Why does brightness of the picture for the same situation vary. why ?

Marc Sabatella · 04-09-2009, 05:51 PM

Originally posted by OregonJim

Wrong. You have to REDUCE the image to see it onscreen, unless you happen to have a 10 or 14MP monitor (I don't think they exist yet).

Magnification in this context is more literal than that - it refers to physical dimensions. An APS-C sensor is 16x24mm (roughly). If you want to see the image larger than that, you are magnifying it, and hence, amplifying the effect of camera shake. It has nothing to do with number of pixels; the effect is just as real when using APS-C *film* cameras.

This also has an effect on DOF calculations, BTW.

Quote:

Magnification in the context of thread means enlarging a crop-sensor image to the equivalent size of a full-frame sensor image. E.G, to make 8x10 prints from both (assuming resolution is identical), the crop-sensor image must be enlarged 1.5 time the FF image in order for the images to look "similar" (same field of view).

Precisely. And because the APS-C image requires more magnification, it also requires that much faster a shutter speed in order to control camera shake when using any given lens.

Another way of seeing the exact same phenomenon: you need a faster shutter speed to make an acceptably sharp 8x10" enlargement of a given negative than to make an acceptably sharp 4x6", at least if you plan on viewing both from the same distance. Of course, normally, you might vidw the 8x10" from a somewhat greater distance, nullifying the need for greater sharpness to some extent. But then if you cropped the 8x10" enlargement to 4x6", you'd have an exact analogue of the situation with an APS-C camera.

**DAZ** · 04-09-2009, 06:00 PM

Originally posted by Marc Sabatella

Magnification in this context is more literal than that - it refers to physical dimensions. An APS-C sensor is 16x24mm (roughly). If you want to see the image larger than that, you are magnifying it, and hence, amplifying the effect of camera shake. It has nothing to do with number of pixels; the effect is just as real when using APS-C *film* cameras.

This also has an effect on DOF calculations, BTW.

Precisely. And because the APS-C image requires more magnification, it also requires that much faster a shutter speed in order to control camera shake when using any given lens.

Another way of seeing the exact same phenomenon: you need a faster shutter speed to make an acceptably sharp 8x10" enlargement of a given negative than to make an acceptably sharp 4x6", at least if you plan on viewing both from the same distance. Of course, normally, you might vidw the 8x10" from a somewhat greater distance, nullifying the need for greater sharpness to some extent. But then if you cropped the 8x10" enlargement to 4x6", you'd have an exact analogue of the situation with an APS-C camera.

(Slap head) That what I was trying to say, but you did it better!

DAZ

OregonJim · 04-09-2009, 08:39 PM

Originally posted by Marc Sabatella

Magnification in this context is more literal than that - it refers to physical dimensions. An APS-C sensor is 16x24mm (roughly). If you want to see the image larger than that, you are magnifying it, and hence, amplifying the effect of camera shake. It has nothing to do with number of pixels; the effect is just as real when using APS-C *film* cameras.

This also has an effect on DOF calculations, BTW.

Another way of seeing the exact same phenomenon: you need a faster shutter speed to make an acceptably sharp 8x10" enlargement of a given negative than to make an acceptably sharp 4x6", at least if you plan on viewing both from the same distance. Of course, normally, you might vidw the 8x10" from a somewhat greater distance, nullifying the need for greater sharpness to some extent. But then if you cropped the 8x10" enlargement to 4x6", you'd have an exact analogue of the situation with an APS-C camera.

Ahhh, I understand where you're coming from now. I think we were trying to say the same thing at one point, but somehow my brain got derailed along the way. In any case, we're in agreement now. It's been one of those days....

res3567 · 04-12-2009, 01:59 PM

Originally posted by OregonJim

Wheatfield,

While these references are appropriate for any of us to read, I don't think they'll solve the OP's problem. Besides, they're probably not easy to find in India.

The problem he's having is specific to the "quirks" of his particular camera - as Quension pointed out, the auto-ISO behavior and the program line for Av that limits shutter speed choices based on focal length. I think that this forum is the proper place to ask such a question (and to expect a friendly answer).

Amen and Thank You!!

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04-09-2009, 05:51 PM	#46
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Originally posted by OregonJim Wrong. You have to REDUCE the image to see it onscreen, unless you happen to have a 10 or 14MP monitor (I don't think they exist yet). Magnification in this context is more literal than that - it refers to physical dimensions. An APS-C sensor is 16x24mm (roughly). If you want to see the image larger than that, you are magnifying it, and hence, amplifying the effect of camera shake. It has nothing to do with number of pixels; the effect is just as real when using APS-C film cameras. This also has an effect on DOF calculations, BTW. Quote: Magnification in the context of thread means enlarging a crop-sensor image to the equivalent size of a full-frame sensor image. E.G, to make 8x10 prints from both (assuming resolution is identical), the crop-sensor image must be enlarged 1.5 time the FF image in order for the images to look "similar" (same field of view). Precisely. And because the APS-C image requires more magnification, it also requires that much faster a shutter speed in order to control camera shake when using any given lens. Another way of seeing the exact same phenomenon: you need a faster shutter speed to make an acceptably sharp 8x10" enlargement of a given negative than to make an acceptably sharp 4x6", at least if you plan on viewing both from the same distance. Of course, normally, you might vidw the 8x10" from a somewhat greater distance, nullifying the need for greater sharpness to some extent. But then if you cropped the 8x10" enlargement to 4x6", you'd have an exact analogue of the situation with an APS-C camera.

04-09-2009, 06:00 PM	#47
DAZ Loyal Site Supporter Join Date: Sep 2006 Location: Everett, WA USA Photos: Gallery Posts: 744	Originally posted by Marc Sabatella Magnification in this context is more literal than that - it refers to physical dimensions. An APS-C sensor is 16x24mm (roughly). If you want to see the image larger than that, you are magnifying it, and hence, amplifying the effect of camera shake. It has nothing to do with number of pixels; the effect is just as real when using APS-C film cameras. This also has an effect on DOF calculations, BTW. Precisely. And because the APS-C image requires more magnification, it also requires that much faster a shutter speed in order to control camera shake when using any given lens. Another way of seeing the exact same phenomenon: you need a faster shutter speed to make an acceptably sharp 8x10" enlargement of a given negative than to make an acceptably sharp 4x6", at least if you plan on viewing both from the same distance. Of course, normally, you might vidw the 8x10" from a somewhat greater distance, nullifying the need for greater sharpness to some extent. But then if you cropped the 8x10" enlargement to 4x6", you'd have an exact analogue of the situation with an APS-C camera. (Slap head) That what I was trying to say, but you did it better! DAZ

04-09-2009, 08:39 PM	#48
OregonJim Veteran Member Join Date: Mar 2009 Location: Willamette Valley, Oregon Posts: 1,327	Originally posted by Marc Sabatella Magnification in this context is more literal than that - it refers to physical dimensions. An APS-C sensor is 16x24mm (roughly). If you want to see the image larger than that, you are magnifying it, and hence, amplifying the effect of camera shake. It has nothing to do with number of pixels; the effect is just as real when using APS-C film cameras. This also has an effect on DOF calculations, BTW. Another way of seeing the exact same phenomenon: you need a faster shutter speed to make an acceptably sharp 8x10" enlargement of a given negative than to make an acceptably sharp 4x6", at least if you plan on viewing both from the same distance. Of course, normally, you might vidw the 8x10" from a somewhat greater distance, nullifying the need for greater sharpness to some extent. But then if you cropped the 8x10" enlargement to 4x6", you'd have an exact analogue of the situation with an APS-C camera. Ahhh, I understand where you're coming from now. I think we were trying to say the same thing at one point, but somehow my brain got derailed along the way. In any case, we're in agreement now. It's been one of those days....

04-12-2009, 01:59 PM	#49
res3567 Veteran Member Join Date: Sep 2008 Location: Houston Tx. Photos: Gallery Posts: 1,876	Originally posted by OregonJim Wheatfield, While these references are appropriate for any of us to read, I don't think they'll solve the OP's problem. Besides, they're probably not easy to find in India. The problem he's having is specific to the "quirks" of his particular camera - as Quension pointed out, the auto-ISO behavior and the program line for Av that limits shutter speed choices based on focal length. I think that this forum is the proper place to ask such a question (and to expect a friendly answer). Amen and Thank You!!