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Old Jul 21, 2003, 1:33 PM   #31
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Good questions Bert, I'll be interested in learning the answers as well......john
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Old Jul 21, 2003, 2:54 PM   #32
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1) Vignetting is when something happens around the edges of the picture, usually a black border due to part of the camera assembly (or attached lens) coming into the picture...it could be as severe as http://www.shortcourses.com/how/attach/vignetting.jpg or as light as http://www.dolabs.com/img/challenges/vignetting.jpg
Pincushioning is siminar to what happens to a pin cushion when you push a pin in or say your skin when you poke it with your finger...it's deepest where your finger is and rises up where your finger isn't. Look for the "Barrel/Pincushion Distortion" example on this page, http://www.htu.at/~sascha/ptguide/01.htm

2) filters can cause vignetting IF they are smaller then your lens opening (say 37mm while your lens is 46mm). In the case of the Olympus C-7x0 you shouldn't have a problem until you get use the 46mm or 37mm tubes or go wide angle with several filters on the camera.

4) DOF is Depth of Field, say you're shooting a close subject and you want the background blurry or clear...there's a great simulator at http://www.photonhead.com/exposure/simcam.htm
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Old Jul 21, 2003, 3:11 PM   #33
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Well, now I am confused. Both my present cameras have sensors with a 4:3 aspect ratio. The E20 is 2560x1920, and the Nikon CP 950 is 1600x1200.
All the cameras you listed just like my D7 and the CP990 are 4:3 ratio. On the Coolpixes however, Nikon provides the option of getting a 3:2 frame by cropping the pixels horizontally through the menu.
The 10D has a sensor with 3:2 ratio (3088x2056), so it's more film like in this aspect. The 4/3 system is no different than the other camera, but profits from the smaller diagonal size sensor to design smaller lens as compare to the full frame 35mm which requires twice the inner diameter! The downside will be the DOF as everyone is aware with their current digicams, but not so drastic I would hope!
http://www.kodak.com/global/plugins/...CELongSpec.pdf

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1 - What's the diff between pincushioning and vignetting?
Pin cushion is caused by the lens, and will always be present. Vignetting in my case is external... ie if I remove the filter the artifact disappear.

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2 - How does a Tiffen filter (UV, I assume?) cause vignetting (I shoot with the same kind of filter on my Oly- C-730)?
Well... How wide is the lens on your C730? With the D7 @ 28mm wider angle the thickness of the filter's ring get in the way and darkened the corners of the picture.

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3 - What's a B&W filter?
B&W, Heliopan, Hoya are brands that all make slim-line filter without the front filter thread so you can not stack them -> decreasing the thickness that cause the vignetting in the lens @ wide angle setting!

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4 - What does defocus DOF mean (Manual focus?)?
See above - all small sensor digicams have extreme DOF, ie almost everything is in focus -> It's why some people do large/medium format over 35mm for their even lower DOF! Portrait for example requires subject to be extremely sharp, but the background totally blurred out.

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5 - What's an EF mount and its signifcance to a less than full size sensor? What's sigificance of Canon possibly introducing an EF lens?
The EF is the current standard electronic full frame mount for Canon. By making smaller lens like the Nikon (ie with smaller diameter) for the smaller sensor of the 10D with the same EF mount, Canon can have the same benefit as the 4/3 format. This lens would not work well when mounted on a regular 1Ds for example... It will truly pincushion!

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6 - How did you come to own so many cameras ?
I sweet talk my lovely wife? :lol:
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Old Jul 21, 2003, 3:32 PM   #34
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Posting Freak,
Thanks for a very informative post from which I learned a lot!
A couple of comments:

1. Pincushion and barrel distortion...think of it this way. The image should be a rectangle. If the sides bow out, it looks like a barrel. If the sides bow in, it looks like an old-fashioned pincushion...thus the names. If you want a demonstration of both, take a look at the control panel on your monitor. It probably has adjustments for both, so you can see what they look like on the screen shape.

2. DOF...depth of field can be controlled with any lens by varying the aperture (F-stop). The wider the aperture (smaller number) the shallower the DOF. So, if you want to do selective focus, you could decrease the DOF by going to aperture priority and selecting a low number. This will force a fast shutter speed (assuming autoexposure). Under very bright outdoors conditions, your shutter may not have a short enough interval for this to work, though.
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Old Jul 21, 2003, 3:37 PM   #35
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Originally Posted by Bert Bigelow
Posting Freak,
Thanks for a very informative post from which I learned a lot!
A little note, the smaller text where it says, "Posting Freak" is actually our rank, just like your name isn't "Member". Both NHL and myself are the same rank, "Posting Freak".

(that's two different times I had to clarify that in two days, not to the same member).
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Old Jul 21, 2003, 3:41 PM   #36
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2. DOF...depth of field can be controlled with any lens by varying the aperture (F-stop). The wider the aperture (smaller number) the shallower the DOF. So, if you want to do selective focus, you could decrease the DOF by going to aperture priority and selecting a low number. This will force a fast shutter speed (assuming autoexposure). Under very bright outdoors conditions, your shutter may not have a short enough interval for this to work, though.
But it's never shallow enough the smaller the sensor regardless of how wide the aperture!... and that's the key point between the different formats ie from the view cameras to the Minox!
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Old Jul 21, 2003, 4:31 PM   #37
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Mike_Peat,
Thanks for the heads-up on the "posting freak" thing. I should have noticed that.

NHL,
I guess it depends on how fast your lens is. Most digital SLRs have pretty fast lenses...my E20 is F2.8 @ 35mm...not a screamer, but I can do selective focus with it. Not like I could with my old Pentax film SLR with the 1.4 lens, though. By the way, it seems to me that when you zoom, the DOF gets narrower, even though the aperture is smaller.
Of course you couldn't do much with an F4.5 rangefinder cam, but even with the LCD, I think it would be difficult. The TTL viewfinder is really necessary, IMO to do selective focus. And I mean optical, not electronic TTL. I find the electronic ones unsatisfactory. Maybe that's just my SLR prejudice, though. I tried a CP5700 before I bought the E20 and didn't like it at all.
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Old Jul 21, 2003, 6:18 PM   #38
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Hi Mike - Actually, yes, that was me that made the "posting freak" error twice (my, this is awkward....) in two different forums, but THX for taking the time to mention. I just got in a hurry and didn't read the ID's correctly "Never time to do a job right, but always time to do it over again..." Best - john
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Old Jul 21, 2003, 6:25 PM   #39
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THX for all the great info, I'll read over in detail and go to the links later when I have a little more time; I'll also post my WebShots site if you'd like to look at a few of my pics. You about have me ready to go out and buy a Canon 10D - NHL, you'll have to give some pointers on sweet talking my wife......HA! Best - john
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Old Jul 21, 2003, 7:04 PM   #40
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Bert

I agree with you on the wider aperture = less DOF part, but it's not what I'm referring to: the f2.8 DOF is not the same in all cameras, ie you get more of it as the sensor get smaller for the same aperture!
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I expected the depth of field in digital cameras to be significantly greater than that in 35 mm models. Everybody and his mother knows that. What I didn't expect, is how large the difference is...

...The Olympus E-20 has the focal length ratio of 1:4, therefore its lens at F/2.8 provides depth of field of an equivalent 35-mm camera lens at F/11.2
http://wrotniak.net/photo/dof/


John

Have you talk your wife into modeling? :lol: :lol: :lol:
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