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Odd aberations at pixel peeping level with the Tamron 150-600mm


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#1 dave's clichés

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Posted 12 May 2015 - 01:54 AM

Hi guys,

             As it's quiet here so I'm posting some observations. I've been using the Tamron 150-600mm zoom for about a month now (second copy, first de-centered) and am very  pleased with it, it's easily hand holdable and for the most part a sharp lens, holding up very well till 500mm where it's very good at F-8-11. At 600mm the inevitable happens and sharpness drops a little, but with a little sharpening very decent results remain. The VC is a great bonus and works very well although it has a slight tendence to hang on and let go, which causes a little jerking if you have drunk too much coffee. The AF needs no AFMA and seems spot on. 

 I've noticed however, on looking at images @ 500-600mm at 100%,  most noticeable in the fine detail of grass, very small patches of localized blurring occurring in the frame. I've also noticed this with the Bigma maybe to a worse effect.

  I just wondered if this is caused by the lack of perfect smoothness of the lens elements which causes  these localized  patches of softening and it does suffer from onion ring specular highlights,   I don't think it's of any real concern given 100% magnification and am not suggesting a fault with the lens, just observing this effect!

 The accompanying image shows this small soft patch (there seem to be three or four of them across the frame) in an otherwise decently sharp 600mm  100% crop. I've seen this several times always on lenses of 400mm or longer.

 

  Klaus, Airydicus?

 

 

  Sorry I should have highlighted the soft area but it is in the middle of the clip!

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#2 dave's clichés

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Posted 12 May 2015 - 02:43 AM

Attached File  Marseillan boat race 109.jpg   177.24KB   3 downloads

 

  Highlighted area.



#3 danida12

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Posted 12 May 2015 - 08:50 AM

Heat blur?



#4 dave's clichés

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Posted 12 May 2015 - 09:31 AM

Heat blur?

It's true it was a fairly hot day!

 

A RAW shot @600mm F8, you can see one of the lens's minus points here, onion ring specular highlights. I think it shows good sharpness for a zoom lens!

 

https://www.dropbox....ce 062.NEF?dl=0

 

 

The same image in PSD form with the background softened using the adjustment brush.

 

https://www.dropbox....0mm F8.psd?dl=0



#5 AiryDiscus

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Posted 12 May 2015 - 03:39 PM

Aspheres cause there to be funky hotspots in the image, the more you add the worse things get.  E.g this happens:

http://i.imgur.com/9w7v9PV.jpg

where a lens may have little to no coma in the corner, but "a lot" of coma in the center. 

 

The tamron does not have an asphere, so that can't be the case.  The first few elements need to be made on a large diameter grinder and likewise for the polisher, which is expensive.  Lower quality machines exist, but they leave surface defects - this is probably the case.  You can actually fairly clearly see the steps in the grind/polish process as the tool or workpiece is moved and then spun (the rings in the bokeh). 

 

Such defects will hurt contrast and typically do not result in a "clear aberration" in the image, a very narrow faced edge would have to be made which is unlikely. 

 

It most likely has to do with the VC, atmospheric conditions, or subject motion.

 

Looking at the image more closely there appears to be a circle centered around that spot which is also fuzzy, so it may be something to do with a filter of some kind, a bad element inside the lens, or some other defect.



#6 dave's clichés

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Posted 12 May 2015 - 08:13 PM

Thanks for your autopsy, Airydiscus, strange business as the Sigma 50-500m scewdrive non OS and both the samples of the Tamron have done it, always at the long end. 



#7 AiryDiscus

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Posted 13 May 2015 - 12:20 AM

It probably has to do with the optics around the OS/VR unit not being "properly" desensitized to tilts.  Theory is that the IS/VR will only translate the group in the X-Y plane with no Z movement or tilt, but in practice this is never the case so the optics there must be insensitive to tilts.  If this is not done with sufficient care, the OS/VR will impact image quality in a way that is time consuming to predict with computers and impossible to predict by eye.



#8 dave's clichés

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Posted 13 May 2015 - 07:52 AM

  I'll try a test on a tripod some time with the VR off!

 

 

 

   Thanks!



#9 dave's clichés

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Posted 31 July 2017 - 12:50 PM

  A long time later I think I now know what's going on.............

 

      I think it's Nissan bokeh that causes the effect....the spiting of OOF subjects making double edges , given the right distance apart these double edges combined with the double edges of other grasses  etc. (by chance). and produce interference patterns that  mask detail by adding and subtracting "clutter" in localized areas of the image.

 It never happens on flat areas even when there is much detail!



#10 you2

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Posted 31 July 2017 - 03:17 PM

Yes. My guess is something was in front of the soft area; very close and small so it was diffused by the time you reach the subject. If you were to go back to the location and re-shoot the image i bet the area would be gone. I do not think it is heat or atmospheric; as it is too localize.



#11 borisbg

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Posted 31 July 2017 - 05:50 PM

Hi Dave,

 

Can you re-shoot the photo on tripod with VC off?

 

What shooter speed did you use? And did you hand hold the lens?



#12 dave's clichés

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Posted 31 July 2017 - 08:29 PM

 First off, I can't even find the photo, it took some time to find the thread!

 

   Yes it was hand held, and I don't know if there was VC, my typical settings are 1/1250-1600 F8-11, but it changes little, I've seen this many times in similar situations although less so with the G2.

  Here it is just too hot for tele-shots at the moment!  I'll take some shots when there's some clear air!



#13 dave's clichés

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Posted 31 July 2017 - 08:36 PM

Yes. My guess is something was in front of the soft area; very close and small so it was diffused by the time you reach the subject. If you were to go back to the location and re-shoot the image i bet the area would be gone. I do not think it is heat or atmospheric; as it is too localize.

   

    I was shooting across water, nothing in front!



#14 stoppingdown

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Posted 01 August 2017 - 09:00 PM

Time ago I posted some photos here with a similar problem. But at the moment I can't find that old post.


stoppingdown.net

 

Sony a6300, Sony a6000, Sony NEX-6, Sony E 10-18mm F4 OSS, Sony Zeiss Vario-Tessar T* E 16-70mm F4 ZA OSS, Sony FE 70-200mm F4 G OSS, Sigma 150-600mm ƒ/5-6.3 DG OS HSM Contemporary, Samyang 12mm ƒ/2, Sigma 30mm F2.8 DN | A, Meyer Gorlitz Trioplan 100mm ƒ/2.8, Samyang 8mm ƒ/3.5 fish-eye II | Zenit Helios 44-2 58mm ƒ/2 
Plus some legacy Nikkor lenses.

#15 stoppingdown

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Posted 01 August 2017 - 09:04 PM

Found:

 

http://forum.photozo...blur-sel70200g/

 

It seem we all agreed that OSS was most probably the culprit. I'm not sure it was the same defect, because the whole vertical strip of the image was affected.


stoppingdown.net

 

Sony a6300, Sony a6000, Sony NEX-6, Sony E 10-18mm F4 OSS, Sony Zeiss Vario-Tessar T* E 16-70mm F4 ZA OSS, Sony FE 70-200mm F4 G OSS, Sigma 150-600mm ƒ/5-6.3 DG OS HSM Contemporary, Samyang 12mm ƒ/2, Sigma 30mm F2.8 DN | A, Meyer Gorlitz Trioplan 100mm ƒ/2.8, Samyang 8mm ƒ/3.5 fish-eye II | Zenit Helios 44-2 58mm ƒ/2 
Plus some legacy Nikkor lenses.

#16 miro

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Posted 02 August 2017 - 10:42 AM

Hi Dave,

You already received many suggestions and possible cause of this issue.

My proposal is to exclude some of them. To do this can you please make test image in more LAB environment?

E.g. shoot flat peace of newspaper with controlled light condition – use different focal length and aperture, For calibration you can use old trusty lens with similar focal length.

Other interesting lab test is AF accuracy at different AF points.

 

Regards,

Miro



#17 dave's clichés

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Posted 03 August 2017 - 09:36 AM

Hi Dave,

You already received many suggestions and possible cause of this issue.

My proposal is to exclude some of them. To do this can you please make test image in more LAB environment?

E.g. shoot flat peace of newspaper with controlled light condition – use different focal length and aperture, For calibration you can use old trusty lens with similar focal length.

Other interesting lab test is AF accuracy at different AF points.

 

Regards,

Miro

Hi Miro,

  I haven't the appropriate building for shooting such tests.....I live on a 9.3 mts boat.

 

 However, I will post further examples as and when I come across them, on a flat plane this effect does not show up, I think it's to do with the quailty of the Nissan bokeh at the focus transition which causes this strange softness, the outer edges are hard and highlighted and while the center of the stem is somber and transparent.

  The Tamron A011 (G1) hasn't the softest OOF rendering with onion ring bokeh as well and I noticed this patchy softness, the G2 has much softer bokeh and I see the issue less often. The Nikor AF-S suffers from Nissan bokeh in front of the plane of focus, but is soft in nature behind.

  Another weird bokeh effect is bubble bokeh, again I have the Helios 44-2 which produces the bubble effect, but the distance between the subject and the background has to be just right or the effect doesn't happen. Like moiré conditions have to be just right to see it.......(or wrong depending on your POV)!



#18 Brightcolours

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Posted 03 August 2017 - 09:59 PM

Hi Miro,

  I haven't the appropriate building for shooting such tests.....I live on a 9.3 mts boat.

 

 However, I will post further examples as and when I come across them, on a flat plane this effect does not show up, I think it's to do with the quailty of the Nissan bokeh 

In the good old days we marvelled in Datsun bokeh...  :)



#19 dave's clichés

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Posted 05 August 2017 - 01:58 PM

    Yeah based on the old Ford model "T" stops!  :o



#20 photonius

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Posted 06 August 2017 - 06:19 PM

Aspheres cause there to be funky hotspots in the image, the more you add the worse things get.  E.g this happens:

http://i.imgur.com/9w7v9PV.jpg

where a lens may have little to no coma in the corner, but "a lot" of coma in the center. 

 

The tamron does not have an asphere, so that can't be the case.  The first few elements need to be made on a large diameter grinder and likewise for the polisher, which is expensive.  Lower quality machines exist, but they leave surface defects - this is probably the case.  You can actually fairly clearly see the steps in the grind/polish process as the tool or workpiece is moved and then spun (the rings in the bokeh). 

 

Such defects will hurt contrast and typically do not result in a "clear aberration" in the image, a very narrow faced edge would have to be made which is unlikely. 

 

It most likely has to do with the VC, atmospheric conditions, or subject motion.

 

Looking at the image more closely there appears to be a circle centered around that spot which is also fuzzy, so it may be something to do with a filter of some kind, a bad element inside the lens, or some other defect.

 

 

looks like Panasonic has some laborious way of getting rid of the onion rings bokeh when grinding lenses:

 

http://www.imaging-r...aspheric-lenses

 

not sure if that is used now regularly, probably not.






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