[turtle]

Originally Posted by stevegong yay or nay? (taken with an infrared filtre, more on my site www.stevegongphoto.com)

The image gives me an eerie feel . Like she's about to go banshee on me or something. Her eyes being so dark and her facial expression just compound that feel.

I love the concept though. If that above was your goal, then yea.

[åsen]

Originally Posted by stevegong yay or nay? (taken with an infrared filtre, more on my site www.stevegongphoto.com)

Which IR filter?
Or has your D70 been IR-modified?

[Dorian Gray]

Moogs, resolution is the accepted term for what Powerdoc was talking about. The fact that the same term is used as shorthand for pixel count in the computer world is merely confusing, especially with Bayer sensors. In fact, you've fallen victim to the "marketing hype" you so detest!

Originally Posted by Moogs But I still question whether the images will have the "enlargeability" (new word!) of a true 8MP DSLR shot (from a good lens) when shooting real world subjects.

This statement reveals you are fundamentally not understanding how these sensors work. An 8 MP Bayer sensor with eight million photosites cannot deliver anywhere near 8 MP of spatial resolution because the photosites are divided into red, green and blue sensors, each of which can only measure the respective colour component of the light falling on that site. A strong anti-aliasing filter, needed to eliminate the artefacts created by the interpolation process, further blurs the result. On the other hand, a 4.6 MP Foveon sensor actually delivers a genuine 4.6 MP of resolution, subject to the lens being good enough (i.e. far better than the tiny lenses on pocket digicams which are not capable of 4.6 MP of resolution).

Let me try to explain this with a simple diagram. Imagine a line of "pixels" on a Bayer sensor as follows:

R G B R G B R G B
1 2 3 4 5 6 7 8 9 (reference numbers used below)

The G "pixels" record only the green component of light falling on them (R = red, B = blue). Now let's imagine we're trying to record a purely green subject (e.g. a tree) against a perfectly white background (the sky). If the vertical green/white edge falls on the border of "pixels" number 5 and 6 (i.e. green light falls on "pixels" 1-5 and white light falls on "pixels" 6-9), one might expect the Bayer sensor to then record 1-5 as green and 6-9 as white. In reality however, the Bayer sensor has no way of knowing that 5 is green: the camera can only estimate that it might be green because 2 is reporting green and 1, 3 and 4 are all reporting a value of zero, while 7, 8 and 9 are reporting equal values and therefore might be white. Therefore the Bayer sensor can make no distinction between the vertical green/white line falling between 5 and 6, or between 6 and 7, or between 7 and 8. It can only make a distinction between it falling between 5 and 6, and falling between 8 and 9. So even though you would say my diagram has 9 pixels of resolution, the actual resolution for green against white objects is only one-third of that: i.e. 3 pixels.

A real Bayer sensor interpolates both vertically and horizontally, with a more complex RGB pattern, and so does a better job than my hypothetical example above. But the real resolution (in pixel count terms) is still less than half what the pixel count would suggest. And the anti-aliasing filter further reduces this resolution.

By contrast, here's how a Foveon sensor would look like. Each photosite ("pixel") can record the complete colour of the light falling on it:

R G B R G B R G B
B R G B R G B R G
G B R G B R G B R
1 2 3 4 5 6 7 8 9

Therefore regardless of where the green/white edge of our tree falls, the Foveon sensor will be able to record with 100% accuracy the exact edge of the tree (to the limit of the pixel count, of course). The true resolution is therefore equal to the pixel count, i.e. 9 pixels.

Yet another shorthand way to explain this is to consider the 8 MP Bayer sensor image to be a ~4 MP Foveon image that has already been enlarged (i.e. interpolated) in Photoshop by a spatial factor of the square root of 2 (i.e. 2x the pixel count).

The only case where a Bayer sensor actually delivers something close to the resolution its pixel count suggests is with a completely monochromatic subject, e.g. a test pattern of black lines on a white background. In all other cases - the real world, in other words - the resolution of the Bayer sensor is much lower than its pixel count.

By the way, there is nothing subjective about all of this. Likewise, there is no theoretical reason why the "colour" (colour saturation?) should be better with a Foveon sensor rather than a Bayer sensor. If the Sigmas produce better colour saturation it is because of a better implementation, not the Foveon versus Bayer technique.

PS. Sorry for contributing to turning your thread into a geekfest, Windswept!

[Moogs]

Dead linkage for me, but your site looks pretty good Steve. Those are some good looking college (?) girls you've got on your roster. I can imagine what a horror it must be having them remove some or all of their clothes so you can photograph them.

Dorian: great post. Informative and useful. And I do understand the concept of bayer pattern sensors vs. how a Foveon records light. I was more talking about the end result. In all this, the camera's processing capabilities, the camera's meter, and a host of other factors contribute to the end result. If all there was, was the difference between how the two systems record light, I dare say no photographer would be without a Sigma camera.

Likewise, this is how some cameras from the same company, end up with better color and noise performance than other cameras using the same lens and subject. Anyway, the theory matters not but rather the end result, which is why so many people swear by the S3 even though it is slow and "low" MP count. There's something special about the way it captures golden light in particular. I've seen some shots from an S3, on a misty golden morning that look ... different than all the rest. Not necessarily more or less detailed, just more life-like. The S4 suffers from a similar problem as the SD-14, the MP count hasn't changed, but rather the processing speed and I'm sure the noise algorithms.

And the bottom line for all of us, no matter which platform we use / tout, is that

a)everything still follows the light. bad light = bad picture

b)MP for MP sake is useless if you have no print-based need for them. My boss ponders the idea of going from a 22MP MF back to a 39MP back, and I'm like "For God's sake why?" Other than more efficient shooting because of the use of CF cards, and a larger preview, it would gain us nothing. If you don't shoot for billboards, who cares, once you get beyond about 12 or 14 MP. All you're really doing is giving yourself more room to crop and still make a large print.

[Dorian Gray]

Originally Posted by Moogs everything still follows the light. bad light = bad picture

Absolutely, nearly always.

Window light.

Backlight.

Multiple lights.

Reading light.

Harsh light.

Street light.

Bar light.

Sunlight. (In trouble after Queenside castling, as is usually the case. )

Overcast light. (Colour photo. Cloudy days are perfect for getting rich, saturated colours, which surprises many novice photographers.)

Crap light. Good moment though!

Crap light. Good subject though!

(All photos from The Family of Man 2.)

[Moogs]

Those are some great photos though the last one is fekkin scary I must say.

[stevegong]

Originally Posted by Moogs Dead linkage for me, but your site looks pretty good Steve. Those are some good looking college (?) girls you've got on your roster. I can imagine what a horror it must be having them remove some or all of their clothes so you can photograph them.

Thanks. I've had a few requests for that, but I don't have them on my site. Most of them are friends or the models of the Fashion Design Club here. Last night there was a fashion show and I made a few pics as they were getting ready in the bathroom. I'm going to put the link here, not embed the image since they are not Black and White.

http://gong.smugmug.com/gallery/2117384

Oh, and the image link does seem dead. Here it is again:

[turtle]

Hey Steve, if you right click on the image placeholder and open in another window it works. The you'll be able to see the image.

[Moogs]

You see this is why I don't photograph young scantily clad women, because if I did I wouldn't be able to maintain a stable marriage.

[stevegong]

Took this one yesterday at the hospital.

[turtle]

Well that image says a lot about the person sitting there. Nice catch!

[Barto]

Another photo from me...

[turtle]

I thought I would add a photo to this thread. I took this one last (almost) full moon here, I was a day late.


f/14, 1/25, 0ev

I will say, you can't tell the difference between the original color and B&W, but I liked the detail I managed to get with this shot.

[GSpotter]

The moon moves surprisingly fast (and is rather bright if your tele is big enough). I once made a shot with 1/320s - f/11

[turtle]

Originally Posted by GSpotter The moon moves surprisingly fast (and is rather bright if your tele is big enough). I once made a shot with 1/320s - f/11

Yours sure looks better than my attempt. At least I'll be able to aspire to something better! Also, my lens was only 300mm.

[Powerdoc]

Here is one of my attempt :

[turtle]

Ok, I just noticed how blurry my image is compared to these two and I must not have chosen my best.

*runs to Aperture to find a better version*

[Powerdoc]

Take one shot of the moon, and you will have it all (except for the crescents and the eclipses)
I wonder, how someone can claim any copyright on a moon shot ?

[stevegong]

And here's the same picture but in colour.

http://gong.smugmug.com/gallery/1871...12621296/Large

I prefer colour, what do you guys think?

[turtle]

Originally Posted by stevegong Here's one I snapped over Thanksgiving break. This was black Friday in Norfolk. And here's the same picture but in colour. http://gong.smugmug.com/gallery/1871...12621296/Large I prefer colour, what do you guys think?

That's MacArthur Center and I like both images. It really shows the girl in her own world!

*hot linking doesn't work well for you though, I can see the image when I right-click and open the image in a new tab.

[stevegong]

Fixed Link. The pictures seem to not work only in Safari.

[turtle]

Did you know the girl standing there? Where did you set the camera? Please do tell because I really like that picture.

[stevegong]

if you look at the exif, the exposure is 1 second. I didn't have a tripod so I tried to set it on a railing. I had to shoot a few pictures since for some of them she was in fact moving. Sometimes you get lucky, sometimes you don't.

[turtle]

I did look at the exif, that's why I had to ask. I knew it couldn't have been handheld. Great timing for you, great shot!

[Powerdoc]

Steady during one second, with only the help of a rail : good shot. The number of false attempt do no count in photo

[Mac+]

Great shot - Powerdoc is right too. Once you get the shot, the number you took beforehand don't matter.

[Eugene]

Originally Posted by Powerdoc Steady during one second, with only the help of a rail : good shot. The number of false attempt do no count in photo

Maybe not that photo, but it does matter to a lot of photographers, particularly PJs

[stevegong]

Originally Posted by Eugene Maybe not that photo, but it does matter to a lot of photographers, particularly PJs

Except the reason of the number of false attempts are high on that one only because I wanted the people walking around to produce streaks.

Photojournalists who just document events, such as a pic of bush at the whitehouse most often do not aim for creativity. They need to get that pic of bush for the press or whatever. If they had to take that scene, they'd just set a fast shutter speed.

National Geographic photographers whom have a lot of freedom in what they shoot are however encouraged to experiment and bring out their own personal styles.

so I don't quite understand the point of your post.

[turtle]

Originally Posted by Eugene Maybe not that photo, but it does matter to a lot of photographers, particularly PJs

IMHO, the only truth to this is when it's a matter of pride that "only one shot was needed". PJs need only cature a moment to show the story in an image. This is best achieved by shooting a chain starting before the image was needed and ending after that image. I.e. when a boy is about to be announced the victor and you want his expression.

[Eugene]

Originally Posted by turtle2472 IMHO, the only truth to this is when it's a matter of pride that "only one shot was needed". PJs need only cature a moment to show the story in an image. This is best achieved by shooting a chain starting before the image was needed and ending after that image. I.e. when a boy is about to be announced the victor and you want his expression.

From a technical standpoint, you're relying on constant autofocus when you take a high-FPS, high motion sequence of shots. From a more human standpoint. If you've got to spend 10s taking just the right photo, that's 9s of opportunity lost. You may have taken the photo of the victor, but you missed the opponent angrily kicking the dirt in defeat.