[kristoffon]

I have the 77 mm and I can attest autofocus is VERY fast.

HOWEVER, I have a K20D. Before I had a K200D and af was MUCH slower on the K200D. At least two times slower.

The 77 is a pretty small lens, as is the 70. In my experience AF speed in these screw driven lenses depends more on the body than on the lens itself.

[creampuff]

...Plus the 77 isn't as sharp wide open as the 70, so the AF system also might have a harder time for that reason.

FA 77mm not sharp wide open? Not from my experience.

[Voe]

FA 77mm not sharp wide open? Not from my experience.

I agree. Of the three FA Limiteds I have the 77mm is the sharpest wide open.

[beaumont]

I love the 77. I have not used the 70. I chose the 77 for the extra speed and FF capabilities. Having said that, if I was starting out fresh, knowing how the ISO speeds are getting better and that FF is not a large factor for me, I would likely go with the smaller, less expensive DA. (Also with the DA, you have the ability to go with the funky Pentax lens case that holds 3 DA LTD's!)
If the 70 didn't exist, the 77 would be considered perfection. If the 77 didn't exist, the 70 would be considered perfection...
Just one chubby guys opinion.

[MikePerham]

I have the 77 and decided on that one for 3 additional reasons not yet mentioned on this thread:

1. It is FF compatible, meaning I use it also on the beautiful black MX i just landed;

2. Lens hood is integrated. Once you add the hood to the 70, it looses its size advantage.

3. It is "prettier": reminiscent of some of my old Leica M lenses in shape, size and heft.

On AF speed: AF is "fast enough" for my photography, but it is true that K7+FA ltd lenses is far from being the fastest focusing DSLR outfit out there. I can see why people would want faster and the DA ltd line could well be the only way for Pentaxians to get anywhere near the sort of reactivity D300 users (for example) are accustomed to.

I can see a case for owning both. For that matter, I can see a case for owning absolutely all the ltd lenses....

Good points ...I got the FA77 to mate up with a DA15 and DA35 to have a compact/travel kit. I did cogitate on whether to go with the DA70 but the f1.8 cinched it for me. Mark makes a good point about the very limited DOF wide open but when you need it ...if you don't have it, well you just don't have it! And that particular focal length is more likely to get used at faster speeds than the 15 ...would like the 35 to be faster, but then you are trading macro focusing capability for a faster lens.

[Voe]

I had both the DA 70mm and the FA 77mm for about an year. I could not fault the DA 70mm. It's a great lens. But I could not afford having two similar focal length lenses especially when I wanted to buy other lenses as well. Keeping in mind that both lenses are FF capable,
and after much consideration and personal testing for subjective IQ I decided to keep the 77mm Limited and sell the DA 70mm.


If I have to use only one word to summarise each lens IQ I would call:

DA 70mm - Perfect!
FA 77mm - Magic!

And I think a perfect lens is easier to find than a magic lens. Hope I could help.

[roentarre]

Personally, Fa 77mm does focus accurately as it is stopped down to f2.2 while Da 70mm focuses more reliably and accurately at f2.8

On k10d, both suck.

On k20d, they are more or less reasonable for accuracy.

On k7, they are both reliable and fast enough (not as good as nikon medium level cams though)

[xhanatos]

The FA77 is probably my slowest focusing (next to the da 50-135) and least accurate focusing-AF (next to FA 50mm 1.4) on the K10D. It has improved greatly with the K-7 and I have been using the FA77 more often as a result.

[Marc Sabatella]

FA 77mm not sharp wide open? Not from my experience.

Not *as* sharp wide open. I'm going primarily be the MTF numbers in the Photozone.de reviews. It shows the 77 being *significantly* softer wide open (especially on the orders) than it is at f/4. This really shouldn't be surprising, since most lenses get better as you stop them down a bit. But it's also the case that the FA77 is softer wide open than the DA70 is. Sure, one expects this too because the FA77 is about a stop faster - but this has relevance to focus speed, since focusing is done with the lens wide open. So if the DA70 is sharper wide open (and the numbers say it is), then would also help the DA focus faster. BTW, Photozone also agrees the FA77 is the sharpest wide open of the FA limited - it's just not as sharp wide open as the DA70.

Of course, you'd expect stopping the FA77 down to f/2.4 would put it ahead of the DA70 when used at f/2.4 - but the numbers don't seem to support that, either. Photozone doesn't show the FA77 at f/2.4, but it does show it at f/2.8, and the DA70 at f//2.4 comes out almost as sharp as in the center, and quite a bit sharper than on the borders, than the FA77 at f/2.8. Assuming the FA77 performance at f/2.4 would be somewhere between its performance wide open and its performance at f/2.8, it seems the DA70 would almost certainly beat the FA77 by a pretty decent margin in both center and border resolution, comparing both at f/2.4. Although to be sure the FA77 has better center sharpness at its peak of f/4. And pixie dust and all that. So I'm not saying it isn't a great lens - obviously it is. But relevant to the point about focus speed, the fact that the DA70 *is* sharper wide open might be a contributing factor to its greater AF speed. I'm guessing it's mostly the focus throw and weight, though.

[kristoffon]

Personally, Fa 77mm does focus accurately as it is stopped down to f2.2 while Da 70mm focuses more reliably and accurately at f2.8

On k10d, both suck.

On k20d, they are more or less reasonable for accuracy.

On k7, they are both reliable and fast enough (not as good as nikon medium level cams though)

You might as well say the K10D sucks. Specially with fast primes the body does all the work, the lens just sits there. If AF is wrong it's the body's fault.

[creampuff]

Hey Mark, please don't base your opinion solely based on the tests of one website. As we know, there are sample variations however slight in all lenses and the tests while indicative, relate solely to that particular lens that was tested.

Check back when you actually own the FA 77mm Limited yourself.
Until you actually own and have used it enough, then your views carry more weight as you're not regurgitating what photozone has to say. Very easy to generalize from a single instance. No need to go at length about sharpness wide open contributing to focus speed - that's unsubstantiated bunkum imo and I challenge you to prove it.

In practice I have found the FA 77mm sharp and focuses much faster than what my eyes can react. I fail to see the point to make the comparison in focusing speed with the DA 70mm simply because the two lenses differ a lot in size, weight, design and optics. Focusing speed is also dependent on the camera body. And we all know the build quality of the FA 77mm easily surpasses that of the DA 70. The faster maximum aperture definitely helps when focusing, especially in falling light.

[Marc Sabatella]

Hey Mark, please don't base your opinion solely based on the tests of one website. As we know, there are sample variations however slight in all lenses and the tests while indicative, relate solely to that particular lens that was tested.

True.

Check back when you actually own the FA 77mm Limited yourself.

OK, but similarly, do you have the DA70 to compare with to be able to to provide at least one counterexample? Right now, photozone might be only one data point, but it's the only one we have. Seems if you want to refute photozone's conclusion, the burden of proof would be on you to provide at least one additional data point.

No need to go at length about sharpness wide open contributing to focus speed - that's unsubstantiated bunkum imo and I challenge you to prove it.

Not sure what you are saying here - are you claim sharpness wide open does *not* factor into AF speed? I can't prove it, but I thought that was common knowledge. Do you have references that suggest otherwise?

I fail to see the point to make the comparison in focusing speed with the DA 70mm

OK, it doens't matter to *you*, but obviously, *someone* is interested, or they wouldn't have asked. And others who own both have reported that the difference *is* noticeable. So I'm not sure why this seems to bother you so much.

And we all know the build quality of the FA 77mm easily surpasses that of the DA 70.

"Easily"? I don't know about that. I've used the 77 only briefly, and no doubt it's a great lens and very well built, but so are the DA limiteds. I get the sense you've never handled or used the DA70. It's an extremely well-made and high quality lens too.

The faster maximum aperture definitely helps when focusing, especially in falling light.

No doubt. Could well be that the DA70's focus speed advantage disappears below a certain light level.

[ll_coffee_lP]

The hilarity of the debating club ensues...

To the OP and the question of AF speed... for those of us who have actually owned and used both lenses, yes the DA70 is faster. That being said, the FA77 is quick also.

c[_]

[WMBP]

The hilarity of the debating club ensues...

To the OP and the question of AF speed... for those of us who have actually owned and used both lenses, yes the DA70 is faster. That being said, the FA77 is quick also.

c[_]

Thanks, coffee. I'm the OP and this is what I want to know. "Faster" is not as important to me as "fast enough." As long as the 77 doesn't have a tendency to hunt badly for focus, it should be fine for me.

I'm taking the 70 out this morning to the Dallas Arboretum. This will be my first time to take actual photos with it. I can't get the 77's wider max aperture out of my mind, but I'm going to give the 70 a try this weekend and then make my decision.

Thanks again to everybody for your views.

Will

[creampuff]

OK, but similarly, do you have the DA70 to compare with to be able to to provide at least one counterexample?

Well I do not own one but I did loan one from my local Pentax agent to demo awhile back. And yes the DA 70mm does focus a little faster, but I attribute it to the fact that the lens elements are smaller. Being smaller and lighter in weight less effort is needed for the motor to initiate AF. Practically speaking yes there is a difference, but to me it is small and not significant.

Not sure what you are saying here - are you claim sharpness wide open does *not* factor into AF speed? I can't prove it, but I thought that was common knowledge. Do you have references that suggest otherwise?

I am merely asking for proof to the assertion you had made earlier here:

...But relevant to the point about focus speed, the fact that the DA70 *is* sharper wide open might be a contributing factor to its greater AF speed...

Please let us know how a lens' sharpness wide open has any correlation to greater AF speed? I think it is you that needs to show the evidence, not me. Please don't call it common knowledge when it isn't.

OK, it doens't matter to *you*, but obviously, *someone* is interested, or they wouldn't have asked. And others who own both have reported that the difference *is* noticeable. So I'm not sure why this seems to bother you so much.

No need to misdirect by saying I am bothered when I am not.
As I stated earlier there is a difference AF speed, but to me it is not a big deal.

"Easily"? I don't know about that. I've used the 77 only briefly, and no doubt it's a great lens and very well built, but so are the DA limiteds. I get the sense you've never handled or used the DA70. It's an extremely well-made and high quality lens too.

Don't assume...
I'm not disparaging the DA Limiteds. I've owned and used a few.