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APS-C versus Full Frame


Steppenwolf 3 1.2k
15 Mar 2013 8:28AM

Quote:You guys are just suckers for the marketing hype. I bought my 5DII because I like the badge. And the number II in Roman numerals [I concede the number III might be even nicer]. Can't think why anyone else would want one. Wink


Yes, it's often very easy to imagine you see a difference between two pictures that it isn't really there - the brain is very suggestible. The only way to tell for sure is to take identical pictures with both cameras (with adjustments for DOF) and then view them side by side, and it's crucial that you don't know which picture was taken be each camera. It's easy to see differences if you know which is which. Of course there are sometimes differences beteen the output of two cameras which just reflect different default settings, or slightly different processing, so you need to try to take these out of the equation too. I've done this with various camera sensor sizes and it's remarkable how little difference there is. Provided you keep the camera "in its comfort zone" (i.e. less than ISO 200 for compacts, for example) it's very difficult to tell between them.

The only differences I can see are that the bigger sensors are better at high ISO and have a shallower DOF at any given aperture.

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Paul Morgan Plus
14 16.8k 6 England
15 Mar 2013 8:33AM

Quote:The only differences I can see are that the bigger sensors are better at high ISO and have a shallower DOF at any given aperture


If using the same lenses ?

Depth of Field is greater using full frame, not shallower Smile
mikehit Plus
5 7.7k 12 United Kingdom
15 Mar 2013 9:04AM
If using the same lens, the large sensor forces you to move closer to get the same framing so DOF drops.
15 Mar 2013 9:13AM

Quote:
Depth of Field is greater using full frame, not shallower Smile


Steppenwolf did say identical pictures adjusting for depth of field.
I am satisfied Steppenwolf was, without any doubt, referring to the same viewfinder crop.
For the same viewfinder crop (angle a view) and focus distance full frame has less depth of field.
Steppenwolf 3 1.2k
15 Mar 2013 9:37AM

Quote:Depth of Field is greater using full frame, not shallower Smile
Steppenwolf did say identical pictures adjusting for depth of field.
I am satisfied Steppenwolf was, without any doubt, referring to the same viewfinder crop.
For the same viewfinder crop (angle a view) and focus distance full frame has less depth of field.



Exactly.

I was referring to taking the same photo - so that means taking the photo from the same distance, or the perspective will be different. The bigger frame camera will need a proportionately longer focal length lens to get the same AOV also. Then you need to select a smaller aperture on the larger sensor camera or it's really obvious which camera is which by the DOF.
ChrisV 8 1.1k 26 United Kingdom
15 Mar 2013 10:24AM
In practical terms it is distance from subject which gives equivalence in composition, so for all intents and purposes a 45mm lens on M4/3 = 90mm on 36x24 sensor. I mention that because if you took a 90mm lens on a m4/3 camera into the studio, you'd either have a huge studio, be photographing small details or be shooting through the window, from over the road. If you photograph close up subjects with telephoto lenses, DoF will naturally decrease. You can get tight DoF on superzoom cameras at the tele end, but you do of course need bags of space, bags of light/a tripod to achieve that.

As we all know, with technological advances sensitivity increases [even if arguably the pace of development has slowed on that front after the tremendous gains of a few years ago] as does dynamic range. It's in the way of things that today's M4/3 cameras will match or exceed the designs of larger formats from five years ago in these respects. But given similar technological approaches, there is always going to be an advantage in larger formats of the same generation. Simply put if the sensor/processor combination is of equivalent efficiency, that's going to result in greater sensitivity and increased dynamic range.

This of course is just in the same way that the m4/3 format offers the same advantage over smaller formats still. Pretty much a Janet and John statement of photographic technology - it's fairly mystifying to me that anyone should see this as at all contentious.

But going back to practical usages, in normal day to day use for an ordinary photo journalist [for example] it's far easier to get better subject isolation with a larger sensor camera. That doesn't look all that likely to change in the forseeable future and is a feature of the 35mm sensor which is [IMO] not given the weight it truly merits. Well isolated subjects are a tremendous aid to picture composition, just as cluttered backgrounds are the thumbprint of an amateur snapper.

Conversely, in some situations - particularly in poor light - there is real advantage to having greater effective DoF at smaller apertures, especially if you can't introduce any artificial light. That means at a gig for example, stood in the same spot, one may be able to shoot with m4/3 at f1.7 and ISO 800 rather than f4 and consequently ISO3200 if using 35mm format.

It's swings and roundabouts - I think it's better to have your eyes open about these characteristics and make a proper assessment about how these would suit your own way of working than just having a knee-jerk one format is better or worse than another.

I like both and for the time being am enjoying the luxury of using both.

As if photography wasn't an expensive enough pastime with just one camera and set of lenses...
Paul Morgan Plus
14 16.8k 6 England
15 Mar 2013 7:46PM
People concern themselves far too much over Dof, when I choose a lens my primary interest is in its reach.
ChrisV 8 1.1k 26 United Kingdom
15 Mar 2013 10:21PM
Yeah, I've noticed you're not that worried about subject isolation.
Paul Morgan Plus
14 16.8k 6 England
15 Mar 2013 10:29PM
Its not very clever isolating subjects just for the sake of it.
Sooty_1 5 1.4k 213 United Kingdom
15 Mar 2013 11:07PM
All subject isolation shows (very often) is that the photographer owns a wide aperture lens, or knows how to manipulate the depth of field. Only occasionally does it really have impact in the digital world, other than the fact that it is almost invariably the worst-performing part of the lens' aperture range.

I was under the impression that the depth of field effect between FX and DX was only there because of the way we view the different images.

If you take 2 photos from the same spot with a FX and DX cameras using the same lens, and enlarge the images the same amount, the apparent depth of field should be the same. All the DX image is, is the same as the centre of the FX one.
I don't mean the physical dimensions of the photo, but the elements within it - ie if you shoot a building, it is the same size in both, though the FX image will have a wider angle of view and be a physically bigger picture due to the larger sensor. The change of depth calculation occurs when you enlarge the images different amounts to make the pictures the same physical size, or change lenses to achieve the same angle of view on different formats.

Besides all this, one factor in the depth of field calculation is the size of the circle of confusion, which is an arbitrarily decided figure anyway. Pixel peeping is becoming too common - we shouldn't look at different sized prints from the same distance and expect to see the same thing, nor should we be looking at prints close up and splitting hairs. Get out and shoot pictures in the real world.

Nick
Carabosse Plus
12 39.7k 269 England
16 Mar 2013 12:33AM
It's not rocket science to get subject isolation. This was done on M4/3 using a lens with the modest max aperture of f3.5. All a big deal over nothing much! Wink

si.jpg

Paul Morgan Plus
14 16.8k 6 England
16 Mar 2013 12:48AM
And shallow DOF using a compact Smile






Quote:But going back to practical usages, in normal day to day use for an ordinary photo journalist [for example] it's far easier to get better subject isolation with a larger sensor camera


Chris Journalist tend to like to include at least a little of a subjects environment when shooting, your never stop do you Smile
GlennH 10 1.9k 1 France
16 Mar 2013 7:35AM
Surely it's better just to pick up the best camera for the job, rather than try to champion a particular format or another to the death like it was some kind of jousting contest. To 'isolate' a subject with a compact you normally have to get so close to it [invariably in 'wide-angle' mode] that the subject is distorted.
Paul Morgan Plus
14 16.8k 6 England
16 Mar 2013 8:00AM
The best camera for the Job is the one you have in your hand Smile
Steppenwolf 3 1.2k
16 Mar 2013 8:29AM

Quote:
If you take 2 photos from the same spot with a FX and DX cameras using the same lens, and enlarge the images the same amount, the apparent depth of field should be the same. All the DX image is, is the same as the centre of the FX one.
I don't mean the physical dimensions of the photo, but the elements within it - ie if you shoot a building, it is the same size in both, though the FX image will have a wider angle of view and be a physically bigger picture due to the larger sensor. The change of depth calculation occurs when you enlarge the images different amounts to make the pictures the same physical size, or change lenses to achieve the same angle of view on different formats.

Nick



If you use the same lens on each camera then the only way that you can get the same AOV from the larger sensor camera is to crop the photo - at which point you're effectively using a crop sensor camera so it's pretty obvious that the DOF will be the same.

However, that's not the way you normally use a camera. You tend to choose the lens focal length to frame the shot as you require (as far as possible), so the FF camera will need a lens with a 50% (roughly) longer lens than the DX. Longer focal length lenses have a shallower DOF. FF cameras are better at isolating the subject - which can be an advantage or not. To get the smaller sensor camera to achieve the same DOF you'd need a larger aperture and large aperture lenses can be expensive.

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