understandign actual pixels

[Caveboy_Ken]

Hi Eric,
Sure does help, Thanks!

I think I am describing this Tokina lense incorectly.
Here is one on e-bay http://cgi.ebay.com/ws/eBayISAPI.dll...category=48556
the only difference is that mine is for Olympus. I bought it used back in '76 or '77 timeframe.
It is an odd beast for sure.
I looked at the adjustment ring to get the numbers.
Also on the lense is printed 35-200 1:3.5-4.5 67
I know the 67 is the diameter of the front of the lense as the filter is 67mm, do the other numbers make more sense?
Just goes to show ya how little I know and understand about all this stuff. So.... makes me wonder what it really is @ F22. I'm guessing that's at 35MM not at 200MM.


Ken

[eric s]

So largest aperture at 35mm is f3.5 and at the longest end (200) is f4.5. The normal way to describe this is:
35-200 f3.5-4.5

This is not an uncommon zoom and it has a reasonable range that people find to be useful. It isn't extremely wide angle, but wide enough and 200mm is reasonable long for normal usage.

Because of the sensor crop factor, it will be harder to find something that wide (the equivalent to 35mm) that also goes out as far as the equivalent to 200mm. You could do it in two lenses fairly easily, but not in one.

A quick look at lenses shows shows that getting the exact range you have with film will be expensive. One of these:
Sigma 20-40mm F2.8 EX is $650
Canon EF 17-40mm f/4L USM is $690

and one of these:
Sigma 24-135mm f/2.8-4.5 is $300
Canon EF 28-135mm f/3.5-5.6 IS USM is $410

Would do it. You normally want some overlap in the the focal length so you don't have to always change lenses.

I'm betting the f22 is the smallest aperture (largest fstop) the lens can do. It's a fairly reasonable number.

Eric

[NHL]

FYI

There's a new 28-200mm equivalent... The wide angle is what eveyone is missing in a dSLR after the 1.6x crop factor, especially for close quarter. It's small enough with nothing else to carry (the included hood will also prevent knocking the front element against rock)!

You don't want to be changing lens crawling in the mud (and in the dark): http://www.sigmaphoto.com/Html/18-125.htm

[eric s]

I didn't know of the 18-125. Is that for sale yet? I didn't see it at adorama.

Eric

[Caveboy_Ken]

Got a chance this past weekend to check out Canon 10D, nice camera and feels good in my hands given their size. Wanted to compare the Fuji S2 or S3 but the camera shop didnt have any in stock. Apparently they are selling quite well here in Mi.
My purchase ofa new camera will be delayed a bit now though. Got nailed pretty hard for taxes this year and figure I better annie up and pay the feds or I'll be looking at the world through metal bars.
Its not all that bad though becuase it will give me more time to check out the other cameras before I go and plunk down $5K

[eric s]

I know someone who upgraded from the Nikon D100 to the Fuji S2 Pro. He was fairly happy with the D100, he is very happy with the S2. After reading the specs for the S3, he was impressed. He had hoped for more resolution, but better dynamic range is even better.

Since you have no lenses or flashes to guide your choice, do consider the S2.

I didn't think the S3 was out yet, although it has been anounced.

Eric

[Caveboy_Ken]

Been looking at the S2 as far as reviews go. Also talked with the guy at hte local photo store. He mentioned that the S2 has 2 batteries, one set of AA rechargeables and another non rechargeable which is a huge bummer! I await the S3, hopefully they have changed that.

This is hte link where I am puting up some of my stuff.
http://www.iserv.net/~kendj/photo.html
There isn't much there yet as I have been busy dong other stuff for work that needed to get done. I'll be putting more up this weekend as time permits.
Feel free to check it out and comment good or bad, I welcome all suggestions.

Caveboy_ "not a pro by any means" _Ken

[JerryF]

Originally Posted by LTBerry

The Fuji is a great camera but it's plastic. I dropped mine once and the only thing that saved it was the Sunpak flash it landed on. (bye bye flash)
OK I'm done rambling.

The camera is in fact polycarbonate, not plastic. It is used to make it lighter and to absorb shock.

[WmAx]

I'm not going to read all of the replies in this thread, so please forgive me if I give a redundant answer. :-)

This is why the Sigma images seem to have a lot better clairity as in any given color there are more actual pixels than what would be in a 6MP chip after they are all divied up into seperate colors therefore it would take an 8MP chip to exceed only the color green and still lack in the blue and red?

Your word 'seems' is very accurate. It is mainly a perception. The Sigma images look better at 100 percent size on your monitor. However, they are not better then a 6MP DSLR, nor do they resolve more usefule data, for example. The 6MP image will look worse on screen becaue you are viwing the same amount of resolution but on a larger size image. You will see a more magnified view on screen. If you resample the Foveon image to the size of the 6MP DSLR, you will see nearly identical results. This is important, as this is what happend when you print(the images are rescaled to a common size). Anotehr factor is the Foveon images are always aliased. The Sigma SD9 and SD10 have no anti-alias filter. In a digital sampling system(camera), where you exceed the Nyquest limit of the sensor(0.5 factor actual sampling pionts) the device begins to alias. A gradual 'blurring' filter is required to maintain a somewhat linear accutance at higher frequencies, realtive to low frequencies. If the filter is not present, then edge to edge pixel transitions for example, will have a much higher contrast as one result(resulting in jaggies in some edges), the other is false low frequency data(patterns) when sampling a frequency that is higher then the sensor is capable of resolving. The aliasing, howver, is interesting in appearance. Perceptibly, it often sensed as added sharpness. Some people like this unique 'distortion' that these cameras offer.

The Foveon images still look neat at 100 percent, though. :-)

This leads me to my next question, how does Fuji come up with 12MP using a 6MP chip? Are they doubling up on the greens or something silly like that?

Fuji sensors are 'odd'. They use a dianolly oriented sensor as oppose dto a square format sensor. In ordet to get a square format end result, they must insert pixels into the diagnol grid to create a usable file. Here is a crude example:

X=sensor
0=interpolated pixel

Standard Sensor(square format):

XXXX
XXXX
XXXX
XXXX

FUJI SCCD Sensor(45 degree)

X_X_X_X
_X_X_X_
X_X_X_X
_X_X_X_

Now, this is what must be done to get a square format output:

X0X0X0X
0X0X0X0
X0X0X0X
0X0X0X0

Thus, a 12MP file output MUST be created to use the 6MP sensors in the S2 PRO without loss of resolution, for example.

Why does FUji use a diagnol sensor? Simple. Most scenes have more high frequency spatial information on the horizontal and vertical planes. Sampling diagnolly increases the effective resolution of the camera on these scenes. In optimal situations, it seems the SCCD can resolve approx. 1.3-1.5x the rated sensor MP rating, as compard to standard orientation sensors.

-Chris

[Caveboy_Ken]

Hi WmAx,
Thanks much for the detailed info on the sensors.

Do you happen to know what Fuji means by S and R pixels?
Here is their description from their web page for the S3

"APS size 12 megapixel (S-pixel: 6.45 million, R-pixel: 6.45 million) Super CCD SR sensor technology for high image quality with wide dynamic range"

I'm also understanding that pretty much all cameras interpolate except maybe Sigma's. The S3 also does this however because of their photosite layout they basically do a much better job of it right?

Is the aliasing you talk about what causes the purple hue that is sometimes seen at areas of high brightness with darker backgounds such as a flashes reflection off something shiny such as chrome?

Ken