Potential dead horse: how bad is FF's deep DoF disadvantage?

Started Mar 5, 2014 | Discussions thread
Great Bustard Forum Pro • Posts: 42,280
Re: no disadvantage

bobbarber wrote:

Keep it apples to apples. I never said anything about a wide angle lens. But a 36 MP FF would be able to generate a print with the same resolution as your point and shoot with a 135mm lens cropped.

I'm not sure about this. If you read the review of the D800 on this site, they are cautious about promising extra resolution. You have to use the best lenses, best tripods, etc. to get the most out of the camera.

That's true of *any* camera.

And if you want to get the same pixel density as my SX230HS on one of those cameras, you would need a lot more than 36 Mp and you would need consequently better lenses.

The greater pixel density would give greater resolution regardless of the lens.

Let's start with stabilization. Let's say that on an 8 Mp FF camera, the shutter shakes the camera, even on a tripod, the width of a pixel. Since it's only the width of a pixel, the image is perfectly sharp. But that same shutter shake is 2 pixels wide on a 32 Mp camera. Your image is now no sharper than the 8 Mp camera.

It will still resolve better.  Not twice the resolution, but more resolution.  The more you shake the camera, the greater the motion in the scene, or if you stop way down (diffraction), the less the resolution advantage.

So to do ridiculous crops, you have to have ridiculous image stabilization, and that's a huge disadvantage compared to smaller formats. You don't get what I'm assuming you think 36 Mp of sharpness should be by swinging a 135mm lens around in the air after a bird.

Let's say we had a FF sensor made with the exact same pixels as a much smaller sensor.  If we took a photo with the same focal length, f-ratio, and shutter speed, and cropped the FF photo to the same framing as the photo from the smaller sensor, the photos would be all but identical so long as the FF lens were as sharp as the lens used on the smaller sensor over the area of the crop.

On the other hand, if the FF camera used a longer lens to get the same framing without cropping, then it would have significantly more resolution, although this resolution advantage could be eaten away by camera shake, motion blur, and/or diffraction softening.

Now what about lenses? You need the "best" lenses, according to dpreview, to take advantage of 36 Mp.

You need the "best" lenses to take advantage of *any* pixel count.  But you will get more resolution with 36 MP than with a lower pixel count, regardless of the lens.

Let's say you want a long lens, 600mm. Why don't you price the best FF long lenses, via Google? Here's a hint: they're in the $10,000 range.

The reason they are so large and expensive is because of their huge apertures.  For example, the aperture diameter for a 600 / 4 is 600mm / 4 = 150mm.  The aperture diameter for the Panasonic FZ200 at full zoom (600mm EFL) is 108mm / 2.8 = 39mm.  Big difference.

(Actually, even crappy 600mm lenses are really expensive on FF. Only the junk ones are affordable.) However, even those $10,000 lenses would not be adequate for a 50 Mp, or 100 Mp sensor, which you would need to match the zoom capabilities of smaller sensors.

Again, you will get more resolution out of 50MP, and more still out of 100 MP, for *any* lens.

I'm not denying that you can crop somewhat from a good FF sensor, but you can't achieve anything remotely like the zoom capabilities of a smaller sensor.

But you could if the FF sensor were made from the same pixels and the FF lens were as sharp over the area you'd be cropping to.

As things stand now, small sensor formats have done a better, more affordable job of solving their inherent disadvantage, i.e., wide-angle shooting, then large sensor formats have done solving their inherent disadvantage, i.e., affordable, sharp long lenses. I can get a premium, razor sharp 7mm (14mm FF equivalent) wide lens for around $1,000 on m43. Many FX shooters keep a DX body just for zoom work. They know that cropping FX is not a solution.

The Panasonic FZ200, for example, has a 4.5 - 108 / 2.8 lens, which is impressive.  Making such a lens for the FF image circle would be quite a challenge.  On the other hand, the lens is equivalent to a 25-600 / 16 on FF.  This lens would be quite doable, methinks.  The thing is, why make such a lens for FF when the lens itself would be larger, heavier, and more expensive than the FZ200?

No format is perfect. I've said in pretty much every post here that FF wins on dynamic range and noise. It's no contest, really. FF photos are smooth and beautiful. But other formats have advantages too. Zoom range goes to the smaller formats. If you don't see it, I'm not sure you're being honest, unless you can do better than the "crop" myth, which falls apart under examination, not even to speak of real world experience.

There are definite strengths and weaknesses to every format, but most don't understand the nature of those strengths and weaknesses.

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