Full Frame Sensors

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MHollanders
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Full Frame Sensors

Post by MHollanders »

Hi,

I was under the impression that full-frame sensors allowed for larger images as there'd be less enlarging to do with a larger sensor. However, my dad pointed out that if two cameras (say the D300 and D700) have the same resolution (12MP) then it shouldn't matter, as the smaller sensor still has the same resolution. So I dove on the internet and found out that a larger sensor supposedly has larger pixels will allow for a greater dynamic range. Can anyone add any other benefits (apart from wide-angle photography) of full frame sensors?

Thanks, Matthijs Hollanders
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Hans Breuer (twoton)
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Re: Full Frame Sensors

Post by Hans Breuer (twoton) »

Hi Matt,

here are a few articles. If you also happen to be a birder, though, do not get an FFS unless you have the moolah to invest in a yardlong telephoto lens. The crop factor in DSLRs has given joy to millions of impoverished birders all over the world.
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MHollanders
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Re: Full Frame Sensors

Post by MHollanders »

I see your point, but my 24mm is a fantastic lense which looks not-very-wide on a DX...
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Hans Breuer (twoton)
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Re: Full Frame Sensors

Post by Hans Breuer (twoton) »

That's indeed a drawback.
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Kevin Price
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Re: Full Frame Sensors

Post by Kevin Price »

Full frame sensors will allow for larger images if they are printed. A full frame sensor will allow you to print larger sizes and at higher resolutions. This is important if you print large images for display. If you don't, there's not any real improvement by going full frame. I'm generalizing here, but that one of the big reasons. Most lenses are all designed to the standard 35mm size of film. That lens used on a crop frame APS-C sized sensor will capture the centermost portion of the image, and when printed out it shows only that section. This is why people like crop frame sensors for longer tele-photo style shots, the result is the appearance of a more zoomed in image. The other side of this is that a wide angle lens and an APS-C sensor will not be as wide an angle anymore for the very same reason; the image is taken from the center of the lens. A lens designed for the smaller sensor takes this into account. My 24-70 lens does not produce images that look as good on my crop frame camera as it does on a full frame camera.

A full frame will have larger pixels, and the micro lenses that accompany them, so the resolution will be higher than on a APS-C sized sensor with the same mega-pixel count. This is the reason a camera with a much smaller sized sensor, like that found in a point and shoot, may have the same amount of pixels on the sensor but cannot print to the same sizes at the same resolutions. The more area a sensor has the more flexibility is available in which to place the pixels and how many it may have available.

I have a crop sensor camera will a 10 mega-pixel count, almost ancient by today's standards, but I routinely print 12 X 18 images with no loss of resolution. When I have printed larger I have noticed some degradation when viewed up close, but that's the key, the viewing distance of a printed image. If viewed from even a modest distance no problems can be noted.
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MHollanders
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Re: Full Frame Sensors

Post by MHollanders »

Kevin,

I see your point. Does that mean that the larger pixels are the sole reason for high resolution?
Erik Williams
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Re: Full Frame Sensors

Post by Erik Williams »

the difference is higher quality pixels. The pixels are higher quality because the sensor cells are larger and the signal can encounter less resistance on its way off the chip. Although now they are cramming more, smaller pixels into full frame sensors and the opposite becomes true. Many pixels of moderate quality are better than fewer pixels of high quality.

There are two roadblocks: make a sensor pixel too big and it is not able to record fine detail. Make a sensor pixel too small and the output loses quality because of the signal/noise ratio. Truth be told, all of the DSLRs look good and you'd be hard pressed to tell the difference between them at low ISO. High ISO is a very specialized application that is only beginning to be possible; there certainly is no ISO 6400 film on the shelf at walgreens.
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Re: Full Frame Sensors

Post by gabrielgartner »

What the above said...the key is that a full frame 12 mp sensor vs a crop sensor at 12 mp is that the full frame will have considerably less noise at high ISO. This is why the high end nikon cameras (D3 series) are desirable...they work very well in low light because you can crank the ISO with relatively low noise.

For large print reproductions without interpolation (e.g., photoshops bicubic smoother and others) the larger your sensor size, the higher the resolution. That's why medium format digital cameras produce such amazing photos at enormous sizes--they have like 50 mp sensors.

Cheers,
Gabriel.
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MHollanders
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Re: Full Frame Sensors

Post by MHollanders »

gabrielgartner wrote:What the above said...the key is that a full frame 12 mp sensor vs a crop sensor at 12 mp is that the full frame will have considerably less noise at high ISO. This is why the high end nikon cameras (D3 series) are desirable...they work very well in low light because you can crank the ISO with relatively low noise.

For large print reproductions without interpolation (e.g., photoshops bicubic smoother and others) the larger your sensor size, the higher the resolution. That's why medium format digital cameras produce such amazing photos at enormous sizes--they have like 50 mp sensors.

Cheers,
Gabriel.
I am confused about why the resolution is higher on a full frame sensor when you print. Is this because of the lower noise?
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Kevin Price
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Re: Full Frame Sensors

Post by Kevin Price »

Sorry for not getting back to you sooner.
It's not the noise; it's the size of the pixels themselves within the sensor. The larger the pixel the more light it can gather. More light allows for better image quality and a finer image. Here's a chart showing sensor sizes. The bottom row are what is commonly found on point and shoot cameras, especially the one at the bottom center and the one to the right. Look how small they are even compared to a APS-C sized crop sensor (Nikon DX, Canon).

Image

Pixels are not standardized as to their size. You can think of them as little buckets that gather light. Each one has a small micro lens over it to focus the available light towards the center of each pixel. This increases the amount of available light that would be lost due to scattering. The larger the bucket, the more available light can enter it. The smaller the bucket, the less available light can enter. Look at the full frame sensor diagram above and then look at the Nikon DX size. The DX sensor is smaller than the full frame, but with the same pixel count. The DX sensor has less room to work with using the same amount of pixels. Nothing's free, so to have the same amount of pixels on both sensors requires some type of give and take. The result is that the DX sensor has smaller pixels to fit onto it's sensor, and that reduces the light available to each pixel. At larger reproductions that will be an issue. You can start to imagine why an image printed at 12X18 taken with a smaller point and shoot camera does not look anywhere near as good as an image taken with a crop size or full frame camera, pixel count being equal.

So, when thinking about pixel size don't think about the amount of pixels available, think about the size of the sensor in relationship to the pixel count. Manufacturers are realizing that there is a point of diminishing returns that can be reached by putting too many pixels on too small of a sensor.
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MHollanders
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Re: Full Frame Sensors

Post by MHollanders »

Kevin,

Thanks for the explanation. I've read some reviews saying the Sony A900 has pretty bad high ISO results because it has so many MP.
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Owen
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Re: Full Frame Sensors

Post by Owen »

MHollanders wrote:Kevin,

Thanks for the explanation. I've read some reviews saying the Sony A900 has pretty bad high ISO results because it has so many MP.
The high ISO isn't bad in the A900, but mediocre in the default jpeg processing. People that shoot raw seem to not have issue. This has nothing to do with too many pixels. The newer Sony 16.2MP APS-C sensors have much better noise performance (also used by Nikon and Pentax) and these have a much higher pixel density: 4.4 MP/cm² pixel density vs. 2.9 for the A900. That bodes well for a 40MP FF in the future if you can put up with storing such large files.
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