If you will be able to get f/4 zooms for the K-1, they will be no bulkier than your current f/2.8 zooms (and provide the same images).

That actually is cherry picking partial arguments you personaly want to push. Either we account for actual market availability or not.

If we we forget theory and check real availability we see no FF lens being able to compete with the portability and handiness of the DA 15 limited. And only then you can say FF can deliver more shallow DoF than APSC. Similarly there are no nicely portable FF competitors to mFT UWA zooms, only clunky huge monsters available from CaSonikon.

If we stick to theory and forget real availability certainly you could build a smallish FF DFA 22mm F5.6. But all the same you could easily build a 23mm F1 APSC lens so nobody complains about it missing versus a FF 35/1.4

Either or. You always could build an equivalent lens, but they simply don't do it in reality always.

[Wired]

[/COLOR]@ Wired : and so what ? Dont you forget the several other advantage of the Pentax IBIS system, or future sensor properties, or ergonomic innovations versus traditional canikon product lines ?

None of the other advantages mean squat if the main elements of the brand/product do not meet your wants/needs.

The best IBIS system and ergonomics in the world mean nothing if your constantly fighting the flash system if flash is a major part of your work.

so why am I still here?

Because I love the feel of my Pentax cameras and the FA Limited. period. it's just disappointing that my needs have changed and I need more out of the tech now.


BUT yes, I am waiting on a decision until the FF comes out. if the FF comes out and doesn't meet my needs in the flash system I'll keep my K3 and FA Limiteds, but the rest will probably go up for sale so I can fund the switch to Fuji and get a pair of zooms and a prime.

[Class A]

f2.8 is still f2.8 for light gathering.

No, it isn't.

Warning: This discussion can easily end up in an "equivalence" debate which more often than not derails a thread and creates arch enemies for life.

Seriously, though, the "light gathering" you refer to that is constant for any given f-ratio (such as f/2.8) across all formats refers to "light gathered per surface unit" (aka "exposure").

That, however, means a larger sensor gathers more total light as the same intensity "light / surface-unit" is multiplied by a larger area. For image properties we care about, such as overall image noise, the global total light gathered is relevant (not the local exposure).

Intuitively, it should be clear that the 8.5/1.9 lens for the Q does not gather the same total amount of light as a ~50/1.9 lens on FF, and the difference in gathering ability can easily been in images. The Q lens only collects as much light as a ~50/11 lens would (which also causes the difference in DOF that would exist if you compared the images of the Q lens to images from a 50/1.9 lens wide open). DOF and total light gathering ability are intrinsically connected. You cannot treat these properties separately.

How long will it take to get the f4 zooms?

I don't know. The 150-450 already is a variable aperture f/4.5-5.6 lens and hence smaller/lighter than it would have been as an f/4 or even f/2.8 lens. I guess Pentax will release some more slower lenses and you can always use APS-C glass (which is equivalent to slower FF glass, albeit with a forced reduction of the image circle).

Perhaps I should not have been quite as affirmative ("you will be able to get") because I only assume that, as opposed to knowing it. I really only wanted to express that

• it isn't the FF image circle that makes an FF lens heavy / big.
• an FF system need not comprise of heavy / big lenses.
• one should not compare FF f/2.8 lenses to APS-C f/2.8 lenses without "currency conversion".

Ahem, did you heard about something called image circle ?

Yes, but for the size / weight / price of a lens, the maximum aperture plays a much bigger role than the size of the image circle. Details differ regarding wide-angle vs long focal length designs, but in general the statement holds.

That actually is cherry picking partial arguments you personaly want to push.

Good morning to you too.

Either we account for actual market availability or not.

Please see above for my real intentions.

There are already slower FF zooms available so you can have a smaller than "f/2.8 heavy" system already. This may necessitate availing oneself to the used lens market, but, again see above for the real intentions I had when objecting to the idea that FF lenses are big and heavy.

But all the same you could easily build a 23mm F1 APSC lens so nobody complains about it missing versus a FF 35/1.4

And which manufacturer could offer a 23/1 APS-C lens for a price that anyone could afford?

Note that the manufacturing tolerances for an APS-C lens have to be tighter compared to an FF lens which compounds the challenges associated with an f/1 design.

[bxf]

f2.8 is still f2.8 for light gathering.

No, it isn't.

Yikes!

[bdery]

This kind of brings me to an observation in this thread and elsewhere in the forums: people are seeing the 70-200mm f2.8 as too big and heavy to be used as a general purpose telephoto zoom, which is exactly what it is. It's also on par with the Canikon equivalents. This is the problem with FF, Pentaxians are used to small, compact bodies and lenses that are not all too heavy.

True, and that's why I said FF won't likely be for me. I enjoy small bodies that I can take everywhere.

A proper strap or bag will help you adapt.

to some extend. for me, the test of any lens is whether I can handhold it and avoid using a tripod or monopod. the 70-200 fails that test.

the truth is they already have it, albeit without image stabilization

SR and WR are two of the main perks of Pentax. Let's not dismiss them

I don't know why anyone says they look cheap because they look and feel beautiful.

I think the finish looks plasticky, with printed letters that look like they will wash out (probably won't) and a failed retro look to them. But then I also think that in general Nikon lenses are ugly. I really like the look of the Sony lenses, and the Pentax. But that's just me, and that's just looks.

I think thats why Pentax enjoys the size advantage because many of the lenses we love in the compact form factors don't have those advanced pieces of glass or the servo/ring motors.

Not necessarily. That's not irrelevant, but marginal to the total size. For instance, the DA40 is actually a FF lens, you could add a little bit of volume to it (to accomodate extra tech) and still be leagues ahead of the mainstream offerings from Canikon.

For image properties we care about, such as overall image noise, the global total light gathered is relevant (not the local exposure)

I'd like to hear more about this opinion, because I don't see how it can be true. Noise is mostly caused by dark current and its amplification, and that's a per-pixel matter. It will be mostly constant for a given pixel, regardless of its size, so if the pixel gets bigger its signal to noise ratio WILL be better (same noise, more signal). However with the increasing resolution on FF the pixel size difference isn't that big between APS-C and FF.

[Pål Jensen]

Either or. You always could build an equivalent lens, but they simply don't do it in reality always.

The only equivalent lenses are those with the same maximum speed, same close focusing distances, same angle of view and same max magnification,. In short they don't exist in real life. DOF is not involved in the definition of f-stops and ISO is not a property of the lens.

---------- Post added 11-17-15 at 02:29 PM ----------

That, however, means a larger sensor gathers more total light as the same intensity "light / surface-unit" is multiplied by a larger area. For image properties we care about, such as overall image noise, the global total light gathered is relevant (not the local exposure). .

No. The idea with a larger sensor is to collect more light than a smaller one; not the same (anyone who choose an, say, FF camera in order to collect the same amount of light as a cell phone is a certified moron). The concept of F-stops is based around exposure. Everything else is a misunderstanding of the concept. Manufacturers are not cheating; F2.8 is 2.8 regardless of format and this value is not calculated from DOF.

[Class A]

I'd like to hear more about this opinion, because I don't see how it can be true.

It is not an opinion, but a fact. Please look up "shot noise" and "Equivalence" or "Camera Equivalence".

I strongly suggest not discuss this further here, but to open a new thread or continue in one of the many existing ones on this topic.

...F2.8 is 2.8 regardless of format...

I will not respond to anything else you said, nor shall I respond to further posts from you on this topic because you keep making the same statements in every thread that touches on this topic without ever taking into account the arguments other posters make.

Let me just say this. Yes "F2.8 is 2.8 regardless of format" is true, in very much the same way as "50mm is 50mm regardless of format" is true.

[Wired]

No, it isn't.

I dunno man... my light meter can't tell the difference of which sensor I'm using when I'm setting up my strobes. It still calculates f2.8 as f2.8, 1/125" as 1/125" and iso100 as iso 100

[Class A]

I dunno man... my light meter can't tell the difference of which sensor I'm using when I'm setting up my strobes.

That's because your light meter measures "exposure" (light-per-unit-area).

As I said, light-per-unit-area is the same for all f/2.8 lenses, so your light meter isn't lying.

However, knowing light-per-unit-area is not enough to know the resulting image quality. For the latter, you also need to know the area size with which you are collecting the light.

Say you are thirsty and you get one rain drop per square meter.
Would you rather have a small field (one square meter), or a large field (four square meters)?

The (rain-) exposure is the same for both fields (one drop per square meter), but you'll be less thirsty when you own the bigger field. The thirstier you are, the noisier your pictures are.

[Kunzite]

This nonsense, again? There's one way to know the quality of a resulting image: look at it. That irrelevant theory people loves so much to shove into our face these days won't tell you what the image quality is.

[normhead]

After going through this thread if people are finally going to get it. Most people who currently shoot Pentax, because for them, as I've said for years "APs-c is the best compromise of affordability, weight, image quality and price." There seems to be this on going notion expressed that the reason most Pentax users don't want an FF because Pentax doesn't have one. Once the FF is released it will become crystal clear. Most Pentax users don't want an FF because, it's not for them. I've never bought a 70-200 ƒ2.8 because of the size. Hearing that the Pentax is the same as everyone else's doesn't change a thing. Hearing that it's as expensive as everyone else's doesn't change a thing.

[Wired]

That's because your light meter measures "exposure" (light-per-unit-area).

As I said, light-per-unit-area is the same for all f/2.8 lenses, so your light meter isn't lying.

However, knowing light-per-unit-area is not enough to know the resulting image quality. For the latter, you also need to know the area size with which you are collecting the light.

Say you are thirsty and you get one rain drop per square meter.
Would you rather have a small field (one square meter), or a large field (four square meters)?

The (rain-) exposure is the same for both fields (one drop per square meter), but you'll be less thirsty when you own the bigger field. The thirstier you are, the noisier your pictures are.

This nonsense, again? There's one way to know the quality of a resulting image: look at it. That irrelevant theory people loves so much to shove into our face these days won't tell you what the image quality is.

exactly.



At the end of the day the technical hubbalub for this doesn't matter a drop if your not out there shooting and enjoying the images your creating.

[Class A]

That irrelevant theory people loves so much to shove into our face these days won't tell you what the image quality is.

It isn't an "irrelevant theory".

It is not a "theory", it is an empirically provable understanding of the laws of physics.
Calling it "nonsense", is a reflection on your ability to understand it as opposed to an applicable description.

It is not "irrelevant", as it can be helpful in many ways, one of which is to make informed gear buying decisions.
One can also make buying decisions based on a gut feeling or ill-conceived ideas, that's fine, but it does not make sense to ridicule people who make informed decisions.

Finally, "people loves (sic) so much to shove into our face" does not apply. It was only when someone started comparing f/2.8 APS-C zooms with f/2.8 FF zooms again, concluding that FF makes lenses "bigger" and "heavier", when I pointed out that this is not the case. Only when someone said "f/2.8 = f/2.8 regarding light gathering", I pointed out that this is wrong. Nothing was "shoved".

If someone said, "The sync-speed on a K-5 is 1/160s.", you'd correct them, right? Pointing out that they can go up to 1/180s with the right exposure step settings, wouldn't you? You'd be considered helpful, correct? Try to do the same with a topic that some people don't get and you are portrayed as someone who "shoves an irrelevant theory into people's faces". Oh, well.

At the end of the day the technical hubbalub for this doesn't matter a drop if your not out there shooting and enjoying the images your creating.

Agreed.

But let's assume one is out there shooting and enjoying the images one is creating. Then better technical understanding can lead to even more enjoyment and better gear buying decisions. One can have a lot of enjoyment without technical understanding as well; I wasn't forcing a technical perspective on anyone. If nobody had said "f/2.8 = f/2.8", I would not have said anything and I indeed warned people multiple times to further put forward their views, as I know that it often does not end well.

All good, AFAIC. I just don't like to be considered to be the bad guy when I'm really just trying to help people shed off some misconceptions.

[Kunzite]

Oh, the "you disagree with me, thus you are incapable of understanding - because I can't possibly be mistaken" treatment.

I was prompted to respond by one such mistake - the claim that "total light" can give you "the resulting image quality". It can't. It can only give you a measure of the shot noise, but that's it.
The best methods for assessing the resulting image quality are empirical.

And in your response, there's another serious mistake: that without "equivalence" you have nothing but "gut feelings" and "ill-conceived ideas". How arrogant is that? I know some physics/optics, I know some geometry - I knew them well before they were misused into "equivalence"; that's nothing special by the way, only basic knowledge. I can still use them according to my needs. I also know the importance of empirical methods, which are even more important with a visual craft. And how, at times, a "rule of thumb" is good enough, while a seemingly precise methodology is not because it doesn't cover factors which are important for you.
The only thing I'm missing is someone telling me "I don't care what you're doing, you have to compare system A and system B this way".

Don't get me wrong - I appreciate that you're trying to help people. But what did they say about good intentions?

[Class A]

...the claim that "total light" can give you "the resulting image quality". It can't.

I did not use "can give you" or implied any of that. Please read carefully.
I only implied that the total light gathered influences image quality, which is undoubtedly true.

Obviously in this context, I was only using "image quality" as being influenced by "image noise". That goes without saying, AFAIC. I even just used "noise" in an preceding post, and only used "quality" later to allude to the importance of "noise" as it not only causes "graininess" but also impacts on resolution. Another good reason to use "image quality" rather than "noise" is because people often jump on "pixel noise" when they read "noise", which is not helpful.

Obviously, "quality" interpreted in a general manner, can refer to image content (subject matter), will vary with camera movement, and a ton of other things. I would have thought that it is clear as day that "quality" as I used it was not meant to include any of that.

And in your response, there's another serious mistake: that without "equivalence" you have nothing but "gut feelings" and "ill-conceived ideas".

I did not say that. Please don't put words into my mouth.

I mentioned "gut feelings" and "ill-conceived ideas" because the latter were actually used before and the former are often used. This, however, does not imply that one doesn't have anything else but these, if one doesn't use equivalence. Far from it.

How arrogant is that?

I know with certainty that the principles I was talking about are not bogus.

If you want to call my confidence in the matter "arrogance", that's your choice. I reckon, however, that you would not appreciate to be called "arrogant" just because you are firm when stating to people that normal apples fall from trees to the ground and never fly upwards escaping into the stratosphere.

Possibly, you call me "arrogant" because you read messages into my statements which I did not intent (such as "you either have equivalence, or you have no idea"). Potentially, the person who you think I am is arrogant, but I'm not.

I also know the importance of empirical methods, which are even more important with a visual craft. And how, at times, a "rule of thumb" is good enough, while a seemingly precise methodology is not because it doesn't cover factors which are important for you.

No disagreement.

As I said, AFAIC, anyone can use whatever approach they see fit.

I only take exception when someone says something that does not make sense and is misleading for others. In other words, if someone works on the assumption that "light gathering and DOF are unrelated" in their head and has success with it, that's great for them. But that someone should not post "light gathering and DOF are unrelated" to a forum and expect agreement only. Fair enough?

The only thing I'm missing is someone telling me "I don't care what you're doing, you have to compare system A and system B this way".

Well, I did not do that, so I'm not sure why you are addressing me with this.

Again, I could not care less about how you or anyone else I don't know personally is doing things, as long as they don't mislead others by making incorrect statements.

N.B., I'm always happy to have a constructive debate. However, if you continue to put words into my mouth in a manner that I don't appreciate then I will not reply anymore. I hope we can keep this civilised and friendly.