Friday, February 27, 2009

DA* 55/1.4 Vs FA 50/1.4 - A Measurebating Shootout

Here is a very interesting shootout on the two "similar" Pentax lenses of different generations with some unique and effective measurebations:-

The test report is concisely and clearly written and all the findings and observations are self-explanatory. Still, I extract some of the more interesting sentences below which I would add the comments of mine:-

"Disclaimer: This is a test by a layman, who does not really know what he is doing."

This guy is surely not a layman! His tests are cleverly and carefully designed. They are all simple and effective. I have rarely seen people who could do such excellent works at that high level! He even measured bokeh and has been able to qualify the difference in an easy way! He also plotted the spatial frequency charts which give us a general idea on the MTF response and changes from low to high spatial frequencies! "Layman"? :-o Well, he is just an humble guy who does not like to say loudly (unlikely me ;-D). Indeed, I would say he is just an excellent "measurbator"! (Thumb Up)

"AF Speed: The big disadvantage of the DA55 is that it is much slower compared to the FA50 in AF speed (measured using Audacity). The DA55 is about 3 times slower than the FA! I am wondering why this is so and what Pentax has to say about it. Isn't it a confession of failure that an almost 20 year old lens focusses so much faster?"

Oh, yes. Why's that? The SDM was found to be slower, but now this time it is even *much* slower!!? It is not about the travel and throw of the mechanical movement range of the focusing part of the lens, nor it is about the weight of the lens element to be focused, as it is found that:-

"Throw of the focussing ring:
FA85: ca. 90 degrees (superfast AF)
DA55: ca. 110 degrees (slow AF)
FA50: ca. 120 degrees (fast AF)"

So, the FA 50 has longer travel but the FA* 85 undoubtedly has much heavier glass, but neither of them is as slow as the DA* 55. Now, the culprit? IMO it *must* be the SDM, which is inferior in terms of speed (weak torque?), which is even much slower than the old type Pentax body-driven screw-type AF! (but why?)

Circle of confusion in the background:
(below the brightness across the ring is shown)"

He simply plotted the lightness response curve and it shows the "bright ring" bokeh which quite some Pentaxians have been puzzled about (provided that they know it)! Amazing! Well Done, Mr. ! You're my Hero!

And, his series of bokeh test shots are well thought and well done. More importantly, they are simple enough but yet clearly presented.

In the end, I don't think the DA* 55 is anything that really worth to invest, with its three time higher price tag than the old FA 50. Yes, it is somehow sharper from corner to corner when the lens is wide opened. Except this, there is no clear advantage optically and in image quality. But what's the real point for a portrait lens to have corner to corner sharpness when wide opened?

Furthermore, it is bulkier and heavier and subjectively I regard the outlook of the lens is Ugly, and so do all the DA Star lenses. In contrast, the FA Star lenses are beautiful (Sad). And yes, it is weather sealed and has the USM. But so what? Especially considered that the USM focuses rather sloooowly despite it is *almost* silent (but not totally). And, as the tester said, it is really ridiculous to have a lens made almost 20 years later, it is yet focusing far slower than a lens made with the technology of late 80s! OMG!


Anonymous said...

This is business. It follows the same pattern in every kind of industry. New product is NEW, is meant to replace the old one - built using technologies which are no longer in use. And yes, it cost 3x more then the older version of the same product. Every company does that!Arguing about it is pretty childish, it's like saying there's no point in paying for a new car cause despite some few gadgets it's pretty same as the one you own since 20 years.

And DA*'s aren't ugly :] I like the new look, but also understand your "diss everything from Pentax" philosophy...


RiceHigh said...

Isn't the FA 50 "from Pentax" then?

Anonymous said...

Come on Rice, all you have to admit is that you are getting a little old and the world has turned since you were a young and enthusiastic pentaxist. It does the same to me sometimes. I was a music lover teenager in the 90's and now I don't like the music listened by the kids of today... It's just like you and the DA lenses... as simple as that.

Anonymous said...

DA*55 is a bit slower than FA50/1.4,
it's truth. but not 3 times :). AF is very smooth and silent. resolution is close to FA43. maybe it's one of the best Pentax lens in terms of resolution. very good contrast and color from f1.4

RiceHigh said...

I think I still like some of the new music and pop songs nowadays but of course many of my favourite songs are older ones.

As for the DA*55 Vs the FA 55, I think it is not about the sentiment of old Vs new, but the above test does reveal something. Anyway, I am not convinced about the price and size/weight differences for what we would gain with the new Star. And, the slower AF of the SDM of the DA* is yet a really disappointing thing.

You may be right for what I don't like the latest appearance of those Pentax Star lenses, though - that's just a matter of taste anyway.

Anonymous said...

Tried DA*55. AF is very smooth and silent. Very cool. It makes effect of slow AF. But, it's not fast lens. But not very slow. Normal.
As for optical performance - no doubts - it's the big success of Pentax.

Yes, micro-SDM of Pentax is close to Canon micro-USM. Pentax has no ring motor.

Anonymous said...

Just one remark - DA*55 works faster at K-m.

Anonymous said...

The most likely reason that the DA*55 is slower to auto focus is the added friction from the weather seals.

RiceHigh said...

Weather sealing has nothing to do with AF. Just internal focusing with SDM/USM has already isolated the glass elements well mechanically from outside without any speed penalty, e.g., Canon L lenses are lightning fast in AF and yet they are all weather sealed.

Anonymous said...

Rice, try DA*55, it's not slow. Not fast.
AF speed is usual, but not slow.
SDM is the most silent motor in the world.
As for speed - DA*55 is not slower than FA77.
But smoother and quieter.

Anonymous said...

Jim said...

Most people on the forums agree that it is rather slow. This is poor.
Even if it would be as fast as the FA50 I would consider it poor. The FA50 is 20 years old.
I would expect some improvement in technology since then.
Giving excuses doesn't help.

RiceHigh said...


Anonymous said...
Rice, relax. It's the best Pentax lens ever made.

Benjamin said...

I agree that thee FA 50 1.4 is a much better value than the 55 f1.4 which is way over priced. Quality wise very similar.

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