FF than the Canon 10-22 at 10mm on a cropped format, which translates to 16mm. That 1mm difference can be surprisingly noticeable, as it is with the Nikkor at 14mm compared with the Sigma at 15mm.

The following images have received only default sharpening in ACR. Other adjustments have been made to contrast and brightness to get compared images looking close with regard to tonality and vibrance.

Because lens performance can vary according to which side or corner one is comparing (lenses are not symmetrical in performance), I've produced 200% crop comparisons of all corners plus the mid-point of the two shorter sides, which represent a distance of up to 12mm from the cente.

I start with the full scene from both lenses, so you can see the difference between 14mm and 15mm. However, this difference is very evident in all the crops also. I also include  100% crop comparisons of the central area and mid-bottom side showing that resolution is very similar for both lenses within that 24mm diameter, and 200% crops for all the corners and mid-sides.

[attachment=9209:The_scene.jpg]  [attachment=9210:100__cro...of_focus.jpg]  [attachment=9211:F8_botto...t_corner.jpg]  [attachment=9212:F8_mid_left_side.jpg]  [attachment=9213:F8_top_left.jpg]  [attachment=9214:F8_top_r...t_corner.jpg]  [attachment=9215:F8_mid_right_side.jpg]  [attachment=9216:F8_botto...t_corner.jpg]  [attachment=9217:F8_mid_bottom_side.jpg]
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BernardLanguillier
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« Reply #6 on: October 27, 2008, 04:19:59 AM »
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Quote from: Ray
I'm completely staggered by how much better corner performance is, with the Nikkor 14-24 at 14mm, compared with the Sigma 15-30 at 15mm.

I am somehow jalous, your life could still get even better if you decided to buy a Nikon body... while I have already consumed all that potential for enhancement.

Cheers,
Bernard
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Ray
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« Reply #7 on: October 27, 2008, 05:06:52 AM »
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Quote from: BernardLanguillier
I am somehow jalous, your life could still get even better if you decided to buy a Nikon body... while I have already consumed all that potential for enhancement.

Cheers,
Bernard

I know what you mean. On the 5D this Nikkor lens does not have autofocussing and the autoexposure appears to be useless. My impression is, the autoexposure defaults to spot meter mode. Exposure fluctuates wildly with just a slight movement of camera. I'll have to investigate this further. If it really does default to spot meter mode with Nikkor lens attached, I could use that fact to achieve accurate ETTR. Ie. take a reading of the brightest part of the scene then increase exposure by 4 stops (or whatever) in manual mode.

I think you have probably already guessed; if Nikon produce a 24mp upgrade to the D700 with outstanding high ISO noise performance, I'll be very interested   .
« Last Edit: October 27, 2008, 09:16:11 AM by Ray » Logged
Ray
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« Reply #8 on: October 27, 2008, 08:30:45 PM »
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Just for the record, autoexposure now works fine after cleaning the contacts on the adapter. I think that's what the slowly flashing, red activity light was trying to tell me.... poor contact between lens and camera. It now no longer flashes when the camera is switched off. Everything is fine apart from the aperture guesswork between the 3 markers which signify F16, F8 and F2.8.
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Guillermo Luijk
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« Reply #9 on: October 29, 2008, 07:58:31 AM »
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Very interesting tests Ray, the Nikkor shows to be quite superior but I wonder at which sutter speed you shot (some of the tests seem blurred) and why did you shoot at ISO200 with the Sigma while ISO100 was used inthe Nikkor shots?

Another question: the aperture setting which has marks for 2.8, 8 and 16, goes beyond f16? is simply has got those marks, or for those particular values the ring can be set precisely?

BR
« Last Edit: October 29, 2008, 09:27:25 AM by GLuijk » Logged

Ray
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« Reply #10 on: October 29, 2008, 09:34:18 AM »
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Quote from: GLuijk
Very interesting tests Ray, the Nikkor shows to be quite superior.
Why did you shoot at ISO200 with the Sigma while ISO100 was used inthe Nikkor shots?

Another question: the aperture setting which has marks for 2.8, 8 and 16, goes beyond f16? is simply has got those marks, or for those particular values the ring can be set precisely?

BR

Hi Guillermo,
I took a number of shots at different apertures and ISOs during this test. The resolution of the Sigma in the corners is so bad at F8, I decided to compare the Nikkor at 1/400th second and ISO 100 with the Sigma at 1/1000th and ISO 200, to avoid giving any impression that these results were influenced by a gale force wind that just happened to spring up as I pressed the shutter, when using the Sigma lens   . In fact, there was a slight breeze now and again, but nothing serious.

The three marks on the adapter, red, green and silver, are supposed to signify F16, F8 and F2.8 but I haven't yet done a thorough check on their accuracy. I've assumed that the Sigma's exposure of 1000th instead of an 800th was due to changing lighting conditions, but it might be the case that the F8 mark on the Nikon adapter is actually signifying F11, which would partly explain the reason those corners are so very much sharper.

Setting the 5D to ISO 3200 and pointing the camera at a bright part of the wall, lit with constant artificial lighting, I see the exposure varies from 1/4 sec to 1/500th as I rotate the lens from its maximum position, just beyond the red spot, to its maximum position just beyond the silver spot. The progression is: 1/4th, 1/6th, 1/13th, 1/25th, 1/40th, 1/60th, 1/125th, 1/200th, 1/320th, 1/400th, 1/500th. That seems to me a 7 stop range, which indicates that the Nikkor's aperture range is F32 to F2.8. Does that sound right? I'll have to check the specs of this lens. I didn't know it stopped down as far as F32. If this is the case, the above Nikkor shots are probably at F11. I've bungled the comparison. Sorry!  
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Tony Beach
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« Reply #11 on: October 29, 2008, 11:28:01 AM »
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Quote from: Ray
That seems to me a 7 stop range, which indicates that the Nikkor's aperture range is F32 to F2.8. Does that sound right? I'll have to check the specs of this lens. I didn't know it stopped down as far as F32.

f/2.8 plus 6 stops is f/22, which is the smallest aperture available on that lens.
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Ray
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« Reply #12 on: October 29, 2008, 11:43:22 AM »
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That's odd. The manual states F2.8 to F22 which is a 6 stop range, so I shall have to assume that rotating the lens just past the F16 mark gives me F22 and probably just past the F8 mark in the opposite direction gives me F8. Judging by the histograms of two images I've found, both taken at 1/200th and ISO 100 close together so there's little chance of much lighting variation, I would estimate I've been using the Nikkor at F9 or F10 since the Nikkor image requires a -0.3 EV adjustment as opposed to the Sigma's -0.8 EV adjustment. However, I'll need to experiment more with these exposures, because in constant lighting in-doors at this very moment, I find that the Sigma at F3.5 in AV mode gives me the same 500th sec exposure as the Nikkor at the F2.8 mark, focussing on the same bright part of the wall. The Nikkor seems to transmit less light at the same aperture. Maybe I haven't bungled the comparison.

Below are the ACR windows showing the adjustment and histograms for both images, plus a comparison of the bottom left corner which still shows the vastly superior resolution of the Nikkor.

[attachment=9283:ACR_wind..._ISO_100.jpg]  [attachment=9284:ACR_wind..._ISO_100.jpg]  [attachment=9285:Bottom_l...1___7087.jpg]


And at F22 and 15mm the Sigma gives a reading a 1/13th sec whereas the Nikkor at F22 and 15mm gives a reading of 1/4th in AV mode.
« Last Edit: October 29, 2008, 11:57:30 AM by Ray » Logged
Ray
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« Reply #13 on: October 29, 2008, 07:16:27 PM »
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It now seems clear that the Nikkor 14-24 has a lower 'light transmission efficiency' than the Sigma 15-30, so the comparisons I've made would appear to be perfectly valid, ie. the Nikkor really was set at F8, the same aperture as the Sigma.

Transmission efficiency is not something that's mentioned much on photographic forums. We tend to assume that all lenses at the same aperture and focal length will give the same exposure reading for the same scene. But this is not quite true. For example, at F4 and 50mm, my Canon 24-105 zoom will give a reading of 1/400th sec (just tried it), yet the 50/1.8 prime at F4 produces an exposure reading of 1/640th under exactly the same lighting conditions. The 50mm prime would appear to have about 2/3rds of a stop greater light transmissive efficiency than the 25-105 zoom at that particular aperture and focal length.
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httivals
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« Reply #14 on: October 30, 2008, 05:38:22 AM »
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It's well known that different lenses transmit light at different efficiencies at the same f-stops.  For cinema cameras, lenses are typically marked with an f stop and a t-stop, the t-stop being the one used to judge exposure.

Quote from: Ray
It now seems clear that the Nikkor 14-24 has a lower 'light transmission efficiency' than the Sigma 15-30, so the comparisons I've made would appear to be perfectly valid, ie. the Nikkor really was set at F8, the same aperture as the Sigma.

Transmission efficiency is not something that's mentioned much on photographic forums. We tend to assume that all lenses at the same aperture and focal length will give the same exposure reading for the same scene. But this is not quite true. For example, at F4 and 50mm, my Canon 24-105 zoom will give a reading of 1/400th sec (just tried it), yet the 50/1.8 prime at F4 produces an exposure reading of 1/640th under exactly the same lighting conditions. The 50mm prime would appear to have about 2/3rds of a stop greater light transmissive efficiency than the 25-105 zoom at that particular aperture and focal length.
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Ray
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« Reply #15 on: October 30, 2008, 07:43:54 AM »
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Quote from: httivals
It's well known that different lenses transmit light at different efficiencies at the same f-stops.  For cinema cameras, lenses are typically marked with an f stop and a t-stop, the t-stop being the one used to judge exposure.

Maybe, but what's not well known is the specific transmission efficiency for specific lenses for still cameras. It generally doesn't appear to be mentioned in the lens specifications. This has only become an issue for me because the Nikkor 14-24 does not have aperture markings on the lens body or any information regarding aperture on the 5D's LCD screen or viewfinder. Nor is the information included in EXIF.
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Slough
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« Reply #16 on: October 30, 2008, 08:23:55 AM »
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Quote from: Ray
It now seems clear that the Nikkor 14-24 has a lower 'light transmission efficiency' than the Sigma 15-30, so the comparisons I've made would appear to be perfectly valid, ie. the Nikkor really was set at F8, the same aperture as the Sigma.

Transmission efficiency is not something that's mentioned much on photographic forums. We tend to assume that all lenses at the same aperture and focal length will give the same exposure reading for the same scene. But this is not quite true. For example, at F4 and 50mm, my Canon 24-105 zoom will give a reading of 1/400th sec (just tried it), yet the 50/1.8 prime at F4 produces an exposure reading of 1/640th under exactly the same lighting conditions. The 50mm prime would appear to have about 2/3rds of a stop greater light transmissive efficiency than the 25-105 zoom at that particular aperture and focal length.

Some lenses have T stops marked on them. I seem to recall that was true for some old cine/TV camera lenses I had.
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Ray
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« Reply #17 on: October 30, 2008, 08:43:56 AM »
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Quote from: Slough
Some lenses have T stops marked on them. I seem to recall that was true for some old cine/TV camera lenses I had.

Yes, I came across a bit of information on that doing a Google search, but I was surprised at how little information I could find on this subject, which is why I got the impression it might be one of the hidden secrets of lens performance, swept under the carpet, so to speak.

People buy fast lenses because they are fast, as well as offering a shallow DoF. It seems that the Nikkor 14-24 at 15mm and F2.8 is no faster than my Sigma 15-30 at 15mm and F3.5.
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