Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Sony Alpha dSLR / Konica Minolta dSLR, Sony SLT

Reply
 
Thread Tools Search this Thread
Old Nov 1, 2006, 3:19 PM   #1
Junior Member
 
Join Date: Nov 2006
Posts: 10
Default

Good day, group!

I purchased the sony alpha within a day or two of it's arrival at my local camera shop.
I had been using film (KM maxxum 5) and a canon A620 digital until this time.
The A-100 gives very good results.
I find the anti-shake very helpful, although I shoot with a tripod at slower speeds when possible.

What has bothered me about the camera or rather the images it produces, is that from time to time, brighter small areas that are surrounded by darker areas tend to come out a bit square-ish. I have noticed this in RAW mode images converted to tiff, so it is not a jpeg (compression) artifact.

A good example would be a photo of distant city lights at night. When I zoom in close (say 66%-100% scale) on my 17" CRT monitor and look at traffic lights or bright sources, the shape tends to be square instead of round. Even the glow around the light, a halo, might show square edges. The images were shot in RAW mode and converted to tiff.

I have also seen this in images of some animals I have shot. The reflection of the sun in the eyes tends to be square. I do not know if it a camera issue, a software issue or if I am just being too picky and it is a common effect with modern DSLR cameras.

I wanted to compare with another 10 MP sensor. I was told the D-200 uses the same sensor.
I looked at a shot of city lights on the D-200 test review (Steve's digicam, reviews).
I did not see this square effect. I do not know how this image has been processed except that it is jpeg. I do not know if when I have zoomed into this image 100% (I get a + or a - in a circle to zoom in or out of the image). It looks big enough to be a 100% scale as I have to scroll around enough. Just about every light I can see in the D-200 image looks fine.

I would like it if when Steve puts test images up for the Sony A-100, maybe he could perhaps keep my observation in mind.
I look forward to seeing these images when they are posted.

In the mean time, has anyone else noticed this? Is it a common effect with modern cameras?

Waz




wazungy is offline   Reply With Quote
Sponsored Links
Old Nov 2, 2006, 5:23 AM   #2
Senior Member
 
Join Date: Jul 2006
Posts: 101
Default

Look at in print, they might not be there (the squares)
belgian pie is offline   Reply With Quote
Old Nov 2, 2006, 11:23 AM   #3
Senior Member
 
tmoreau's Avatar
 
Join Date: Dec 2005
Posts: 477
Default

Sounds like a possible lens issue, what lens are you using?

If you've only ever looked at slides/prints before, then looking at an image on screen is going to be WAY different. I second that you make a couple prints and compare that way.
tmoreau is offline   Reply With Quote
Old Nov 2, 2006, 1:03 PM   #4
Junior Member
 
Join Date: Nov 2006
Posts: 10
Default

Definately not a lens issue.
Sigma 70-200 f2.8 APO.
I get the same with a 28-75mm F2.8-D KM lens.

I do not think a print will show this effect unless I choose to crop and zoom in on a specific part. As I do not currently own a printer that is worthy of making prints, this point is moot.

What I would like to find out is why I get this in enough of my images for it to be a concern, is it normal and why a similar camera gives an image of city lights that look fine but I tend to get squarish lights.
Both images (D-200 from steve's reviews and my images) were seen on the same monitor, so it is not a monitor issue. If anything I would think it might be the way the firmware processes the image or the way the software converts it to tiff or jpeg. Or possibly an effect seen with all sensors unless something specific is turned on or off (ie: sharpen or noise reduction).

Waz
wazungy is offline   Reply With Quote
Old Nov 2, 2006, 3:59 PM   #5
Junior Member
 
Join Date: Jan 2006
Posts: 9
Default

If I remember correctly the reason you see this with the alpha more than some other cameras, is that Sony wanted to keep the resolution as high as possible. So they apply less anti-aliasing (I think they use a weaker anti-aliasing filter in front of the sensor). Anti-aliasing tends to blur the edges a bit, so with other cameras with a stronger anti-aliasing filter you would get smother edges but would loose some detail.
alexperez is offline   Reply With Quote
Old Nov 3, 2006, 2:51 PM   #6
Junior Member
 
Join Date: Nov 2006
Posts: 10
Default

Alex,
So far this is the best answer I have heard.
It seems feasible.

I think I might start looking for anti-aliasing in the menus and try it out.
Thank you very much for this possibility.

Waz

wazungy is offline   Reply With Quote
Old Nov 3, 2006, 11:06 PM   #7
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

wazungy wrote:
Quote:
I think I might start looking for anti-aliasing in the menus and try it out.
Thank you very much for this possibility.
There is no anti-aliasing menu choice. It's a filter over the CCD. I doubt that has anything to do with what you're seeing anyway. Sharpening algorithms are designed to increase contrast at edge transitions. So, you may even be seeing that. Also, edge transitions tend to be smoother from some demosaic algorithms versus others.

How are you looking at these images? Chances are, you're just seeing processing artifacts trying to view them at a size much larger than you'd be printing at (at least without interpolation)

Or, you may be seeing a lens issue, or something else entirely, like not enough pixels representing the highlights you're referring to because they are taking up too little space in the image.

If you have a concern about a specific image, I'd suggest posting a sample (or a link to a sample) for comments.

The only way to tell how two cameras compare is going to take photos of the same subject at the same time, using the same camera settings, using lenses of equivalent quality. Even then, unless they're processed identically using the same raw converter, you're going to have differences in how they're rendered (demosaic algorithms used by a specific raw converter and more).

JimC is offline   Reply With Quote
Old Nov 4, 2006, 11:49 PM   #8
Junior Member
 
Join Date: Nov 2006
Posts: 10
Default

I would love to be able to try taking the same picture with two different DSLR camera's with (almost) identical lenses, but I am afraid I am not made of that sort of money.

It is my hope that those who do have more than one camera, or those who have noticed this effect might be able to tell me what the cause is, whether it can be corrected or not, or if I am just being too picky.

In my mind turning round objects that are several pixels wide into squares at under 100% zoom is a bit of a problem that I have to resolve.

I have considered that I might have the camera on a setting that is causing this. I will be trying different sharpen settings in the future. I also thought that the firmware update might have fixed it, but it has not. If I remember correctly the firmware update alters the way the image is processed when the shutter is open for more than a second.

In any case,...I look forward to seeing the A-100 test photos in the review section when they are posted.

Waz










wazungy is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 11:13 AM.