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04-04-2016, 08:49 AM - 4 Likes   #1
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IN answer to the question "Can a DA*200-f2.8 handle stacked TCs.

K-3 Stacked 1.4 and 1.7 TCs

ƒ8, 800 ISO, AV


While I realize the true test of a lens is distance, not close ups, the short answer is yes, it does, it's awesome. So, in good light, I present 476mm and ƒ8 with the 1.4 TC next to the body and the F 1.7 AF converter in the middle.













It would appear the problems I've had stacking in the past were caused by not having an ƒ2.8 lens to start with. The other thing that comes to mind is, this package, going to 476mm and ƒ6.3 wide open, is a fraction the size of a Bigma. Not only that, starting at ƒ4 with my 60-250, this combo doesn't work well. My maximum reach with the 60-250 and 1.7 is 425. The maximum reach with the 300 is 510. Essentially it looks like I'm going to get all the performance of those two lenses well as the Bigma and various 500mm zooms. Compared to anything else, of equal range, this is a joy to carry, and these images are all taken hand held.


Last edited by normhead; 04-04-2016 at 08:55 AM.
04-04-2016, 09:07 AM   #2
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Nice,

and how is the AF ?

Is there an issue in case of short distance ?

Last edited by chrisfer; 04-04-2016 at 09:12 AM.
04-04-2016, 09:28 AM   #3
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Norm, which 1.7 TC? The Pentax one?
04-04-2016, 09:30 AM   #4
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How far away from you were the subjects?

This is great! The only issue (and depending on what you're shooting and where, it may not be one) is that the DOF seems to be really, really thin.

04-04-2016, 09:57 AM   #5
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QuoteOriginally posted by chrisfer Quote
Nice,

and how is the AF ?

Is there an issue in case of short distance ?
On images like this and the smaller K-3 AF points, I lifted the camera and the AF was instant, from the bird in front to the bird in back, however if you go beyond the range of the F-1.7 AF converter, you have to manually focus, and then start over, so it's either really fast or really slow.



QuoteOriginally posted by jatrax Quote
Norm, which 1.7 TC? The Pentax one?
Here's everything here.



QuoteOriginally posted by pathdoc Quote
How far away from you were the subjects?

This is great! The only issue (and depending on what you're shooting and where, it may not be one) is that the DOF seems to be really, really thin.
Between 12-15 feet.
Thin DoF is pretty much a function of long.
04-04-2016, 10:13 AM   #6
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Interesting... so the DA converter and the lens are not doing the focusing, the 1.7 sandwiched in the middle is?
04-04-2016, 10:24 AM   #7
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Yes.... thats the way it works. I guess someone could also try two 1.4 TCs for full AF and less magnification, I just don't own 2 1.4 TCs .
04-04-2016, 10:59 AM   #8
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QuoteOriginally posted by SBeck Quote
so the DA converter and the lens are not doing the focusing, the 1.7 sandwiched in the middle is?
Which carries its own advantages, as the 1.7 is "seeing" an f/2.8 lens, not the whole shebang that the in-camera AF would have to cope with. How does all this go down with quickshift?

---------- Post added 04-04-16 at 15:30 ----------

QuoteOriginally posted by normhead Quote
Thin DoF is pretty much a function of long.
One would have thought distance would minimise that, but yeah, not at the ranges you're talking.

04-04-2016, 11:07 AM   #9
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QuoteOriginally posted by pathdoc Quote
Which carries its own advantages, as the 1.7 is "seeing" an f/2.8 lens, not the whole shebang that the in-camera AF would have to cope with. How does all this go down with quickshift?
The quick shift is very nice. I'm not sure if a non-quick shift lens would be any different. Taken resting on my kitchen window, instead of the blind.

Here are a few more images from 100 feet away, uncropped


DA*200 Stacked 1.4 and 1.7 TCs/
What's everyone looking at?


Cropped to 2300x 1900 to show that I do have a redwing blackbird hanging out with the grackles.


Probably wrapping up the day, DA* 200 plus stacked TCs day, a few more from the blind, farther than the first images much closer than the kitchen window images.

All the usual suspects







Plus the first Junko of the year.



Last edited by normhead; 04-04-2016 at 06:25 PM.
04-04-2016, 11:25 AM   #10
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QuoteOriginally posted by normhead Quote
Yes.... thats the way it works. I guess someone could also try two 1.4 TCs for full AF and less magnification, I just don't own 2 1.4 TCs .

This would be very interesting. We would get 392mm with f5.6.
Small size, lightweight set. Just perfect as walkaround combo.


One question concerning your test. You mentioned it resulted in f8. But why?
f2.8 x 1.4 x 1.7 is 6.66, so I would expect something like f7.1.
04-04-2016, 11:36 AM   #11
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Norm - I'm astounded by the results. I really wouldn't have thought stacking TCs would allow for such nice IQ. Great stuff!
04-04-2016, 11:44 AM   #12
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QuoteOriginally posted by zzeitg Quote
This would be very interesting. We would get 392mm with f5.6.
Small size, lightweight set. Just perfect as walkaround combo.


One question concerning your test. You mentioned it resulted in f8. But why?
f2.8 x 1.4 x 1.7 is 6.66, so I would expect something like f7.1.
Two stacked 1.4 would also maintain the weather sealing through the whole thing (and transmit focal length to the camera, I believe?). Although putting the 1.7 in the mix is an easy way of using screw drive instead of SDM on the 200. Wonder how either of these combos is at tracking moving subjects at a distance?
04-04-2016, 12:40 PM   #13
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QuoteOriginally posted by zzeitg Quote
This would be very interesting. We would get 392mm with f5.6.
Small size, lightweight set. Just perfect as walkaround combo.


One question concerning your test. You mentioned it resulted in f8. But why?
f2.8 x 1.4 x 1.7 is 6.66, so I would expect something like f7.1.
Because it's almost 500mm and DoF is an issue. Also, I have no idea what that means. Opened the lens right up and it said said ƒ4.5, which is probably the ƒ2.8 and 1.7, but did not include the 1.4 SO I was stopped down at least 1 stop. I just guessed ƒ8. The camera said 5.6.

QuoteOriginally posted by BigMackCam Quote
Norm - I'm astounded by the results. I really wouldn't have thought stacking TCs would allow for such nice IQ. Great stuff!
I have seen so many poor results with stacked TCs, I only did this because someone asked me to. I think the difference between myself and others might be, starting with a high quality ƒ2.8 lens, and then adding two high quality TCs.

QuoteOriginally posted by SBeck Quote
Two stacked 1.4 would also maintain the weather sealing through the whole thing (and transmit focal length to the camera, I believe?). Although putting the 1.7 in the mix is an easy way of using screw drive instead of SDM on the 200. Wonder how either of these combos is at tracking moving subjects at a distance?
I so rarely have an opportunity for BiFs it may be a while before I get a chance to test this.

Last edited by normhead; 04-04-2016 at 12:53 PM.
04-04-2016, 12:49 PM   #14
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I'd be more interested in sports field distances than birds in flight, personally. Either way, I'm impressed and sorely tempted to spend some more money that I don't have.
04-04-2016, 01:33 PM   #15
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QuoteOriginally posted by normhead Quote
I have seen so many poor results with stacked TCs, I only did this because someone asked me to. I think the difference between myself and others might be, starting with a high quality ƒ2.8 lens, and then adding two high quality TCs.
Indeed, there are lenses and there are lenses I wouldn't even think to try this with anything other than an excellent lens, but you've demonstrated that if you work with decent glass, the results can be very good indeed. Honestly, if a new user had come onto the forum showing these results and claiming they were from a stacked TC setup then, frankly, I'd have been sceptical...
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