[maxfield_photo]

Here's an exercise that will help you understand why FF folks long for the "good old days" of a 35mm frame. Take your favorite zoom lens, mine for instance on my K20d is the DA* 50-135. Now, go out shooting for a day, but don't allow yourself to shoot at less than 75mm. You can zoom out so that you can see what you're missing, but when you press the shutter, the lens has to be at 75mm or higher. The problem is even more frustrating with a wide angle lens of course. Or another way to do it is shoot at 50mm all day, and then go home and crop out the outer third of all your shots in post. That's why we miss it.

[Rondec]

I think people need to forget the crop factor. It doesn't make your lenses longer on APS-C, it doesn't really do anything to them. Just learn how your lenses shoot on your camera (field of view and depth of field) and use them appropriately.

The conversion factor is really only useful for photographers who were used to shooting 35mm (film or digital) and need to visualize how the lenses behave on a different sized (smaller) sensor).

[Marc Sabatella]

Here's an exercise that will help you understand why FF folks long for the "good old days" of a 35mm frame. Take your favorite zoom lens, mine for instance on my K20d is the DA* 50-135. Now, go out shooting for a day, but don't allow yourself to shoot at less than 75mm. You can zoom out so that you can see what you're missing, but when you press the shutter, the lens has to be at 75mm or higher. The problem is even more frustrating with a wide angle lens of course. Or another way to do it is shoot at 50mm all day, and then go home and crop out the outer third of all your shots in post. That's why we miss it.

That doesn't explain a thing. With APS-C, you simply shoot with shorter lenses than you would have with FF.

[maxfield_photo]

That doesn't explain a thing. With APS-C, you simply shoot with shorter lenses than you would have with FF

Which means you have to buy a whole new set of glass. I can't speak for others, but the main thing that kept me with the Pentax brand during the transition from film to digital was that I could still use my old lenses. Now for the teles, it's not so bad, I can usually just zoom out a bit to get a wider FoV, but for wide angles, it sucks. I have a great wide angle zoom that used to take exciting, dynamic pictures; now it takes boring vanilla shots.

Back at the dawn of the digital age the camera industry promised us that APS-C was only a temporary solution, that they'd be getting back to a 35mm frame as soon as they could make an affordable one. They've forgotten their promise.

I've just plopped down 700 bucks on a Sigma ultra wide to compensate for the shortcomings of my camera. That money would have gone to Pentax if they'd only offer a full frame digital option. Their loss, but I'm done compensating. My next camera will be a FF, if that means changing brands, then so be it.

[noblepa]

Back at the dawn of the digital age the camera industry promised us that APS-C was only a temporary solution, that they'd be getting back to a 35mm frame as soon as they could make an affordable one. They've forgotten their promise.

I sympathize and I, too, miss the angle of view that some of my older lenses gave on 35mm film. However, I don't think that the dslr market is driven by owners of old glass any more, if it ever was.

For that reason, the manufacturers have realized that they can get IQ that is more than acceptable to most people, in an APS-C sensor. A buyer coming to the dslr party, with no prior film SLR experience really doesn't care about backward compatibility very much, since he/she has no old glass in the first place. More and more dslr users are in this category. This fact is precisely why we see questions about the "crop factor" so often. Its very confusing to someone with no 35mm experience.

I suspect that most dslr buyers have no old glass and don't haunt ebay, Craigslist and KEH to find old glass to use on their brand spanking new dslr. If they buy additional lenses, they buy new, either from Pentax or from Tamron or Sigma.

I *DO* have a lot of 35mm experience (I bought a Spotmatic, new, in 1967, while in high school), and, while I understand the advantages of FF (low light IQ, DOF, etc.), I personally couldn't care less if Pentax ever makes a FF dslr. I'm not saying that YOU shouldn't care, just that I don't. I think that many dslr users are happy with APS-C.

In any discussion of the K-7 or K-5, one thing that always comes up as a good thing, is the small size and low weight of the cameras. I don't think that there is any way to put a FF sensor into a body that small. Never mind the cost. You might get one into a K10D/K20D sized body, but not the K-7/K-5. Nikon and Canon are also building smaller dslrs. Compactness sells.

When the industry made the promise you refer to, even the FF cameras were only one or two megapixels and the IQ was terrible, by today's standards. A good APS-C dslr today, such as the K-5, has IQ that was undreamed of, even in FF cameras of six or eight years ago. The promise is not nearly as important to most buyers as it was back then.

Even if we reach the day when the manufacturing costs of FF and APS-C sensors are the same (which we won't), I don't think that a FF camera would be as cheap as an APS-C camera. The size and weight advantages will win over most casual buyers, so economy of scale will keep the FF sales price higher than for APS-C.

But then, mirrorless cameras may conquer the photographic world and kill off the dslr altogether, just as the film slr killed off the rangefinder. It wouldn't surprise me a bit.

[Wheatfield]

I've just plopped down 700 bucks on a Sigma ultra wide to compensate for the shortcomings of my camera. That money would have gone to Pentax if they'd only offer a full frame digital option. Their loss, but I'm done compensating. My next camera will be a FF, if that means changing brands, then so be it.

That money could also have gone to Pentax, and you would have had a better lens, more than likely.
Pentax makes money selling lenses, not camera bodies. This is the perhaps unfortunate way of the world, and it's the same for all the camera manufacturers.
If everyone just bought cameras, and didn't buy lenses, the supply of cameras to put those lenses on would dry up with attrition in very short order.
So, it is hardly Pentax's loss if you change brands, with you, all they have lost is someone who doesn't want to be a customer anyway.

[Marc Sabatella]

Which means you have to buy a whole new set of glass.

Well, not a whole new set - just some new lenses at the wide end. My point, though, is that this isn't something inherently worse about APS-C; it's just a case of having lenses for a different system. If one originally shot and then moved to FF, one would experience the exact same phenomenon but in the other direction. You'd be grumbling how your telephoto lenses aren't as long any more, how your normal lens isn't any more, etc.

Back at the dawn of the digital age the camera industry promised us that APS-C was only a temporary solution

Not that I doubt that someone might have said something like that, but how can "the camera industry" promise anything? Do you have specific quotes from specific people?

[maxfield_photo]

That money could also have gone to Pentax, and you would have had a better lens, more than likely.

If they made an 8mm rectilinear, I would have been happy to buy it; I like my weather seals

So, it is hardly Pentax's loss if you change brands, with you, all they have lost is someone who doesn't want to be a customer anyway.

Quite the opposite, I love the brand dearly, been with them for 30 years. Switching brands is the last thing on earth that I want to do, but if they can't offer what I need then my choice is made for me.

[maxfield_photo]

Not that I doubt that someone might have said something like that, but how can "the camera industry" promise anything? Do you have specific quotes from specific people?

It's a metaphor

[RioRico]

...I learned to like 80-85mm lenses, often around f/3.5-4, often around the same distance (~1.5-2m). That combination of focal length and aperture and distance IMHO gives the nicest roundness to human features, without distortion. Each different format just captured a different crop of basically the same projected image, with the same DOF and perspective.

*All* lenses have the same perspective. Perspective is not a function of focal length or FOV - just of distance to subject. There is nothing special about 85mm lenses - it would have been pure coincidence that you happened to like that same focal length on different formats.

I specifically said "the same distance" which of course gives the same perspective. And that it is the combination of factors that produce those results. The same would be true with any certain focal length in other applications. So for a bit less roundness with somewhat thinner DOF, we might use a 127-135mm lens at f/3.5-4 at around 3.5-4m. That combination would give fairly consistent results no matter the format, just with different crops of basically the same projected image.

My point was that at the same focal length and aperture and distance, format / frame size is irrelevant.I'll also stipulate that image dimensionality (roundness, flatness, whatever) is strongly determined by lighting. And format remains irrelevant.

[MPrince]

Back at the dawn of the digital age the camera industry promised us that APS-C was only a temporary solution, that they'd be getting back to a 35mm frame as soon as they could make an affordable one. They've forgotten their promise.

No they haven't. Canon, Nikon, and Sony all have cameras with a 35 mm sized sensor. If you want a camera with that sensor you have options.

Pentax is on record as saying they have no plans to introduce such a camera. They might by lying, they might change their mind one day, but everyone clamoring for such a camera today should take Pentax's word and switch to another system.

Then everyone will be happy.

Until they find something else to complain about.

Which they will.

[Marc Sabatella]

I specifically said "the same distance" which of course gives the same perspective.

Well, I realize that, but you made it sound like the fact that you also shot with an 85mm lens played a role in this. You could have shot with any lens - from the DA15 to a 500mm mirror and obtained precisely the same perspective. You probably knew this, but it might not have been clear to a beginner.

My point was that at the same focal length and aperture and distance, format / frame size is irrelevant.

Sure it's relevant - if you keep focal length constant, frame size determines the FOV and nothing else*. But just as surely, if you keep frame size constant, focal length determines the FOV and nothing else*. Again, the way you've worded it might seem to imply otherwise.

*DOF is held the same if we use the same *absolute* aperture rather than same *relative* aperture.

[normhead]

It's a myth that longer focal lengths compress perspective. Focal length has nothing to do with it, perspective compression is purely a function of distance to subject.

That's highly misleading statement. What a longer focal length compresses is not perspective but field of view. Taking a picture of a subject in the foreground with a 35mm lens, and then back up and taking the same image, keeping the subject the same size, doesn't compress perspective, it compresses the amount of visible background, or Field of View. All you've done is misstate the concept and then disagree with it.

[Marc Sabatella]

That's highly misleading statement. What a longer focal length compresses is not perspective but field of view. Taking a picture of a subject in the foreground with a 35mm lens, and then back up and taking the same image, keeping the subject the same size, doesn't compress perspective, it compresses the amount of visible background, or Field of View. All you've done is misstate the concept and then disagree with it.

Huh? You said it yourself above: "what a longer focal length compresses is not perspective". That's exactly what I was observing as well. But you are wrong if you are claiming that backing up and taking the same image does not change the perspective. It most certainly does - it's the *only* thing that changes perspective. And this change is generally called "compression". Whether you keep the subject size the same or not is irrelevant.

A simple example: have a person stand 20 feet in front of a house and take a picture from just a couple of feet in front of the person. They will look fairly large compared to the house, and the house will appear to be quite far in the distance because of this. It doesn't matter *what* the focal length or FOV is; this perspective is constant when shooting from that position. Now take the picture from 100 yards away. The person will now look much smaller than the house, and the house will thus look much closer to the person - again, regardless of what that focal length or FOV is. This is what "compressing perspective" means.

There is also a more technical description. Linear perspective is characterized by the fact that horizontal lines will appear to be diagonals that converge on "vanishing points" along the horizon line to either side of the frame. As you come closer to a subject, these diagonals get more extreme, and the vanishing points move corresponding closer together. As you move farther away from the subject, the diagonals become increasingly horizontal, and the vanishing points move correspondingly farther apart.

Yes, shooting with a longer focal length reduces the amount of background visible. But that has nothing to do with perspective or what "perspective compression" refers to.

[normhead]

A simple example: have a person stand 20 feet in front of a house and take a picture from just a couple of feet in front of the person. They will look fairly large comapred to the house, and the house will appear to be quite far in the distance because of this. It doesn't matter *what* the focal length or FOV is; this perspective is constant when shooting from that perspective. Now take the picture from 100 yards away. The person will now look much smaller than the house, and the hosue will thus look much closer to the person - again, regardless of what focal length or FOV you use. This is what "compressing perspective means".

That's funny, I think maybe you should read it over a few times. See if it still makes sense.