[Frogfish]

But quick shift overrides the AFA's auto-focus, correct?

No Dan - the AFA can not be 'switched off' so will continually attempt to focus on half depress.

[DreTAX]

Why wouldn't you turn off half press AF and use the dedicated AF button?

[Frogfish]

Thank you, Frogfish.
In case of the pentax 1.7 TC: it doesn`t support SDM, right? So one gets regular screwdrive-speed?
Did you ever tested another type of TC, that does support SDM? Is there any noticable speedincrease?

As El Jamo says above.

I also have the Tamron x1.4 and cropping shots from the DA*300 + x1.4 to the FoV of the 300+x1.7 is almost, but not quite, at the same IQ level. The Tamron can AF for the full range of the 300 whereas the AFA only works once you've 'got it within range' which is usually quite simple and the whole process is possibly faster than with the 300+Tamron because the AFA is much faster than any camera/lens motor (having it's own 'motor' and only having to move a small element a very short distance).

The problem is always, for me when birding, when the bird is in a low contrast area (hiding in a bush for example) and the camera/lens combo can not identify the bird. Then the AFA will perpetually rack in and out as long as you have the shutter button have depressed and you have no manual over-ride.

[steve1307]

Why wouldn't you turn off half press AF and use the dedicated AF button?

Yes you can, either to autofocus when the AF button is pressed, or you can program the AF button to disable the focus on the half press of the shutter button.
I've tried both. (with limited sucess due to my own lack of coordination)

The problem is always, for me when birding, when the bird is in a low contrast area (hiding in a bush for example) and the camera/lens combo can not identify the bird. Then the AFA will perpetually rack in and out as long as you have the shutter button have depressed and you have no manual over-ride.

For those that don't have one, To use the AFA 1.7x you manually focus the lens to approximately the right range first. Then the AutoFocus Adapter should be able to very quickly lock the focus within that short range.

Kevin is highlighting a difficult thing to work around with AFA. It does rack in/out very quickly if it mis focuses on branches etc.
The problem is that there is no focus ring on the AFA 1.7 itself so you cannot manual focus it.

Of course you can overide the AFA (say using the AF button as I described above) and then use the attached lens to Manual focus but......

.......when the AFA misses, it might go in - out - in - out - in and then you stop it and you don't know where it is.

Then you try to manually focus the lens itself and you cant do it effectively because often it is outside the range of the focus throw.
Where did the elements inside the AFA stop? where they "in" or were they "out"? Will I not be able to infinity focus properly or will I not be able to focus closer properly?
Murphy's law dictates that the AFA will always stop in the wrong position for what you want to manual focus on.

Thats the only thing that annoys me about it. Quite happy with my DA*300 & 510 f4-f6.7 otherwise.

I'm not interested in the upcoming DA 560 lens at all, thats why I keep checking this thread everyday.

[audiobomber]

No Dan - the AFA can not be 'switched off' so will continually attempt to focus on half depress.

So effectively, the AFA is like putting the camera in AF-C. That's a bummer, I'd never heard that before. My usual target is a bird in tree, not an easy target for any AF system.

Why wouldn't you turn off half press AF and use the dedicated AF button?

Unnatural, because that's not how I shoot. With an AF lens, I half-press to set the focus and SR, and I'm ready to fire. The AF button is extraneous, and I would only use it with the TC, so it becomes one more thing to think about at the crucial moment; partially focus, half-press shutter for SR, press AF button, shoot. For birding, I'd much rather do what I do now with the A*300 and Kenko PZ 1.5X; half press, manually focus, shoot.

[steve1307]

So effectively, the AFA is like putting the camera in AF-C. That's a bummer, I'd never heard that before. My usual target is a bird in tree, not an easy target for any AF system.

No not like AF-C, it operates fine in AF-S mode fast and accurate in most situations (the attached lens's autofocus motor or screwdrive does nothing).

It can miss focus just like any other AF lens might do. Its just that then you can't manual focus the adapter, so you have to switch to MF or disable the AF

Unnatural, because that's not how I shoot. With an AF lens, I half-press to set the focus and SR, and I'm ready to fire. The AF button is extraneous, and I would only use it with the TC, so it becomes one more thing to think about at the crucial moment; partially focus, half-press shutter for SR, press AF button, shoot. For birding, I'd much rather do what I do now with the A*300 and Kenko PZ 1.5X; half press, manually focus, shoot.

You can (kind of) do a similar thing with the AFA and then manual focus with the lens.

If you are shooting a bird among branches and the AFA keeps locking focus on the branches then switch the camera to MF and then you can use the lens focus ring as normal.

If the AFA keeps racking in and out and wont focus you have to stop it in the right range by aiming at a "contrasty" object similarly distant then switch to MF.



I havent tried the Kenko but i've read that it's great but the DA*300 SDM (or FA*300 screwdrive) tends to overshoot in less than ideal light. Not an issue with your A*300 still MF.
BTW I'm sure you know the AFA 1.7x would effectively turn your A*300 into an autofocusing lens with focus limiter.



I wonder when(if?) the DA 1.4x SDM converter will be announced.

I guess it's unlikely to be at the same time as the DA 560.

[DreTAX]

So effectively, the AFA is like putting the camera in AF-C. That's a bummer, I'd never heard that before. My usual target is a bird in tree, not an easy target for any AF system.



Unnatural, because that's not how I shoot. With an AF lens, I half-press to set the focus and SR, and I'm ready to fire. The AF button is extraneous, and I would only use it with the TC, so it becomes one more thing to think about at the crucial moment; partially focus, half-press shutter for SR, press AF button, shoot. For birding, I'd much rather do what I do now with the A*300 and Kenko PZ 1.5X; half press, manually focus, shoot.

I would have thought asking a left handed person to shoot a right handed DSLR unnatural!
I find it natural (some training required) to use the AF button to have full control over the camera; MF & AF become equal choices in AF-S. Furthermore I also have the choice to lock exposure with the focus point through hold or release of AF button. I understand the "see saw" AF problems, similar to my DA*200 with a sdm 1.4xTC, very frustrating!
I hope Pentax get the performance/price right with this lens as they should be on a real winner. I don't really need this lens length, but just looking at it makes me want one.

[audiobomber]

No not like AF-C, it operates fine in AF-S mode fast and accurate in most situations (the attached lens's autofocus motor or screwdrive does nothing).

It can miss focus just like any other AF lens might do. Its just that then you can't manual focus the adapter, so you have to switch to MF or disable the AF

If it's not in AF-C, then I don't understand how it ignores Quick-Shift. Here's what should happen if the lens is in AF-S: I aim at a bird in the bush, the TC locks focus on a branch in front of the bird. Still keeping the shutter release half-pressed, I re-focus the lens using the DA 300 focus ring (quick-shift). I take the shot with the new focus distance.

Frogfish stated that he has no manual override, the AFA will continue to hunt for focus. I guess he means that it will hunt until it locks on something and stops, at which point QS would be useable?

I havent tried the Kenko but i've read that it's great but the DA*300 SDM (or FA*300 screwdrive) tends to overshoot in less than ideal light.

BTW I'm sure you know the AFA 1.7x would effectively turn your A*300 into an autofocusing lens with focus limiter.

I haven't tried the Kenko with a DA*300 but most reports with this combo have not been favourable. I tried the Kenko with a DA*50-135 and it was hopeless, lots of stutter and inaccurate when it locked.

I am aware that the AFA was designed to add AF to A lenses, but I have not been terribly tempted to buy one. It is not true AF, it's partial AF. I find using the MF switch on the camera annoying, and f/6.7 max aperture is not terribly appealing up here in the north country. I can't even use the Kenko in the woods on a sunny day, I have to remove it for f/4 and lower shutter speeds, especially in winter. That's why I'll probably get a DA*300 and new TC instead of the 560mm. I went to California last winter and I was shocked at the luxurious intensity of light.

I wonder when(if?) the DA 1.4x SDM converter will be announced.

I guess it's unlikely to be at the same time as the DA 560.

The new TC is on the roadmap for 2013 or later. The AFA price should plummet when the new 1.4X is finally released, and the AFA once again becomes what it was intended to be, pseudo AF for a A lenses.

[VladimirYo]

The new TC is on the roadmap for 2013 or later.

Why so long?

[audiobomber]

Why so long?

I don't know. I've never even heard an explanation of why the 1.4X TC was shown in the 2008 Roadmap and never released. Is the delay due to technical reasons, or economic reasons? I don't believe this has ever been answered by Pentax.

[TenZ.NL]

The Tamron + 300 SDM is slow. It overshoots focus and has to come back.

The 1.7x and 300 is fast. It might be faster than the 300 alone. Of course you have to pre-focus.

Very usefull, thanks

As El Jamo says above.

I also have the Tamron x1.4 and cropping shots from the DA*300 + x1.4 to the FoV of the 300+x1.7 is almost, but not quite, at the same IQ level. The Tamron can AF for the full range of the 300 whereas the AFA only works once you've 'got it within range' which is usually quite simple and the whole process is possibly faster than with the 300+Tamron because the AFA is much faster than any camera/lens motor (having it's own 'motor' and only having to move a small element a very short distance).

The problem is always, for me when birding, when the bird is in a low contrast area (hiding in a bush for example) and the camera/lens combo can not identify the bird. Then the AFA will perpetually rack in and out as long as you have the shutter button have depressed and you have no manual over-ride.

Just curious...will the AFA work in AF-c once it is locked on? And if so would it eliminate the hesitation between a subject and a busy background?

[cheekygeek]

I have a Pentax 560mm in my hand right now. It's called a Pentax-F 100mm Macro on a Pentax Q. Bet mine will be faster and focus closer than the one Pentax releases!

[coreyhkh]

I have given up on this lens and I have my eyes set on a canon 500 f4. Still keeping my Pentax though its weather sealing is hard to ignore.

[bobmaxja]

They mention 2012, as I know, still 4 months to go for this year

[Medium FormatPro]

The new TC is on the roadmap for 2013 or later

Plus might I also add in; please take a look into ones instruction books. I don't have access to my K-5 book at hand right now - so here goes on the Pentax K-01 - but the specs for lens' are about the same - except for focus speed...

For the K-01 manual; (starting on) page 232 - there's a chart - Functions available with various lens combinations,,,

On the left sde of the chart it caught my interest that... Function ~ Autofocus (lens only)(with AF adapter 1.7x) and then the asteric, which leads to... Lens with a maximum aperature of f2.8 or faster.

And this isn't the only reference to this in the book?!?

Sure it will work at any aperature, but...


I personally cannot wait until at least one teleconverter and also set of extension tubes hit the market, but... for the teleconverter - it will be optically considerably worse than even cropping the image. For those distances it might just be worth the telescope option using mostly manual settings