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09-08-2019, 11:12 AM   #181
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QuoteOriginally posted by normhead Quote
For me a 300 2.8 would be a better option. I use my Tamron 300 2.8 with the 1.4 TC, the 1.7x AF adapter and the Tamron NC7 2x adapter. 420 ƒ4, 510 ƒ4.5 and 600 ƒ5.6 in a lighter easier to carry package.



Not really.
I've been getting queries about the DA 55-300 on a K-1.

I took a couple screen caps to show the amount of vignetting. At 300mm vignetting is minimal and image files are typically larger after cropping than APS_c file taken with ak-3.


You can see with this image the vignetting is heavier, but still produces a 16:9 cropped 24 MP image.


The largest I can get cropping a K-3 image to 16:9 is 16 MP, so there is still a distinct resolution advantage on FF even if you can't use the whole frame. You just have to leave a bit of space around the desired part of the image. And it sure beats carrying a heavier lens.
This one taken at 108mm, but you will see similar vignetting at many other focal lengths.

Some magazine rated the DA 55-300 PLM against everyone else's comparable lenses and rated it best in class, and it's extremely quick focusing. Maybe it's Sony, Canon, Nikon, Tamron and Sigma that need to catch up. They corrected it better form the older design with more elements and groups, Does it even have competition among the other brands? Plus it was designed for a 24 MP APS_c camera, so way overkill in sharpness on a K-1.

You might be mistaken in just who need to catch up here.
Did you try the same experiment with the DA 1.4X? Does using it reduce the amount of vignetting? {I believe 'focal reducers' work by concentrating the image circle onto a smaller area, so I thought a TC might enlarge it}.

09-08-2019, 11:41 AM   #182
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QuoteOriginally posted by reh321 Quote
Did you try the same experiment with the DA 1.4X? Does using it reduce the amount of vignetting? {I believe 'focal reducers' work by concentrating the image circle onto a smaller area, so I thought a TC might enlarge it}.
No experiments here, these images from a recent camping trip. I previously decided that the DA 55-300 PLM isn't good enough to use with the TC. Some get good results with theirs, sample variation rears it's ugly head. The 1.4 TC is an APS-c version that will vignette on FF with many lenses.
09-08-2019, 10:27 PM   #183
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QuoteOriginally posted by reh321 Quote
Did you try the same experiment with the DA 1.4X? Does using it reduce the amount of vignetting? {I believe 'focal reducers' work by concentrating the image circle onto a smaller area, so I thought a TC might enlarge it}.
In theory, but the DA concerter doesn't cover FF AFAICR.
09-11-2019, 08:55 AM   #184
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Btw, there's an old thread about an D FA 400/4:
Pentax - Thoughts on making a DA*/DFA 400mm F4? - PentaxForums.com

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