F & FA lens focus speeds


RJ

Link Posted 21/09/2013 - 12:33
I've noticed my F35-70 lens focuses really quickly (on my nearly new K30 - thanks Russ) whereas my DA14 2.8 is not as quick - not to mention my 18-55mm.

Does anybody know of a chart/table giving focus speed times of older F & FA lenses? One of the reasons I love the F35-70mm zoom is the speed at which I'm ready to shoot. I'm wondering if there are any other gems out there.

Rod

MattyH

Link Posted 21/09/2013 - 13:06
F 70-210mm up there with the best and faster AF then the newer lenses.

RJ

Link Posted 21/09/2013 - 16:08
MattyH wrote:
F 70-210mm up there with the best and faster AF then the newer lenses.

Thanks Matty, I've heard good things about the F70-210. Hadn't realised focus speed was one of them though.

Russ

Link Posted 21/09/2013 - 16:12
F70-210 is really speedy and great optics to boot

The newer lenses, like the 55-300, make a lot of noise but not very quick. The 50-200WR was a lot better than the 55-300 though.

The 18-55WR seemed okay too, quite nippy and no fuss.

Mongoose

Link Posted 21/09/2013 - 18:11
the Fs tend to be fast, I suspect because they're designed to work with the very early SAFOX bodies, consequently the lenses are designed for auto focus speed almost at all costs.
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RJ

Link Posted 21/09/2013 - 18:29
Mongoose wrote:
the Fs tend to be fast, I suspect because they're designed to work with the very early SAFOX bodies, consequently the lenses are designed for auto focus speed almost at all costs.

I don't understand then why Pentax didn't continue with the fast auto focus speeds when they developed the FA and DA series.

RJ

Link Posted 21/09/2013 - 18:30
Russ wrote:
F70-210 is really speedy and great optics to boot

The newer lenses, like the 55-300, make a lot of noise but not very quick. The 50-200WR was a lot better than the 55-300 though.

The 18-55WR seemed okay too, quite nippy and no fuss.

So the F70-210 is faster than the 50-200WR?

MattyH

Link Posted 21/09/2013 - 20:00
RJ wrote:
Russ wrote:
F70-210 is really speedy and great optics to boot

The newer lenses, like the 55-300, make a lot of noise but not very quick. The 50-200WR was a lot better than the 55-300 though.

The 18-55WR seemed okay too, quite nippy and no fuss.

So the F70-210 is faster than the 50-200WR?

Have owned and used both at the same time, sold the 50-200mm.......says it all

LennyBloke

Link Posted 03/10/2013 - 08:29
The focus on the F 70-210 used to worry me, I'd press the button and it felt (and sounded) as though it was about to launch the front element at the subject I was focusing on

But they are still fine quality and fast focusing - I've owned more than I can remember and never been disappointed by one
LennyBloke

johnriley

Link Posted 03/10/2013 - 08:46
It will depend on the lens in question and the type of construction.

The SMC Pentax-DA 40mm f/2.8 Limited is blisteringly fast for example, presumably because the focusing has such a short throw. The 55-300mm has a lot more work to do.
Best regards, John

Russ

Link Posted 03/10/2013 - 09:54
LennyBloke wrote:
The focus on the F 70-210 used to worry me, I'd press the button and it felt (and sounded) as though it was about to launch the front element at the subject I was focusing on



Yes its a bit brutal.

Mongoose

Link Posted 03/10/2013 - 14:43
RJ wrote:
Mongoose wrote:
the Fs tend to be fast, I suspect because they're designed to work with the very early SAFOX bodies, consequently the lenses are designed for auto focus speed almost at all costs.

I don't understand then why Pentax didn't continue with the fast auto focus speeds when they developed the FA and DA series.

this is a guess again, but because people didn't like the manual focus feel of the F series. Their focus is so loose and the throw is so short that they are very hard to focus manually. Also, people wanted features like non-rotating front elements and quick-shift focus clutches, all of which increase the complexity of the drive train and therefore make it slower.

I'd bet that a DA 55-300 on a K5II is still faster focusing than an f70-210 on an SFX
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Last Edited by Mongoose on 03/10/2013 - 14:44

RJ

Link Posted 03/10/2013 - 15:09
Mongoose wrote:
RJ wrote:
Quote:
the Fs tend to be fast, I suspect because they're designed to work with the very early SAFOX bodies, consequently the lenses are designed for auto focus speed almost at all costs.

I don't understand then why Pentax didn't continue with the fast auto focus speeds when they developed the FA and DA series.

this is a guess again, but because people didn't like the manual focus feel of the F series. Their focus is so loose and the throw is so short that they are very hard to focus manually. Also, people wanted features like non-rotating front elements and quick-shift focus clutches, all of which increase the complexity of the drive train and therefore make it slower.

I'd bet that a DA 55-300 on a K5II is still faster focusing than an f70-210 on an SFX

Yes, this makes sense. I couldn't understand why Pentax would design a backward step in terms of auto focus speeds. But if, as you say, it might be because of smoother manual focus and non rotating front elements then this makes sense.

cabstar

Link Posted 03/10/2013 - 15:12
johnriley wrote:
It will depend on the lens in question and the type of construction.

The SMC Pentax-DA 40mm f/2.8 Limited is blisteringly fast for example, presumably because the focusing has such a short throw. The 55-300mm has a lot more work to do.

Was just going to post this and saw John's reply.

The da 35mm 2.4 is super fast as it has a really short focus throw, for the same reason the da* 50-135mm is slow to focus as it has a long focus throw.
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RJ

Link Posted 03/10/2013 - 15:16
cabstar wrote:
johnriley wrote:
It will depend on the lens in question and the type of construction.

The SMC Pentax-DA 40mm f/2.8 Limited is blisteringly fast for example, presumably because the focusing has such a short throw. The 55-300mm has a lot more work to do.

Was just going to post this and saw John's reply.

The da 35mm 2.4 is super fast as it has a really short focus throw, for the same reason the da* 50-135mm is slow to focus as it has a long focus throw.

Seems to make sense in theory but my DA14mm f2.8 is slower to focus than the old F35-70 f3.5-4.5.
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