Re: LR profiles...


Get the "Adobe Lens Profile Downloader" application.
There's a "smc pentax-f 35-70mm f3.5-4.5" profile listed that was created on the *ist DS.
That should be good to go.

Creating a profile isn't that difficult, but is very time consuming and needs a large space to setup and create it. (I did one for the MX-1) Use the "Adobe Lens Profile Creator" tool.

Hope that helps!
Matt

I sometimes reply "Yes, and 30 years of experience"

Like the auxiliary question "Have you modified this image on the computer?"
It's easier just to smile and say "Yes. Do you like it?"

Matt

Nigel,
The flash thinks it's P-TTL, but to the camera it is "dumb" manual. So, no, it's not P-TTL exposure from the camera's point of view.

Gareth, that's really odd that it works at all. 1/180s is the fastest speed at which the sensor is completely exposed in one go. At higher speeds the two shutter curtains travel as a slit across the frame. Consequently I would expect only part of the frame to be exposed by flash - the part where the slit is when the flash fires. However, usually the flash trigger on the camera hotshoe stops firing above 1/180s. But, alas, I don't have a K3 to verify this Am happy to try if out if someone wants to lend me one

i'm not saying it doesn't work for you Gareth, just am puzzled (knowing how both shutter and flash work!)

Matt

That's a fair summary. Flash power only (not zoom).

The Cactus also allows very short bursts 1/256 for freezing fast events - this is not HSS. You have a long-ish shutter speed and a low flash power for the shorted burst of light. It allows you to freeze drops, balloons bursting etc.

The Cactus in RX mode communicates with the flash through the hot shoe - emulating P-TTL signals tha would've come from the camera. The flash thinks it's on a camera that's doing exposure control, but it's the Cactus in RX just simulating this to provide the power control.

Cactus to Cactus is radio (2.4GHz spectrum). Their own flash gun has the radio electronics built in, and can be used as a manual master on-camera too. (It may be cheaper getting that than extra dedicated guns and Cactus RX/TX units)

Hope that helps!

Having read the manual, I'm sorry but I can't see that it does

Section 14.3 of the manual shows three usages: HDR style shots (so different flash powers), slave group sequencing, speeding up recycle time (so you can have 2 or more slaves and alternate).

The burst mode in the Cactus allows for multiple firings, but not the HSS type. The Cactus V6 will be limited to 1/180s sync speed of the dSLR.

Just to clarify: the Cactus will allow you to use TTL (analogue) and P-TTL flash guns as slaves (and i-TTL etc of other makes) as controllable manual slaves. Effectively the trigger is manual, but the Cactus allows complete control of the slaves from the transmitter's LCD panel + dials, so you don't have to jump up and down to adjust the slave power ratios etc.

I'm seriously tempted by a set of three... would make portable studio work really easy (though it's not that difficult TBH!)

Matt

Direct web-based link: app.photoephemeris.com

Interesting there is an optical-radio-optical trigger system available. Essentially it pipes the light signals down radio, popping out the receiving end as IR. Trouble is you will need two flashes and this gizmo. It's a lot of dosh for something that may well not be needed!

Aokatec AK-TTL(TX+RX) Radio Wireless TTL Flash Trigger Kit for Nikon, Canon, Pentax DSLR cameras and Speedlights. It doesn't connect to the hot shoe at all, but picks up optically.

You really need a leaf shutter in lens. The Q can cope with that and sync all the way with studio flashes. Or a 645Z

Not all radio triggers are the same. The Cactus V6 look very tempting and support higher sync speeds than most others. That has other advantages (not HSS) in that you can control other makes of flashguns and have power control from the camera.

Worth saying that HSS roughly halves the power, and a Stofen will halve again. So a GN54 becomes a bit pathetic GN13 or so! May not even be enough to make a difference in bright sunlight. Must do the maths....

Matt

There are severe limitations using HSS slave guns in bright sunlight. From experience, I wouldn't rely on it - especially if when using a light modifier the front of the flash gets even slightly obscured. The preflash communication signal is very low power (1/128 or lower) - so sunlight can overpower it, making the trigger unreliable.

It's why I suggested a cable, or other non-flash solutions, for the OP's situation

Matt

Neil,
Apologies if it came over that way... My comment on lighting principles wasn't at you at all, not being 'smart', but a comment in general (I rewrote the reply several times, and an earlier edit made that clearer). Over the years I've often heard expresions that indicate that lighting can be somehow miraculously produced with flashguns - when mostly what was needed was some basic understanding of good lighting techniques. Saves a lot on equipment too! Frustration can run very high with flashguns - especially with everything on auto.

Going back to the OP... To achieve the snoot look you don't do that in harsh sunlight of course. That technique is definitely worth learning of course.

Rightly or wrongly, my assumption was that the OP is trying to take shallow DoF images in very sunny conditions and is looking for ways to reduce the harsh look. That's definitely a job for shade and/od a diffuser.

Hope that clarifies things - I'm not knocking anyone, just sharing 30+ years of experience

Matt

Hmmm. All the demo shots are not in "harsh sunlight" - they are on cloudy days and twilight.
Maybe it'll work for you though.

:
Believe me, having a remote flash go AWOL on a shoot is no fun, and a simple reflector is infinitely easier to set up and carry.


Always better to understand lighting principles first before plunging in with flash.
Just my opinion.

Matt