[quarc]

I just wanted to report I have tried stacking the new converter. The main reason is I was a bit disappointed there was no 2.0 launched. That would have been the ideal combination for my 200, 300 and 60-250. So when they finally arrived 1.5 weeks ago, I bought two :-)
One of course works great, but how does two actually work.
First some technical limitations. The camera does not recognise there are stacked converters, so inly multiplies the focal length ones.... That is a pity as it will give the wrong information to SR. I have no idea if this is a bug, or if it is a technical limitation with the way Pentax lenses communicate.
I did expect AF not to work on my DA300 or at least to be very poor, and I was right. I managed to get the focus to lock, but it took a lot of time and could not always be trusted. IF you manage to get the focus right, the combintation actually delivers decent quality.
Attaching a photo, ISO 1600, no tripod at full and 100% crop. One without noce reduction and one with (and a bit more sharpening).

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[leungclj]

thanks for the info!
my x1.4 just arrived in the mail, I have always wondered what stacking the two would be like.

[quarc]

I am definitely going to use stacking more...but preferrable on a tripod, and with enough time to focus... It is definietly not for sport (on the 300 or 60-250).

[reytor]

Do you have any f2.8 lens (not important what focal length) to test autofocus on one of those?

[jpzk]

I just wanted to report I have tried stacking the new converter. The main reason is I was a bit disappointed there was no 2.0 launched. That would have been the ideal combination for my 200, 300 and 60-250. So when they finally arrived 1.5 weeks ago, I bought two :-)
One of course works great, but how does two actually work.
First some technical limitations. The camera does not recognise there are stacked converters, so inly multiplies the focal length ones.... That is a pity as it will give the wrong information to SR. I have no idea if this is a bug, or if it is a technical limitation with the way Pentax lenses communicate.
I did expect AF not to work on my DA300 or at least to be very poor, and I was right. I managed to get the focus to lock, but it took a lot of time and could not always be trusted. IF you manage to get the focus right, the combintation actually delivers decent quality.
Attaching a photo, ISO 1600, no tripod at full and 100% crop. One without noce reduction and one with (and a bit more sharpening).

So, you now have a 2.8X TC after stacking ? Am I interpreting this right?
That must be one heck of a PITA to try to AF this combo ... on any lens.
Just for info, have you tried the stacked TC's on the DA*300/4 with manual focusing ?

JP

[Cold Iron]

So, you now have a 2.8X TC after stacking ? Am I interpreting this right?
That must be one heck of a PITA to try to AF this combo ... on any lens.
Just for info, have you tried the stacked TC's on the DA*300/4 with manual focusing ?

JP

I have, as long as I put my reading glasses so I can see clearly it works well

Woodpecker at feeder with stacked DA 1.4x tc's. Only cropping was to move the left side of frame in using LR. DA*300 f/4 x2 DA 1.4x tc (588mm)


Same woodpecker and feeder cropped about 50% using DA*300 f/4. Rainy dark weather not the best shots today


AF hunts and sometimes even gets lucky but for the most part not so much, have to switch to manual focus for a decent shot. Surprisingly the 60-250 does well in the little bit of testing I have done with it in AF and LV. Later I will test it some more.

All of my lenses need +3 fine focus adjustment. With 1 tc they take +7. Stacked +9. I need to send the K-3 in for focus adjustment but will have to wait a few months with the birds returning here don't want to be without a camera. Stacked the tc's will not work for BIF but I am stuck with the second tc due to the store return policy that I purchased it from using Amazon. Not sure what I am going to end up doing with it. For manual focus shots on wildlife looks like it will work satisfactory, but still not a Sigma 500 f/4.5 or 560mm when all is said and done.

[grahame]

So, you now have a 2.8X TC after stacking ?

No, it should be 1.4x1.4=1.96x, so about 2x TC.
The result looks very good!

[romeck]

No, it should be 1.4x1.4=1.96x, so about 2x TC.

Not exactly.
1.414113562373095 x 1.414113562373095 = 2.000000000000000

Because 1.4 is short from √2

[grahame]

Because 1.4 is short from √2

You are right. :-)

[reytor]

Hi. I'm not sure if someone noticed my note before, so I ask again if it's possible to make a test with any f2.8 lens to check if these new Pentax TC's focus reliably when stacked?
I have now only a Kenko 1.5TC and it is a nightmere even on f2.8 lens when it comes to auto focus and I was hoping I could have two of the Pentax TC's to covert a AF 300mm f2.8 into a AF 600mm f5,6

[Cold Iron]

I tried stacking both tc's with the DA*16-50 f/2.8 and also the DA*55 f/1.4. It required manual focusing for both lenses to focus reliably all of the time. They hunt for focus with the tc's stacked on my K-3, sometimes they hit focus but most of the time they don't. At least in my testing.

[audiobomber]

I stacked an HD 1.4x and Kenko 1.5x on a DA*300. AF was as bad as the Kenko alone. IQ was not up to standard (not pixel sharp). I will use the lens and HD TC from now on, and crop.

[reytor]

Thanks for the news. So I will save $600 as I will buy only one TC ...

[johnc]

Tried a stack of a HD 1.4 and AFA 1.7x. No extra detail revealed, and AF / aperture limitations were frustrating. So just using the HD going forward, it seems to me to be a fine investment so far.

[quarc]

I will try stacking on my DA200/2.8. I have not seen any reason to do it as it makes more sense (for me) to put a signle TC on the 300. But for those with only a 200 it of course makes sense, so will try. As I managed to get AF to lock even on the 300/4, I would guess it to work better on the 200/2.8, but will let you know when I have tried it.