[vc13130]

Hi! Just signed up and wanted to let you know that this site is awesome.



I'm considering to buy a Nikon Tamron 60 f/2.0 lens, since I'm interested in dabbling in macro while also using the lens as a faster-than-normal moderate tele lens for portraits or other things. However, I've heard a lot of bad things about the lens. My understanding is that there are two majors issues. The first is that D90 and higher level Nikon cameras can't actually get the camera to go wider f 2.8 or 2.4. Supposedly the problem was due to a failure of the camera to properly turn the aperture lever. This totally defeats the purpose of using it as a fast tele. The second problem, which is a less big deal, is that it consistently underexposes on some cameras.



I've read about these problems on PZ and also on DPR (most notably at http://forums.dpreview.com/forums/readfl...e=34079707), but these things are all old. I was wondering what the most recent status is. Do you know if these issues have been resolved? Do you know if there are fixes or anything?



Many thanks!

[mst]

First of all, welcome on board and thanks for your kind words.



[quote name='vc13130' date='14 June 2010 - 04:14 AM' timestamp='1276485247' post='480']

The first is that D90 and higher level Nikon cameras can't actually get the camera to go wider f 2.8 or 2.4. Supposedly the problem was due to a failure of the camera to properly turn the aperture lever.[/quote]



Interesting thought. I will check this tonight.



Certainly would explain why shots at f/2 are even more underexposed than with other apertures.



However, also note that the lens alway reports effective aperture (like most macro lenses with Nikon mount). For closer focus, the maximum effective aperture decreases, so at usual portrait distances f/2 will already be unavailable. However, that's just the numercial value, the aperture is still wide open, even though the aperture value changes with closer focus. Effective aperture deals with exposure, not with DOF.



[quote name='vc13130' date='14 June 2010 - 04:14 AM' timestamp='1276485247' post='480']

The second problem, which is a less big deal, is that it consistently underexposes on some cameras.[/quote]



Not sure if "some" is correct. It certainly applies to all Nikon DSLRs I've tried the lens with, which as of today is (hope I remember them all correctly): D40, D40x, D80, D90, D200, D300, D300s, S5, D700, D3, D3x (FX cameras in DX mode, of course).



[quote name='vc13130' date='14 June 2010 - 04:14 AM' timestamp='1276485247' post='480']Do you know if these issues have been resolved? Do you know if there are fixes or anything?[/quote]



I haven't heard of any solution. A lens I tried in a store just recently still had the issue, but I don't know if this was old stock or a recently delivered one.



-- Markus

[vc13130]

Yes...someone did a "bokeh test" where they manually set the focus to 1 m and looked at the bokeh of background lights at f 2.2, 2.8, 4.0, etc. and showed that it was the same between 2.2 and 2.8 but different between 2.8 and 4.0. It also explains why the 2.0 and 2.8 resolution levels are the same the PZ Nikon mount test but different on the Canon mount test.



It's a shame that this lens has such major problems. It sounds perfect on paper (fast aperture, double working distance of the native Nikon 60), but the inability to reach maximum aperture makes the lens useless on Nikon mount <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/sad.gif' class='bbc_emoticon' alt='' />

[mst]

[quote name='vc13130' date='14 June 2010 - 01:34 PM' timestamp='1276518897' post='494']

someone did a "bokeh test" where they manually set the focus to 1 m and looked at the bokeh of background lights at f 2.2, 2.8, 4.0, etc. and showed that it was the same between 2.2 and 2.8 but different between 2.8 and 4.0.[/quote]



Well, at 1m that's hardly surprising, since wide open isn't reported as f/2.0 anymore (probably f/2.2 instead) and consequently f/2.8 isn't a full stop away. If this is how the test was performed, than it was doomed to fail because of a faulty setup.



And in addition it tells nothing about a possible misalignment of the aperture lever. Nonetheless I will check this theory tonight (I have my doubts, though).



Not to say the Tamron doesn't have a problem wide open ... it certainly does. But my feeling is more that some people posting "test results" are completely unfamiliar with the effective aperture reported by macro lenses with F mount.



Finally: our MTF measurements are done at a larger distance, 60 times the focal length, so 3.6m in this case.



-- Markus

[mst]

Oh, and: yes, it's a pity. Marvelous lens otherwise.



-- Markus

[mst]

Quick check on D40x, D200 and D3x: Aperture is physically fully opened on all three cameras.



-- Markus

[Guest]

[quote name='mst' date='14 June 2010 - 02:23 PM' timestamp='1276521801' post='496']

Well, at 1m that's hardly surprising, since wide open isn't reported as f/2.0 anymore (probably f/2.2 instead) and consequently f/2.8 isn't a full stop away. If this is how the test was performed, than it was doomed to fail because of a faulty setup.

[/quote]



Hi, I'm the one who started the mentioned dpreview thread.

The computation I did took the f/2.2 into account. You can judge yourself. Pictures from bokeh test are here:

http://jtra.cz/foto/tamron-underexposure-vs-bokeh/

The first picture shows target. Then I set manual focus and set 1m, I stayed at the same distance from target.

The second is f/2.2, the third f/2.8, the fourth is f/4, the last is f/8.

Disregard the blueish tint on the f/2.2 picture, at this aperture, the speed was 1/200s which was interfering with multi-color cycle of the compact fluorescent lights.



Circles of bokeh in this setup should be in size relative to aperture. This is valid for f/4 compared to f/8. I measure about 128 pixels diameter for f/4, while about 63 pixels diameter for f/8.

I measure about 180-190 pixels diameter for f/2.8. That is ok too, compared to f/4, the expected value is 4/2.8*128=183. But for f/2.2 I measure 190 pixels while it should be about 4/2.2*128=233.



In other shop which has had better lighting, I measured light intensity in the center of picture (should not be affected by vignetting) for corresponding combinations of increasing aperture and decreasing time in manual mode (which is not affected by camera metering). Result was the widest effective aperture was f/2.7. See here:

http://forums.dpreview.com/forums/read.a...e=34305325



After three month without any better lens (I tried about 6 over three months) I decided to go with different lens.



I do not know what was the reason for the behavior. Canon users of the lens were happy indeed. Only Nikon's were not. That lead me to speculate about nature of the problem. It might have been caused by aperture level interface the Nikon uses but Canon does not. The lens looked it opened fully via DOF preview, but perhaps at high shutter speed, the things may be different. Other reason might be the lens design is restrictive so that wide open aperture blades to not contribute fully to light path, but Canon users would be affected by that too.



Main attraction to Tamron was bokeh for me, not macro. The background bokeh was very pleasant (foreground bokeh is often opposite in pleasantness to background bokeh as explained at http://www.sony.ca/html/uf/microsite/Cap...ite/2.html in section "Aberration and the Defocused Image").



In comparison current Nikons 50/1.4 AF-S is awful for background bokeh. This photozone's picture shows it clearly: http://photozone.smugmug.com/photos/4571...447C-O.jpg

In background, the bokeh has pronouced circle edges (moreover they are green) - in foreground, the bokeh is pleasant. I wanted a lens that has good background bokeh, or at least neutral.



Nikon has such lens, it is 85/1.4 AF-D from what I have seen, but that was out of my price range.



So I choose Sigma 50/1.4 which is the only fast and current 50mm known to me that has pleasant background bokeh. Bokeh is still slightly colored (green in background, magenta in foreground as usual for fast non-apochromatic lenses).

I'm quite happy with that lens. Only issue is a bit unreliable AF accuracy at large apertures on my D90.

Other issue is size, it is quite big and heavy among 50mm, which intimidates some subjects.

[vc13130]

My new Tamron 60 just arrived and I did some side-by-side tests between it and my old Nikon 60. I set both to infinity focus and compared the bokeh in pictures taken of a nearby object. I found that the Tamron showed the same bokeh at 2.0, 2.2, 2.5, and 2.8, BUT the Tamron at 2.2 still showed more out of focus regions than the Nikon at 2.8 did. That suggests to me that the Tamron is UNDERESTIMATING its speed--when the camera says it's at 2.8 it's really at 2.2 or 2.0. That explains why the PZ-tested sample showed such high MTF at "f/22"--the lens was actually at f/16 or f/13! That also explains why the lens underexposes more at "2.0" than at "2.8": at "2.8" the camera thinks it's 2.8 when it's actually 2.0 (sets speed X), while at "2.0" the camera thinks it's 2.0 and it is 2.0 (sets speed X/2, but the aperture is the same as it was at "2.8" when the camera set speed X, so you get underexposure).



I think the issue of CONSTANT underexposure is a different problem. My copy doesn't have it.



I don't have a tripod so my tests are not as quantitative as they could be. Also, I have to do some more tests to see whether this finding is consistent at other f-stops. But if this hypothesis is correct, then the lens is more or less redeemed. It CAN still be useful as a portrait lens! You just have to keep in mind that the aperture the camera reads is not the actual aperture, and maybe add some exposure compensation if your lens has that issue.

[vc13130]

Just realized that due to the different macro working distance of the two lenses it's possible that they rendered the nearby object differently (maybe one of them rendered it as 1:2 and the other as 1:5, for example). I don't remember how close the nearby object was. I'll need to check again.



EDIT: I'm finding the "bokeh tests" difficult to perform since I don't have a tripod. However, I did find that at 2.8 the Tamron has double the light gathering ability as the Nikon. I shot a picture at ISO 400 1/100s with the Tamron and at ISO 400 1/50s with the Nikon and the pictures and histograms were identical, minus the increased vignetting on the Tamron.