Low light focus on Digital Cameras

[turbodog]

OK, I've done the search thing.

I find complaints about low light focusing are widespread, not limited to 1 or 2 brands. My Fuji 3800 has exhausted my patience. In my living room, with every lamp/overhead light on, the thing will not focus. I do the 'find something it WILL focus on, the APPROXIMATE distance away' and I find (only after the prints are made and the 'kodak moment' is long gone) that the focus is indeed 'approximate'!

I've now tried a 10 candella green LED, a 2AA maglight and a laser pointer as external AF assist lights. None solve the problem more than 50% of the time.

What do I mean by 50% of the time? My benchmark for a '100% solution' would be my 3 AF point and shoot 35mm cameras. I have a $120 Samsung, a $300 waterproof Pentax, and a $400 Canon (all prices at time of purchase, over a 7 year period). ALL of these focus acceptably fast, and completely accurately in the same conditions which befuddle the Fuji.

I have learned (thanx to this forum) that most of the digicams use a contrast optimization on a readout from the CCD to focus (sometimes just final focus). Obviously, the 35mm cameras used some other method, not having a CCD.

Are there any digicams out there (under, say, $500) that use the tried-and-true AF technology from the 35mm AF cameras?

I estimate that we are disappointed in 20% of all the shots we get printed with the Fuji (yes that excludes the ones so gross we can tell in the LCD and have a chance to re-shoot). Yes, we are fairly demanding.... but aren't y'all (Texas thing) too?

Interested in specific camera suggestions (again, with 35mm AF technology) or in general discussion. I'm not particularly interested in 'my 3800 focuses just fine' stories. Sorry, either our cameras have significant manufacturing variance, or our standards are not the same. I'm ready to make a switch, but hear low-light AF horror stories from all brands.

Thanks for listening!

 

[chiks]

get the Sony 717 or 828

EOS.

OK, I've done the search thing.

I find complaints about low light focusing are widespread, not
limited to 1 or 2 brands. My Fuji 3800 has exhausted my patience.
In my living room, with every lamp/overhead light on, the thing
will not focus. I do the 'find something it WILL focus on, the
APPROXIMATE distance away' and I find (only after the prints are
made and the 'kodak moment' is long gone) that the focus is indeed
'approximate'!

I've now tried a 10 candella green LED, a 2AA maglight and a laser
pointer as external AF assist lights. None solve the problem more
than 50% of the time.

What do I mean by 50% of the time? My benchmark for a '100%
solution' would be my 3 AF point and shoot 35mm cameras. I have a
$120 Samsung, a $300 waterproof Pentax, and a $400 Canon (all
prices at time of purchase, over a 7 year period). ALL of these
focus acceptably fast, and completely accurately in the same
conditions which befuddle the Fuji.

I have learned (thanx to this forum) that most of the digicams use
a contrast optimization on a readout from the CCD to focus
(sometimes just final focus). Obviously, the 35mm cameras used
some other method, not having a CCD.

Are there any digicams out there (under, say, $500) that use the
tried-and-true AF technology from the 35mm AF cameras?

I estimate that we are disappointed in 20% of all the shots we get
printed with the Fuji (yes that excludes the ones so gross we can
tell in the LCD and have a chance to re-shoot). Yes, we are fairly
demanding.... but aren't y'all (Texas thing) too?

Interested in specific camera suggestions (again, with 35mm AF
technology) or in general discussion. I'm not particularly
interested in 'my 3800 focuses just fine' stories. Sorry, either
our cameras have significant manufacturing variance, or our
standards are not the same. I'm ready to make a switch, but hear
low-light AF horror stories from all brands.

Thanks for listening!

 

[turbodog]

So, no digicam under $500 can match the low light focus ability of a $120 35mm camera.... amazing!

get the Sony 717 or 828

EOS.

 

[stuartd]

I'd suggest the Sony V1 or F717.

Compact digital camera's, and by that I mean all digital camera's other than D-LR's, have very small CCD's. This means there is only a small area gfor light to be captured on, and as sensor resolution increases the sensors on this CCD become smaller, thus affecting low light performance again, and commony resulting in additional noise compared to lower resolution sensors.

In addition the aperture of the lens affects the amount of light entering the camera, and so can limit the amount that can hit the tiny ccd, that's why in low light it is far better to take pictures at wide angle rather than telephoto, as lenses allow far more light in at their wide angle setting.

Many digital camera's have a focus assist beam to helpwith low light focussing, I know that the Canon G2 does, and think the Canon G5 has that as well. I've read reviews saying that the Minolta A1 has an excellent low light AF ability.

The Sony V1/F717/F828 can focus in complete darkness through the use of its hologram AF system that projects a laser matrix to enable auto focussing. They also provide a 'green tinted' nightshot feature similar to that in many camcorders.

I had a Konica 510z and returned it due to appalling low light performance, I got a Sony F717 and the difference is amazing. Yes, I know that they are very different camera's, but the 717 satisfies my needs for now.

OK, I've done the search thing.

I find complaints about low light focusing are widespread, not
limited to 1 or 2 brands. My Fuji 3800 has exhausted my patience.
In my living room, with every lamp/overhead light on, the thing
will not focus. I do the 'find something it WILL focus on, the
APPROXIMATE distance away' and I find (only after the prints are
made and the 'kodak moment' is long gone) that the focus is indeed
'approximate'!

I've now tried a 10 candella green LED, a 2AA maglight and a laser
pointer as external AF assist lights. None solve the problem more
than 50% of the time.

What do I mean by 50% of the time? My benchmark for a '100%
solution' would be my 3 AF point and shoot 35mm cameras. I have a
$120 Samsung, a $300 waterproof Pentax, and a $400 Canon (all
prices at time of purchase, over a 7 year period). ALL of these
focus acceptably fast, and completely accurately in the same
conditions which befuddle the Fuji.

I have learned (thanx to this forum) that most of the digicams use
a contrast optimization on a readout from the CCD to focus
(sometimes just final focus). Obviously, the 35mm cameras used
some other method, not having a CCD.

Are there any digicams out there (under, say, $500) that use the
tried-and-true AF technology from the 35mm AF cameras?

I estimate that we are disappointed in 20% of all the shots we get
printed with the Fuji (yes that excludes the ones so gross we can
tell in the LCD and have a chance to re-shoot). Yes, we are fairly
demanding.... but aren't y'all (Texas thing) too?

Interested in specific camera suggestions (again, with 35mm AF
technology) or in general discussion. I'm not particularly
interested in 'my 3800 focuses just fine' stories. Sorry, either
our cameras have significant manufacturing variance, or our
standards are not the same. I'm ready to make a switch, but hear
low-light AF horror stories from all brands.

Thanks for listening!

--
See my gallery at http://www.pbase.com/stuartd

 

[turbodog]

Thanks for the input. I played with a V1 in the store yesterday, saw the laser assist. They even had an open box special under my $500 target price. It was just too bright in there to determine how much the laser assist really helps. Heck, even the Fuji focused fine in store lighting. Nice to hear a first-hand report.

I am aware of the difference in image area on film vs a CCD, and the effects of lens aperture on light capture. From 1996 to 1998 I reverse-engineered digital cameras for a living. I guess I should have torn down some 35mm AF cameras to better understand their AF systems, so I would better understand why they can not be employed in a digital camera. I guess I still have the sneaking suspicion that they CAN, and we, the consumer, are suffering low light focus problems because the camera makers don't want to spend an extra $20 to give us an AF system seperate from the CCD.

Compact digital camera's, and by that I mean all digital camera's
other than D-LR's, have very small CCD's. This means there is only
a small area gfor light to be captured on, and as sensor resolution
increases the sensors on this CCD become smaller, thus affecting
low light performance again, and commony resulting in additional
noise compared to lower resolution sensors.

In addition the aperture of the lens affects the amount of light
entering the camera, and so can limit the amount that can hit the
tiny ccd, that's why in low light it is far better to take pictures
at wide angle rather than telephoto, as lenses allow far more light
in at their wide angle setting.

Many digital camera's have a focus assist beam to helpwith low
light focussing, I know that the Canon G2 does, and think the Canon
G5 has that as well. I've read reviews saying that the Minolta A1
has an excellent low light AF ability.

The Sony V1/F717/F828 can focus in complete darkness through the
use of its hologram AF system that projects a laser matrix to
enable auto focussing. They also provide a 'green tinted' nightshot
feature similar to that in many camcorders.

I had a Konica 510z and returned it due to appalling low light
performance, I got a Sony F717 and the difference is amazing. Yes,
I know that they are very different camera's, but the 717 satisfies
my needs for now.

OK, I've done the search thing.

I find complaints about low light focusing are widespread, not
limited to 1 or 2 brands. My Fuji 3800 has exhausted my patience.
In my living room, with every lamp/overhead light on, the thing
will not focus. I do the 'find something it WILL focus on, the
APPROXIMATE distance away' and I find (only after the prints are
made and the 'kodak moment' is long gone) that the focus is indeed
'approximate'!

I've now tried a 10 candella green LED, a 2AA maglight and a laser
pointer as external AF assist lights. None solve the problem more
than 50% of the time.

What do I mean by 50% of the time? My benchmark for a '100%
solution' would be my 3 AF point and shoot 35mm cameras. I have a
$120 Samsung, a $300 waterproof Pentax, and a $400 Canon (all
prices at time of purchase, over a 7 year period). ALL of these
focus acceptably fast, and completely accurately in the same
conditions which befuddle the Fuji.

I have learned (thanx to this forum) that most of the digicams use
a contrast optimization on a readout from the CCD to focus
(sometimes just final focus). Obviously, the 35mm cameras used
some other method, not having a CCD.

Are there any digicams out there (under, say, $500) that use the
tried-and-true AF technology from the 35mm AF cameras?

I estimate that we are disappointed in 20% of all the shots we get
printed with the Fuji (yes that excludes the ones so gross we can
tell in the LCD and have a chance to re-shoot). Yes, we are fairly
demanding.... but aren't y'all (Texas thing) too?

Interested in specific camera suggestions (again, with 35mm AF
technology) or in general discussion. I'm not particularly
interested in 'my 3800 focuses just fine' stories. Sorry, either
our cameras have significant manufacturing variance, or our
standards are not the same. I'm ready to make a switch, but hear
low-light AF horror stories from all brands.

Thanks for listening!

--
See my gallery at http://www.pbase.com/stuartd

 

[Sandy]

turbodog

I guess I should
have torn down some 35mm AF cameras to better understand their AF
systems, so I would better understand why they can not be employed
in a digital camera. I guess I still have the sneaking suspicion
that they CAN, and we, the consumer, are suffering low light focus
problems because the camera makers don't want to spend an extra $20
to give us an AF system seperate from the CCD.

Film cameras use Phase detection see:

http://www.sciam.com/article.cfm?colID=9&articleID=000E3DD0-F20E-1C73-9B81809EC588EF21

I am told the focal length of digital cameras means this sytem cannot be used until you get to the DSLR size - and even then only a couple use currently it I believe.

Companies are working on solutions eg AF assist (although the range can be limited) and other tricks as on the Minolta G400. My KD510 (same as G500) isn't too bad in low light - there seems to have been a lot of camera to camera variation in that model but perhaps I know not to expect too much and to be prepared to use manual focus.
--
Sandy

 

[Chris Birkett]

Film cameras use Phase detection see:

http://www.sciam.com/article.cfm?colID=9&articleID=000E3DD0-F20E-1C73-9B81809EC588EF21
Sandy

Actually, his three cameras probably just use a simple infrared rangefinder, like most point and shoot film cameras.

• Chris

 

[chiks]

AFAIK,

Even Digital Cameras use the same Phase detection (contrast) method.
And why not?
Even Film SLRs use CCD's for the AF function.
In case of the DigiCam, the CCD is already there to begin with.

I guess I should
have torn down some 35mm AF cameras to better understand their AF
systems, so I would better understand why they can not be employed
in a digital camera. I guess I still have the sneaking suspicion
that they CAN, and we, the consumer, are suffering low light focus
problems because the camera makers don't want to spend an extra $20
to give us an AF system seperate from the CCD.

Film cameras use Phase detection see:

http://www.sciam.com/article.cfm?colID=9&articleID=000E3DD0-F20E-1C73-9B81809EC588EF21

I am told the focal length of digital cameras means this sytem
cannot be used until you get to the DSLR size - and even then only
a couple use currently it I believe.

Companies are working on solutions eg AF assist (although the range
can be limited) and other tricks as on the Minolta G400. My KD510
(same as G500) isn't too bad in low light - there seems to have
been a lot of camera to camera variation in that model but perhaps
I know not to expect too much and to be prepared to use manual
focus.
--
Sandy

 

[turbodog]

Looking at the Canon and Pentax, I believe you are correct. Both have obvious IR windows, larger than needed for a remote sensor. Wife had the Samsung with her, so didn't check.

So, is there any reason a digital cannot have this focus system?

Assuming the Samsung does, and it retails at $120, the product cost (parts and labor to build) can't be over $50, so the AF portion can't cost Samsung more than about $10 implement. Seems to work pretty well....

Actually, his three cameras probably just use a simple infrared
rangefinder, like most point and shoot film cameras.

• Chris

 

[turbodog]

Even Digital Cameras use the same Phase detection (contrast) method.
And why not?

Well, my observation is that it doesn't work all that well in low light, at least in comparison to my 35mm AF point&shoot cameras, which appear to use an IR system.

 

[AO]

Actually, his three cameras probably just use a simple infrared
rangefinder, like most point and shoot film cameras.

Looking at the Canon and Pentax, I believe you are correct. Both
have obvious IR windows, larger than needed for a remote sensor.
Wife had the Samsung with her, so didn't check.

So, is there any reason a digital cannot have this focus system?
Assuming the Samsung does, and it retails at $120, the product cost
(parts and labor to build) can't be over $50, so the AF portion
can't cost Samsung more than about $10 implement. Seems to work
pretty well....

My guess is that the P&S cameras just close the aperture and focus on infinity for everything beyond the several meters that the IR is effective for (was that English???).

http://www.olympusamerica.com/cpg_section/cpg_product.asp?p=11&bc=4&product=923&fl=4

--
Maintainer of the unofficial FZ1 FAQ.
Tentative location:

 

[AO]

Even Digital Cameras use the same Phase detection (contrast) method.
And why not?

Well, my observation is that it doesn't work all that well in low
light, at least in comparison to my 35mm AF point&shoot cameras,
which appear to use an IR system.

Active autofocus vs. passive autofocus.
Speed vs. range.

--
Maintainer of the unofficial FZ1 FAQ.
Tentative location:

 

[Ghislain Carrier]

I know that phase detection and contrast detection (not the same thing) don't care if you shoot through a window but Active systems like IR will focus on the window instead of the subject.

Follow this link to learn about active and passive (contrast) methods.
http://www.howstuffworks.com/autofocus.htm

This link explains the phase detection method.
http://www.sciam.com/article.cfm?articleID=000E3DD0-F20E-1C73-9B81809EC588EF21

Even Digital Cameras use the same Phase detection (contrast) method.
And why not?

Well, my observation is that it doesn't work all that well in low
light, at least in comparison to my 35mm AF point&shoot cameras,
which appear to use an IR system.

Active autofocus vs. passive autofocus.
Speed vs. range.

--
Maintainer of the unofficial FZ1 FAQ.
Tentative location:

--

Ghislain

 

[GordonBGood]

AFAIK,

Even Digital Cameras use the same Phase detection (contrast) method.
And why not?
Even Film SLRs use CCD's for the AF function.
In case of the DigiCam, the CCD is already there to begin with.

Not all digital cameras use Phase detection, even though they all have digital (CCD/CMOS) sensors, as they don't all have the phase splitter prism and two separate sensor arrays (compact film/digital cameras don't have room). That leaves them with only contrast detection in the case of digicams or Active IR systems in the case of compact film and some auxiliary systems on new designs of digicams.

Regards, GordonBGood

 

[Sandy]

AFAIK,

Even Digital Cameras use the > same Phase detection (contrast) method.

Chiks

As stated by others, Phase detection and Contrast detection are two distinct methods of focus. Only a couple of digital cameras (DSLR's) use the better and faster Phase detection. I can't say how many cameras use infrared alone but it has a limited range. The short focal length and resultant large depth of focus of digital cameras means they are more forgiving than film cameras. So, if the subject is beyond a few metres, focusing on infinity won't be too far out (as suggested by another poster).

Sandy

Not all digital cameras use Phase detection, even though they all
have digital (CCD/CMOS) sensors, as they don't all have the phase
splitter prism and two separate sensor arrays (compact film/digital
cameras don't have room). That leaves them with only contrast
detection in the case of digicams or Active IR systems in the case
of compact film and some auxiliary systems on new designs of
digicams.

Regards, GordonBGood

--
Sandy

 

[turbodog]

Sandy wrote:
.

The short focal length and resultant large depth of focus of
digital cameras means they are more forgiving than film cameras.
So, if the subject is beyond a few metres, focusing on infinity
won't be too far out (as suggested by another poster).

This is good. One of my (unsuccessful) tactics was to use the (limited) manual control capability to force the aperture wide, hoping for better light capture. This did not help the camera focus. However, when using the "focus on something approximately the same distace away" technique, I want to be forcing the aperture to it's smallest setting to improve depth-of-field. I should have realized that. Thanks!