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Author Topic: A900 Update  (Read 44036 times)

Nick Rains

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A900 Update
« Reply #40 on: September 22, 2008, 05:49:02 am »

Quote
Hi,

The shot on DPReview is taken with 24-70/2.8 at f/8.0, I would still argue that it is significantly less sharp at the edge then at the center. Just follow the rails from the center to the right and left edges.
http://a.img-dpreview.com/gallery/sony_a90...dsc01990_dw.jpg

Erik
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This shows how benchtests sometimes can differ from real world shots. I see the same edge softness on many of my own test shots on the same lens. Not too bad, but certainly visible.

OTOH...

[a href=\"http://www.photozone.de/sony-alpha-aps-c-lens-tests/380-zeiss_za_2470_28?start=1]Photozone[/url]

shows this lens as being very consistent across the frame at F8.

Confusing...
« Last Edit: September 22, 2008, 05:49:40 am by Nick Rains »
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Nick Rains
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Deep

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A900 Update
« Reply #41 on: September 22, 2008, 06:31:46 am »

Quote
This shows how benchtests sometimes can differ from real world shots. I see the same edge softness on many of my own test shots on the same lens. Not too bad, but certainly visible.

OTOH...

Photozone

shows this lens as being very consistent across the frame at F8.

Confusing...
[a href=\"index.php?act=findpost&pid=223199\"][{POST_SNAPBACK}][/a]


I can't say I did specific "chart type" testing but I did shoot a couple of shots at 24mm and 70mm to look for distortion on the 1st 24-70 into New Zealand and those shots were evenly sharp right across the frame.  I guess we're not really going to know how consistent this lens is until there are many production lenses in use.

This disagreement reminds me of how people talk about the Canon 24-70L.  Mine was excellent, one of my all time favourite lenses in fact, but there seem to be quite a few that aren't.  From my small test, the Zeiss had sharpness to match the Canon and better distortion control but I can't say about the contrast because the camera was set to produce very flat jpegs when I tried it.  What I did like was that the Zeiss does not extend to go wide like the Canon and, from memory of my Canon, it seems a bit more compact.
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Don

bob mccarthy

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A900 Update
« Reply #42 on: September 22, 2008, 07:10:24 am »

Photodo uses a crop camera to test (A700), so the corners are never tested. Same issue with Nikon lenses. No sure about Canon.

bob
« Last Edit: September 22, 2008, 07:10:46 am by bob mccarthy »
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ErikKaffehr

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A900 Update
« Reply #43 on: September 22, 2008, 02:41:59 pm »

Hi,

Were you testing thae 24-70/2.8 on an Alpha 900? Any other Alpha DSLR is APSC format and does not utilize the full frame.

It's really a qustion what is the state of the art in "normal zoom" lens design. Some of the new Nikon lenses show that the obtainable quality is is pretty high.
The 14-24/2.8 seems to be impressive and so does the 16-85 APS zoom.

Best regards
Erik



Quote
I can't say I did specific "chart type" testing but I did shoot a couple of shots at 24mm and 70mm to look for distortion on the 1st 24-70 into New Zealand and those shots were evenly sharp right across the frame.  I guess we're not really going to know how consistent this lens is until there are many production lenses in use.

This disagreement reminds me of how people talk about the Canon 24-70L.  Mine was excellent, one of my all time favourite lenses in fact, but there seem to be quite a few that aren't.  From my small test, the Zeiss had sharpness to match the Canon and better distortion control but I can't say about the contrast because the camera was set to produce very flat jpegs when I tried it.  What I did like was that the Zeiss does not extend to go wide like the Canon and, from memory of my Canon, it seems a bit more compact.
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Erik Kaffehr
 

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A900 Update
« Reply #44 on: September 22, 2008, 04:08:29 pm »

Quote
Hi,

Were you testing thae 24-70/2.8 on an Alpha 900? Any other Alpha DSLR is APSC format and does not utilize the full frame.

It's really a qustion what is the state of the art in "normal zoom" lens design. Some of the new Nikon lenses show that the obtainable quality is is pretty high.
The 14-24/2.8 seems to be impressive and so does the 16-85 APS zoom.

Best regards
Erik
[a href=\"index.php?act=findpost&pid=223353\"][{POST_SNAPBACK}][/a]

Yes, I was testing on the Alpha 900.  Sorry, I should have made that clear.  I tried a number of lenses that day: 85/1.4; 24-70/2.8; 70-200/2.8; 35mm/1.4; 16-80DT and 11-18DT (the last two were decidely weird to use as you see a vignetted picture in the viewfinder, with faint corner guides, but the photos work like a crop sensor, just fine).  The four big lenses were all top quality but that sensor is quite brutal - if you miss focus it stands out hugely at 100% on a computer screen, if not so much in print!
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Don

Ray

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A900 Update
« Reply #45 on: September 22, 2008, 07:44:02 pm »

Quote
This shows how benchtests sometimes can differ from real world shots. I see the same edge softness on many of my own test shots on the same lens. Not too bad, but certainly visible.

OTOH...

Photozone

shows this lens as being very consistent across the frame at F8.

Confusing...
[a href=\"index.php?act=findpost&pid=223199\"][{POST_SNAPBACK}][/a]

Nick,
As Bob McCarthy mentioned, Photozone test all lenses with APS-C size cameras. Nevertheless, I suppose one can extrapolate the results and not be far wrong, but that's not ideal. Some lenses can have a very flat response to about 15mm from centre of frame, then take a steep dive towards the corners.
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Nick Rains

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A900 Update
« Reply #46 on: September 22, 2008, 09:07:20 pm »

Quote
Nick,
As Bob McCarthy mentioned, Photozone test all lenses with APS-C size cameras. Nevertheless, I suppose one can extrapolate the results and not be far wrong, but that's not ideal. Some lenses can have a very flat response to about 15mm from centre of frame, then take a steep dive towards the corners.
[a href=\"index.php?act=findpost&pid=223431\"][{POST_SNAPBACK}][/a]
Yes, re-read the specs on the Photozone site, I missed it before.

Big difference between 22mm across and 36mm. The DPR Lens Reviews show the difference clearly.
« Last Edit: September 22, 2008, 09:08:42 pm by Nick Rains »
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Nick Rains
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aaykay

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A900 Update
« Reply #47 on: September 23, 2008, 12:06:08 am »

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Yes, re-read the specs on the Photozone site, I missed it before.

Big difference between 22mm across and 36mm. The DPR Lens Reviews show the difference clearly.
[{POST_SNAPBACK}][/a]

There are some posts in a different Sony/Alpha website, where the 24-70 f/2.8 Zeiss clearly shows corner-to-corner sharpness on the A900.  Consistently.  

Here are some additional A900 + 24-70CZ pictures:

[a href=\"http://www.dyxum.com/dforum/forum_posts.asp?TID=36184]http://www.dyxum.com/dforum/forum_posts.asp?TID=36184[/url]

Another A900 + 24-70 f/2.8 image (slow download since large image but don't see any softening that was mentioned above and is sharp across the 36mm frame):

http://74.86.43.122/a900/2008-09-10-123927-09790.jpg
« Last Edit: September 23, 2008, 12:14:08 am by aaykay »
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Christopher

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A900 Update
« Reply #48 on: September 23, 2008, 02:49:12 am »

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There are some posts in a different Sony/Alpha website, where the 24-70 f/2.8 Zeiss clearly shows corner-to-corner sharpness on the A900.  Consistently. 

Here are some additional A900 + 24-70CZ pictures:

http://www.dyxum.com/dforum/forum_posts.asp?TID=36184

Another A900 + 24-70 f/2.8 image (slow download since large image but don't see any softening that was mentioned above and is sharp across the 36mm frame):

http://74.86.43.122/a900/2008-09-10-123927-09790.jpg
[a href=\"index.php?act=findpost&pid=223485\"][{POST_SNAPBACK}][/a]

I think there is nothing more to say, and this is a slap for canon. No way any Canon L zoom will produce such corner to corner sharpness. Kinda sad.
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Christopher Hauser
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Ray

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A900 Update
« Reply #49 on: September 23, 2008, 05:31:51 am »

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I think there is nothing more to say, and this is a slap for canon. No way any Canon L zoom will produce such corner to corner sharpness. Kinda sad.
[a href=\"index.php?act=findpost&pid=223515\"][{POST_SNAPBACK}][/a]


I must be missing something. I don't see any sharp corners in any of these shots.

Most of the images have too shallow a DoF to be sharp in the corners and the image of the building at F6.3 is reduced resolution and doesn't have any fine detail in any of the corners. In fact the resolution of the F6.3 shot, when opened on my computer, is only 17MB, less than the file size of a 6mp camera, never mind 24mp.
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Deep

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A900 Update
« Reply #50 on: September 23, 2008, 06:20:42 am »

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I must be missing something. I don't see any sharp corners in any of these shots.

Most of the images have too shallow a DoF to be sharp in the corners and the image of the building at F6.3 is reduced resolution and doesn't have any fine detail in any of the corners. In fact the resolution of the F6.3 shot, when opened on my computer, is only 17MB, less than the file size of a 6mp camera, never mind 24mp.
[a href=\"index.php?act=findpost&pid=223543\"][{POST_SNAPBACK}][/a]
You don't need 24Mp to see if a lens is bad.  These examples show just the sort of look I like to produce.  I was disappointed when I tried the Zeiss 16-80 on an A700 but the 24-70 on the A900 was a completely different experience.
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Don

Ray

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A900 Update
« Reply #51 on: September 23, 2008, 07:11:12 am »

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You don't need 24Mp to see if a lens is bad.  These examples show just the sort of look I like to produce.  I was disappointed when I tried the Zeiss 16-80 on an A700 but the 24-70 on the A900 was a completely different experience.
[a href=\"index.php?act=findpost&pid=223547\"][{POST_SNAPBACK}][/a]

I don't think anyone is saying that the lens is bad. It's just that corner resolution is the big disadvantage of full frame, and 24mp full frame is likely to show a greater difference than 12mp in the corners.

The sample images linked above have not been taken in order to display corner resolution so it's still a moot point.

Now the new Zeiss 21/2.8 Distagon really is sharp from corner to corner on the 1Ds3; clearly better than the Nikkor 14-24/2.8.
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aaykay

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A900 Update
« Reply #52 on: September 23, 2008, 12:16:49 pm »

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In fact the resolution of the F6.3 shot, when opened on my computer, is only 17MB, less than the file size of a 6mp camera, never mind 24mp.

The pictures with shallow DOF were just pictures taken with the camera - not intended to show corner-to-corner performance of the 24-70CZ on FF.

But the f/6.3 building shot was SPECIFICALLY shot to show corner to corner performance on Full-frame, with objects in the very corners (of 35mm FF) that can demonstrate the sharpness of the image at the borders.  Actually the full-size JPEG was around 30+MB in size and had to be downsized but I would be very surprised if anybody were to make statements that they saw any kind of softness in it (there was NO softness, either at the borders or in the center, as an FYI  )

This f/6.3 picture was specifically picked (among a bunch of others with less DOF or shots taken at an angle, which could be misleading) to counter the "internet rumor mill" which will tend to propagate speculations about performance, based on some shot somebody saw in some website.      I think dpreview should have shot some brick-walls to demonstrate border resolution of the lens, than shooting images with a lot of depth or with variable depths once one gets to the borders, which will in turn be seized by people who are out to prove their own pre-set decisions.

Bottomline, the lens is SHARP, corner-to-corner on FF according to the shooter/beta-tester this person (who is also a Nikon D700/D3 shooter) was more impressed with the corner-to-corner performance of the CZ on A900, when compared to the new 24-70 f/2.8 Nikon version, which in turn is rated better than the Canon 24-70 f/2.8L (and this corner-to-corner rating has nothing to do with the Alpha/CZ version being Stabilized, while the others are not) .  Does this provide any added talking points ?  
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Deep

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A900 Update
« Reply #53 on: September 23, 2008, 02:16:53 pm »

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I don't think anyone is saying that the lens is bad. It's just that corner resolution is the big disadvantage of full frame, and 24mp full frame is likely to show a greater difference than 12mp in the corners.


[a href=\"index.php?act=findpost&pid=223551\"][{POST_SNAPBACK}][/a]
Well, I'm not going to argue about this but I have tried the A900 Zeiss combination for myself and I know what it is like.  Corner softness is not a significant issue with this lens, nor with the three other full frame lenses I've tried.  Quite unlike what people have come to expect with certain lenses from Canon, Nikon and, in fact, the Zeiss 16-80 on the Sony DT system, which is actually very poor in the corners despite being a cropped sensor system.
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Don

Ray

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A900 Update
« Reply #54 on: September 23, 2008, 09:23:29 pm »

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Well, I'm not going to argue about this but I have tried the A900 Zeiss combination for myself and I know what it is like.  Corner softness is not a significant issue with this lens, nor with the three other full frame lenses I've tried.  Quite unlike what people have come to expect with certain lenses from Canon, Nikon and, in fact, the Zeiss 16-80 on the Sony DT system, which is actually very poor in the corners despite being a cropped sensor system.
[a href=\"index.php?act=findpost&pid=223672\"][{POST_SNAPBACK}][/a]

Fair enough! I'm merely pointing out that the above samples do not demonstrate corner sharpness particularly well. At this point in time we'll have to take your word for it.
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Ray

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A900 Update
« Reply #55 on: September 23, 2008, 09:33:19 pm »

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But the f/6.3 building shot was SPECIFICALLY shot to show corner to corner performance on Full-frame, with objects in the very corners (of 35mm FF) that can demonstrate the sharpness of the image at the borders.  Actually the full-size JPEG was around 30+MB in size and had to be downsized but I would be very surprised if anybody were to make statements that they saw any kind of softness in it (there was NO softness, either at the borders or in the center, as an FYI  )

[a href=\"index.php?act=findpost&pid=223637\"][{POST_SNAPBACK}][/a]

It's true that the building shot does have two corners at the bottom with at least some detail. However, when you downsize an image, you inevitably throw resolution away, and the resolution you throw away is where it counts, ie. the parts of the image where resolution is highest, not the parts where resolution might be lowest, such as the corners.

Whatever difference there may be between resolution in the corners and resolution in the centre, downsizing the image inevitably reduces such differences.
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aaykay

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A900 Update
« Reply #56 on: September 23, 2008, 10:01:54 pm »

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It's true that the building shot does have two corners at the bottom with at least some detail. However, when you downsize an image, you inevitably throw resolution away, and the resolution you throw away is where it counts, ie. the parts of the image where resolution is highest, not the parts where resolution might be lowest, such as the corners.

Whatever difference there may be between resolution in the corners and resolution in the centre, downsizing the image inevitably reduces such differences.
[a href=\"index.php?act=findpost&pid=223786\"][{POST_SNAPBACK}][/a]

This image was "downsized" (not cropped) from the original.  Thus what you see is the actual corners/borders on FF.  But it has been downsized from its original size of 30+MB, which is unfortunately not available.  Thus you will have to take the word of the shooter (incidentally who shoots Nikon D700 FF too), that it was SHARP to the borders of FF.
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Ray

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A900 Update
« Reply #57 on: September 23, 2008, 11:27:22 pm »

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This image was "downsized" (not cropped) from the original.  Thus what you see is the actual corners/borders on FF.  But it has been downsized from its original size of 30+MB, which is unfortunately not available.  Thus you will have to take the word of the shooter (incidentally who shoots Nikon D700 FF too), that it was SHARP to the borders of FF.
[a href=\"index.php?act=findpost&pid=223790\"][{POST_SNAPBACK}][/a]

I'm afraid I subscribe to the 'seeing is believing' school of thought   .
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Deep

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A900 Update
« Reply #58 on: September 24, 2008, 02:37:29 am »

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I'm afraid I subscribe to the 'seeing is believing' school of thought   .
[a href=\"index.php?act=findpost&pid=223807\"][{POST_SNAPBACK}][/a]
Fair enough.  If I can get this to work, here is an unsharpened, straight crop out of the corner of an image.  I'll include a downsized version of the original image so you can place it.  Focus was on the vertical rail in the centre of the photo.
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Don

Ray

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A900 Update
« Reply #59 on: September 24, 2008, 03:18:05 am »

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Fair enough.  If I can get this to work, here is an unsharpened, straight crop out of the corner of an image.  I'll include a downsized version of the original image so you can place it.  Focus was on the vertical rail in the centre of the photo.
[a href=\"index.php?act=findpost&pid=223848\"][{POST_SNAPBACK}][/a]

Deep,
Thanks for your trouble in providing this shot. However, I don't see any crops of corners. You've shown an edge which appears to be okay considering the low resolution of the scene, but even with this edge, we can't be sure about resolution fall-off because there's no fine detail (hairs, grass stalks, grains of sand).

Glossy paint is just not an ideal target for checking resolutiuon.

In any case, many good Canon lenses are also okay up to the edges. The middle of the extreme edge of a 35mm frame is only 18mm from the centre. It's the area from 18mm to 22mm (from centre) which represents the corner. It's this area where most lenses show a marked softness with full frame 35mm.
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