[Serkevan]

I think lenses definitely do not scale well with cost. You could easily take pro level photos with non pro priced gear if you have a bit of skill.

Pareto principle in play, as usual. Getting the main part of it (moderately fast aperture with good center resolution, usable corners and moderate aberration control) incurs a fraction of the engineering cost of a corner-to-corner sharpness monster with little to no aberrations at very large apertures.

And even if we ignore the non-linearity of cost/performance, there is such a thing as overkill. I'd wager that the overwhelming majority of photographers are not pushing their lenses to the absolute limit. And no, pixel-peeping does not count - I'm talking high quality prints, displays in large high resolution screens and extreme cropping.


You won't see much* difference between the D FA* 50 and the F-50/1.7 in an f/2 image printed at A4 size, I'd say...


*Okay, I'm gonna contradict myself: somehow the 77 is straight up magical and makes beautiful images but that's not just sharpness at play. Fairy dust is real

[GUB]

It is fairly entertaining to see the different schools of thought at war.

Yeah but it is not entertaining to have to concede defeat
I wonder how many others presumed those graphs were for a set EV

[stevebrot]

Yeah but it is not entertaining to have to concede defeat
I wonder how many others presumed those graphs were for a set EV

Probably me...normalized to EV100 of course.


Steve

[GUB]

Not to mention that of contemporary 50/1.4 variants. The Pentax 55/1.8 (2.0) and 50/1.7 lenses generally equal or better the performance of their f/1.4 siblings at the same apertures. The D FA* 50/1.4 is stellar, but in practical terms...perhaps not worth the weight and money.


Steve

I thought this test was interesting. I wonder if it reflects the difference between an 8 and 7 element super tak.
SMC Pentax-FA 50mm f/1.4 Review | ePHOTOzine
Pentax FA 50 1.4

Attached Images

 

[ZombieArmy]

I thought this test was interesting. I wonder if it reflects the difference between an 8 and 7 element super tak.
SMC Pentax-FA 50mm f/1.4 Review | ePHOTOzine
Pentax FA 50 1.4

I would love to see a comparison with the 7 element tak, however I don't think it'd be as dramatic as that example because of the radioactive doping. I'd assume the 1.4s became worse around the k to m series onwards.

What I think is kind of interesting is just how much worse the FA 50 1.4 is at f2 compared to the 55mm f2 tak in both center sharpness and edge sharpness.

I think the moral of the story is just buy Taks.

[stevebrot]

I'd assume the 1.4s became worse around the k to m series onwards.

The 7-element design was refactored for the A-series lenses and has remained the same since.


Steve

[GUB]

What I think is kind of interesting is just how much worse the FA 50 1.4 is at f2 compared to the 55mm f2 tak in both center sharpness and edge sharpness.


Depends what you mean by "worse" . I feel the large edge sharpness dropoff by the 8 element with the centre remaining sharp is a real bonus. This end of the apertures is an art lens , stop down to f4 and you have a landscape beauty.

The 7-element design was refactored for the A-series lenses and has remained the same since.

By "refactored" do you suggest resized rather than redesigned?

[Ian Stuart Forsyth]

I wonder how many others presumed those graphs were for a set EV

What do you think iso is its an exposure value index, for a given iso the camera setups the cameras metering system and processes the images lightness for that exposure value

---------- Post added 11-08-2020 at 03:17 PM ----------

In that case agreed - in practical application increasing the iso does not decrease the dynamic range.
Then the sole gain of utilising iso-invariance is having more control over the tone curves. ie bringing up shadows to the equivalence of say iso 3200 while still being able to hold the bright end back .

If there is not clipping at the higher iso then you still can hold back the highlights at the top end of the raw file

---------- Post added 11-08-2020 at 03:22 PM ----------

Ah, that is the thing - when talking about lower DR at higher ISO the assumption is that the shutter speed will be faster, to keep exposure constant. In that scenario, you will need more gain and therefore suffer from shadow detail loss.

But that was not discussed when responding to GUB
"GUB;5112769]If you process a one stop lower iso one with +1EV in post processing then yes you have an identical image noise wise.
But the lower iso shot has a higher dynamic range which you can harvest via the curve tool creating more tonal control in the image."

To me this is telling me that if Shoot the camera at iso 100 and iso 400 that they will have the same noise but the iso 100 shot will have more DR and this is not the case

[stevebrot]

I feel the large edge sharpness dropoff by the 8 element with the centre remaining sharp is a real bonus.

Do you have test results for the 8-element?

By "refactored" do you suggest resized rather than redesigned?

Sorry for the jargon. The lens was redesigned within the constraints of its Planar roots. The A-series and later still have seven elements, but the design has been tweaked. From the K-mount Page Web site (LINK)

7-element Super/S-M-C/SMC Takumars, K/M-series Pentax 50/1.4*



A/F/FA-series Pentax 50/1.4



Steve

* Despite difference in body physical size, the K and M-series 50/1.4 share the same optics.

[GUB]

Do you have test results for the 8-element?

The first test was the 8 element . I should have stated that at the time. I have edited it now

[GUB]

If there is not clipping at the higher iso then you still can hold back the highlights at the top end of the raw file

And that is the issue in many images - keeping the highlights in -especially if you are entrusting it to your metering.
In the lower light bush photography that I enjoy highlight control is paramount.

[ZombieArmy]

Depends what you mean by "worse" . I feel the large edge sharpness dropoff by the 8 element with the centre remaining sharp is a real bonus. This end of the apertures is an art lens , stop down to f4 and you have a landscape beauty.

I don't think I mentioned the 8 element

[GUB]

I don't think I mentioned the 8 element

Yeah sorry true. But the same thing applies - did they design the fast fifties to be more of an "art" lens?
And how much of the overall sharpness difference is sample variation?

[stevebrot]

did they design the fast fifties to be more of an "art" lens?

Back then, there was no such thing as an "art" lens. Dreamy was the look you got at the lower end pricewise.


Steve

[GUB]

Back then, there was no such thing as an "art" lens. Dreamy was the look you got at the lower end pricewise.


Steve

But this is not "dreamy". It would be a sad thing today if these fast fifties performed like the f2.
And history repeated itself with the introduction of the rock solid M50 1.7 - I suspect it's chart would be like the 55 f2 with perhaps a little drop off on the last half stop.
So for extra money both times, instead of the kit lens, you could have the f1.4 and end up with a lens with more "character" at the open end.
I guess with the limited iso range back then that extra stop would have been a godsend despite the fact it would have been a miracle to nail the focus.