Image sensor size & size of photo-detectors (Question)

[Rriley]

small cameras, small lenses, small budgets, small size
in my trade i need everything in focus so its an asset to me

one can tire of the 'expectations' of people and iso in small cameras
where were they when the kodak brownie was around
in 35mm iso 400 film grain was thought to add drama to a photograph

even on dSLRs, what became of low iso
iso 25, iso 64 ?

[BenjaminXYZ]

even on dSLRs, what became of low iso
iso 25, iso 64 ?

Do you thinkthat is important, when considering the lowest ISO leveron a typical dSLR; is already so good? :-)

[JimC]

Lower ISO speeds can help to prevent the need for Neutral Density Filters. For example, you may want to shoot at wide open apertures in very bright light for depth of field purposes and "run out of shutter speed", depending on the camera's capabilities (available shutter speeds may not be fast enough to prevent overexposure).

Or, you may want to deliberately use slower shutter speeds (for example, blurring water) and the lens doesn't allow you to stop down the aperture enough to achieve them without overexposure (or without unwanted softness due to diffraction).

Or, you may want to use shutter speeds that allow you to remain within the flash sync speed limitations of a camera at wider apertures, and lower ISO speeds can help you achieve that, without the need to use High Speed Sync features of a flash (which will reduce their power output significantly), or you may want to use a strobe without that capability.

[Rriley]

i think its a better approach than ND filters

Riley

edit to add: Jim beat me too it

[BenjaminXYZ]

Lower ISO speeds can help to prevent the need for Neutral Density Filters. For example, you may want to shoot at wide open apertures in very bright light for depth of field purposes and "run out of shutter speed", depending on the camera's capabilities (available shutter speeds may not be fast enough to prevent overexposure).

Or, you may want to deliberately use slower shutter speeds (for example, blurring water) and the lens doesn't allow you to stop down the aperture enough to achieve them without overexposure (or without unwanted softness due to diffraction).

Or, you may want to use shutter speeds that allow you to remain within the flash sync speed limitations of a camera at wider apertures, and lower ISO speeds can help you achieve that, without the need to use High Speed Sync features of a flash (which will reduce their power output significantly), or you may want to use a strobe without that capability.

Yeah, you are right.

However, this issue can usually besolved by neutral density filters, faster shutter speeds, and [or] withsmaller apertures.

If you want shallow dept of field + slower shutter speed, I guess fitting on a N.D. filter should solve the problem. :-)

If you are shooting in a very bright place, and alsodesire a shallow dept of field; then a faster shutter speedshould help. Or else, you can once again use an N.D. filter! :G

If shallow DOF is not essential in those situations, then just use a smaller aperture to solve the problem. :idea:

IF you shoot in a very brightplace, desire a shallow DOF, and also a slower shutter speed; then a N.D. filter will still help! :lol:

[JimC]

Yes, you can use Neutral Density Filters to reduce light (which is the reason the very first sentence in my reply said " Lower ISO speeds can help to prevent the need for Neutral Density Filters"). ;-)

But, they have drawbacks. Any time you add another piece of glass in front of your lens, you risk image degradation and the possibility of increased flare..

Also, when you use a Neutral Density Filter you end up with a darker viewfinder, and the Autofocus Sensors don't get as much light either (which can impact Autofocus Speed and Accuracy).

As for shutter speed, you may "run out" of available shutter speed with the aperture wide open in low light if the ISO speed can't be set low enough (many cameras have limitations, and you may want to use a bright lens with wider available aperture for DOF purposes), as I mentioned, too.

As for using smaller apertures, I also mentioned in my first reply that you can get softer images from difraction if you set the aperture too small. Most lenses are going to be sharpest two or 3 stops down from wide open.

Yes, for some conditions, depending on what you want to accomplish, you may have to use a Neutral Density Filter with most cameras (although some of the Kodak DSLR models can go down to ISO 6). But, a lower available ISO speed would be preferrable.

[Rriley]

about additional glass, exactly right
i didnt think of the auto focus tho

seems everyone missed the idea of using iso 25 AND an ND

Riley

[BenjaminXYZ]

Also, when you use a Neutral Density Filter you end up with a darker viewfinder, and the Autofocus Sensors don't get as much light either (which can impact Autofocus Speed and Accuracy).

Isn't it true that you will mostlikely be using the N.D. filters under bright lighting conditions?

The N.D. filters shouldn't be posing such a problem to the viewfinder under such a bright lighting condition isn't it? (Same goes for the A.F. IMO)

seems everyone missed the idea of using iso 25 AND an ND

You would rather get a slow lens for that! :GPerhaps a reflex mirror thatoffers F/9or up. :idea:

I heard someone's reflex mirror reached up to F/40 + !!

[JimC]

You'd probably be using it in better light. But, it depends on why you're using one.

For example, you may be trying to slow down shutter speeds for taking photos of cars going by to get light trails without overexposure, versus taking photos of running water in daylight.

But, it doesn't take a lot of light reduction to impact AF speed either.

Most cameras have problems Autofocusing when effective apertures are much smaller than f/5.6 or so, even in good light (you can get hunting with lenses that aren't as bright). Some cameras can't AF at all once you get to a largest available aperture of around f/8. So, when you use an ND filter, you can cause the same types of issues with Autofocus if your lenses are not bright enough (since you're reducing the amount of light seen by the AF sensors).

That's one reason a DSLR always focuses with the aperture wide open, then stops it down to your set aperture when the photo is taken. That helps get the most light to the viewfinder and AF Sensors. If you use an ND filter, you're blocking some of that light.

[BenjaminXYZ]

For example, you may be trying to slow down shutter speeds for taking photos of cars going by in darker conditions to get light trails without overexposure, versus taking photos of running water in daylight.

Hmmm, it will also depend on the situation...

I can set my camera at ISO 100 and get nice light trails in the evening light. Usually at this case, the camera will be at infinity focus, so no focus issues to talk about here. (I can also usesmaller apertures to slow the shutter even more)

I agree that lower ISO to substitute an N.D. filter will always seems a better option. However if you don't have it, smaller apertures and N.D. filters are the way to go. :-)

If you don't have a lower ISO and you don't want to blow out highlights in the bright, then a faster shutter will also come in helpful. (To control the incoming light)

Heck, there is always a way around it! :-)