Couple of newbie questions about speed and light.

OK, I'm the first to admit I'm just an amateur photographer but I
do have a little technical knowledge (a little knowledge is a dangerous
thing). A couple of things I just want to check my understanding:

1. With all else being equal (lens, light, aperture etc. etc.) if you
have a FF sensor instead of a cropped one could you use a faster shutter
speed for a given image because of more light falling on the sensor?

2. Similarly, all else being equal, if you have a lens with a larger
front element could you use a faster shutter speed because more light
would be collected?

I (try to) take a lot of pictures of birds but there's rarely enough
light for me to get a fast enough shutter speed. I'm trying to work
out what equipment I'd be best off getting for faster shutter speeds.
A lens with a larger aperture and/or a body with better high ISO
performance would, I guess, be the main considerations but would the
above (FF and larger front element) help as well? Not that I can afford
another lens or body at the moment. :-)

I'm hoping these aren't completely stupid questions. If they are, at
least it will show the gaps in my understanding.

Cheers,

Ollie

Ollie Clark wrote:
OK, I'm the first to admit I'm just an amateur photographer but I
do have a little technical knowledge (a little knowledge is a
dangerous thing). A couple of things I just want to check my
understanding:

1. With all else being equal (lens, light, aperture etc. etc.) if you
have a FF sensor instead of a cropped one could you use a faster
shutter speed for a given image because of more light falling on the
sensor?

No. Usable shutter speed depends on the amount of light, the ISO speed and
the aperture. Size of the sensor (or film) does not change any of that. At
any given f-number, the quantity of light falling on any given sized part of
the sensor is the same regardless of sensor size, all else being equal. This
is because larger sensors imply larger apertures at the same f-number,
assuming the same field of view.


2. Similarly, all else being equal, if you have a lens with a larger
front element could you use a faster shutter speed because more light
would be collected?

No. If more image-forming light is collected, this will be reflected in the
f-number. Certain lens designs (e.g., some wide angles) have very large
front elements, but this does not necessarily imply anything about the
amount of image-forming light falling on the sensor.

It is true of course that "fast" (low f-number) lenses typically have larger
front elements than slower lenses of the same design and focal length.


I (try to) take a lot of pictures of birds but there's rarely enough
light for me to get a fast enough shutter speed. I'm trying to work
out what equipment I'd be best off getting for faster shutter speeds.
A lens with a larger aperture and/or a body with better high ISO
performance would, I guess, be the main considerations but would the
above (FF and larger front element) help as well? Not that I can
afford another lens or body at the moment. :-)

The solution to your problem is in most cases a faster lens (one which will
pass more light in the same fraction of a second). Unfortunately, faster
lenses are more expensive, often very much more expensive.


I'm hoping these aren't completely stupid questions. If they are, at
least it will show the gaps in my understanding.

No, it's never stupid to ask questions about something you're not sure of.
The stupid thing would be to *not* ask the question, and not learn.

Neil Harrington wrote:
Ollie Clark wrote:
OK, I'm the first to admit I'm just an amateur photographer but I
do have a little technical knowledge (a little knowledge is a
dangerous thing). A couple of things I just want to check my
understanding:

1. With all else being equal (lens, light, aperture etc. etc.) if you
have a FF sensor instead of a cropped one could you use a faster
shutter speed for a given image because of more light falling on the
sensor?

No. Usable shutter speed depends on the amount of light, the ISO
speed and the aperture. Size of the sensor (or film) does not change
any of that. At any given f-number, the quantity of light falling on
any given sized part of the sensor is the same regardless of sensor
size, all else being equal. This is because larger sensors imply
larger apertures at the same f-number, assuming the same field of
view.

I may not have made this as clear as I should have. What I am saying is that
for the same field of view, the focal length of the lens will have to
increase in direct proportion to any increase in the size of the sensor. For
that reason the *physical* size of the aperture will also have to increase
in the same proportion, in order to keep the same f-number.

The f-number used to describe aperture is in fact a simple fraction, and is
properly written that way. For example, f/4 means the physical size of the
aperture is one-fourth the focal length of the lens.

On 06/09/2010 17:26, Ollie Clark wrote:
I (try to) take a lot of pictures of birds but there's rarely enough
light for me to get a fast enough shutter speed. I'm trying to work
out what equipment I'd be best off getting for faster shutter speeds.
A lens with a larger aperture and/or a body with better high ISO
performance would, I guess, be the main considerations but would the
above (FF and larger front element) help as well? Not that I can afford
another lens or body at the moment.:-)

The larger font element translates into a smaller f-number. The two
things are related. Going FF definitely not going to help, because that
will require longer lens and the longer the lens, the harder/more
expensive it is to make it "fast".

Something you don't tell is why you need a better shutter speed. Is it
to compensate for your own movements when shooting perched birds or is
it to avoid blur caused by the bird moves (wings flutter, etc...)? In
the first case, if you haven't done so already, use a stabilized lens,
or a monopod, or both. In the second case, your best bet is to find a
camera body allowing more ISOs (but OS and monopod can still be useful).

You can also use a faster but shorter lens, and improve your approach
technique (a camo vest is equivalent to a doubling of your focal length) :-)

--
Bertrand

"Ollie Clark" wrote in message
...
OK, I'm the first to admit I'm just an amateur photographer but I
do have a little technical knowledge (a little knowledge is a dangerous
thing). A couple of things I just want to check my understanding:

1. With all else being equal (lens, light, aperture etc. etc.) if you
have a FF sensor instead of a cropped one could you use a faster shutter
speed for a given image because of more light falling on the sensor?

No.


2. Similarly, all else being equal, if you have a lens with a larger
front element could you use a faster shutter speed because more light
would be collected?

I am going to disagree with other posters here - the answer is probably
because it would almost certainly have a lower f number.


I (try to) take a lot of pictures of birds but there's rarely enough
light for me to get a fast enough shutter speed. I'm trying to work
out what equipment I'd be best off getting for faster shutter speeds.
A lens with a larger aperture and/or a body with better high ISO
performance would, I guess, be the main considerations but would the
above (FF and larger front element) help as well? Not that I can afford
another lens or body at the moment. :-)

I'm hoping these aren't completely stupid questions. If they are, at
least it will show the gaps in my understanding.

Cheers,

Ollie

The usual answer is to get faster glass (lower f number).

On film higher ISO number translates to lower resolution because the grain
size is greater, however on digital sensor it translates to more noise in
the picture.

If you can afford it you will get better results with a full frame sensor,
however if you don't have any equipment maybe you should look at systems
designed for smaller sensors*, where faster glass will be cheaper and
lighter.


* but NOT a 35mm camera with a smaller sensor in it.

On 2010-09-06 10:48:57 -0700, "R. Mark Clayton"
said:


"Ollie Clark" wrote in message
...
OK, I'm the first to admit I'm just an amateur photographer but I
do have a little technical knowledge (a little knowledge is a dangerous
thing). A couple of things I just want to check my understanding:

1. With all else being equal (lens, light, aperture etc. etc.) if you
have a FF sensor instead of a cropped one could you use a faster shutter
speed for a given image because of more light falling on the sensor?

No.


2. Similarly, all else being equal, if you have a lens with a larger
front element could you use a faster shutter speed because more light
would be collected?

I am going to disagree with other posters here - the answer is probably
because it would almost certainly have a lower f number.

But then all else would not be equal, eh?

--
Waddling Eagle
World Famous Flight Instructor

On 2010-09-06 08:26:47 -0700, Ollie Clark said:

OK, I'm the first to admit I'm just an amateur photographer but I
do have a little technical knowledge (a little knowledge is a dangerous
thing). A couple of things I just want to check my understanding:

1. With all else being equal (lens, light, aperture etc. etc.) if you
have a FF sensor instead of a cropped one could you use a faster shutter
speed for a given image because of more light falling on the sensor?

No. Same amount of light falling on each part of the sensor.


2. Similarly, all else being equal, if you have a lens with a larger
front element could you use a faster shutter speed because more light
would be collected?

No. If you are using the same aperture then what you have is a lens
with a bigger front element. The aperture determines how much light
gets through.


I (try to) take a lot of pictures of birds but there's rarely enough
light for me to get a fast enough shutter speed. I'm trying to work
out what equipment I'd be best off getting for faster shutter speeds.
A lens with a larger aperture and/or a body with better high ISO
performance would, I guess, be the main considerations but would the
above (FF and larger front element) help as well? Not that I can afford
another lens or body at the moment. :-)

Use flash if you do not have enough light. You can greatly increase the
range of the flash by putting a Fresnel lens in front of it. There are
kits that do that, such as the Better Beamer. Alternatively, you can
mount a flash near the bird's favorite perch and fire it remotely.
Birds, for some reason, are rarely put off by flash. They are much more
afraid of big lenses. I guess they evolved in a system where predators
had big eyes, but didn't use flash.

The biggest single thing that will improve your bird pictures is to get
closer. The closer you get, the less digital noise or film grain matter
because you don't have to crop so much. Use feeders, build a blind,
turn yourself into a tree -- whatever it takes to get closer.

--
Waddling Eagle
World Famous Flight Instructor

On Mon, 6 Sep 2010 12:42:59 -0700, C J Campbell
wrote:

On 2010-09-06 08:26:47 -0700, Ollie Clark said:

OK, I'm the first to admit I'm just an amateur photographer but I
do have a little technical knowledge (a little knowledge is a dangerous
thing). A couple of things I just want to check my understanding:

1. With all else being equal (lens, light, aperture etc. etc.) if you
have a FF sensor instead of a cropped one could you use a faster shutter
speed for a given image because of more light falling on the sensor?

No. Same amount of light falling on each part of the sensor.


2. Similarly, all else being equal, if you have a lens with a larger
front element could you use a faster shutter speed because more light
would be collected?

No. If you are using the same aperture then what you have is a lens
with a bigger front element. The aperture determines how much light
gets through.


I (try to) take a lot of pictures of birds but there's rarely enough
light for me to get a fast enough shutter speed. I'm trying to work
out what equipment I'd be best off getting for faster shutter speeds.
A lens with a larger aperture and/or a body with better high ISO
performance would, I guess, be the main considerations but would the
above (FF and larger front element) help as well? Not that I can afford
another lens or body at the moment. :-)

Use flash if you do not have enough light. You can greatly increase the
range of the flash by putting a Fresnel lens in front of it. There are
kits that do that, such as the Better Beamer. Alternatively, you can
mount a flash near the bird's favorite perch and fire it remotely.
Birds, for some reason, are rarely put off by flash. They are much more
afraid of big lenses. I guess they evolved in a system where predators
had big eyes, but didn't use flash.

Flash ruins any nature-photography subject. It also imparts unnatural
colors due to its intensity and UV light output, causing many structures
like feathers of birds and exoskeletons of insects to fluoresce in
unnatural hues. Not to mention what using flash does to the eyesight of
some bird that has its pupils dilated for hunting at dusk. There goes any
chance of it getting any meal that day. Let me put a flash in your face
after you've been in a dark room for 10 minutes and then see how long it
takes for you to get your eyesight back.

Taking photos of birds in dim light levels has more to do with skill than
any kind of equipment. Size of camera sensor doesn't even matter when you
have skill. Both of these available-light (no flash) photos taken with
1/2.5" sensor superzoom camera.

Taken deep in the Everglades swamps near sunset.
http://farm5.static.flickr.com/4133/4964883939_71fc42a8c5_z.jpg

Taken in the shade of a dense forested area.
http://farm5.static.flickr.com/4088/4964883943_6c45c771a9.jpg

(strong jpg-degradation intentional for the web)

Both print quite nicely to 17" sizes, in case you were wondering about
image-quality and noise.


The biggest single thing that will improve your bird pictures is to get
closer. The closer you get, the less digital noise or film grain matter
because you don't have to crop so much. Use feeders, build a blind,
turn yourself into a tree -- whatever it takes to get closer.

This is why you can't use any dSLR for decent bird photography, unless you
want to get only one shot per subject as the clattering mirror and shutter
scares them away.

On Mon, 06 Sep 2010 16:53:04 -0500, Superzooms Still Win
wrote:


Flash ruins any nature-photography subject. It also imparts unnatural
colors due to its intensity and UV light output, causing many structures
like feathers of birds and exoskeletons of insects to fluoresce in
unnatural hues.

Here's a good example of what high-powered flash does to the colors in
birds' feathers.

Broad-tailed Hummingbird (female, both images)

http://farm2.static.flickr.com/1307/1027755241_f0b4caf468.jpg

Compare to the same species taken using available light alone.

http://www.hocus-phocus.com/Images/CRW_6518BroadtailedHb1.jpg

You'd never find the artificially and garishly colored one taken with flash
in any birder's ID guide. People who put photos like that on their walls
also have a collection of black-velvet fluorescent Elvis paintings lit by
black-lights. The have no concept of reality left.

"Superzooms Still Win" wrote in message
...
On Mon, 6 Sep 2010 12:42:59 -0700, C J Campbell
wrote:

On 2010-09-06 08:26:47 -0700, Ollie Clark said:

OK, I'm the first to admit I'm just an amateur photographer but I
do have a little technical knowledge (a little knowledge is a dangerous
thing). A couple of things I just want to check my understanding:

1. With all else being equal (lens, light, aperture etc. etc.) if you
have a FF sensor instead of a cropped one could you use a faster shutter
speed for a given image because of more light falling on the sensor?

No. Same amount of light falling on each part of the sensor.


2. Similarly, all else being equal, if you have a lens with a larger
front element could you use a faster shutter speed because more light
would be collected?

No. If you are using the same aperture then what you have is a lens
with a bigger front element. The aperture determines how much light
gets through.


I (try to) take a lot of pictures of birds but there's rarely enough
light for me to get a fast enough shutter speed. I'm trying to work
out what equipment I'd be best off getting for faster shutter speeds.
A lens with a larger aperture and/or a body with better high ISO
performance would, I guess, be the main considerations but would the
above (FF and larger front element) help as well? Not that I can afford
another lens or body at the moment. :-)

Use flash if you do not have enough light. You can greatly increase the
range of the flash by putting a Fresnel lens in front of it. There are
kits that do that, such as the Better Beamer. Alternatively, you can
mount a flash near the bird's favorite perch and fire it remotely.
Birds, for some reason, are rarely put off by flash. They are much more
afraid of big lenses. I guess they evolved in a system where predators
had big eyes, but didn't use flash.

Flash ruins any nature-photography subject. It also imparts unnatural
colors due to its intensity and UV light output, causing many structures
like feathers of birds and exoskeletons of insects to fluoresce in
unnatural hues. Not to mention what using flash does to the eyesight of
some bird that has its pupils dilated for hunting at dusk. There goes any
chance of it getting any meal that day. Let me put a flash in your face
after you've been in a dark room for 10 minutes and then see how long it
takes for you to get your eyesight back.

Taking photos of birds in dim light levels has more to do with skill than
any kind of equipment. Size of camera sensor doesn't even matter when you
have skill. Both of these available-light (no flash) photos taken with
1/2.5" sensor superzoom camera.

Taken deep in the Everglades swamps near sunset.
http://farm5.static.flickr.com/4133/4964883939_71fc42a8c5_z.jpg

Taken in the shade of a dense forested area.
http://farm5.static.flickr.com/4088/4964883943_6c45c771a9.jpg

(strong jpg-degradation intentional for the web)

Both print quite nicely to 17" sizes, in case you were wondering about
image-quality and noise.


The biggest single thing that will improve your bird pictures is to get
closer. The closer you get, the less digital noise or film grain matter
because you don't have to crop so much. Use feeders, build a blind,
turn yourself into a tree -- whatever it takes to get closer.

This is why you can't use any dSLR for decent bird photography, unless you
want to get only one shot per subject as the clattering mirror and shutter
scares them away.



I see you have also managed to bend light so the rays appear to come at
different angles in different parts of the image. Good work.

--
Peter