[pingflood]

Crop factor is nothing more than marketing speak and so is "full frame", no matter how anyone tries to rationalize it. In the 6x4.5 film world do we refer to 220 film as "full frame" and 120 film as "cropped"? No. Do they record a different field of view when paired with same focal length lenses? Yes.

Errr... what?

The only difference is that 220 is twice as long, and doesn't have the paper backing. It'll still capture the same format as 120 film.

[drewdlephone]

Thank you!

The whole "crop factor" thing has probably caused more confusion and generated more mis-information than any other subject in the history of photography. I know it baffled me for months until I figured out how to ask the question properly.

Crop factor is nothing more than marketing speak and so is "full frame", no matter how anyone tries to rationalize it. In the 6x4.5 film world do we refer to 220 film as "full frame" and 120 film as "cropped"? No. Do they record a different field of view when paired with same focal length lenses? Yes.
An APS-C (23mm) sensored camera is NOT a 35mm camera. Most of them use the same lens mounts as their same branded 35mm cameras. That's it. Mystery solved.

I think my point was a fast fifty has become less useful due to the crop factor, and was seeing if you guys agreed. I understand the crop factor. What I don't get is that fast fifties are still the lens of choice even though their FOV has definitely changed from film bodies. Thats why my curiosity on the 30-40mm lens range. I used to shoot a lot with my Tak 55 on my Spotmatic, and actually managed some decent landscape images. Because I found the difference frustrating, I was wondering if others did as well.

[pingflood]

I think my point was a fast fifty has become less useful due to the crop factor, and was seeing if you guys agreed. I understand the crop factor. What I don't get is that fast fifties are still the lens of choice even though their FOV has definitely changed from film bodies. Thats why my curiosity on the 30-40mm lens range. I used to shoot a lot with my Tak 55 on my Spotmatic, and actually managed some decent landscape images. Because I found the difference frustrating, I was wondering if others did as well.

To be honest, I think it's mostly bad advice being perpetuated.

When we used film bodies, a "fast fifty" was the always recommended lens for new photographers. This just somehow carried over to the DSLRs, and partially because the 50 is still a cheap, fast lens (e.g. Canon's 1.8 I think cost me $79 new) and there generally aren't any APS-C size "normals" that are cheap and good. I would guess the Pentax FA 35/2 is the closest we can get.

So, two reasons I see:
1) Habit (people who used film always like to recommend the 50)
2) Availability/price (the 50 is generally a cheap lens and performs very well, and there aren't (m)any 30-35mm lenses that are fast, good and cheap)

[rparmar]

Also, when you take this into consideration, would not a DA Limited 40 be more akin to the original idea behind the "normal" aspect lens, being an equivalent of 60mm?

I have an FA43 which is a totally amazing, incredible, fantabulous lens... that I almost never use. I do not find the focal length that appealing on digital Pentax. Ditto my Cosina 55 f/1.2. Going either wider or more tele suits me better. I use the FA77 when I need extra reach, always handy for portraits. I use a Vivitar 24 f/2 or 28 f/2 for normal perspectives.

Pentax really needs a fast normal (on digital) lens. I'd prefer it to be on the wider side rather than where the FA31 is. DA 24 Limited f/2 where are you?

I recently bought the DA35mm macro limited and it's become my "normal" lens. It's a terrific lens, and while I'm not exactly a macro photographer I really love the fact that the lens has for all intents and purposes no limit on how close I can focus.

It is another amazing Limited lens, and perhaps one that would be useful to the OP. I do find the FOV a bit cramped for indoor use, but fine for outdoor or when I am using it as a pseudo-macro.

It wasn't my intention to muddy unclear waters, but I thought it interesting to bring up a topic that I've never seen discussed, in person or otherwise.

It's been done to death, which explains some of the reactions you've had. However it is understandable you'd want to clear up this issue if you're translating your knowledge from film to digital.

I think it is important for people to try to get away from this focal length equivalency crutch and start thinking in terms of what focal lengths do on the format they are using rather than some format they are not using.

I know where you're coming from, but the enormous body of 35mm film knowledge out there, in books, magazines etc. all relate to a specific FOV which is not the one we digital Pentax users deal with. So some translation is needed.

Your 50mm lens is technically a 50mm lens. Nothing has changed with the lens, so how has the focal length suddenly become "75mm or so"?

Obviously because the FOV has changed. And that is what is most apparent to a photographer looking through a lens.

[Venturi]

Errr... what?

The only difference is that 220 is twice as long, and doesn't have the paper backing. It'll still capture the same format as 120 film.

I stand corrected, sir. I somehow got it in my head (I'll claim dyslexia for lack of a credible excuse) that the paper backing on 120 was because the film was not as wide.

[pingflood]

I stand corrected, sir. I somehow got it in my head (I'll claim dyslexia for lack of a credible excuse) that the paper backing on 120 was because the film was not as wide.

I think the reason is mainly that there was no way to get 220 length film onto a spool without sacrificing something, that being the paper backing. It allowed for twice the amount of frames without much change to the camera design (really only moving the pressure plate and removing any see through windows on the back), something which would've been a much bigger deal had the spool size had to change.

[Marc Sabatella]

Pentax really needs a fast normal (on digital) lens. I'd prefer it to be on the wider side rather than where the FA31 is. DA 24 Limited f/2 where are you?

That's not really "normal" in any classic sense. Not by the completely arbitrary notion of 50mm as normal, nor by the technically defensible but still equally arbitrary notion of 42-43mm as normal.

It does seems Pentax has weighed in on this with the "announcement" some time back or the upcoming DA* 30, which is presumably going to be the new "fast normal".

As for why the concern over fast fifties versus fast normals, it does seem to me there are at least two reasons why we should *expect* to see different priorities. One is that, as I mentioned before, high ISO capabilities have really diminished (although of course not eliminated) the need for the same kinds of speed needed for film. But another thing to consider is that one reason a 50mm lens was such a common recommendation is the assumption was that this was going to be your everyday go-to lens. I'm talking about attitudes formed during the days when zooms were not taken seriously. The "normal" focal length was perceived as a useful compromise for many situations. It's not the focal length itself was ideally suited for anything in particular - it was just a good compromise for many situations. Yes, I realize there are *other* reasons for the normal field of view, but I think the compromise aspect is too often overlooked.

Anyhow, in a world where a slower zoom can cover so many needs, why choose your primes based on what focal length compromises you the least? It seems that the quality of modern zooms and high ISO performance is such that we now have the luxury of choosing focal lengths for our primes more specifically than just, "this focal length won't suck too much too often". Which is to say, bottom line: why care about a "fast normal" lens the way photographers once did?

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Last edited by Marc Sabatella; 11-23-2008 at 12:57 PM.

[pingflood]

Anyhow, in a world where a slower zoom can cover so many needs, why choose your primes based on what focal length compromises you the least? It seems that the quality of modern zooms and high ISO performance is such that we now have the luxury of choosing focal lengths for our primes more specifically than just, "this focal length won't suck too much too often". Which is to say, bottom line: why care about a "fast normal" lens the way photographers once did?

Some of us just like primes, and there are still areas where a fast prime shines.

I was at a restaurant with my wife and daughter this past Friday. It was pretty dimly lit, but thanks to ISO 1600 and my Sigma 30/1.4 I managed to knock out a few good shots around 1/20th - 1/40th second. A two stop slower ("fast") zoom would've made that feat impossible.

[Das Boot]

Call me crazy, but the FA50mm 1.4 is the lens that stays on my camera the most. For kids it's perfect - a short portrait lens. You don't have to get too far away that you can't grab them if they go running off towards the street. As far as general photography, having one lens on my camera most of the time makes it easier for me to judge a distance and light conditions. I guess you could say I have the opposite of LBA - LNBA. Don't get me wrong, there are times I wish I had a little wider lens with me sometimes, but I usually will move on to another shot.

-Brian

[Das Boot]

The only difference is that 220 is twice as long, and doesn't have the paper backing. It'll still capture the same format as 120 film.

I think an easier way of saying it is - you can twice as many shots out of a roll of 220 as you can with 120 - that's all.

-Brian

[Sean Nelson]

Obviously because the FOV has changed. And that is what is most apparent to a photographer looking through a lens.

But "mm of focal length" does NOT describe field of view - it describes the distance the lens is from the focal plane when an object at infinity is in focus. Although the FOV changes, the focal length DOES NOT.

The confusion stems exactly from this - using focal length as a substitute for field of view.

Back in the days when I shot 6x6 and 35mm film, I never once thought of the 75mm "normal" lens on my Bronica as being anything other than a "normal" lens, and the same went for the 50mm on my Pentax.

I don't have a problem with someone saying "this lens has a field of view that's equivalent to a 75mm lens on a full frame 35mm camera". That's an accurate description. But saying that a 50mm lens somehow becomes 75mm (with no other qualification) is very, very misleading.

[rparmar]

That's not really "normal" in any classic sense. Not by the completely arbitrary notion of 50mm as normal, nor by the technically defensible but still equally arbitrary notion of 42-43mm as normal.

Since I have been challenged I will produce my thinking in full, even though this may not be totally relevant to the thread.

Given that 28mm is the exact normal size for digital and we already have a fast 31mm plus a 30mm coming soon, it makes sense for something on the other side of 28mm to provide prime coverage in the large gap from 21-30mm. This is a pragmatic rationale for my call for a fast 24mm lens.

People talk of 50mm as normal on film, when the reality is 43mm. This number is not arbitrary, but based on the diagonal of the frame size. However, most of us are quite willing to accept a range of focal lengths as being "normal", not getting too hung up on a precise measure. Using the same logic, and given that the difference between 24mm and 28mm is distinct but not excessive, I consider both to being the "normal" range. Any wider than 24mm I'd call "wide-angle", but you'd have to get a lot wider than that to satisfy aficionados of such fields of view.

Given that Pentax have produced the excellent FA* 24mm f/2, I think it quite reasonable to expect that a great DA 24mm f/2 Limited (or a DA* 24mm f/2 if Limiteds must now be restricted to being a stop slower) is well within their technical abilities. Since Pentax have never produced an exemplary 28mm lens, I think it better to call for an update to the FA* 24mm.

[audiobomber]

Good post Marc.

I shot film with a 35mm fixed lens for a long, long time. It was a very useable compromise. Maybe I would have preferred 50mm but 35 worked fine for creating a family album.

With my digital kit I like the 50mm (75mm equiv) as a single solution. I have a 28mm lens that I rarely use, because I either want to go wider or longer. For some reason I "see" 75mm photo shots better than I see 42mm shots. What I mean is, I see a photo opportunity and with a 50mm lens I can often just raise the camera and shoot. With the 28mm mounted, I find I have to move in a bit. The other reason I prefer the 50mm is that becomes a classic portrait length on APS-C, and I prefer to shoot people with that longer FL. The fact that the 50mm is so fast and has such great IQ also leads me to choose it over the 28mm.

[audiobomber]

I don't have a problem with someone saying "this lens has a field of view that's equivalent to a 75mm lens on a full frame 35mm camera". That's an accurate description. But saying that a 50mm lens somehow becomes 75mm (with no other qualification) is very, very misleading.

I think that's needlessly picky. We all understand that the lens remains the same and the FOV changes. It's a form of shorthand for people who are involved in the hobby. Another example of shorthand is "100% crop". That doesn't make sense to anyone except people who know what it means.

[offertonhatter]

But "mm of focal length" does NOT describe field of view - it describes the distance the lens is from the focal plane when an object at infinity is in focus. Although the FOV changes, the focal length DOES NOT.

The confusion stems exactly from this - using focal length as a substitute for field of view.

Back in the days when I shot 6x6 and 35mm film, I never once thought of the 75mm "normal" lens on my Bronica as being anything other than a "normal" lens, and the same went for the 50mm on my Pentax.

I don't have a problem with someone saying "this lens has a field of view that's equivalent to a 75mm lens on a full frame 35mm camera". That's an accurate description. But saying that a 50mm lens somehow becomes 75mm (with no other qualification) is very, very misleading.

I could'nt put it better myself. A 50mm lens, is still a 50mm lens and will act like a 50mm lens, no matter what camera type it is on. So, on 35mm it is considered a "normal" lens, on APS-C it will be a short tele, and on medium format, it is a wide angle. But it is still a fifty.
On compacts they will say in the blurb 38-380 (35mm equiv) but in reality the lens as a 5.7mm-57mm lens (my fuji S5000). The blurb has just confused the issue a bit, due to consumers still thinking in 35mm terms, whereas photographers who are used to various film types in the past, know about certain lengths and what they will be on differing formats.
For me? I will just put the lens that will suit the picture, and if it looks right, then take the photo, as that is what photography is all about, taking photos.