Slow AF?


Link Posted 14/02/2010 - 11:32
johnriley wrote:
I was looking at a Tamron 70-300mm on a Canon 350D on Thursday and the focusing on this was positively lethargic. No zip at all.

It makes me wonder where this change in perception has originated as 99% of the time AF does what it days on the box.

AF speed depends on the lens and the camera. The Tamron 70-300mm is relatively slow to AF because of the way it's geared, and the 350D is a low end model.

I believe some of the more recent Canons and Nikons - mid models - do AF more quickly than a Pentax K20D or K-7 when used with a similar lens, mainly because they more often jump straight to point in one move rather than taking several steps like Pentax often does.

I find Pentax AF-S fast enough, but could do with more accuracy and consistency. There is definitely room for improvement there.

The fastest AF I've experienced was an old Pentax-F 28-80mm (non SMC) on a K20D. That was violently fast.


Link Posted 14/02/2010 - 11:41
K10D wrote:
Mike-P wrote:
But truth be said, I miss the good old days of pentax oh the memories, particularly of some heated debates around here

The good old days?
You only had a Pentax for around 12 months

Then better to have used and left than never used at all?


Thank you K10 . its not the amount of days I had it but the number of times I used it. Rarely used it on machine gun mode but during those months i had it I clocked around 30 thousand actuations. Perhaps I should say oh the old good days when I used to lock myself in the shed for days on end with a few sandwiches and a cold drink in a peaceful retreat .


Link Posted 14/02/2010 - 11:45
At least you had pictures on your Flickr site when you had a Pentax Amin .. I rarely see anything from your 7D on there.
No equipment list here but thanks for taking an interest. My Flickr


Link Posted 14/02/2010 - 11:55
I think calling the Pentax AF slow must be a bit misleading as most pentax users are quite happy with it and achieve everything that they want from it, and even some manage to focus accurately and fast enough as many using D300s and 7Ds.

I think the question is only if someone wants to adapt themselves and learn ways that are not straightforward to lock the AF on the subjects or not.

For most things usually D300 and 7D users just have to aim and AF and it gets there faster than the pentax. But let me tell you one thing that prehaps only a 7D or D300 user knows, to achieve that little extra that many people sometimes think that you can get from the 7D or D300 camera and lenses if they think its just purely the same way as point and press the shutter release button then they will have a huge disappointment. And I am sure there are a few who changed systems who might have started finding this out, and then regretting moving over sacrificing other better aspects that the Pentax gear has in comparision to their new kit.

In order to take full advantage of the faster Af system of the 7D for example is quite complicated. The tweaks and menu systems and so many small details that one has to be constantly on top of it and keep changing depending on circumstances its enough to put someone who doesn't like to keep dwelling and learning and updating on it totally off. Unless you are prepared to do it then forget about a generally faster system than the pentax. I have seen many who just jump into a system simply because they thought Ahh, faster AF and then keep complaining that they can't lock focus on a moving subject. Forget flying birds and moving cars, I know some complain even of not locking AF on moving kids. And then they keep complaining also that they were better off with their older models.
So, overall its not exactly plain sailing. I am absolutely sure that a good proportion of people who move systems they just do it without properly researching and have higher expectations and then regret it.
Amin Photo Gallery
Last Edited by aminstar on 14/02/2010 - 11:59


Link Posted 14/02/2010 - 12:01
Mike-P wrote:
At least you had pictures on your Flickr site when you had a Pentax Amin .. I rarely see anything from your 7D on there.

The ones I have done lately are not suitable for my flickr page

Besides, I just did it because I like white lenses ....
hey,,,, just joking, I am not racist
Amin Photo Gallery


Link Posted 14/02/2010 - 14:16
Amin how big is the focus throw on some of your Canon lenses compares to your DA*50-135, I've a feeling that Pentax lenses have a larger throw then others but I might be very mistaken by that.
I asked that because for example the DA40 is a real speed demon, it can focus to close up to infinite and back in less then a second and it looks it's so because of the small focus throw.

aminstar wrote:
Besides, I just did it because I like white lenses ....
hey,,,, just joking, I am not racist

Oh but Pentax have also some white lenses some of the FA* series for example.
Pentax even got some silver lenses and multi coloured ones.

K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
Last Edited by Anvh on 14/02/2010 - 14:18

Daniel Bridge

Link Posted 14/02/2010 - 14:17
ChrisA wrote:
For aircraft in flight, the K10's AF is more than adequate. For birds, I really don't think it is.

Obviously it depends on the birds and the situation, but I wouldn't necessarily write the K10D off for bird pics.

I've had a number of occasions recently which have pointed out to me that Canon's AF system needs as much input from the photographer as any other system.

Several weeks ago I was doing a tuition day in a camera shop, and had two separate people (one with a 40D, one with a 50D) ask me "why are so many of my shots out of focus?".

An acquaintance of mine recently got herself a 50D, popped out to take some shots to show me, and half of them were woefully out of focus (and when I tried it, it seemed to want to focus on anything but what I was pointing it at, although admittedly that was using auto focus point selection).

Finally, I was giving tuition to someone with a 1D mk2 and was shocked when it was focusing on things in several steps, as in: focus a bit, stop, focus a bit, stop, focus a bit, stop, focus a bit (nearly there by now!), stop, focus a bit - focused! That was with a Tamron zoom, but even so...

I'm not saying these people wouldn't get different results from any other camera, just that the idea of Canon's AF system being foolproof, or some sort of holy grail, is clearly a myth.

K-3, a macro lens and a DA*300mm...


Link Posted 14/02/2010 - 14:40
Being a very newby to DSLR coming over from a Fuji Finepix S100fs bridge camera I do find it funny that everyone is so touchy about Pentax's so called failings. I couldn't make up my mind between a K20d because of the WR or a d300. I take a lot of pictures at my local Karting track monthly meetings and sometimes it rains. But the fps of the K20d compared to the d300 leant me towards nikon, then came the announcement of the K7 ... 5.2 fps my attention was then attracted towards Pentax again. I spent months pouring over the K7 reviews (never finding a bad one) and this forum looking at example shots from the K7 and the K20d and I have to say that even though there may be faster AF or fps cameras do they really make that much difference and is it something you use that often.
As a pre season test I took the camera to the track for an evening endurance to see if I had made the correct decision .. you be the judge link. Also while out walking with the wife last weekend I came across a man flying one of thos fancy kites so popped on the sigma 70-300 and took about 100 ish pics only 4 were out of focus and i can assure you his kite was whizzing about ... great exercise for the neck muscles.
If someone could tell me how to attach a photo I would give you some examples
My Flickr link

"Life is what happens to you while you're busy making other plans" (John Lennon)


Link Posted 14/02/2010 - 14:41
is there any actual proof that one system is faster or is it all hearsay

I would have thought it is just practice,practice practice,practice with shooting birds and fast moving objects



Link Posted 14/02/2010 - 15:06
Many issues discussed.
I haven't tried all systems but I have used my K10D, and tried 40D, K20D and D80.
When I tried the 40D it was with an L USM lens. It was noticeably faster than the D80 or K20D.
So no, its not just hearsay.
However, it is noteworthy, than both D80 and K20D had kit lenses on them.
So what people generally talk about is what the best in the brand can do. And the best in the brand for Canon and Nikon are clearly superior to best in Pentax.
However, how many of the forum warriors own, will own or will ever need the best in their brand? Hmmm. Its like school yard children fighting about who's brother is bigger and meaner.

For many, most, photographic subjects speed of autofocus is not relevant. Accuracy however is, including in low light.

There is a lot of claims which in truth make little sense. Especially when advising new DSLR buyers. Pentaxians aren't exempt. WR is great but not relevant to everyone. Not everyone, expecially beginners will want to tinker with manual lenses or search the used market for old lenses... So Pentax's baskwards compatibility means little to them.
These things do work for me, that's why I like Pentax, and that's why Pentax is right for me.

Some people will need speed, and they may find that some brands work better than others...


Link Posted 14/02/2010 - 15:47
pink wrote:
is there any actual proof that one system is faster or is it all hearsay

There are quite some tests around also when Pentax DSLR is in AF-S then it does a double check as one of the few, to make 100% sure that it's in focus.
When you set it in AF-S then it does only a single check making it slightly faster but less accurate.

Also it depends on what lens you use if it's fast or not and the light conditions, when it comes to low light Pentax seems to be closer to the rest focus speed is a bit slower still but it locks on just a bit more often.

We are not of course talking about top end cameras here but all in the same league.

I'm sure that if you google you will find some tests.

K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55


Link Posted 14/02/2010 - 17:14
just trying to come to terms why we use the excuse of old equipment for the lack of patience/knowledge to

nail a shot.If you are into fast movement/sports/wildlife photography then perhaps we should be using the knowledge of our camera i.e the strengths/weakness, work the shot and be satisfied with the way we have controlled the situation.

Failing that we would always be part of the what if !! crowd.

We are suckers for technology from the very moment we bought digital.Marketing divisions know this is our weak-point, hence the 8-10 fps, iso 102000, the different metering/afc etc we are seeing on new products every 12=18 months.

I'm not against a better product which will improve our enjoyment and in that I mean in this case photography,
but to upgrade for the sake of owning something that may have the new bells and whistles not withstanding the extra costs seems a poor way to wards our enjoyment.

I wondered if anyone read an article about a year ago relating to a professional guy when after his death, his relatives
clearing his property found a garage full of golf bags with new clubs. They just could not come to terms why he had all of this equipment until they asked the Club where he played at for the reasons for this unlikely hoard,
their answer was that every time he had a bad day he would blame it on the clubs he was using and bought a new set that he have seen advertised that would improve any golfer's game.

My apologies for the rambling no offence meant!!

I would like to believe the reason we visit and post here is because we use Pentax products and know and enjoy the product,
the strength / weakness and sometimes frustration that goes with our enjoyment.

There are not many forums that are like this one for openness and product loyalty.



Link Posted 14/02/2010 - 17:29
What's AF? Oh yes, that 18-55 standard lens which languishes in the bottom of my kit bag. None of my other lenses are so blessed, so it's thumb and forefinger of left hand needed to ensure sharpness. And I choose which part needs sharpest focus, not a machine.

(Mind you, I tend only to shoot things which don't move much, so what do I know about it?)

Love my Pentax, though!


Best wishes,


"These places mean something and it's the job of a photographer to figure-out what the hell it is."
Robert Adams
"The camera doesn't make a bit of difference.  All of them can record what you are seeing.  But, you have to SEE."
Ernst Hass
My website:


Link Posted 14/02/2010 - 17:30
And to think this thread started because someone asked why the DA* 50-135mm focus is so slow. I went over to my sons house today to see his new Husky pup and took my K10D and 50-135mm f2.8. I also took the Sigma 70-200mm f2.8 so as to compare the two lenses on AF speed.

Now this may be down to the K10D but the Pentax lens was terrible, it took an absolute age to lock (if it did at all) and by that time the dog had moved .. the Sigma on the other hand was a lot faster and locked every time. In the end I resorted to manual focus on the 50-135mm.

Whether Pentax are that far behind in the AF stakes is debatable but SDM certainly does not help the cause.
No equipment list here but thanks for taking an interest. My Flickr
Last Edited by Mike-P on 14/02/2010 - 17:34


Link Posted 14/02/2010 - 17:33
The press see the current AF system on the Pentax range, notice it hasn't changed for twentyodd years and assume it's old fashioned and slow.

What they don't do is compare like for like on similar bodies!

You can't say Pentax are slow if your comparing a standard 18-55 on a K-x with a USM 400 on a 7D.

Try comparing the K-x and standard lens with a EOS450 and standard lens then you see the difference.

Last time I stood next to a Canon user my K200d and Sigma 18-200 were focussing quicker than his White thing on his 450!
Cheers, HG

K110+DA40, K200+DA35, K3 and a bag of lenses, bodies and other bits.

Mustn't forget the Zenits, or folders, or...

I've some gallerieshere CLICKY LINK! and my PPG entries.
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