A Fast Fifty Is Really A Fast 75mm

drewdlephone · 11-23-2008, 12:37 AM

This may be a bit if a noob question/theory, but oblige me if you will: considering the crop on all APS-C format cameras (or at least Pentax) of 1.5, our "Fast Fifty" lenses are technically 75mm or so. For those of you who have had your Fifty since you shot film, how have you adjusted to this change? Has the use of your lens changed?

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? Granted that's at the high end of normal (50-60mm if I understand correctly) but wouldn't it work better for those kinds of shots than, say the new DA*55, which has an equivalent focal range of 82.5mm?

As I'd imagine the DA*55 will be more costly than the DA Limited 40, I figured the comparison was relevant. What are your thoughts?

pw-pix · 11-23-2008, 12:57 AM

It makes the 50mm just about useless for my photography.
It isn't a focal length I like using and don't have much need for it.
I have a 28mm which is more generally useful to me, but it's a stop slower.

Igilligan · 11-23-2008, 01:37 AM

Find a nice 35mm... The FA 35 is F2

Or if the "money is no object" applies in your world... The FA 31 ltd is the ticket.

ariahspam · 11-23-2008, 01:45 AM

A fast 50, in aps-c would be looking at the 28-35mm range. And it is true they aren't as fast, cheap and widespread as the film 50's. The closest would be sigma 30mm 1.4.

The DA*55 is designed to be a portrait lens, mimicking the film 85mm.

Sean Nelson · 11-23-2008, 01:48 AM

Originally posted by drewdlephone

A Fast Fifty Is Really A Fast 75mm

There's enough confusion going around regarding what the "crop factor" really means that I think this is a misleading statement. I would phrase it as "A Fast Fifty really has a 75mm field of view".

I usually use my SMC-M 50mm f/1.4 only when I have a special need to restrict depth of field at longer subject distances. As you alluded, I find that it's frequently too long to use in low light situations since these are often indoors where it's difficult to back up far enough to frame the subject. But it is terrific for head-and-shoulder shots.

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.

For low-light indoor shots I usually find myself using the DA35 or DA12-24. While slower than the fast fifty, the wider field of view (which makes hand-held shots easier) and the ability to shoot up to about ISO 800 with no appreciable noise means that I don't miss the faster lens all that much.

drewdlephone · 11-23-2008, 02:42 AM

Originally posted by Igilligan

Find a nice 35mm... The FA 35 is F2

Or if the "money is no object" applies in your world... The FA 31 ltd is the ticket.

I'll keep an eye out for the first one. Would it end up being as good, optically, as the DA Limited 40?

Originally posted by Sean Nelson:

here's enough confusion going around regarding what the "crop factor" really means that I think this is a misleading statement. I would phrase it as "A Fast Fifty really has a 75mm field of view".

I usually use my SMC-M 50mm f/1.4 only when I have a special need to restrict depth of field at longer subject distances. As you alluded, I find that it's frequently too long to use in low light situations since these are often indoors where it's difficult to back up far enough to frame the subject. But it is terrific for head-and-shoulder shots.

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 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. I find my Tak 55/1.8 is just about useless for anything except portrait shots, and for that, it excels. Taking low light shots of my cats or indoors just doesn't work as well as I'd like.

Igilligan · 11-23-2008, 03:00 AM

I have the DA 40 and I like it fine. But if I wanted the field of view of the old 50mm on film, and I wanted it a little faster, I would swap my DA 40 for the FA 35 or Da 35. The FA 35 is F2 and pretty darn sharp at f2.
Some folks say the DA 35macro is one of the finest lenses out there right now... So take a look at that one too.

But the Da 40 does have a 'look'.

Last edited by Igilligan; 11-23-2008 at 09:52 AM.

Wheatfield · 11-23-2008, 09:19 AM

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.

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"?
The standard focal length on the APC-C format DSLR cameras that we use is ~28mm, so the closest thing that Pentax makes to a normal lens is the 31/1.8. I suspect that if the 30mm project ever sees the light of day, the 31 will go out of production.
The 30mm had better be an f/1.4, though with Pentax's propensity for making slow primes, I'm not holding out much hope.....

As far as what has changed for me with the move to digital, my 50mm lenses are now portrait lenses, my 35mm lenses are now my standard lenses, etc.

What hasn't changed for me is the way I think about focal lengths. Whan I shot 3 different film formats, my 50mm lens was not a 24mm lens, nor was it a 17mm lens. My 105mm lens was not a 50mm lens, nor was it a 35mm lens. My 150mm lens was not a 90mm lens, nor was it a 50mm lens.
And if you find the above to be a bit confusing, you might perhaps realize why I think the whole multiplication factor thing is a really stupid way to think about focal lengths.
Learning what a focal length does on the format being shot is more than just doing some arithmetic in your head.

roentarre · 11-23-2008, 09:33 AM

Still 50mm will have the perspective of the 50mm instead of 75mm

Venturi · 11-23-2008, 09:51 AM

Originally posted by Wheatfield

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"?

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.

jsherman999 · 11-23-2008, 10:18 AM

Originally posted by Venturi

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.

The whole reason this persists is because many people spent years getting used to the FOV of 35mm lenses on film bodies - what to expect to see in the frame when you put a certain lens on.

So I don't think it's surprising to realize that a FOV conversion procedure needs to happens in people's heads still, it's natural.

I never really shot 35mm film SLRs, so to me, a 50mm is a 50mm is a 50mm, but if I had shot film, it would probably take me a little while to get used to 'seeing' in the new FOV vernacular, and discussion of crop factor would be pertinent.

.

Marc Sabatella · 11-23-2008, 10:27 AM

As someone who *didn't* come from a lot of experience with film:

Yeah, 50mm doesn't seems a generally useful focal length. Nice for some kinds of portraits, and the wide aperture is nice for that too. But otherwise, when it comes to low light, ISO 1600 performance from modern DSLR's is good enough that one could claim f/2.8 is the new f/2.0, even f/1.4. Maybe I just don't know what I'm missing, but it seems that with a 28/2.8 and/or a 40/2.8, I can do most of what used to be possible with a 50/1.4.

lithos · 11-23-2008, 10:34 AM

Aw, ferf*cksakes...

We just got the lid back on this can of worms!

troyz · 11-23-2008, 10:39 AM

Originally posted by drewdlephone

This may be a bit if a noob question/theory, but oblige me if you will: considering the crop on all APS-C format cameras (or at least Pentax) of 1.5, our "Fast Fifty" lenses are technically 75mm or so. For those of you who have had your Fifty since you shot film, how have you adjusted to this change? Has the use of your lens changed?

Well, it's been a few weeks since I shot film. . . let me think. . .

(1) I use a different lens as my "fast normal" lens on APS-C (I use an FA31; the FA35 would be my second choice and I also read good things about some of the 28s)

(2) I have to subtract one f-stop from the DOF scale on FA lenses when I'm using APS-C (e.g. use the f/5.6 marks when shooting at f/8)

50-ish lenses are still great for APS-C; you'll just get a tighter composition (if you don't move away from your subject) or different perspective (if you do move away from your subject) than you would get from film.

BTW, for the indoor shots on the Tak 55 try ISO 800 f/2.8 or so. ISO 1600 for moving subjects.

Venturi · 11-23-2008, 10:47 AM

Originally posted by lithos

Aw, ferf*cksakes...

We just got the lid back on this can of worms!

Yeah well... I'm guessing there's no way to weld the can shut though.

11-23-2008, 12:37 AM	#1
drewdlephone Inactive Account Join Date: Sep 2008 Location: Nanaimo, BC Posts: 261	A Fast Fifty Is Really A Fast 75mm This may be a bit if a noob question/theory, but oblige me if you will: considering the crop on all APS-C format cameras (or at least Pentax) of 1.5, our "Fast Fifty" lenses are technically 75mm or so. For those of you who have had your Fifty since you shot film, how have you adjusted to this change? Has the use of your lens changed? 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? Granted that's at the high end of normal (50-60mm if I understand correctly) but wouldn't it work better for those kinds of shots than, say the new DA55, which has an equivalent focal range of 82.5mm? As I'd imagine the DA55 will be more costly than the DA Limited 40, I figured the comparison was relevant. What are your thoughts?

11-23-2008, 01:37 AM	#3
Igilligan Guest	if you are looking for that 50mm film perspective Find a nice 35mm... The FA 35 is F2 Or if the "money is no object" applies in your world... The FA 31 ltd is the ticket.

11-23-2008, 03:00 AM	#7
Igilligan Guest	well I would trade... I have the DA 40 and I like it fine. But if I wanted the field of view of the old 50mm on film, and I wanted it a little faster, I would swap my DA 40 for the FA 35 or Da 35. The FA 35 is F2 and pretty darn sharp at f2. Some folks say the DA 35macro is one of the finest lenses out there right now... So take a look at that one too. But the Da 40 does have a 'look'. Last edited by Igilligan; 11-23-2008 at 09:52 AM.

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11-23-2008, 12:57 AM	#2
pw-pix Senior Member Join Date: Oct 2007 Location: Geelong Photos: Gallery Posts: 138	It makes the 50mm just about useless for my photography. It isn't a focal length I like using and don't have much need for it. I have a 28mm which is more generally useful to me, but it's a stop slower.

11-23-2008, 01:45 AM	#4
ariahspam Forum Member Join Date: May 2008 Location: Lima, Peru Posts: 68	A fast 50, in aps-c would be looking at the 28-35mm range. And it is true they aren't as fast, cheap and widespread as the film 50's. The closest would be sigma 30mm 1.4. The DA*55 is designed to be a portrait lens, mimicking the film 85mm.

11-23-2008, 01:48 AM	#5
Sean Nelson Veteran Member Join Date: Sep 2008 Location: Vancouver BC Canada Posts: 353	Originally posted by drewdlephone A Fast Fifty Is Really A Fast 75mm There's enough confusion going around regarding what the "crop factor" really means that I think this is a misleading statement. I would phrase it as "A Fast Fifty really has a 75mm field of view". I usually use my SMC-M 50mm f/1.4 only when I have a special need to restrict depth of field at longer subject distances. As you alluded, I find that it's frequently too long to use in low light situations since these are often indoors where it's difficult to back up far enough to frame the subject. But it is terrific for head-and-shoulder shots. 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. For low-light indoor shots I usually find myself using the DA35 or DA12-24. While slower than the fast fifty, the wider field of view (which makes hand-held shots easier) and the ability to shoot up to about ISO 800 with no appreciable noise means that I don't miss the faster lens all that much.

11-23-2008, 02:42 AM	#6
drewdlephone Inactive Account Join Date: Sep 2008 Location: Nanaimo, BC Posts: 261 Original Poster	Originally posted by Igilligan Find a nice 35mm... The FA 35 is F2 Or if the "money is no object" applies in your world... The FA 31 ltd is the ticket. I'll keep an eye out for the first one. Would it end up being as good, optically, as the DA Limited 40? Originally posted by Sean Nelson: here's enough confusion going around regarding what the "crop factor" really means that I think this is a misleading statement. I would phrase it as "A Fast Fifty really has a 75mm field of view". I usually use my SMC-M 50mm f/1.4 only when I have a special need to restrict depth of field at longer subject distances. As you alluded, I find that it's frequently too long to use in low light situations since these are often indoors where it's difficult to back up far enough to frame the subject. But it is terrific for head-and-shoulder shots. 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 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. I find my Tak 55/1.8 is just about useless for anything except portrait shots, and for that, it excels. Taking low light shots of my cats or indoors just doesn't work as well as I'd like.

11-23-2008, 09:19 AM	#8
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	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. 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"? The standard focal length on the APC-C format DSLR cameras that we use is ~28mm, so the closest thing that Pentax makes to a normal lens is the 31/1.8. I suspect that if the 30mm project ever sees the light of day, the 31 will go out of production. The 30mm had better be an f/1.4, though with Pentax's propensity for making slow primes, I'm not holding out much hope..... As far as what has changed for me with the move to digital, my 50mm lenses are now portrait lenses, my 35mm lenses are now my standard lenses, etc. What hasn't changed for me is the way I think about focal lengths. Whan I shot 3 different film formats, my 50mm lens was not a 24mm lens, nor was it a 17mm lens. My 105mm lens was not a 50mm lens, nor was it a 35mm lens. My 150mm lens was not a 90mm lens, nor was it a 50mm lens. And if you find the above to be a bit confusing, you might perhaps realize why I think the whole multiplication factor thing is a really stupid way to think about focal lengths. Learning what a focal length does on the format being shot is more than just doing some arithmetic in your head.

11-23-2008, 09:33 AM	#9
roentarre Veteran Member Join Date: Oct 2006 Location: Melbourne, Australia Posts: 11,783	Still 50mm will have the perspective of the 50mm instead of 75mm

11-23-2008, 09:51 AM	#10
Venturi Veteran Member Join Date: Mar 2008 Location: Tulsa, OK Photos: Gallery Posts: 2,636	Originally posted by Wheatfield 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"? 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.

11-23-2008, 10:18 AM	#11
jsherman999 Veteran Member Join Date: Dec 2007 Photos: Gallery Posts: 8,237	Originally posted by Venturi 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. The whole reason this persists is because many people spent years getting used to the FOV of 35mm lenses on film bodies - what to expect to see in the frame when you put a certain lens on. So I don't think it's surprising to realize that a FOV conversion procedure needs to happens in people's heads still, it's natural. I never really shot 35mm film SLRs, so to me, a 50mm is a 50mm is a 50mm, but if I had shot film, it would probably take me a little while to get used to 'seeing' in the new FOV vernacular, and discussion of crop factor would be pertinent. .

11-23-2008, 10:27 AM	#12
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	As someone who didn't come from a lot of experience with film: Yeah, 50mm doesn't seems a generally useful focal length. Nice for some kinds of portraits, and the wide aperture is nice for that too. But otherwise, when it comes to low light, ISO 1600 performance from modern DSLR's is good enough that one could claim f/2.8 is the new f/2.0, even f/1.4. Maybe I just don't know what I'm missing, but it seems that with a 28/2.8 and/or a 40/2.8, I can do most of what used to be possible with a 50/1.4.

11-23-2008, 10:34 AM	#13
lithos Inactive Account Join Date: Oct 2007 Location: Brisbane, QLD, AUS Posts: 3,261	Aw, ferf*cksakes... We just got the lid back on this can of worms!

11-23-2008, 10:39 AM	#14
troyz Veteran Member Join Date: May 2008 Posts: 389	Originally posted by drewdlephone This may be a bit if a noob question/theory, but oblige me if you will: considering the crop on all APS-C format cameras (or at least Pentax) of 1.5, our "Fast Fifty" lenses are technically 75mm or so. For those of you who have had your Fifty since you shot film, how have you adjusted to this change? Has the use of your lens changed? Well, it's been a few weeks since I shot film. . . let me think. . . (1) I use a different lens as my "fast normal" lens on APS-C (I use an FA31; the FA35 would be my second choice and I also read good things about some of the 28s) (2) I have to subtract one f-stop from the DOF scale on FA lenses when I'm using APS-C (e.g. use the f/5.6 marks when shooting at f/8) 50-ish lenses are still great for APS-C; you'll just get a tighter composition (if you don't move away from your subject) or different perspective (if you do move away from your subject) than you would get from film. BTW, for the indoor shots on the Tak 55 try ISO 800 f/2.8 or so. ISO 1600 for moving subjects.

11-23-2008, 10:47 AM	#15
Venturi Veteran Member Join Date: Mar 2008 Location: Tulsa, OK Photos: Gallery Posts: 2,636	Originally posted by lithos Aw, ferf*cksakes... We just got the lid back on this can of worms! Yeah well... I'm guessing there's no way to weld the can shut though.