What is Full Frame and Why? :)

locostbob

locostbob

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hey up..

prob a very silly question, have searched TP but cant see the answer..

What is full frame and the benefit over a cropped sensor?

As i understand it, FF will mean the lens focal length is as it says, the same as the 35mm equivalent, so i guess the sensor is 35mm?

Im on olympus (E1) with a crop factor of 2, so my lens are twice the focal length, so i guess my sensor is half of 35mm so 17.5mm.

As i understand it the smaller the sensor the shallower depth of field as i guess the light is distorted down onto the smaller sensor. Logical i would guess the FF distorts the light less so better image quality?

I guess the FF and croped lens are not compatible between the same manufacture?

im sort of making this up in my mind... could anybody please expand on this and why the FF is better / worse and the right application for each sensor?

cheers

bob :)
 
The sensor (Frame) is bigger (i.e. the same size as a conventional SLR) and so the quality is better
 
locostbob said:
hey up..



I guess the FF and croped lens are not compatible between the same manufacture?



bob :)
Click to expand...

ON this point, an FX lens will work on a DX sensor [albeit with an effective focal lenghth of the crop factor], however a dedicated DX lens, whilst still working on an FX body, will only give an image from a percentge of the sensor, in other words, a smaller image.

Both types have advantages, for instance, a crop sensors effective focal length is often prefered by wildlife/sports photographers where longer lens lengths are required and effective length can mean the difference between frame filling shots, an FF shots that have to be cropped anyway. On the other hand, a full frame is considered by some to be much better for portriats, weddings, etc. Generally, a full frame camera will be significantly more expensive than its cropped frame sister, but its quite normal that the image quality will be significantly better too, though of course that does depend on exactly which bodies you are comparing.
 
35mm film is so called because it is 35mm wide. The image size is actually 36x24mm. Full frame DSLRs have sensors the same as the image size on 35mm film.

Nikon DX (crop-sensor) cameras have sensor sizes roughly 1.5x smaller - near enough 24x16mm. I believe Nikon started with the DX size sensor because of the difficulty in manufacturing a silicon wafer large enough to cover the full frame back in 1999.

Obviously, manufacturing has improved since then and many manufacturers are building sensors as large or larger than the 35mm frame size. However, DX sized sensors work well enough and are cheap, so the amateur DX format looks here to stay for the forseeable future.

The principles of the full frame advantage are as follows. The D700 (FX) and D90 (DX) have the same number of pixels, but the D700 has a larger sensor. Thus, each photosite on the sensor can be made bigger on the FX camera. This means each photosite collects more light on an FX camera, meaning less noise, especially at higher ISOs.

Imagine trying to collect water from an infinite supply in a finite number of buckets. You want to collect as much water as possible over time. Clearly the larger the buckets, the more water can be collected over a fixed period of time. Hope that makes sense! :thinking:

The images from a full frame camera will have less noise, and subjectively, a more pleasing appearance.

There's no "distorting of light" going on anywhere.

Lenses are compatible within manufacturer's ranges. For instance, Nikon cameras can fit Nikon lenses from as far back as 1959. Whether they work usefully or not depends on the camera, but pictures can be taken with them.

Some Nikon lenses are DX only, meaning the image circle is not large enough for FX cameras. I presume DX lenses are cheaper to manufacture, and can be made smaller and lighter than their FX counterparts.

As for which is best... well you can buy into DX for peanuts with a used Nikon D40, D50, D70 etc. But a D700 is going to be in four figures. Most people will be starting out with DX and graduating to FX if they realise they need the subtle improvements in image quality and are willing to put up with larger, heavier equipment.

Telephoto shooters, such as birders or motorsport photographers, tend to prefer DX cameras due to the extra apparent 1.5x reach it gives their telephoto lenses.
 
locostbob said:
As i understand it, FF will mean the lens focal length is as it says, the same as the 35mm equivalent, so i guess the sensor is 35mm?

Im on olympus (E1) with a crop factor of 2, so my lens are twice the focal length, so i guess my sensor is half of 35mm so 17.5mm.
Click to expand...

The actual focal length of the lens does not change. What does change is the field of view.

So a 50mm lens on 1.5 crop factor body would give a field of view similar to a 75mm lens on a full frame body. And on your E1 it would give a field of view similar to a 100mm lens on a full frame body.


Steve.
 
locostbob said:
As i understand it the smaller the sensor the shallower depth of field as i guess the light is distorted down onto the smaller sensor. Logical i would guess the FF distorts the light less so better image quality?

I guess the FF and croped lens are not compatible between the same manufacture?

im sort of making this up in my mind... could anybody please expand on this and why the FF is better / worse and the right application for each sensor?
Click to expand...


Your DoF point is actually the opposite of what happens - on a crop sensor you actually gain DoF so a f/2.8 aperture gives you the deeper DoF equivalent to an f/4 aperture.

So crop sensor: field of view changes to a multiple of the focal length.. on a x1.6 crop and a 200mm lens you get the equivalent of a 320mm lens on a full frame or 35mm camera. Big bonus if you're into wildlife photography or motorsport.
However at the wide end it's a problem so the traditional 50mm lens is more like an 80mm and you need very wide angled lenses to get the similar walkabout abilities of the old 24/28mm wide ends (17mm x1.6 = 27mm).
As mentioned above you also lose a stop's worth of DoF.

Full frame sensors mean you've got access to a much shallower DoF so portrait photographers often prefer these. There's traditionally been less noise but these days that's less of an issue on the newer crop bodies.
 
martsharm said:
35mm film is so called because it is 35mm wide
Click to expand...

135 film. The film is 35 mm (1.4 in) wide. Each image is 36x24 mm in the most common "full-frame" format (sometimes called "double-frame" for its relationship to the "single frame" 35 mm movie format). The image size is only 24mm wide i.e. top to bottom with of film with out the sprockets where as the images is 36mm long
 
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