[bdery]

50 1.7 is sharper, but the 50 1.4 is better.

Wrap your head around that one

Better at bokeh, not better all around

and *IS* sharper than the 1.7 when you stop it down to f5.6.

My experience contradicts this, but we're REALLY splitting hair here.

i just want to clarify that i am talking about the F (and not the FA) version of 1.7 compared to the newest FA 1.4

The F and FA 50s are similar. The F50 f1,7 can be had for between 200 to 225$, the f1,4 usually sells for around 275$ (used in both cases).

The main purpose of a fast 50, to me, is to shoot nearly wide open. For that task the f1,7 is better. Beyong f2,8 they are so close to one another that it's almost impossible to decide which is the sharpest. But the FA50 macro beats both of them. The f1,4 produces slightly smoother bokeh, and has a warmer colour cast (that's not better or worse, just different). I'd say you would be extremely happy with either.

[RioRico]

The main purpose of a fast 50, to me, is to shoot nearly wide open. For that task the f1,7 is better.

And here is a point of disagreement. We don't use f/1.2-1.4 lenses for wide-open sharpness; we use them to grab light, to capture what's otherwise impossible, and for the DOF control. An f/1.7 just doesn't offer that extreme performance.

A simile:

* f/2 is a soccer-mom minivan.
* f/1.7 is a business sedan.
* f/1.4 is a sports roadster.
* f/1.2 is a top-fuel dragster.

(And f/1.0 is a rocket sled!)

Pentax no longer makes minivans nor sedans. Of course my simile is flawed because the f/1.4 *can* also haul the same load as the f/1.7, ie work extremely well a tighter apertures. IMHO the f/1.4 is just more useful.

It's early morning now. In a couple hours I'll drive over Kit Carson Pass again for some brief business in Carson City NV. I'll stop to shoot gorges and cascades along the rocky portion of the Carson River; I'll stop in the pioneer settlement of Genoa to shoot some history; I'll return past Lake Tahoe; and I'll take my FA50/1.4 because it's the tool that can capture dimly-lit artifacts, and moving faces and faces, and vivid mountain'scapes. Other days, I'll take my various 50-55/1.7-1.8's out for a walk, to see how they see. But I don't depend on those. I depend on faster glass, that can do what they do, and more.

[Just1MoreDave]

This thread may be totally baffling to the OP, but it sure makes me feel better about keeping both an F50/1.7 and an A50/1.4.

I notice the OP has the M50/1.7 and therefore suggest the FA50/1.4 is a good choice for him. (The M is just about the same as the F50/1.7.) The FA is something different, and he can decide whether those differences are good or bad.

[bdery]

And here is a point of disagreement.

I find it very pleasing that we can disagree with such civility. I appreciate and respect your arguments.

We don't use f/1.2-1.4 lenses for wide-open sharpness; we use them to grab light, to capture what's otherwise impossible, and for the DOF control.

That's where we somewhat agree AND disagree. For me, using my previous A50 f1,4 wide open was unacceptable because the results were not pleasing to me. I feel more comfortable using my f1,7 wide open than my f1,4 at f2. So I do, and because of this the f1,7 is actually the lens letting me shoot at the widest.

In other words, you are willing to accept a decrease in sharpness to get more light in; I'm not.

For DOF control, nothing beats my macro lens, and the difference between f1,4 and f1,7 is too small for me to notice anyway.

thanks for the discussion.

[paperbag846]

In other words, you are willing to accept a decrease in sharpness to get more light in; I'm not.

I suppose that is the point I am attempting to argue.The importance of sharpness is way overblown if you ask me. Many wonderful, famous photographs are no where close to sharp. And then there are the photos I take, which are neither wonderful nor famous, but bring a smile to my face. The 1.4 allows me to take what I see to be a more pleasing photograph. Smoother, creamier, nicer colours. The sharpness thing barely plays a part in it for me. The trick with the 1.4 is setting the focus properly... easier said than done.

If this mugshot does not convince you, I don't know what will!!!

f1.4, 1/60th, ISO 1100.

[Blue]

And the F 50/1.4 is allegedly the best of the Quartet in sharpness etc.

Photodo scored the MTF of the F 50/1.4 at 4.6 tied with the F 50/2.8 macro and the F 50/1. at 4.4 and the FA 50/1.4 at 4.2. Those are good scores as were the specific scores. However, the also scored the A 50/2 at 4.0 which was a bit of a surprise. I would have guessed it to come in at 3.6 or 3.7.

Camera Lens Search - Find Camera Lenses

Keep in mind though that most tests are from single lens samples and is hardly statistical.

[paperbag846]

Keep in mind though that most tests are from single lens samples and is hardly statistical.

I also think that for the most part, it's pure placebo effect. The FA 50 scores higher sharpness at f5.6 than the DA 40 at f5.6, but the DA 40 is constantly said to be sharper. I think its because the DA 40 has more contrast and more vibrant colours (and more even sharpness across the frame). But, overall, the FA 50 is *sharper* in the purest sense.

However I think that you can't actually see the difference, and even if you can, it counts for a lot less then bokeh rendering, colours, contrast, etc.

In other words, you hear that X Is sharper, and you see that X is sharper. It's purely psychological. However, in my experience you need to find a real DOG of a lens (likely a consumer zoom from the 70s or a VERY BAD prime) to see a lens that has unacceptable *sharpness*. The other things, like CA, colour, contrast, flare resistance... those are much more apparent.

This is why I think the FA 50 is worth it (also, the recent used prices of 275 are not a hard and fast rule... I'd bet you could find it much closer to the asking price for the F 60 1.7 if you look hard enough). The sharpness wide open might suffer a little, but in my humble opinion, all of the other features (including raw flexibility) are superior in the FA 50 1.4 (not to mention the smoother manual focus ring on the FA series).

[bdery]

in my experience you need to find a real DOG of a lens (likely a consumer zoom from the 70s or a VERY BAD prime) to see a lens that has unacceptable *sharpness*. The other things, like CA, colour, contrast, flare resistance... those are much more apparent.

Sharpness is but one element defininf image quality. Its importance is different for each person. for me for instance, even though my 18-55 WR is more than good enough, it is easy to spot pictures taken by it instead of, say, my DA21 or more dramatically my FA50 macro. Even my Sigma 17-70 is very much sharper. And it means that while I have no trouble using the 18-55 in situations warranting WR (that's whay I bought it) I will not use it when IQ is more important.

[Pentaxor]

I also think that for the most part, it's pure placebo effect. The FA 50 scores higher sharpness at f5.6 than the DA 40 at f5.6, but the DA 40 is constantly said to be sharper. I think its because the DA 40 has more contrast and more vibrant colours (and more even sharpness across the frame). But, overall, the FA 50 is *sharper* in the purest sense.

what does this to do with the 50/1.7 comparison? the DA40 is not the 50/1.7.

[paperbag846]

what does this to do with the 50/1.7 comparison? the DA40 is not the 50/1.7.

I hear the same sort of stuff about the 50 1.7. I was drawing a parallel example. You can find the MTF scores for all of these lenses out there. The 50 is sharper than all of them, or just as sharp, or not really different-sharp (to be the most honest). It's likely other rendering differences that would make you prefer the 1.4 or 1.7, not *actual* sharpness.

[Pentaxor]

I hear the same sort of stuff about the 50 1.7. I was drawing a parallel example.

it would be interesting to see where you have heard of such and see some practical basis on it. a parallel example with not the actual lens is not a real comparison nor could we get an actual comparative measurement. it is like substituting a Jaguar for a Ferrari on comparing against a Mercedes.

You can find the MTF scores for all of these lenses out there.

where exactly? can you provide the link?

The 50 is sharper than all of them, or just as sharp

could you be more specific what 50mm it is and what you are comparing it with?

[RioRico]

I find it very pleasing that we can disagree with such civility. I appreciate and respect your arguments.

Oh, I can discuss things civilly, EXCEPT WITH SLIME-SUCKING GOAT-SMELLING PEA-BRAINED AMORAL F/1.7 LOVERS!! Present company excluded, of course.

[/deranged sarcasm]

But I digress. Yes, it comes down to what we like and what we don't. As mentioned, IQ has many components. We may variously value those components according to our individual tastes, preferences, obsessions, delusions. And sometimes IQ doesn't matter. My mantra there: A perfectly-shot image of boring crap is still boring crap. And: Any picture you get is better than any picture you DON'T get. If the 50/1.4 gets me that picture, that's all that matters. As long as it's not boring crap. I shoot enough of those anyway.

[kanzlr]

For DOF control, nothing beats my macro lens

care to explain why?
I know that with increasing magnification DOF gets smaller. But for subjects, say 2m away, a 50/2.8 macro lens will definitely not give you the same shallow DOF a 50/1.4 can give you

so, unless you want to photograph the hairs in my nose, the 1.4 is more flexible here.

[paperbag846]

where exactly? can you provide the link?

Nifty 50 Shootout on Pentax K-7 (updated 1/22) ERPhotoReview

Have a look.

[RioRico]

For DOF control, nothing beats my macro lens

care to explain why?
I know that with increasing magnification DOF gets smaller. But for subjects, say 2m away, a 50/2.8 macro lens will definitely not give you the same shallow DOF a 50/1.4 can give you

so, unless you want to photograph the hairs in my nose, the 1.4 is more flexible here.

No interior nose shot here, please. Not without a Hoya-Pentax endoscope.

Oh sure, macro is good for DOF control! The right macro, anyway. I do great with the Novoflex Noflexar 105/3.5 EL on my Bellowscope. But yeah, with any 50/2.8, DOF only thins-out around 40cm. That's pretty close for most portraits, eh?

I want to bring up one of my favorite subjects: Divide a lens's Focal Length by its APerture (FL/AP) and you get a number, the DOF index. Different lenses with similar FL/APs will have similar DOF. The higher the number, the thinner the DOF. The FL/AP does NOT say how thick or thin the DOF is; it's just a comparison. So 50/1.4 and 77/2 and 100/2.8 and 135/4 and 200/5.6 all have about the same DOF. A moderate 135/2.8 has rather thinner DOF than does a superfast 50/1.2 or fast 85/2.

And my 105/3.5 EL and a 50/1.7 are virtually the same -- except the EL focuses closer. Yeah, good for nose-hair shots...