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Archive 2014 · Starburst issue with Sony sensors (A7r) how big is it?

  
 
therealthings
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p.2 #1 · p.2 #1 · Starburst issue with Sony sensors (A7r) how big is it?


Samuli Vahonen wrote:
Regarding number of aperture blades all mentioned TS-E lenses have 8 blades. That will make the A7r issue less visual.

I found from other virtual machine bookmarks to the discussion about A7r weird starbursts (first discussion from December 2013, it has been since discussed few times). On small webthumbnails (1000px or so) most likely the starbursts won't look that weird, but at bigger size or print the issues are obvious. For example Bob's (rji2goleez) photos on page 120 look quite OK, but at bigger size (page 121) look indeed very weird.

Also comparing his page 120 photos taken with Rokkor
...Show more

Most of these images show a flare issue, different from the muddy or gritty glow between the spikes. Horrible (but another story). Page 121 discusses this issue indeed. Tough find if you don't know where to look. But i have yet to read about a final conclusion which lenses are affected. I have seen a 100% crop shot with a ts-e 90 that showed a perfect starburst. No artifacts to be seen. If it would be less obvious because of the number of blades it should still be present. Maybe retrofocus can re-share it.



Oct 16, 2014 at 03:52 PM
Toothwalker
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p.2 #2 · p.2 #2 · Starburst issue with Sony sensors (A7r) how big is it?


The determining factor for the shape of diffraction stars is the shape of the aperture. A straight edge produces a streak of light radiating out in two opposite directions. When the aperture is nicely symmetrical, the number of blades N gives the number of spikes in the star (2N for odd N and N for even N). When the symmetry is poor and/or the blades are rounded, however, the star can get messy. One regularly sees N double spikes for even N, for instance, and a broadening of the spikes away from the center.

One should be careful with drawing conclusions from a comparison of night shots with different lenses under different conditions. The intensity difference between a star and its surroundings easily varies by a factor of 10 or 100 (or whatever) between shots.

If the cause of the clutter in the star region is an optical one (microlenses, reflections, etc.), I don't think there should be big differences between lenses. Otherwise, I cannot exclude aliasing and lossy compression as causes at this point. And what about the deconvolution sharpening that Sony supposedly applies in the A7r? Maybe it is only used for JPEG file dumps, I don't know, but I would expect visible artifacts in highlight regions. (In this case the garbage presumably only occurs when the camera knows the lens aperture.)

There is need for controlled tests to more shed light on this matter.



Oct 16, 2014 at 04:55 PM
retrofocus
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p.2 #3 · p.2 #3 · Starburst issue with Sony sensors (A7r) how big is it?


therealthings wrote:
Most of these images show a flare issue, different from the muddy or gritty glow between the spikes. Horrible (but another story). Page 121 discusses this issue indeed. Tough find if you don't know where to look. But i have yet to read about a final conclusion which lenses are affected. I have seen a 100% crop shot with a ts-e 90 that showed a perfect starburst. No artifacts to be seen. If it would be less obvious because of the number of blades it should still be present. Maybe retrofocus can re-share it.


Here is the desired 100% crop of my earlier posted photo. The 90 TSE has 8 blades.

http://martinbluhm.zenfolio.com/img/s6/v144/p946875851-5.jpg



Oct 16, 2014 at 06:49 PM
therealthings
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p.2 #4 · p.2 #4 · Starburst issue with Sony sensors (A7r) how big is it?


retrofocus wrote:

Here is the desired 100% crop of my earlier posted photo. The 90 TSE has 8 blades.
http://martinbluhm.zenfolio.com/img/s6/v144/p946875851-5.jpg


Thanks, would you be so kind to leave this image online? This way everyone can see the result with that typical lens.

Toothwalker wrote:
One should be careful with drawing conclusions from a comparison of night shots with different lenses under different conditions. The intensity difference between a star and its surroundings easily varies by a factor of 10 or 100 (or whatever) between shots.

There is need for controlled tests to more shed light on this matter.


Well, i have no other ways to check it at the moment. And when i do i only can do tests with a few lenses.






Oct 17, 2014 at 02:33 AM
retrofocus
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p.2 #5 · p.2 #5 · Starburst issue with Sony sensors (A7r) how big is it?


therealthings wrote:
Thanks, would you be so kind to leave this image online? This way everyone can see the result with that typical lens.



Yes, I will leave it online. Regarding the 24 TSE II lens, I didn't take any starburst photos with this lens and my A7R yet. On my to-do list!



Oct 17, 2014 at 06:17 AM
osv2
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p.2 #6 · p.2 #6 · Starburst issue with Sony sensors (A7r) how big is it?


a7r starburst with a 50mm macro minolta, and the samyang 14mm lens:

http://www.dpreview.com/forums/thread/3741577#forum-post-54592844

i'm not seeing any starburst problems there?



Oct 19, 2014 at 01:14 PM
therealthings
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p.2 #7 · p.2 #7 · Starburst issue with Sony sensors (A7r) how big is it?


osv2 wrote:
a7r starburst with a 50mm macro minolta, and the samyang 14mm lens:

http://www.dpreview.com/forums/thread/3741577#forum-post-54592844

i'm not seeing any starburst problems there?



I cannot be 100% sure, because the image is resized. It seems that these starbursts look ok, wondering about the 4 distant yellow starbursts on the left as they look a little blotchy to me.

Besides that, i see some scratches or hairs in the sky between the distant yellow starbursts on the left and the first greenish light streak of the passing vehicle.



Oct 20, 2014 at 01:48 AM
therealthings
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p.2 #8 · p.2 #8 · Starburst issue with Sony sensors (A7r) how big is it?


Cripes! It seems my MB adapter is still in customs for clearance... I hope sales tax and import duties won't ruin the joy of purchase. The wait is agonizing...


Oct 21, 2014 at 04:57 AM
Matt Grum
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p.2 #9 · p.2 #9 · Starburst issue with Sony sensors (A7r) how big is it?


I wanted to do a comparison between the Sony 35mm f/2.8 (the very lens which produced the effect that started this thread) and an old Olympus OM 35mm f/2.8 (which ought to produce classic starbursts) but I was unable to reproduce the issue using the Sony lens no matter what I tried (different apertures/focus distances) so I gave up.


therealthings wrote:
You can't imagine how much i have read about this camera. Too much information.


I think that's the problem. You can read far far too much and become totally paranoid about the coma from hell, lossy compression, wobbly lens mount, astigmatism inducing cover glass, sensor reflections, shutter shock and now noisy starbursts.

If anyone is still on the fence about the A7/A7ʀ I suggest they read one last thread:

https://www.fredmiranda.com/forum/topic/1321343

...and then go buy one!



Oct 21, 2014 at 07:18 AM
Dpedraza
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p.2 #10 · p.2 #10 · Starburst issue with Sony sensors (A7r) how big is it?


osv2 wrote:
a7r starburst with a 50mm macro minolta, and the samyang 14mm lens:

http://www.dpreview.com/forums/thread/3741577#forum-post-54592844

i'm not seeing any starburst problems there?


only problem with the samyang is they're hideous in my opinion



Oct 21, 2014 at 07:46 AM
therealthings
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p.2 #11 · p.2 #11 · Starburst issue with Sony sensors (A7r) how big is it?


Matt Grum wrote:
I wanted to do a comparison between the Sony 35mm f/2.8 (the very lens which produced the effect that started this thread) and an old Olympus OM 35mm f/2.8 (which ought to produce classic starbursts) but I was unable to reproduce the issue using the Sony lens no matter what I tried (different apertures/focus distances) so I gave up.


So you're saying you could not reproduce this with the exact same lens? That's odd to say the least. I have seen a large number of night shots by now and the rate of which these ugly starbursts present themselves i still find alarming.

Matt Grum wrote:
If anyone is still on the fence about the A7/A7ʀ I suggest they read one last thread:
https://www.fredmiranda.com/forum/topic/1321343
...and then go buy one!


I have seen that post yes, and i like the daylight shots. But the second last image of his first series has reflections within the lantern light (coma as they mention it):

https://farm3.staticflickr.com/2946/15206864868_990734c7e5_o.jpg

All of which i never experienced on any of my DSLR's. (Most extreme example found so far: https://www.fredmiranda.com/forum/ufiles/03/898603.jpg)

I have read about the rest of the quirks of the A7r, of which all of them have a fix, aside from the starbursts and coma which can not be fixed in post. Again, as soon as my wait for the MB adapter is finally over i will do some testing with the Canon 24 TS-E II, Canon 24-105, Canon 50 1.8 II and Sigma 35 1.4 Art.

Update 10-22: Just have been informed by the postal office that customs might take between 9 and 11 days to release the adapter. Insane!



Oct 21, 2014 at 09:29 AM
jhinkey
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p.2 #12 · p.2 #12 · Starburst issue with Sony sensors (A7r) how big is it?


I have not found any significant differences between my A7r and D800 regarding star bust pattern and ghosting/sensor reflections when using the exact same lens for the exact same image. In fact I found some weird 135/2 APO Zeiss issues that I initially attributed to the A7R, but then found the exact same problems with my D800. Are the images identical down to the pixel level on the two cameras - no, but I've not found a situation where it made any significant difference.

That's not to say that the A7R will not have issues when you use adapted lenses that have their rear elements close to the sensor - something impossible to do with the D800.



Oct 24, 2014 at 01:21 PM
therealthings
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p.2 #13 · p.2 #13 · Starburst issue with Sony sensors (A7r) how big is it?


No scientific test, just a simple shoot for starbursts with 3 lenses.

First the 24 TS-E24II

https://dl.dropboxusercontent.com/u/72412377/_DSC3216.jpg

Well, i clearly discover some purple flaring there. I have to test further if i find this acceptable or not.

Then the Sigma 35 1.4 ART. This lens performs reasonable starbursts, but i also discover a little gritty like starburst on the far left. It just looks like it's compressed too much. Some sort of jpg compression. And besides that, this lens is horrible on the a7r. Many times the camera froze and rebooted when taking an image. I also had a couple of times that it din't display any aperture and i had to power on the camera again to solve that problem. So this is no match for me.

https://dl.dropboxusercontent.com/u/72412377/_DSC3222.jpg

Then the 50 1.8II. One big flaring circus. I won't even go there to discuss this option.

https://dl.dropboxusercontent.com/u/72412377/_DSC3226.jpg

More will follow as soon as i have found some testing time again.

P.S. I have no friggin clue why it just won't embed the images in this page. Fred? you reading this? Please fix it! Thanks



Oct 24, 2014 at 02:47 PM
Toothwalker
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p.2 #14 · p.2 #14 · Starburst issue with Sony sensors (A7r) how big is it?


cdz1877 wrote:
I have suspected, the A7R camera is not immune to the Red Dot Flare issue, thanks to the short flange distance. The effect of the red dot flare can be significantly reduced if the rear lens element has non-reflective coating applied to it.


Happily, all glass/air interfaces of modern lenses are coated. Besides, such reflections are not related to gritty starbursts.






Oct 24, 2014 at 03:30 PM
therealthings
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p.2 #15 · p.2 #15 · Starburst issue with Sony sensors (A7r) how big is it?


I don't know guys. I'm not really pleased...
I think i will be needing the flocking paper after all, even though i'm using the IV adapter.
And i will be needing the hairband fix for the light leak issue.

_DSC3362 by Marcus Antonius Braun, on Flickr

_DSC3356 by Marcus Antonius Braun, on Flickr

I really hope i will be happy after those fixes, because this camera seems to have some real issues with night photography up until now.



Oct 25, 2014 at 03:54 PM
therealthings
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p.2 #16 · p.2 #16 · Starburst issue with Sony sensors (A7r) how big is it?


Some starbursts from yesterdays shoot:

https://dl.dropboxusercontent.com/u/72412377/starburst1.jpg

https://dl.dropboxusercontent.com/u/72412377/starburst2.jpg

https://dl.dropboxusercontent.com/u/72412377/starburst3.jpg

https://dl.dropboxusercontent.com/u/72412377/starburst4.jpg



Oct 26, 2014 at 01:05 PM
therealthings
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p.2 #17 · p.2 #17 · Starburst issue with Sony sensors (A7r) how big is it?


FYI, painted the interior with deep matte black paint and definitely see some improvements:

http://www.dpreview.com/forums/post/54672342

Finally a happier camper now. Still not perfect, but i can live with it.



Nov 02, 2014 at 09:17 AM
LightShow
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p.2 #18 · p.2 #18 · Starburst issue with Sony sensors (A7r) how big is it?


I was out shooting with my A7r and X-Fujinon 28/1.9 and had no issues with my stars.
It could be caused by a bad batch of sensors.... I'd try some different lenses(which is being done), and contact Sony.



Nov 02, 2014 at 10:22 AM
therealthings
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p.2 #19 · p.2 #19 · Starburst issue with Sony sensors (A7r) how big is it?




LightShow wrote:
I was out shooting with my A7r and X-Fujinon 28/1.9 and had no issues with my stars.
It could be caused by a bad batch of sensors.... I'd try some different lenses(which is being done), and contact Sony.

Would you be so kind sharing some crops for the benefit of this thread?



Nov 02, 2014 at 02:53 PM
LightShow
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p.2 #20 · p.2 #20 · Starburst issue with Sony sensors (A7r) how big is it?


I do intend to when I have time.
Edit: one sample.

My A7r does appear to be more sensitive to diffraction effects than my NEX-7, I'm not sure if that is caused by the sensor size difference or the over-exposure level of the star burst, I will have to use some lenses I've used at night on my NEX-7 on my A7r to see a better representation of what the sensor is doing vs differences in the lens since this is the first night shoot with this X-Fujunon 28/1.9 I've ever done, and the lens has a huge impact on the look of diffraction.



Nov 02, 2014 at 07:13 PM
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