HD PENTAX DA AF 1.4X AW Rear Converter

I'm thinking about this TC after having just bought a DA*300. However, after using the DA* for just a few days on the K-3, I'm wondering what gains the TC would bring? The sharpness and focus accuracy of the DA*300 on my K-3 is nothing short of staggering to me - I don't know if I've been lucky to drop on a particularly good copy, but I can take a shot of a Robin at 40 feet away, crop it and still see feather details! I'm not sure if any loss of IQ with the TC (however slight) would be a worse compromise than cropping the image, particularly taking into account the reduction in light transmission, less reliable AF etc. that the TC would bring.

One consideration is whether I can do without my 150-500, which although excellent, cannot compete with the DA*300 for IQ. The Siggy at around 470mm is sharp, but the 300 beats it when cropping to the same magnification.

I know a lot's been said already, but I'd be interested in views on whether the DA*300 plus TC produces better IQ than DA*300 alone and cropping, bearing in mind it will be used primarily on the K-3.

Regards
David

I must admit I thought the same David, the price of the teleconverter was almost identical to the difference I would have to pay if I had part exchanged my K-5II and grip for a K-3 and grip. The extra megapixels on the K-3 give you as much cropping power as the converter on a K-5 so I would have thought it's only worthwhile if you plan to print large and need the extra file size.

Or you need to photograph a Robin at 60 feet

And no, I don't think you dropped on a particularly good copy of the DA*300mm ... from what I have seen they are all like that.

Loosing the Sigma is another matter, I have considered selling my 50-500mm OS but sometimes having a long range zoom in your bag can be most helpful.

Thanks for the considered response Mike, very useful information. I'll have to think long and hard about whether or not I should sell the Siggy, I'm reluctant to do so because I do like it.

Regards
David

I'm reading with interest as I have exactly the same questions.

Took the plunge when the price dropped dramatically.
Here a quick and dirty moon shot comparison with my usual workflow (click it to go large).
The straight 300mm shot needed almost nothing done to it. The converted shot was significantly softer and didn't respond well to my usual processing.
In this scenario, the up-sampled 300 shot was at least as nice I think. Which is astonishing really.
I'll upload the raws 'dreckly'.

I posted the following in another, and probably not the best, place, so can anyone here comment:

Anyone done a direct comparison between the Pentax 1.4x & the Sigma 1.4x with the long Sigma zooms (100-300 F4, 150-500, etc.)?

PS: I know it will probably not work with the HSM versions of these lenses.

Thanks in advance.

John

PS I meant to say that the Sigma does not appear to work with HSM lenses whereas the Pentax does

I suspect the benefit will come to wildlife photographers who need to heavily crop, at the point where the image without the TC would be close to getting pixellated, the TC image giving that bit more latitude.

I think it will also be very useful for butterfly and dragonfly pics, to fill the frame a bit more. I'm also going to try the 300 with a 2x TC with the glass removed, but with the aperture contacts, to see if this is more effective than using the Pentax 1.4 TC. The only downside to this will be manual focus.

Regards
David

get an "empty" PZ 2x and AF should work fine. I've tried it.

Yes, arguably doubling the effective pixel count of their sensor (32 MP for a K-5! There will be losses of course but it does reinforce your general point about heavy cropping, if the lens quality is there in the first place.

Good point, I've just bought one and may remove the glass as I think this may be more effective than using it with glass in. Even with a manual focus 2x 'sans glass' focussing is pretty easy in manual mode and the closer focussing with no loss of IQ is a real boon.

Regards
David

SO is the 1.4x better than just cropping on a k-3?

Yes I think so

Just a quick update on this point, I have recently bought a Kenko 2x PZ-AF converter and found that it does not Autofocus with the Pentax SDM lenses, including the DA*300. This is nothing to do with aperture or loss of light as the camera states 'MF' as soon as the converter is attached. Not sure why this is, but the contacts cannot be right. It does work fine with the Sigma 150-500 and Sigma 17-70 HSM lenses though.

Regards
David