Available light - higher ISO, lower resolution, better?

Started Jul 15, 2005 | Discussions
David Ing Junior Member • Posts: 41
Available light - higher ISO, lower resolution, better?

I'm an available light bigot, and decided against a DSLR for now, primarily because of size/weight considerations. I've been reading the "No flash indoor photography" thread at http://forums.dpreview.com/forums/read.asp?forum=1018&message=12991083 , and wanted to check if a different strategy might work.

I shoot primarily snapshots in JPEG that go onto a web server, so most higher resolutions are really overkill. I don't usually make prints. When I used to shoot film, I used to use ISO 400 film (actually Black's brand, probably Fuji OEM).

I understand that boosting ISO to 400 creates noise on digital sensors. To capture more light, am I better off reducing the resolution setting on my camera from 2560 x 1920 (5MP) to 2048 x 1536 (3MP) or 1600 x 1200 (2MP) at the same time as boosting ISO? My understanding of the physics is that the limited light then get distributed across a larger coverage on the sensor.

I had a Canon S30 (3MP), which I lost and replaced with a Canon S60 (5MP). The Canon S30 had an ISO 800 setting, and ISO 400 was considered usable. The Canon S60 (and now the new Panasonic FZ-5 I own) both have a ISO 400 settings, but reviews consider ISO 200 the maximum usable.

Thus, my strategy would be to shoot in daylight at 5MP with auto ISO (probably ISO 80 or 100), and then interiors at 3MP with ISO 400. With limited light, I should try to stay at the short end of zoom (f2.8 on the S60 and FZ-5), and may set the aperture at maximum, manually.

Is there something wrong with my logic? If someone could point to a web site that has tried these experiments, I would be interested in the results. Thanks.

P.S. I really did look hard at the Pentax *ist DS, since I own lenses in P-mount, but the weight of my all-glass Vivitar lens is heavier than the FZ-5, and I can put the FZ-5 in a modest fanny pack without issue!

K1000Photographer Veteran Member • Posts: 6,894
Re: Available light - higher ISO, lower resolution, better?

You do not want a DSLR, but the DS is the low light leader. I went from a megazoom to a DS. The low light photos leave the Point and shoot for dead. The DS is not just about resolution. It is about capturing the light better. shading and color differences are better captured. The differences are even noticeable on web sized photos. It is a little heavier but the Ds and kit is about FZ20 size.

wirehead Regular Member • Posts: 281
Re: Available light - higher ISO, lower resolution, better?

I understand that boosting ISO to 400 creates noise on digital
sensors. To capture more light, am I better off reducing the
resolution setting on my camera from 2560 x 1920 (5MP) to 2048 x
1536 (3MP) or 1600 x 1200 (2MP) at the same time as boosting ISO?
My understanding of the physics is that the limited light then get
distributed across a larger coverage on the sensor.

Not really.

You should continue to shoot at 5 MP, investigate a noise-reduction program, and then downsample if necessary.

You have dramatically more processing abilities in your computer than you do in a camera.... remember the camera has to be inexpensive and get everything done before you hit the shutter button again. So you could probably take advantage of the noise-reduction software that's out there and/or some photoshop editing.

Sheld Senior Member • Posts: 1,899
Re: Available light - higher ISO, lower resolution, better?

David Ing wrote:

I'm an available light bigot, and decided against a DSLR for now,
primarily because of size/weight considerations. I've been reading
the "No flash indoor photography" thread at

http://forums.dpreview.com/forums/read.asp?forum=1018&message=12991083 , and wanted to check if a different strategy might work.

I shoot primarily snapshots in JPEG that go onto a web server, so
most higher resolutions are really overkill. I don't usually make
prints. When I used to shoot film, I used to use ISO 400 film
(actually Black's brand, probably Fuji OEM).

What camera, and what lens did you use? Just curious. I have a Canon G6 that I really enjoy; and a Canon SLR with a 28-80mm lens (I forget the model number), that I don't use. I thought about getting a 50mm F1.8 lens for low light, along with ISO400/ISO800 film -- I'm not sure that it would be as usable as the Canon G6.

The G6 works better than the S60. The 5 megapixel sensor is noisy and the F2.0 vs F2.8 is another 2x delta. In comparing noise, the G5 at ISO200 (5 megapixel sensor) is nearly as noisy as the G6 (7 megapixel sensor) at ISO400 -- especially given the higher resolution of the G6. See my recent post on G6 at ISO200/400, http://forums.dpreview.com/forums/read.asp?forum=1010&message=14235783

I understand that boosting ISO to 400 creates noise on digital
sensors. To capture more light, am I better off reducing the
resolution setting on my camera from 2560 x 1920 (5MP) to 2048 x
1536 (3MP) or 1600 x 1200 (2MP) at the same time as boosting ISO?
My understanding of the physics is that the limited light then get
distributed across a larger coverage on the sensor.

Capture your photos at the highest resolution. Use noise reduction if you like, and then downsize your images afterwards. For my G6, I have chosen not to use neatimage, or other noise reduction software, but such software will work better on the original full size images, than on the downsized images. In other words, even if all you care about is the results for web viewing at 1024x768, you are still better off capturing at full resolution.

I had a Canon S30 (3MP), which I lost and replaced with a Canon S60
(5MP). The Canon S30 had an ISO 800 setting, and ISO 400 was
considered usable. The Canon S60 (and now the new Panasonic FZ-5 I
own) both have a ISO 400 settings, but reviews consider ISO 200 the
maximum usable.

IMHO, on my G6, ISO200 is usable for enlargements, and ISO400 is usable if you understand the limitations. Shoot with a tripod, non-moving subjects, or hand held with the timer, use the wide end of the camera instead of telephoto, and you'll get some winners.

Thus, my strategy would be to shoot in daylight at 5MP with auto
ISO (probably ISO 80 or 100), and then interiors at 3MP with ISO
400. With limited light, I should try to stay at the short end of
zoom (f2.8 on the S60 and FZ-5), and may set the aperture at
maximum, manually.

Is there something wrong with my logic? If someone could point to
a web site that has tried these experiments, I would be interested
in the results. Thanks.

This is a really nice ISO200 result, Canon G6. Original, 3072x2304, downsized to 1136x852, no noise reduction, no other post processing. Tell me what you think. Results like these convince me that I can use ISO200 pretty much whenever I want on the G6, but at ISO400 noise is visible in printouts -- less visible on the web.

P.S. I really did look hard at the Pentax *ist DS, since I own
lenses in P-mount, but the weight of my all-glass Vivitar lens is
heavier than the FZ-5, and I can put the FZ-5 in a modest fanny
pack without issue!

Moretoyz Regular Member • Posts: 164
Re: Available light - higher ISO, lower resolution, better?

For available light indoors stick with your Panasonic FZ5, because of the image stabilization. The image stabilization is worth 3 F stops. You would need a DSLR with an image stabilized lens to do better. MY FZ10 takes sharp indoor photos at up to 1/4 second handheld thanks to its image stabilization, for example this photo shot at 1/4 second in a museum.
http://www.pbase.com/elif/image/42207666/large

OP David Ing Junior Member • Posts: 41
Weight/size [was: Available light - higher ISO, lower resolution, better?]

Thanks, it wasn't the *ist DS that was the issue per se, but the thought of carrying around extra lenses that wasn't very appealing.

In the film world, I moved down from a Canon EF to a Pentax Super Program (which is small for the SLR world!) to a Leica AF-C1 to an Yashica T5. I'm not a serious photographer anymore, and I was taking fewer and fewer photos.

In the digital world, I agree that that DSLR would give me more flexibility, but I'm a business type who spends a lot of time on planes, and the thought of having to carry around more weight and/or luggage isn't very enticing.

I've made my choice, and am just trying to figure out how to optimize the equipment I own.

OP David Ing Junior Member • Posts: 41
Sensor doesn't gather more light? [was: Available light - higher ISO, ...]

Here's a scenario: At ISO 200, my FZ-5 is wide open at f2.8, and the shutter speed is at 1/15 or 1/8. I've been photographing some colleagues giving presentations, and just from turning their heads, the image is blurred. (Their bodies aren't blurred, but people giving presentations turn to watch the faces of people in the audience).

There's nothing on the computer that can help me with this type of blur. I could set the FZ-5 to ISO 400 -- auto mode only goes as far as ISO 200, so the ISO 400 has to be set manually.

The question is then whether there's any real benefit to shooting at 5MP over shooting at 3MP. The end photos are going to be displayed on a computer screen -- either at 1024x768 pixels, or even 800x600 pixels -- so is it better to get a slightly sharper image at less resolution than a blurry one at high resolution?

Bart Hickman Veteran Member • Posts: 7,256
Re: Available light - higher ISO, lower resolution, better?

In principle, you are correct--the noise that you would have had at 5MP would get bandwidth limited when going to 3MP. But this depends on your camera having what amounts to an intelligent anti-aliasing filter for the downsampling process. Do you know if your camera does this?

As others mentioned, you can achieve that result by filtering and downsampling after the fact on your computer--at least then you know for sure the process is being done optimally.

Another trick I pull is setting the camera at ISO400, then turning ev to -1 or -2 thus causing the camera to set shutter speed as though it was at ISO800 or ISO1600 respectively. (Seems like most compacts are around a half-stop brighter than indicated which means the effective ISO is even higher.)

After the fact, you then brighten the image back up, apply noise reduction and possibly smoothing, then do the intelligent downsampling last. With my z750, I get pretty good results with effective resolutions in the neighborhood of 1M-2Mpixels

Bart

 Bart Hickman's gear list:Bart Hickman's gear list
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OP David Ing Junior Member • Posts: 41
Not portraits [was: Available light - higher ISO, lower resolution, better?]

Nice photo. Unfortunately, my challenge is not portraits but candid shots. I'm just trying to figure out how to optimize those, without blinding people with flash. (I've now even turned off the shutter sound, so the camera is totally silent).

What camera, and what lens did you use?

I've always had something around a 50mm f/1.4 (Canon EF) or 50mm f/1.8 lens (Pentax Super Program), 35mm f/2 (Leica AF-C1, and Yashica T5). At ISO 400 with film, all of these cameras seem to beat the pants off compact digital cameras. The Canon G-series is almost the size/weight of a DSLR, so I guess that I've decided to compromise on the lens speed for a smaller camera (now the Canon S60 and Panasonic FZ-5, which is actually big compared to an S60!)

..., even if all you care about is the results for web viewing at 1024x768, you are still better off capturing at full resolution.

Hmmm .... This seems really counter-intuitive to me. If I'm capturing as JPEG, then downsampling is still lossy. In addition, I'm trying to not create more work for myself. My experience so far is that it's easier to try to set the input properly, than to do post-processing.

In the music recording industry, this reminds me of the well-known myth that an engineeer can "fix it in the mix", i.e. make a bad recording good. The experienced professionals know that bad input can't be overcome to that extent, so they work on ensuring the inputs are as good as possible, to start with.

Shoot with a tripod, non-moving subjects, or hand held with the timer, use the wide end of the camera instead of telephoto, and you'll get some winners.

You've nailed the problem. I don't want to be intrusive, and my subjects are moving. So far, the best solution has been to take multiple shots -- unlike film, it doesn't cost anything in digital! -- and hope that the speaker isn't turning his head at the moment that the shutter closes.

OP David Ing Junior Member • Posts: 41
Intelligent anti-aliasing for downsampling? [was: Available light ....]

Bart, thanks for the confirmation. You've now posed a question to which I'll have to dig for a answer:

this depends on your camera having what amounts to an intelligent anti-aliasing filter for the downsampling process. Do you know if your camera does this?

I have two cameras: a Canon S60 (down to 28mm f/2.8) and a Panasonic FZ-5 (down to 36mm f/2.8). I got the FZ-5 recently, and thought that I would use the S60 more for interior shots. The FZ-5 is more fun, however -- the zone focusing that shows up in the Electronic View Finder is reassuring that I'm aimed in the right place -- so I haven't been carrying around the S60.

If it's a case, however, that the S60 does have "intelligent anti-aliasing" when the FZ-5 doesn't, I would carry around the second camera more often. (It's still lighter than carting around an SLR with 2 lenses!)

Can you suggest where I might look this up?

rander3127 Veteran Member • Posts: 4,628
Re: Available light - higher ISO, lower resolution, better?

David Ing wrote:

I'm an available light bigot, and decided against a DSLR for now,
primarily because of size/weight considerations. I've been reading
the "No flash indoor photography" thread at

http://forums.dpreview.com/forums/read.asp?forum=1018&message=12991083 , and wanted to check if a different strategy might work.

I shoot primarily snapshots in JPEG that go onto a web server, so
most higher resolutions are really overkill. I don't usually make
prints. When I used to shoot film, I used to use ISO 400 film
(actually Black's brand, probably Fuji OEM).

I understand that boosting ISO to 400 creates noise on digital
sensors. To capture more light, am I better off reducing the
resolution setting on my camera from 2560 x 1920 (5MP) to 2048 x
1536 (3MP) or 1600 x 1200 (2MP) at the same time as boosting ISO?
My understanding of the physics is that the limited light then get
distributed across a larger coverage on the sensor.

I had a Canon S30 (3MP), which I lost and replaced with a Canon S60
(5MP). The Canon S30 had an ISO 800 setting, and ISO 400 was
considered usable. The Canon S60 (and now the new Panasonic FZ-5 I
own) both have a ISO 400 settings, but reviews consider ISO 200 the
maximum usable.

Thus, my strategy would be to shoot in daylight at 5MP with auto
ISO (probably ISO 80 or 100), and then interiors at 3MP with ISO
400. With limited light, I should try to stay at the short end of
zoom (f2.8 on the S60 and FZ-5), and may set the aperture at
maximum, manually.

Is there something wrong with my logic? If someone could point to
a web site that has tried these experiments, I would be interested
in the results. Thanks.

P.S. I really did look hard at the Pentax *ist DS, since I own
lenses in P-mount, but the weight of my all-glass Vivitar lens is
heavier than the FZ-5, and I can put the FZ-5 in a modest fanny
pack without issue!

-- hide signature --

The logic is thus; Shoot using whatever f-stop, ISO and shutter speed you have to to stop motion blur. If there is no motion, use the lowest ISO you possibly can. A DSLR with a fast prime lens (f1.4) is basically
unbeatable by any prosumer in low light. The only ones that were even

close were the Olympus C-30xx series with their f1.8 lens and the C-5050. All other prosumers that I am aware of have slower lenses.
-Rich

Roger Krueger Senior Member • Posts: 2,785
Re: Available light - higher ISO, lower resolution, better?

Moretoyz wrote:

For available light indoors stick with your Panasonic FZ5, because
of the image stabilization. The image stabilization is worth 3 F
stops.

IS is worth 0 stops if subject motion is your limiting factor

You would need a DSLR with an image stabilized lens to do
better.

No, you'd need a DSLR with a good 1600 speed (most of them) and a lens one stop faster than the P&S (a 50/1.8 would be the bargain choise).

Roger Krueger Senior Member • Posts: 2,785
Re: Available light - higher ISO, lower resolution, better?

Shooting at lower resolution does nothing for you except save card space. The camera shoots at full resolution and then downsamples. You're far better off applying noise reduction at full resolution then downsampling. The trick someone else mentioned of using minus compensation to cheat to higher ISOs works great, especially if you can shoot raw.

K1000Photographer Veteran Member • Posts: 6,894
Re: Weight/size [was: Available light - higher ISO, lower resolution, better?]

I also travel light and usually only take 1 or 2 lenses.

Bart Hickman Veteran Member • Posts: 7,256
Re: Intelligent anti-aliasing for downsampling? [was: Available light ....]

David Ing wrote:

Can you suggest where I might look this up?

No suggestions--sorry. This sort of thing isn't in any spec sheet. I can surmise that my camera must have SOME sort of downsampling filter, otherwise I'd get really bad aliasing for low resolution images--but I don't, details beyond the resolution of the image just turn grey which means they had to be filtered before the downsampling process. The digital filter that converts RAW data to JPEG in all cameras probably has a low-pass stage at the end to manage noise and other sins of the sensor. So I'm guessing they can just use this same filter stage by plugging in different coefficients to band-limit the signal according to the resolution chosen in camera.

I generally don't do this because for the virtual-ISO1600 trick I want to use a good NR program on the max resolution image prior to downsampling.

The stuff about downsampling in cameras is TOTALLY conjecture on my part.

Maybe one of the local mega-experts will chime in with some actual facts

Bart

 Bart Hickman's gear list:Bart Hickman's gear list
Sony Alpha NEX-6 Sony a6000 Sony E 55-210mm F4.5-6.3 OSS Sony E 16-50mm F3.5-5.6 PZ OSS Pentax smc FA 50mm F1.4 +10 more
Moretoyz Regular Member • Posts: 164
Re: Available light - higher ISO, lower resolution, better?

The only thing that will help you with a moving subject indoors is using a flash, which the author of this post was trying to avoid.

OP David Ing Junior Member • Posts: 41
Shoots full resolution then downsampling [was: Available light - higher ISO ...]

Roger, ...

Shooting at lower resolution does nothing for you except save card space. The camera shoots at full resolution and then downsamples. You're far better off applying noise reduction at full resolution then downsampling.

Thanks for that logic. That makes sense to me. It didn't occur to me that the way that the sensors capture light is fixed. Thus, in my 5MP cameras, I really should be shooting at full 5MP. To get a usable image while the subject is moving (i.e. turning his/her head, not running!), I'll need to boost the ISO setting to maximum (or consider applying the underexposure approach).

I had bought an in-store demo Canon S30 for my son, because it was cheap. I would now consider swapping my S60 (widest 28mm f/2.8, max ISO 400) for his S30 (widest 35mm f/2.8, max ISO 800), except that I find the 28mm invaluable in tight spaces.

Maybe I should keep trolling for a low light, wide angle camera to supplement the long zoom of the FZ-5 .... Some people have pointed out the Fuji F10 which seems to shoot down to ISO 1600. (Looking at Fujis previously, their low light capabilities were appalling). Alas, its short end is only 36mm ....

I'll just have to keep my eye out for new cameras for these special circumstances .... Somehow, it's still better for me to have multiple (cheap) cameras than a DSLR with interchangeable lenses. (Good or bad, the automatic mirror cleaning procedure on the Olympus E-300 reminded me that dust becomes an annoying factor on cameras that aren't sealed).

dkloi Senior Member • Posts: 1,952
Re: Not portraits [was: Available light - higher ISO, lower resolution, better?]

Nice photo. Unfortunately, my challenge is not portraits but
candid shots. I'm just trying to figure out how to optimize those,
without blinding people with flash. (I've now even turned off the
shutter sound, so the camera is totally silent).

Taken last night by candlelight:

Details: 7D, EI3200, 100mm/2 wide open, 1/13th second, handheld (standing, no support) with AS. Capture One 3.7 RAW to TIFF, a bit of noise reduction, downsized (from 6MP) and sharpened.

Subject motion can be a problem but sometimes works with you. Depends on the shot.

Cheers,
Daniel.

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rander3127 Veteran Member • Posts: 4,628
Re: Not portraits [was: Available light - higher ISO, lower resolution, better?]
-- hide signature --

That's a great shot. It's sharp and clear where it should be,
but the hand movement emphasises that something is going on.
Nice work!
-Rich

Moretoyz Regular Member • Posts: 164
Re: Not portraits [was: Available light - higher ISO, lower resolution, better?]

Really wonderful photo. Dramatically shows the advantage of the Minolta IS, getting a sharp photo at a low shutter speed with image blur on the hand. Great work!

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