[jstevewhite]

+1 rep, thanks mate i will make a note of it and check it out

Thanks! Enjoy! (I've been having quite a bit of fun with the technique).

And I'm all envious of your LTD 15.

[jstevewhite]

Indeed. I just plugged in the numbers, and sure enough, hyperfocal distance for a 35mm lens at f/16 on APS-C is exactly the same as for a 50mm lens at f/22 on FF, just as one might expect.

I thought the number was 1 1/3 stops, not one stop. That's the number that people toss around on the OTHER end..

Whatever this special magic "different behavior as you approach hyperfocal distance" thing might be that allegedly makes the hyperforcal distance closer for APS-C than FF, it doesn't seem to apply here. The ordinary concept of equivalence seems to apply just as would one expect, according to the calculator on Atkins' site, which most definitely *does* include format as one of its input parameters.

So I'm back to being completely unconvinced there is anything whatsoever to that claim.

It's not magic, it's math. I'm not sure how Bob gets those numbers to match exactly; it makes me think there's a bit of a fudge factor going on. But even using his chart, substituting 31mm for 35mm, or 53.9 (35*1.54) for the 35mm solution changes the answers. If your lens doesn't stop down further, you can't make it. I'd still like to see the problem with my math, or an hyperfocal distance formula that's different than the one I posted.

I'm not particularly invested in this discussion beyond a philosophical stance: Tanstaafl. If you say "You can't get the small DOF on APS-c that FF can *because your lenses don't open far enough*", then it's also true that "You can't get the large DOF on FF that you can on APS-c *because your lenses don't close down far enough*". And you can say "But WHO in the WORLD would want to shoot f22?" and I can say "But Who in the WORLD would want to shoot with a portrait with 1" of DOF?". You can't reasonably say "Mine is right because I don't care about YOUR constraint", unless the complementary answer is also true. When one says "You can't get the short DOF on APS-C that FF can", it's got the understood "Because you can't buy a LENS like that", it's not an inherent limitation of the format.

[Wheatfield]

Yes, it is. The mps are don't matter significantly. The difference is how lenses should work. When compare lenses, you should compare similar FOV, and difference will become huge there: the 31Ltd can be very good, but it loses to any good 47mm lens on FF when working as 47mm one on APS-C. Just because it provides 1.5 times less details than those 47mm lenses

Sorry, I'm not buying this. Like I said previously, I've done the comparison myself.
A good lens is a good lens is a good lens. It doesn't matter what format is put behind it as long as it covers the format fully.

[jsherman999]

I'm not particularly invested in this discussion beyond a philosophical stance: Tanstaafl. If you say "You can't get the small DOF on APS-c that FF can *because your lenses don't open far enough*", then it's also true that "You can't get the large DOF on FF that you can on APS-c *because your lenses don't close down far enough*". And you can say "But WHO in the WORLD would want to shoot f22?" and I can say "But Who in the WORLD would want to shoot with a portrait with 1" of DOF?". You can't reasonably say "Mine is right because I don't care about YOUR constraint", unless the complementary answer is also true. When one says "You can't get the short DOF on APS-C that FF can", it's got the understood "Because you can't buy a LENS like that", it's not an inherent limitation of the format.

This is actually true, it is really a lens limitation, although in discussion it's attributed to an effective format limitation. Any format can achieve almost any DOF for any FOV but the lens designs would not be possible in some cases. No 24 f/1 available, no 35 f/0.9, etc. A P&S could take a shot just like the FA 50 at f/1.4 if it were possible to design a usable 18mm f/.08 lens for it (or whatever specs would be required.)

In the shared FL ranges between aps-c and FF it's often possible to buy a lens for each that could provide equivalence but it's prohibitively expensive to do so. $199 35 mm at f/2.2 == $2000 24mm f/1.4,etc, and the numbers swap at the long end for FF.


.

[Emacs]

A good lens is a good lens is a good lens.

OK, although the 31Ltd is a good normal lens on APS-C (definitely better than 40, which was called "Ltd" due to mechanics, not by its optical quality), but it's worse than true normal, like 43, good 50, etc on FF, because it's moderate wide angle one. And it's significantly worse from my expirience after shooting with D700 and Nikkor 50 f1.4 and Sigma 50 f1.4 on 5d mk II.

On the other hand, what ≈21mm lens (which is about of 31mm on the APS-C) can match 31's rendering? Crappy 21Ltd? It's highly overpriced piece of junk. What ≈21mm EFL lens can match the distagon 21? 15Ltd is good, but it's much worse than this CZ.

[RonHendriks1966]

.I hate comparison test shooting, but here's one image combo that gives you an idea of what you would start to notice (slight framing difference, same distance to subject though) :

Great shots. Thanks.

On APS-c you would probably need to go to f2 to give it the same picturefeeling.

[Wheatfield]

OK, although the 31Ltd is a good normal lens on APS-C (definitely better than 40, which was called "Ltd" due to mechanics, not by its optical quality), but it's worse than true normal, like 43, good 50, etc on FF, because it's moderate wide angle one. And it's significantly worse from my expirience after shooting with D700 and Nikkor 50 f1.4 and Sigma 50 f1.4 on 5d mk II.

On the other hand, what ≈21mm lens (which is about of 31mm on the APS-C) can match 31's rendering? Crappy 21Ltd? It's highly overpriced piece of junk. What ≈21mm EFL lens can match the distagon 21? 15Ltd is good, but it's much worse than this CZ.

So what you are complaining about is to do with the lenses (and I disagree with your assessment of the 21LTD and the 40LTD (again from personal experience)) and not the format per se.
I think you need to look up the word "junk" in an English to Russian dictionary, and come back when you have some credibility.
We are just going to have to agree that you are wrong and I am right on this one since you can't seem to stay on topic, which is format, not lenses.

[Emacs]

You can't seem to stay on topic, which is format, not lenses.

The topic is mine
The format dictates lenses. There's no focal range, but FOV. So, comparing the IQ on formats we should compare pairs (Camera/Sensor,Lens with certain FOV).
And you should understand when decreasing FOV on smaller sensor we made abberations more visible (and decreases details due to lesser magnification). So we need much better optics for the same task. But where is it? The last pentax lenses are overpriced jokes.
It's about wide-normal-portrait range though, I have little interest in telephoto range.

[Rondec]

I would agree that the 31 mm is a different lens on APS-C than it is on 35mm. On 35, it is a fast, fairly wide lens; on APS-C it is a medium speed normal lens. Who, back in the day, would have paid a fortune for a 50 mm f2 lens?

I think the question really comes up as to why people shoot fast lenses. Some people deliberately shoot them to get narrow depth of field, but for many (myself included), that is more a side effect of trying to get adequate shutter speed to freeze motion. I seldom shoot wider aperture than f2.8 on APS-C because the depth of field is too narrow for my purposes. So, I get a little more depth of field because of my format, but I get the benefit of an f2.8 lens with regard to shutter speed. Its all good.

[LFLee]

hm... no one admit because they can't afford a FF?

I think if Pentax have a FF, I will go for it. It would have to be around $2000 though to make it affordable for me.

Lee

[Marc Sabatella]

I thought the number was 1 1/3 stops, not one stop. That's the number that people toss around on the OTHER end..

It is close to 1 1/3 stops, yes. It's just to round off when doing basic comparisons like this - after all, as Atkins says, it's not like these calculation are very precise. They totally depend on the size of the print you are making, the distance you are viewing from, and your visual acuity. It's not like an object 17.4767 meters away is "in" focus and an object 17.4766 meters away is "out" of focus - it's just a gradually decreasing degree of focus as you get further in front of and behind the focus plane, and at some point, we say that it looks "unacceptably" unsharp, but these formulas are just ways of ballparking where that point might be. Also, as Atkins points out, by the time you stop down to the minimum aperture of a lens, you are already so diffraction-limited that all of this needs to be taken with a grain of salt.

It's not magic, it's math.

Well, yes, but math that somehow manages to simplify the factors that an ordinary DOF calculation would need to know. It may well be true that as focus distance approaches hyperfocus distance, the traditional DOF formulas fail. I've seen that suggested. I haven't seen it *proven*, though. I have a degree in math, so I'd be able to follow such a proof were one posted, but I'm not sufficiently interested to actually invested the time that would likely be required.

But even using his chart, substituting 31mm for 35mm, or 53.9 (35*1.54) for the 35mm solution changes the answers. If your lens doesn't stop down further, you can't make it.

Right - like I said, in the very rare cases where you are already stopped down to minimum aperture on the 35 on APS-C and are willing to accept the large amount of diffraction that results, then *if* your 50mm lens doesn't provide an extra stop, you'll will be unable to get *quite* as large a DOF. On the other hand, your image will be less ruined by diffraction. We're definitely talking corner cases here, not something the average photographer would ever care about. But yes, for those rare corner-case-loving photographers,smaller sensors would have advantages in that specific scenario: shooting at hyperfocal distance when DOF is more important than diffraction.

I'd still like to see the problem with my math

Looks like you followed the formula well enougn, assuming your values for CoC in this context are correct.

And you can say "But WHO in the WORLD would want to shoot f22?" and I can say "But Who in the WORLD would want to shoot with a portrait with 1" of DOF?". You can't reasonably say "Mine is right because I don't care about YOUR constraint", unless the complementary answer is also true.

It's not my preferences against yours here. It is the preferences of 99% of photographers against the preferences of 1%. But I will grant that for that 1% - those of you who don't care how much your pictures are affected by diffraction but will do anything possible to get the most DOF, even if what that means is that the sharpest parts of your pictures are significantly less sharp than they would be otherwise - then indeed, smaller sensors do have that advantage.

[Marc Sabatella]

OK, although the 31Ltd is a good normal lens on APS-C (definitely better than 40, which was called "Ltd" due to mechanics, not by its optical quality), but it's worse than true normal, like 43, good 50, etc on FF, because it's moderate wide angle one.

??? 31mm on APS-C is not wider than 43 on FF. It's right between 43 and 50 in that respect.

As for the 40, I don't know what you're basing your opinion of its quality on on, but objective tests prove it is as capable as any of the other limiteds, just with slightly different strengths and weaknesses.

On the other hand, what ≈21mm lens (which is about of 31mm on the APS-C) can match 31's rendering? Crappy 21Ltd? It's highly overpriced piece of junk. What ≈21mm EFL lens can match the distagon 21? 15Ltd is good, but it's much worse than this CZ.

Even if true - and I doubt you can prove it, because any superiority is goign to be subjective - you are again not talking about differences in the format, but accidents of history in terms of which lenses by which manufacturers happen to suit your subjective tastes better.

[TaoMaas]

hm... no one admit because they can't afford a FF?

I think you're on the right track. I don't think people deny the benefits of FF so much as they question whether those benefits are worth the increase in price to them.

[normhead]

It's not my preferences against yours here. It is the preferences of 99% of photographers against the preferences of 1%. But I will grant that for that 1% - those of you who don't care how much your pictures are affected by diffraction but will do anything possible to get the most DOF, even if what that means is that the sharpest parts of your pictures are significantly less sharp than they would be otherwise - then indeed, smaller sensors do have that advantage.
Today 11:33 AM

You're sounding a little desperate dude. Maybe you should let this go. your point is pretty much insignificant. Your 99% of photographers, you made that up.. in the same way you embellish the importance of FF over APS-C. You're framing the argument in a way that gives way to much importance to things of negligible effect.

As has been pointed out. If you feel that strongly about the difference between FF and APS-C, you need to be shooting 645. You can't claim these things make that much difference to you and then claim FF is the place to stop. 35mm cameras, and before them 35 film cameras have always been a intermediate compromise. FF is not the be all and end all of photography. In school we used 8x10 film cameras. To someone used to that any fixed focal plane camera is "not what 99% of photographers want."

There's this whole sliding scale of what is available. To pick a place ie FF somewhere in the spongy middle of the scale and say "this is the spot" is arbitrary. The advantages and disadvantages of both systems have been explored and 99% of photographers are not lining up to get FF cameras. You seem to think it's because they don't know what you know. It's more likely because they know what you don't know. It doesn't make that much difference, and in many cases, it makes no difference at all.

[Marc Sabatella]

You're sounding a little desperate dude. Maybe you should let this go. your point is pretty much insignificant. Your 99% of photographers, you made that up.

Just because you apparently don't understand my point doesn't make it insignificant. I'd say it's patently obvious to most people following this discussion. You're right that I just made up the numbers (obviously), but if you don't think more way people care about the inability to get an extra f-stop at the wide open end than the inability to get an extra f-stop at the stopped down end, then you don't clearly don't have nearly as much experience with photography as you make it sound. My statement here is should *not* be particularly controversial at all. When it comes to DOF control - and DOF control *only*, not looking at any any other factors - APS-C beats FF for the vast majority of use cases that photographers who care enough to invest in either system would care about, for the quite simple reasons I've been patiently explaining.

in the same way you embellish the importance of FF over APS-C.

Not at all. I am simply trying to correct the errors when others have attempted to make the advantage seem smaller - or bigger - than it actually is. Perhaps you haven't noticed, but I've actually been correcting perceived errors on *both* sides of the debate. I have no illusions about the magnitude of the difference; I'm just interested in getting the facts straight.

You're framing the argument in a way that gives way to much importance to things of negligible effect.

I don't see how someone with the amount of experience you imply having could possibly claim DOF control is "negligible effect". It is *very* important to some, sort of important to most, and not important at all to a small few. I guess you're in that latter group, but if you truly studied photography in school and have experience with large format systems, you cannot possibly believe there aren't a lot of people who do care about DOF control.

But is it the only thing that matters? No, of course not. It doesn't matter enough to *me* to make it a determining factor, but I recognize that the difference exists, so when someone incorrectly states that FF always has less DOF than APS-C, I think it important to correct that misunderstanding.

There's this whole sliding scale of what is available. To pick a place ie FF somewhere in the spongy middle of the scale and say "this is the spot" is arbitrary.

Indeed, but note I have never said anything remotely like that - you're arguing a straw man here. In the ways that FF is better than APS-C, 645 is better still - clearly. However, the ways in which FF is *not* better than APS-C (size, weight, price) also become more significant. At best, I'd say historical accident is such that 135 format *does* happen to represent a sweet spot, not in terms of best IQ or anything, but in price/performance, for a certain type of photographer. But I'd also say APS-C hits tht sweet spot for more photographers. And the P&S hits a sweet spot for more still. There's room for all these types of photographers.

But just because APS-C hits a sweet spot for a given photographer doesn't mean that FF *doesn't* provide more DOF control for the vast majority of use cases. It's OK with me to prefer APS-C - I am among those who do. It's not OK with me to spread misinformation about the nature of the tradeoffs, though.

A point that hasn't really been made (except in passing, as an object of ridicule) is that if maximizing DOF is your primary concern - so important that it trumps diffraction and other elements of IQ - then you might as well skip right past APS-C and just use a P&S. Others have said things to that effect but meant them to be tongue-in-cheek, because for *most* purposes, that is not in fact the right answer. But if your primary consideration is maximizing DOF and you're willing to sacrifice all else to get there - and this is what the arguments in favor of APS-C over FF have basically amounted to - then indeed, a smaller sensor still is better. I am dead serious about that.

The advantages and disadvantages of both systems have been explored and 99% of photographers are not lining up to get FF cameras. You seem to think it's because they don't know what you know.

Not at all. Again, you completely misunderstand me. I use APS-C, and you couldn't *pay* me to trade it in for FF. I totally get why most people prefer APS-C - I'm one of those people. But I also like to make sure people are getting their facts straight about what the tradeoffs actually are.