[Digitalis]

I just think the main reasons to get fast lenses have to do with faster shutter speeds and increased sharpness at similar apertures.

but it is also to get greater sharpness at wider apertures E.G: the SMCP-K 50mm f/1.2 is considerably sharper in the corners than the SMCP-A 50mm f/1.7 at f/2.8 . Faster lenses still have to be stopped down to achieve their optimum sharpness, but they hit that peak at a wider aperture than a slower lens would. Also most faster lenses give a photographer more freedom to work with available light, and a brighter viewfinder. I prefer to stick to ISO 100 on my DSLR cameras the use of an f/1.2 lens gives me that ability*.


*of course subject matter has a strong bearing on whether an f/1.2 aperture is appropriate or whether more DOF is needed.

[Pentaxor]

Of course there is a difference, I just think the main reasons to get fast lenses have to do with faster shutter speeds and increased sharpness at similar apertures.

that is one great reason. although something's gotta give if we were to illustrate DOF equivalence in restrospect to focal length, FOV, speed, and background bokeh. lenses could show the same amount of DOF but not without any noticeable effect with the factors mentioned.

[TOUGEFC]

In addition to the larger aperture's of the FA vs DA debate, shallow DOF control is alot more important to some, some people will find that f/2.4- f/2.8 is more than enough for their need's, while others it wont be enough, and thats where the FA LTD has the appeal.

eg- shot of mine on my wedding day, taken with FA77 @ f/1.8

[Impartial]

but it is also to get greater sharpness at wider apertures E.G: the SMCP-K 50mm f/1.2 is considerably sharper in the corners than the SMCP-A 50mm f/1.7 at f/2.8 . Faster lenses still have to be stopped down to achieve their optimum sharpness, but they hit that peak at a wider aperture than a slower lens would. Also most faster lenses give a photographer more freedom to work with available light, and a brighter viewfinder. I prefer to stick to ISO 100 on my DSLR cameras the use of an f/1.2 lens gives me that ability*.


*of course subject matter has a strong bearing on whether an f/1.2 aperture is appropriate or whether more DOF is needed.

Part of the issue between FA and DA is this business of stopping down. Many would argue that, for corner sharpness especially, the DA 70 equals the FA 77 at f2.4, and the DA 40 equals the FA 43 at f2.8. Which limits the debate again to DOF (and rendering, of course.)

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Last edited by Impartial; 12-23-2010 at 09:36 AM.

[Ash]

Part of the issue between FA and DA is this business of stopping down. Many would argue that, for corner sharpness especially, the DA 70 equals the FA 77 at f2.4, and the DA 40 equals the FA 43 at f2.8. Which limits the debate again to DOF (and rendering, of course.)

Let's see then:
going by measureable IQ numbers only from Photozone we have:

Vignetting
FA 43 at f/2.8 = 0.24 stops
DA 40 at f/2.8 = 0.9 stops

FA 77 at f/2.8 = 0.25 stops
DA 70 at f/2.8 = 0.67 stops
(No f/2.4 numbers available for FA 77, but out of interest - at f/1.8 = 0.7 stops whilst for DA70 at f/2.4 = 0.8 stops)

MTF (centre/corner)
FA 43 at f/2.8 = 2311/1993
DA 40 at f/2.8 = 1995/1979

FA 77 at f/2.8 = 2121/1954
DA 70 at f/2.8 = 2099/1987

CA
FA 43 at f/2.8 = 1.24 px
DA 40 at f/2.8 = 0.24 px

FA 77 at f/2.8 = 0.15 px
DA 70 at f/2.8 = 0.38 px

Interestingly the DA 40 gets much better overall scores from Photozone than the FA 43 in exactly the same way the DA 70 got rated compared with the FA 77. This all despite the numbers for the FAs significantly beating those of the DAs apart from CA between the FA 43 and DA 40. I do realise that IQ is more than these figures but from these figures alone we can see that the DA 40 does not equal the FA 43 at f/2.8 and neither does the DA 70 with the FA 77.

[paperbag846]

I do realise that IQ is more than these figures but from these figures alone we can see that the DA 40 does not equal the FA 43 at f/2.8 and neither does the DA 70 with the FA 77.

Since price/performance is 1/3rd of his rating scheme, I can understand why the DA ltds. get a highly recommended, while he recommends the FA litds with reservations.

Clearly the FA ltds preform statistically better in some ways, but the value of those gains are going to be personal choice. For *my* purposes, the snappy AF beats the fact that the FA 43 is 14% sharper in the center at f2.8 (to use the most significant difference you quote as an example), and that decision was compounded by the price difference.

I don't think anyone would argue that the DA lenses are overall better than the FA's, unless one was to consider price a major factor (most hobbyists do), or believe that ergonomics trump IQ for their particular type of photography (snappy AF, quickshift).

The verdict on the FA ltd's. value is going to be a very personal thing.

Therein lies the greatest difference between the lines. The DA ltds give you very sharp rendering, on par or exceeding the pro zooms at a very small fraction of the size, with better handling, and faster AF (generally). They are very modern lenses built with a modern mentality, for the demographic who is accustomed to zooms dominating SLR use. The FA ltds., on the other hand, are more specialized, permitting greater DOF control, unique rendering, and a more oldschool tonal palette. They are prestige lenses, and come with a prestige price. Of course, the FA ltds. are also infinitely more useful on film.

[GregX999]

Being the OP, the first 4 or 5 pages made me feel like I made a snow-ball and started it rolling uncontrollably down the mountain. But I think in these last few pages I've really been able to zero-in on the "real-life" differences between the two series.

So thanks for hashing it out so "thoroughly".
(Not that you need my thanks...)

I had a DA70 but wasn't super-happy with it. It sounds like the FA77 might fit me better, even though it's a bit more $$$.

And it sounds like I might want to try a DA40 eventually and see how it stacks up against the Sigma 30 I have (A fast, but rather large lens, with no quick-shift and AF that tends to hunt a bit).

Greg

[Impartial]

Let's see then:
going by measureable IQ numbers only from Photozone we have:

Vignetting
FA 43 at f/2.8 = 0.24 stops
DA 40 at f/2.8 = 0.9 stops

FA 77 at f/2.8 = 0.25 stops
DA 70 at f/2.8 = 0.67 stops
(No f/2.4 numbers available for FA 77, but out of interest - at f/1.8 = 0.7 stops whilst for DA70 at f/2.4 = 0.8 stops)

MTF (centre/corner)
FA 43 at f/2.8 = 2311/1993
DA 40 at f/2.8 = 1995/1979

FA 77 at f/2.8 = 2121/1954
DA 70 at f/2.8 = 2099/1987

CA
FA 43 at f/2.8 = 1.24 px
DA 40 at f/2.8 = 0.24 px

FA 77 at f/2.8 = 0.15 px
DA 70 at f/2.8 = 0.38 px

Interestingly the DA 40 gets much better overall scores from Photozone than the FA 43 in exactly the same way the DA 70 got rated compared with the FA 77. This all despite the numbers for the FAs significantly beating those of the DAs apart from CA between the FA 43 and DA 40. I do realise that IQ is more than these figures but from these figures alone we can see that the DA 40 does not equal the FA 43 at f/2.8 and neither does the DA 70 with the FA 77.

I would see those numbers differently. I am surprised by the DA 40 light dropoff, as I did not ever notice it in using the lens, but I wonder how these numbers would compare with, e.g., the FA 43 or 77 vignetting on 35mm, which I would expect to be more significant.

What I would say about sharpness is that the DA 70 ties the FA 77 at centre and corner sharpness at f2.8, while the DA 40 ties the FA 43 at corner sharpness at f2.8, but is bested (as is well known) in the centre, the FA 43 centre resolution being legendary.

For CA the DA 40 clearly beats the FA 43, while the FA 77 (surprisingly) edges out the DA 70 -- are the problems of the FA 77 only evident wide open?

So to me this is not "the DA lenses do not equal the FA lenses at f2.8" -- the DA 40 loses centre sharpness (and light falloff, if this is significant) but "wins" CA, while the DA 70 and FA 77 come essentially to a draw.

[Ash]

but I wonder how these numbers would compare with, e.g., the FA 43 or 77 vignetting on 35mm, which I would expect to be more significant

Results aren't comparable between an APS-C lens on an APS-C sensor and a FF lens on a FF sensor. The results are what they are on APS-C - the only useful comparison in FF is to have the DA 70 and DA 40 measured on a FF sensor as well.

are the problems of the FA 77 only evident wide open?

No, have a look at Photozone's results and be even more surprised... It's the PF that lets the FA 77 down (if you think of it that way) - most applications of the FA 77 don't test the lens's PF tolerance.

So to me this is not "the DA lenses do not equal the FA lenses at f2.8 -- the DA 40 loses centre sharpness (and light falloff, if this is significant) but "wins" CA, while the DA 70 and FA 77 come essentially to a draw

See it however way you want - if you're happy with the results you get with the lens, then all else doesn't matter. Objective measures are what they are, nevertheless.

[Impartial]

Results aren't comparable between an APS-C lens on an APS-C sensor and a FF lens on a FF sensor. The results are what they are on APS-C - the only useful comparison in FF is to have the DA 70 and DA 40 measured on a FF sensor as well.



No, have a look at Photozone's results and be even more surprised... It's the PF that lets the FA 77 down (if you think of it that way) - most applications of the FA 77 don't test the lens's PF tolerance.



See it however way you want - if you're happy with the results you get with the lens, then all else doesn't matter. Objective measures are what they are, nevertheless.

My point about vignetting is that "acceptable" vignetting on 35mm, as seen in the FA Limiteds wide open, is probably notably more than either FA or DA limiteds deliver at f2.8. So I would take the "significantly higher" DA 40 result with a grain of salt, especially since I never noticed it in actual photography.

And if the "objective" tests don't show the FA 77 purple fringing then they have missed the major weakness of that lens. I would be quite interested, e.g. in an objective test of PF between FA 77 and DA 70.

And my point about the objective measures at f2.8 is that they show a difference in vignetting -- of which I am unsure of the relevance -- and on the rest of the measures the FA 77 and DA 70 are a wash while the FA 43 wins centre sharpness (only) and the DA 40 wins CA. To me, the statement "the DA limiteds do not equal the FA limiteds at f2.8" is essentially misleading, since one's conclusion depends entirely on how one values different elements of performance.

[Ash]

To me, the statement "the DA limiteds do not equal the FA limiteds at f2.8" is essentially misleading, since one's conclusion depends entirely on how one values different elements of performance.

The value of performance lies solely in your results with the lens. So you can dismiss all the objective tests that you like, which doesn't change the findings, but in the end, as mentioned before, it's all about the lenses meeting your needs and you being pleased with what you get out of them.

[Impartial]

The value of performance is solely on your results with the lens. So you can dismiss all the objective tests that you like, which doesn't change the findings, but in the end, as mentioned before, it's all about the lenses meeting your needs and you being pleased with what you get out of them.

But I am not dismissing the tests (except perhaps the vignetting measurement, for which I would like some context). For the sharpness and CA measurements, I am not dismissing the tests, I am disputing your characterization of them. They do not show the FA limiteds to be better at f2.8 -- they show the 77 and 70 to perform very similarly, and the 43 to have better centre sharpness and worse chromatic aberration than the 40. Objectively, that is simply not an unequivocally better performance at 2.8 from the FA limiteds.

Of course, I agree that the proof is in the pudding, and in reality the better lens is always the one that enables the photographer to take better pictures. And in that, sharpness and CA may play very little role . . .

[Ash]

Of course, I agree that the proof is in the pudding, and in reality the better lens is always the one that enables the photographer to take better pictures. And in that, sharpness and CA may play very little role . . .

Then there's no point to any of these objective tests, and I'm even sorry I brought them up... time to move on...

[whojammyflip]

I've seen similar posts on here before: quite an emotive topic, rife with confirmation bias. Strikes me that once quality of a lens rises above a certain threshold, its no longer the weakest link in the chain, which means that the quality of the photo is being limited by a different factor, other than the lens.

[Cambo]

Of course, the FA ltds. are also infinitely more useful on film.

Film...?



What's that, grandpa?



Cheers,
Cameron