Hi all, Hi Photozone team,
I have the Tamron AF 17-50mm f/2.8 SP XR Di II LD Aspherical [IF] VC (Canon) on my EOS1000D.
By chance, I noticed that under good lighting conditions (e.g. daylight/outside) the lens produces much sharper images when VC is switched off, compared to VC being switched on. I'm talking a decent level of sharpness being added once VC is off, as if a thin layer of unsharpness has been removed.
Under not so good lighting conditions (e.g. indoor lighting, candle light), the VC of course is a huge benefit and images produced at slow speeds are much sharper than without VC.
Photozone team, have you observed this behaviour under good lighting conditions with VC on/off before in any of your Tamron tests? Have you ever tested Tamrons with VC enabled/disabled during your tests? When you tests lenses, do you usually have VC/IS/OS enabled or disabled?
Anyone else experienced this?
Cheers,
Alex
Quote:Hi all, Hi Photozone team,
I have the Tamron AF 17-50mm f/2.8 SP XR Di II LD Aspherical [IF] VC (Canon) on my EOS1000D.
By chance, I noticed that under good lighting conditions (e.g. daylight/outside) the lens produces much sharper images when VC is switched off, compared to VC being switched on. I'm talking a decent level of sharpness being added once VC is off, as if a thin layer of unsharpness has been removed.
Under not so good lighting conditions (e.g. indoor lighting, candle light), the VC of course is a huge benefit and images produced at slow speeds are much sharper than without VC.
Photozone team, have you observed this behaviour under good lighting conditions with VC on/off before in any of your Tamron tests? Have you ever tested Tamrons with VC enabled/disabled during your tests? When you tests lenses, do you usually have VC/IS/OS enabled or disabled?
Anyone else experienced this?
Cheers,
Alex
Well, I don't know what degree you are talking about here but yes, technically images taken from a tripod or at high shutter speeds will be sharper than an IS image.
Hey Klaus, thanks; to be clear: I am referring to same lighting conditions, same shutter speeds etc, but one pic taken with VC enabled, one with VC disabled. Purposefully I did some hand held sample shots a while ago, under "field conditions" without any tripod, two shots in a row, one with VC disabled, one with VC enabled, have a look if you have a spare minute.
The "ohneVC" have VC disabled, the "mitVC" have VC enabled. I'm not a pixel peeper, but at 100% it seems the "ohneVC" shots are a bit sharper, with more contrast. E.g. look at the black fluff/dirt on the knob to the most right on the Lego brick - it is more contrasty/sharper without VC. I also noticed the same with any other shot e.g. portraits outside - they seem to be that little bit sharper once VC is disabled.
Now that I probably have amused the general public talking about fluff on my Lego brick ... I am thinking that VC might add a slight unsharpness into the mix due to it's very nature of operation? I know that the non-VC version of the lens is generally considered having a better sharpness, so it would be interesting to see how this (or any Tamron VC lens) compares with VC disabled vs their non-VC variants?
(The pics are control JPGs out of my Canon, slightly reduced in size so I could upload them here)
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I can spot a very marginal difference in there.
Without know anything about the exact conditions here, I'd say that this is perfectly normal.
VC/IS/VR/OS/... introduces a minimal degree of jittering. After all you have a "loose" elements that is moved according to the shake. The IS counteraction is performed according to a certain frequency. At the end of the day this means "steps" and whatever motor is used to control the motion it is never perfect.
That being said I have doubts whether this aspect is really relevant in the real life.
The more significant impact from an optical image stabilizer is the introduction of a potentially higher degree of decentering and a reduced long term consistency.
If I can chime in with some thoughts?
Firstly referring to Nikon's VRII system, users of quite a few VR II lenses have been complaining of softness in images around the 1/100-1/200 sec exposure time, I have also noticed it with my AF-S 70-300mm VRII lens with these speeds and especially at 1/160 sec. the image is blurred slightly, longer shutter speeds are better down to 1/60 and above 1/200 they are also sharp.
The (half) technical explanation is that the VRII system runs at (I think it's) 300HZ and certain shutter speeds have some sort of conflict with the frequency of the VR, Nikon received many returned lenses especially the AF-S 300mm F4 fresnel lens and were unable to improve the situation by firmware updates.
Eventually they issued a statement to the effect that, "due to the way the system functions some users may experience blurring at certain shutter speeds, these speeds should be avoided"!
I have and use regularly the Tamron 150-600mm VC for the most part it's system functions fine at shorter to medium focal lengths, however at the long end the systems seems to be over zealous in it action of trying to hold steady the image, till finally it let's go and restarts again. This means when panning at the long end most of the shots are blurred and the only remedy is turn the VC off!
This effect of over zealous VC is also noticeable as a certain jerkyness in video when panning with many Tamron lenses. (see Christopher Frost's utube videos)
I would suggest trying a series of test shots with a range of shutter speeds to try and find the speed where the problem is the most troublesome and avoid them, à là Nikon! If that doesn't resolve the situation you could either leave the VC off or return the lens to Tamron,
Your version was one their first ventures into stabilized lenses.
10-28-2015, 10:39 AM
(This post was last modified: 10-28-2015, 10:42 AM by Klaus.)
Quote: If I can chime in with some thoughts:
Firstly referring to Nikon's VRII system, users of quite a few VR II lenses have been complaining of softness in images around the 1/100-1/200 sec exposure time, I have also noticed it with my AF-S 70-300mm VRII lens with these speeds and especially at 1/160 sec. the image is blurred slightly, longer shutter speeds are better down to 1/60 and above 1/200 they are also sharp.
The (half) technical explanation is that the VRII system runs at (I think it's) 300HZ and certain shutter speeds have some sort of conflict with the frequency of the VR, Nikon received many returned lenses especially the AF-S 300mm F4 fresnel lens and were unable to improve the situation by firmware updates.
Eventually they issued a statement to the effect that, "due to the way the system functions some users may experience blurring at certain shutter speeds, these speeds should be avoided"!
I have and use regularly the Tamron 150-600mm VC for the most part it's system functions fine at shorter to medium focal lengths, however at the long end the systems seems to be over zealous in it action of trying to hold steady the image, till finally it let's go and restarts again. This means when panning at the long end most of the shots are blurred and the only remedy is turn the VC off!
This effect of over zealous VC is also noticeable as a certain jerkyness in video when panning with many Tamron lenses. (see Christopher Frost's utube videos)
I would suggest trying a series of test shots with a range of shutter speeds to try and find the speed where the problem is the most troublesome and avoid them, à là Nikon! If that doesn't resolve the situation you could either leave the VC off or return the lens to Tamron,
Your version was one their first ventures into stabilized lenses.
I can confirm that the Tamron 150-600mm's VC struggles beyond 500mm. First I thought it was a defect but then others reported this as well. The Sigma 150-600mm S has no issues here.
I must say, I admire a photographer able to handhold a Sigma 150-600 Sports. I tried a couple of times but prefer a gimbal head or monopod. However, in my hands Sigma's OS is steadier and more reliable than Nikons's VR (I, II or III)
Since the original question was about Tamron 17-50 on Canon I hesitated to answer. My experience was with Pentax and in-body-shake reduction. I was never happy with that combination. Nikon D7000 and Sigma 17-50/2.8 was in each aspect much higher IQ. Pentax with other Sigma's or Pentax lenses was also better than the Tamron combination.
Quote:I can confirm that the Tamron 150-600mm's VC struggles beyond 500mm. First I thought it was a defect but then others reported this as well. The Sigma 150-600mm S has no issues here.
Tamron have a firmware update which is supposed to cure the VC problem when panning, all it does is switch off the VC, so far I haven't sent it in to be upgraded.
I have the Tammy 17-50mm non VC version and have used it on the Pentax K20/K5/K3 with no SR problems, great lens, very sharp.
One strange problem however, which I did post here some years back. Wide open to F5 the AF is spot on, when you stop down to F5.6 it front focuses. Put the camera into AF-C half-press the shutter button, and with the rear wheel, change aperture from F5-5.6 and it refocuses and becomes front focused. but only at less than 3-4 meters.I posted my findings on DPreview and had six to eight replies from other users who found the same thing. Strange!
Quote: Tamron have a firmware update which is supposed to cure the VC problem when panning, all it does is switch off the VC, so far I haven't sent it in to be upgraded.
I have the Tammy 17-50mm non VC version and have used it on the Pentax K20/K5/K3 with no SR problems, great lens, very sharp.
One strange problem however, which I did post here some years back. Wide open to F5 the AF is spot on, when you stop down to F5.6 it front focuses. Put the camera into AF-C half-press the shutter button, and with the rear wheel, change aperture from F5-5.6 and it refocuses and becomes front focused. but only at less than 3-4 meters.I posted my findings on DPreview and had six to eight replies from other users who found the same thing. Strange!
Sounds like RSA to me.
Quote:Sounds like RSA to me.
On the K3.
Reasonable assumption (residual spherical abberation) but "no"! The lens AFs with the diaphragm fully open F2.8 always (auto diaphragm) ,normal!
When you select F2.8-F5.0 and half press to activate AF, the point of focus (also indicated by the distance scale) is perfect on the subject, ie image perfectly focused!
Directly you select F5.6 or more and half press to activate AF the point on the distance scale changes to closer,and front focuses.
You can check this in AF-C by holding half press to activate the AF continuously, and with the rear wheel choosing between F5 then F5.6 (obviously the diaphragm is always fully open) and it changes focus the position on the distance scale and front focuses.
It's in fact it's a FW problem within the lens. It took me a while to realize what was happening, mostly I shoot at F5 close up, the error diminishes at distance, at infinity it's fine.
The problem has completely disappeared now use the D750 with it's flawless AF. Next question, do I sell my Pentax gear?
https://www.flickr.com/photos/124690178@N08/
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