Hi,

Something that I have noticed on the sample pictures on buth DPReview and Dave Kilpatricks site is that corner sharpness is nothing to write home about on some of the samples. Although I think Zeiss lenses are used near their optimal aperture.

Anyone care to comment?

http://www.pbase.com/davidkilpatrick/sony_alpha_900

http://a.img-dpreview.com/gallery/sony_a90...dsc01990_dw.jpg

I also ask how Nikons famous 14-24/2.8 lens would hold up on an 24 MPixel body? I guess we need to wait and see.

Erik

Erik,
The lens looks slightly worse on the right side than the left side, indicated by the blurier cobble stones on the far right of the frame.

However, the lens appears to have better edge performance than my Sigma 15-30 at F5.6 .

Hi,

I presume that you mean the picture on the Kilpatrick page? The Sigma 15-30 is it "fullframe"?

I might be interested in the A900 but I would probably not like to invest serious money in bad lenses.

Erik

The picture on pbase is 16mm @ f2.8. So I don't wonder about edge performance. There are some exzellent lenses in the Minolta/Sony line!

Hi!

The info on pbase says f/5.6, but also that it is a "Not for use prototype lens".

I should have read all info.

Yes, they are some excellent lenses in the Minolta/Sony line of which I posess quite a few, by the way. Problem is that we have very little experience or tests on how those lenses perform on fullframe high pixel density sensor.

Erik

ah, yes, you are right - sorry!

yes, but time to check it out. The good primes should be fine at f8... but we will see...

Yes to both questions. Whilst the Sigma is described as a full frame lens, corner sharpness is definitely one of its weaknesses. However, this wasn't a problem until I started using a 5D. If I end up getting a Nikon D700 instead of an A900 (or the successor to the 5D), it will be because of the reputation of the Nikkor 14-24/2.8 which I would buy at the same time.

Erik, just a clarification. These are pictures from a PROTOTYPE version of the 16-35 f/2.8....actually one of the SEVERAL prototypes.

I am surprised that Sony did not have a tighter agreement with the participants during their Edinburgh introduction, which would have prevented the publication of shots from such a sample.

Remember this lens would not even get to production for several months and several "properties" of the lens are yet to be fine-tuned and finalized for production.

If I am Sony, this particular participant would not gain a future "Press Pass".

At a recent show (where I tried the A900 and a few lenses), they gave us a couple of hard cover books full of sample images - ones they had control over, if you want to be cynical - taken with the 16-35 and they were sharp edge to edge. The four full frame lenses I tried (24-70; 85; 35/1.4; 70-200) seemed the same, though I didn't carry out technical tests. Let's just say I was impressed enough to seriously consider saving up for the system.

As a confirmed Minolta user, the 900 suits me: all those lovely prime lenses in my bag give me a head start. I know I'm out of step with most people. I use film, too!

But - the late Barry Thornton, in his book on sharpness, concluded that no zoom lens is suitable for fine art work... Despite improvements, zooms are still a big compromise - you lose out on weight, cost, and aperture, even if the quality is impeccable.

From what I've read, any full-frame digital camera may struggle in the corners, and it's always the part of the field where lenses are least good.

In all honesty, though, how often do you need sharp corners? The odd architectural shot, perhaps... But most shots I take have the main subject around a third of the way across.

Or am I missing the point?

I think it depends a heap on your intended use for the photo. "Fine art" is a very loose term these days (and much of what goes for sale just does not make any demands on equipment as people intentionally do quite destructive editing for effect). For portraiture, it is quite often perfectly acceptable to have a lens that is a bit softer in the corners but, if you are selling landscapes or shooting for magazines and so on, you really want to be able to completely control what is sharp and what isn't. For a lot of this work, many better zoom lenses (such as the Olympus ZD range I mostly use nowadays) have a "sweet range" of sharpness which makes them perfectly acceptable, provided you don't end up with depth of field and speed issues through using slower glass. Nearly all the prints I sell were taken with zooms and sharpness is not an issue at all. Ironically, zooms seem to be cheaper than primes which may only be a half stop quicker, in some ranges!

I don't think a full frame digital has to struggle in corners if the lens was designed for it (colour issues aside). I have some test shots I took on the Sony 900 with the Zeiss 24-70 zoom and they are sharp right across, which is nice. I will even stick my head on the block and say that lens is sharper than the two Minolta primes I had (28/2.8 and 50mm macro), which weren't Minolta's finest hour!

Don.

QUOTE (dudler @ Nov 10 2008, 09:11 PM)
From what I've read, any full-frame digital camera may struggle in the corners, and it's always the part of the field where lenses are least good.


Or am I missing the point?
[/quote]


In the case of the Nikon D3, that incorporates double micro lenses, the limiting factor, regarding edge resolution, will be the quality of the optics - http://luminous-landscape.com/forum/index....100#entry216878 - post 105

Nick

Hi!

There has now been a lot of published materials on lenses for the Alpha 900. Among other information I found this thread quite interesting:

http://forums.dpreview.com/forums/read.asp...essage=29938511

According to the info above the Zeiss 24-70/2.8 has a weakness in the corners but is very good otherwise. Image quality is said to be astonishing.

There has also been a test in the Swedish monthly Foto and they say that the camera is "top class". They say that "raw" is needed for best sharpness. ISO-s up to 1600 are said to be usable. According to Foto it's a very good camera landscape, travel or agency type pictures, less for sports and photojournalism.

Erik

Erik, I have both - A900 and Zeiss 24-70 f/2.8. I don't see any "weakness in the corners", unless I am specifically trying to get a narrower DOF, which obviously would mean that the non-focused portion of the image would be deliberately blurred.

I personally don't seen any other "weakness in the corners" from this combo that you spoke about, and have been speaking about for the past several months. If anything, the lens is too sharp, which in my estimation is a good thing. I remember you spoke about the corner of the CZ 85mm f/1.4 being "mush" in a different post, until your assertion was corrected.

Going by the sheer quality from the Zeiss 24-70, I eagerly look forward to adding the upcoming CZ 16-35 Vario-Sonnar to my list of lenses.