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Old Jun 25, 2006, 2:18 AM   #1
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After playing with my 30D for several months now, i find that i'm using what i consider high ISO settings most of the time, in order to obtain decent shutter speeds. even on bright sunny days, using a polarizer, i find that i can only manage shutter speeds of, say, 1/250-1/320 @ f11-16, and i need ISO 800 to get that!in very bright settings, like snow,i can up the shutter to 1/400 or so at f20-22. seems to me i should be able to get these speeds and apertures at much lower ISO settings... is there something i'm doing wrong, or am i just expecting too much from the camera?
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Old Jun 25, 2006, 7:24 AM   #2
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I don't know, sounds strange to me. I would leave the polorizer off unless there was a problem with glare. On bright sunny days you should always be able to use the sunny 16 rule. f/16 and set the shutter speed to what ever your ISO is set at, and you should be able to set it at 100, or 200 with no problem. Maybe it is the lens that is the problem?
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Old Jun 25, 2006, 8:49 AM   #3
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A Polarizer will typically cost you two stops of light when rotated for best effect.

So, you'd need to shoot at ISO 800 to get shutter speeds up to where they'd be at ISO 200 without the Polarizer.

But, unless you have a genuine need, I probably wouldn't stop down the aperture so much:

"...i can up the shutter to 1/400 or so at f20-22..."

I'd try to use a wider aperture instead of increasing ISO speed so much if a polarizer is needed.
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Old Jun 25, 2006, 10:00 AM   #4
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On the 1.6 crop cameras you are typically using much shorter focal lengths, so you generally have greater depth of field than 35mm so there should be little need to go to f22.

In fact the diffraction limitation of the sensor is at about f14, which is to say that your pictures will start to get blurry at apertures below f14, certainly f22 is noticably less sharp.

Try experimenting with f11 -f14, I think you'll find your depth-of-field is sufficient for most purposes.

f14 on a 30D with 17mm lens has approximately the same hyperfocal distance as f22 on 35mm with a 28mm lens.

http://www.dofmaster.com

But basically what you're experiencing is just how photography works. If you're shooting low ISO an small apertures you need to use a tripod, and if you're using a filter then that applies even on sunny days.

This is why landscape photographers carry tripods everywhere with them.
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Old Jun 25, 2006, 11:06 AM   #5
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squirl033 wrote:
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... even on bright sunny days, using a polarizer, i find that i can only manage shutter speeds of, say, 1/250-1/320 @ f11-16, and i need ISO 800 to get that!...
Everyone is correct...

-> you're putting a 'sunglass' on on your lens with that polarizer which will cost you 2 to 3-stops at least!

This is what it should be for any camera: http://www.earthboundlight.com/photo...tops-here.html
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Old Jun 27, 2006, 3:20 PM   #6
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thanks, guys, i know all that. i've been using polarizers ever since my days with an old Pentax ME Super. what puzzles me is that i seem to need to use higher ISO settings even without the filter, in what my other camera seems to "think" is good light. i probably haven't taken 10 frames with this 30D at ISO settings less than 400... it just doesn't seem to give me enough shutter speed to avoid camera shake and/or maintain a decent aperture (i.e. > wide open) witheither of my lensesunless i bump the sensitivity up. is this typical for the Canon cameras? i know they're less noisy at higher ISO settings than other cameras, is that because users have to employ those higher settings to get proper exposures?shouldn't i be able to set the ISO to 100 or 200 in bright light (without the polarizer), and still yield acceptable shutter speeds? or am i just expecting too much?
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Old Jun 27, 2006, 3:32 PM   #7
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The shutter speed you can use is dependent on three things:

* Light Levels (typically measured as EV or Exposure Value for photography)

* Aperture

* ISO speed (same thing as ASA speed or film speed).

If you're getting different results from another camera, it's probably using different aperture settings for the same film (ISO speed) and lighting, or you're metering the scene differently (resulting in a darker exposure for the same aperture and film speed before "pushing" in PP).

There shouldn't be any difference in shutter speed, if the lghting, aperture and ISO speed (a.k.a., film speed) is identical, if you want the same exposure (brighter or darker), unless you're doing something that's robbing the camera of light (like using a Polarizer will do).

The same exposure calculators you see for film also apply to digital, unless the manufacturer is "fudging" the ISO speeds. If anything, Canon cameras tend to be off in the other direction (sometimes they test slightly more sensitive than their indicated ISO speed).

Here is a handy online exposure calculator you can use to get an idea of the relationship between film speed (ISO speed), light, aperture and shutter speed.

http://www.robert-barrett.com/photo/...alculator.html

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Old Jun 27, 2006, 4:26 PM   #8
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You can transpose an EV reading from a handheld meter to any camera (i.e. the same as Pentax, Nikon or Canon) :idea:
What time of day are you shooting at??? :lol: :-) :G

I never exceed 400... Most of my shots are around 100-200 (check the Exif):
http://www.pbase.com/nhl/p_wildlife

-> I pop my flash up after that! :?
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Old Jun 28, 2006, 3:17 AM   #9
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squirl033 wrote:
Quote:
thanks, guys, i know all that. i've been using polarizers ever since my days with an old Pentax ME Super. what puzzles me is that i seem to need to use higher ISO settings even without the filter, in what my other camera seems to "think" is good light. i probably haven't taken 10 frames with this 30D at ISO settings less than 400... it just doesn't seem to give me enough shutter speed to avoid camera shake and/or maintain a decent aperture (i.e. > wide open) witheither of my lensesunless i bump the sensitivity up. is this typical for the Canon cameras? i know they're less noisy at higher ISO settings than other cameras, is that because users have to employ those higher settings to get proper exposures?shouldn't i be able to set the ISO to 100 or 200 in bright light (without the polarizer), and still yield acceptable shutter speeds? or am i just expecting too much?
You're not expecting too much. If you are correct about this, then there is something wrong with your camera.

ISO is ISO is ISO. That is the whole point. (Well OK, perhaps there are slight variations, but always less than 1 stop between exposure and metering systems.)

If anything the Canon ISO rating is supposed to be higher than the correct value. i.e. ISO 100 is closer to ISO125, ISO 3200 is closer to ISO 4000.

A few things to consider (overlap with what Jim said):

1. Make sure youare not using ANY filters, including UV and all those "protective"pieces ofcheap glass people seem determined to cover their expensive lenses with.

2. What metering mode you are using? It is possible that you have set the metering to a mode you are not familiar with, and which behaves differently from your previous camera. If in doubt set your camera to spot metering and get yourself an 18% grey card and meter that way.

3. Are you sure you haven't dialled in any exposure compensation? It's quite easy to do by accident on the 20D and I presume therefore on the 30D too. Just check the top LCD to make sure.

4.What is the histogram telling you about your exposures?


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Old Jun 28, 2006, 6:22 AM   #10
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There's a reason as to why they called it ISO: http://www.iso.ch/iso/en/CatalogueDe...CSNUMBER=37777

-> It could be the lenses you're using too
In the older days I always shoot with a 50mm f/1.4 or some other primes (zooms were not that good back then). The zooms now are f/5.6 on average so that's like 4-5 stops difference, and twice the light loss in a polarizer...

Plus where can one buy >400 ASA film back then? :-) :lol: :G
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