[Marc Sabatella]

No. See equivalency.

Actually, depending on exactly what you're comparing, Equivalence can go either way. Quoting from Joseph James' site:

For the same perspective, framing, f-ratio, and display size, larger sensor systems will yield a more shallow DOF than smaller sensors in proportion to the ratio of the sensor sizes.

For the same perspective, framing, aperture diameter, and display size, all systems have the same DOF.

If both formats use the same focal length and f-ratio (and thus also the same aperture diameter), but the larger sensor system gets closer so that the subject occupies the same area of the frame, and the images are displayed at the same dimensions, then the larger sensor system will have a more shallow DOF in proportion to ratio of the sensor sizes.

For the same perspective and focal length, larger sensor systems will have a wider framing. If the same f-ratio is used, then both systems will also have the same aperture diameter. As a result, if the image from the larger sensor system is displayed at a larger size in proportion to ratio of the sensor sizes, or the image from the larger sensor system is cropped to the same framing as the image from the smaller sensor system and displayed at the same size, then the two images will have the same DOF.

The bottom line being that if you choose the right - "equivalent" - aperture, DOF is the same for the same perspective. But that means matching the physical aperture diameter as opposed to f-stops. For instance, using 200/4 on FF and 135/2.8 on APS-C.

[clockwork247]

This is from what I know about DOF.

1) DOF is influence by a few factor.
a) aperture (everyone know this one)
b) Focal length (longer lens = shallower DOF provide that you keep the same distance to subject)
c) Distance to subject (nearer = shallower DOF)
d) Sensor size, yes it does matter, look at the P&S, their sensor size is tiny, even if the lens is an f/1.8 you can barely produce a shallow DOF (aka bigger sensor = shallower DOF).

2) As of current, the best crop sensor from the k-5/D7000/A580/D5100 does not match the FF sensor of the canon 5D2 or the A900 or the nikon 3Ds, it's really close but not quite there yet, however everything else the newest line of crop sensor cameras tend to be better since it's got newer tech (burst rate, ect...).

Is there a benefit to FF? hell yeah, unlike what they say about men's ding dong, larger sensor is always better. Pentax has it's market with the crop sensor, hopefully they'll produce a FF to fill the line up. For most shots you don't need a FF. So far I've found that the only situation I would want a FF over my crop sensor camera is when I'm at a stage performance and i have absolutely no control over the lightning, all i've got control over is the lens, the sensor, the shutter, and the ISO, with a larger sensor it would help me keep the noise down a little better. Other wise in most situation providing the right lightning equipment, everything should turn out real close between a FF and a crop sensor.

[stevebrot]

Oh no! Not another DOF/FFvsAPC thread!

It was bound to happen. Just when we thought that everyone on the forum had been adequately educated on the basics of what bigger vs. smaller means, there comes a new crop of people who need some teaching. Perhaps we need a sticky to summarize the obvious and the not so obvious pertinent points:

• bigger = more information per frame without noise penalty
• bigger = less DOF per a given final image size
• bigger = generally larger, nicer viewfinders
• bigger = generally larger, heavier cameras
• bigger = generally larger, heavier lenses
• bigger = better performance from less sophisticated optics (tolerances are much tighter for a smaller format)
• bigger = much larger file size = much more storage space needed
• bigger = $$$$$

There will be lots of discussion, particularly about the second point. To those that doubt, I would suggest that they spend some time with a bit larger format to find out what real limited DOF means. There is a reason why medium format lenses with maximum apertures over f/3.5 (f/5.6 for large format) are relative rare. The matter of "negatives" brings up the larger issue of the initial assertion. With the exception of a few head-in-the-sand idiots, I don't believe that there is a general lack of appreciation for larger formats on this forum. I wonder if it had occurred to the OP that many of us who shoot APS-C digital also shoot with 35mm and larger film and get our larger format experience and quality through a route other than digital.


Steve

(Likes his K10D, also likes his film cameras up to and including a 4x5 field camera. Likes the idea of FF digital, but would prefer a lighter and more compact body than current offerings from Nikon, Canon, or Sony.)

[labnut]

That's because the APS-C format is ubiquitous, adequate and affordable. It's given us a useful, practical tool so that we can get on with the business of taking good photos. And that is precisely the point, right now we can get very good photos from the format. Because the lion's share of development effort has gone into the APS-C format.

In time the FF format will become ubiquitous and affordable and we will happily embrace the improvements that it brings.

Given your alias of 'Emacs' I presume you publish your photos under the GPL (v 3.0) and not the the Creative Commons licence. (I also admire Richard Stallman)

[Jasvox]

Admitting a superiority for FF doesn't mean Pentax is going to create one. Pentax can barely keep the market share by releasing decent APS-C bodies. Developing and releasing a FF isn't going to steal away customers from Nikon and Canon and only maybe 1 in 8 Pentax owners would invest in a FF system anyway. Where is the business justification in Pentax releasing a FF model and supported lenses? The trend seems to be smaller = better these days, hence the buzz over the small, mirrorless bodies...Besides, there are already FF bodies out there if you simply must own one.

Jason

[Ash]

That's defeatist Jason. And what makes you think Pentax won't get into the FF game? It's irrelevant that the FF market is already led by the C&Ns around now, and now Sony has 'beaten' Pentax to it.

[Emacs]

It's because about the only advantage that 135 format has over APS=C at the moment in the size of the viewfinder (which is no small thing).

LOL
So, show me the APS-C proper equivalent of 77Ltd mounted on full frame — the A50 f1.2 is quite good, but its color rendering much worse than one of Ltd, and it's too soft when wide open
the APS-C equivalent of 31Ltd mounted on full frame: just no match.

BTW, the FF clear advantage is sum of two aspects:

1. Larger sensor means lesser effective focal length, so they uses the lens with larger physical focal length (larger magnification). Larger magnification means more details for the optical system (λ times greater magnification ≈ λ times more details, when the lens is properly done and focusing on short distances)
2. Two spots should be reflected into two different sensor pixels in order to be resolved. But the images of these two spots are placed λ times closely on APS-C sensor than on FF one (λ — crop factor) for the given FOV. So, they need λ² times more megapixels to reach the same sensor capability on APS-C.

The conclusion is APS-C images have about [λ,λ²] less details than one from the FF with the sensor of same megapixels. The real number is closer to λ, when the lens outresolves the sensor, but it quickly reach λ², when wide open.
Since we are talking about Pentax, those numbers are 1.5 and 1,5²=2.25

[TOUGEFC]

In regards to the DOF debate between APS-C and FF, excellent comparsion here -
https://www.pentaxforums.com/forums/1474568-post49.html

[Emacs]

In regards to the DOF debate between APS-C and FF, excellent comparsion here -
https://www.pentaxforums.com/forums/1474568-post49.html

Yes. Take a look at the guy's nose: it's much better seen in FF than in APS-C.

[peasant]

Distagon T* 21 ZK

Not relevant to this thread I know, but I'd like to hear your opinion of the Zeiss 21mm sometime.

[Rondec]

The question often isn't one of whether full frame has better image quality, but whether or not APS-C is adequate for one's needs. Many of the people on the forum are hobbyists for whom the cost of full frame would not provide significant benefits in their every day shooting.

Even for "professionals," the need is overblown. I live in a fairly rural area and the two wedding photographers around here use Canon 50Ds with 20Ds to back them up. Not only are they not using full frame, but they aren't even using current technology! Their clients are quite happy with their work and really could care less about the format size or differences in camera generations.

[JohnBee]

Yes. Take a look at the guy's nose: it's much better seen in FF than in APS-C.

I don't see it

[Ash]

Not only are they not using full frame, but they aren't even using current technology!

I'd have no problem shooting weddings or portraits again with the old *ist D, but for poster-sized prints and faster low-light focusing I'm happier with the K-5.

[usayit]

My two cents...

Yes... there is an IQ difference between Larger sensors to smaller sensors. Its been discussed many times all over various photo-related forums. There are so many factors here... from density of the photo-sites to signal to noise rations to loss of dynamic range. Do not forget that the sensor itself is not the only factor that translates to IQ

Yes... CoC is indirectly related to the sensor size. The formula includes a variable for viewing distance which is in turn related to focal length and enlargement. Both of which are impacted by the size of the sensor. Several references for CoC online report a different value depending on the size of the sensor. CoC can be directly related to DOF.

No.. IMO, DOF is not a factor of image quality. Its simply a characteristic of shooting with some specific format. If you shoot subject matter photos (portraits), then how DOF is rendered is an important aspect of the tools chosen to create said photo. If you shoot story telling photos (journalists), then a deeper DOF may be an even more important aspect of the tools chosen. This is just as incorrect as a shooter with a preference towards the "look" of wide angles claiming that IQ of shorter focal lengths is better than longer focal lengths.

Yes... Crop sensors simple crop (in turn enlarge) the middle image circle of a lens. IMO, this places a higher demand on the optics. Enlargement also means a magnification of the inherent flaws of the current lens.

I think this statement is important enough to quote:

The question often isn't one of whether full frame has better image quality, but whether or not APS-C is adequate for one's needs. Many of the people on the forum are hobbyists for whom the cost of full frame would not provide significant benefits in their every day shooting.

The Micro 4/3rds group (2x crop sensors) is highly aware over the disadvantages inherent with choosing a camera with a smaller sensor over DSLRs. A large portion of this group also owns various other pieces of equipment ranging from digital MF to FF (me included). But they are also highly aware of the advantages the Micro 4/3rds system offers.. its more than adequate for their needs in certain situations. Rarely you'll see someone posting that the crop sensor outperforms FF in certain aspects of IQ BUT they still head out the door with the M43 camera in pocket .... quite often.

[Wheatfield]

LOL
So, show me the APS-C proper equivalent of 77Ltd mounted on full frame — the A50 f1.2 is quite good, but its color rendering much worse than one of Ltd, and it's too soft when wide open
the APS-C equivalent of 31Ltd mounted on full frame: just no match.

BTW, the FF clear advantage is sum of two aspects:

1. Larger sensor means lesser effective focal length, so they uses the lens with larger physical focal length (larger magnification). Larger magnification means more details for the optical system (λ times greater magnification ≈ λ times more details, when the lens is properly done and focusing on short distances)
2. Two spots should be reflected into two different sensor pixels in order to be resolved. But the images of these two spots are placed λ times closely on APS-C sensor than on FF one (λ — crop factor) for the given FOV. So, they need λ² times more megapixels to reach the same sensor capability on APS-C.

The conclusion is APS-C images have about [λ,λ²] less details than one from the FF with the sensor of same megapixels. The real number is closer to λ, when the lens outresolves the sensor, but it quickly reach λ², when wide open.
Since we are talking about Pentax, those numbers are 1.5 and 1,5²=2.25

I'm not going to get into your math, I'm not a mathematician.
From a real world perspective, I would say that your math is speculative theory at best.
I'm having no problem resolving sharp images at the pixel level with my K5.
How a 135 format (the term FF is meaningless) sensor is going to do better in this regard is beyond me. One of the guys in my studio is using a 135 format Nikon. My K5 provides more detail than his D3.
What you are complaining about in the first part has nothing to do with sensor size.

I don't expect to see a 135 format DSLR from Pentax. I expect they'll give it a pass on the theory that if you want a larger sensor camera, they have the 645 already.