Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-23-2016, 02:35 PM   #1
Loyal Site Supporter




Join Date: Sep 2010
Location: Madrid
Photos: Gallery
Posts: 30
K-1 and Pentax DA 1.4 converter: surprising results

Well we were told that the DA 1.4 converter was not full-frame compatible. Sure enough it does cause quite a big of vignetting on the Pentax DA 300mm f4 lens. But the news is not all negative.

As far as I can see, the Pentax DA 100mm Macro works fine with the converter attached, with practically no discernible vignetting. Need to check the image quality of course, but previous reports suggest that it should be good. Will be interesting to hear the results from other users. Having an additional working distance would be a big plus for this superb macro lens, which is light an easy to hand-hold.

But perhaps the biggest surprise was with the Pentax DA 55-300 mm zoom. As expected, it had quite a lot of vignetting when used on its own with the K-1, but practically no vignetting at all focal lengths when used with the converter. Hopefully, other users can check this out and confirm with real-life results. (I have not had time to do this yet as the camera has only just arrived.)

Conclusion: with the K-1, the DA 1.4 converter might be quite a useful tool to have in the camera bag, especially if we wish to travel light.

05-23-2016, 02:50 PM   #2
Pentaxian
Tjompen1968's Avatar

Join Date: May 2012
Location: Norrköping, Sweden
Photos: Gallery | Albums
Posts: 1,307
Used with the 150-450 it introduces vignetting. Removes almost all vignetting on the 16-50 and all on the 10-17. IQ vice... It feels like it is not adding any value, no more detail when used with the 150-450, no matter the aperture used.
05-23-2016, 03:02 PM   #3
Senior Member




Join Date: Jun 2010
Photos: Albums
Posts: 132
QuoteOriginally posted by Tjompen1968 Quote
Used with the 150-450 it introduces vignetting. Removes almost all vignetting on the 16-50 and all on the 10-17. IQ vice... It feels like it is not adding any value, no more detail when used with the 150-450, no matter the aperture used.
To my knowledge, a TC never adds detail, just increases FL.
05-23-2016, 03:09 PM   #4
Loyal Site Supporter
Quartermaster James's Avatar

Join Date: Nov 2015
Location: Anchorage, Alaska
Posts: 599
So, with the K-3, the advice regarding the TC with the 55-300 has been to forgo the converter and to crop instead. Does this change with the K-1?

05-23-2016, 03:10 PM   #5
Loyal Site Supporter
RockvilleBob's Avatar

Join Date: Dec 2011
Location: Lewes DE USA
Photos: Albums
Posts: 1,633
With a little luck we can hope for a Pentax 1.4 TC for the K-1......in less time than it took for the DA 1.4
05-23-2016, 03:14 PM   #6
Pentaxian
Tjompen1968's Avatar

Join Date: May 2012
Location: Norrköping, Sweden
Photos: Gallery | Albums
Posts: 1,307
QuoteOriginally posted by ybo1 Quote
To my knowledge, a TC never adds detail, just increases FL.
In that case, why use them? Easier just interpolate in photoshop instead?

Please clarify.
05-23-2016, 03:14 PM   #7
Moderator
Loyal Site Supporter
BigMackCam's Avatar

Join Date: Mar 2010
Location: North East of England
Posts: 6,062
QuoteOriginally posted by Quartermaster James Quote
So, with the K-3, the advice regarding the TC with the 55-300 has been to forgo the converter and to crop instead. Does this change with the K-1?
This is a long-debated topic... I wonder if anyone has done any resolution tests on cropped images vs those with the TC? And, potentially, other TCs?
05-23-2016, 03:33 PM   #8
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 9,737
QuoteOriginally posted by BigMackCam Quote
This is a long-debated topic... I wonder if anyone has done any resolution tests on cropped images vs those with the TC? And, potentially, other TCs?
Not a formal test but you can see the FA* 300 on my K-3 with and without the AF 1.7x TC in this thread I posted:
https://www.pentaxforums.com/forums/12-post-your-photos/321782-night-moon.html

The two were not identically processed to the nth degree so that could be a minor factor also. However they were taken in the same night minutes apart and with the same body/lens at the same effective F/stop - not the same amount stopped down. (as far as I recall).
They were taken with 2 second self timer on a carbon fiber tripod and autofocused with manual tests to confirm that this was working well prior to allowing it to be done. (PDAF not CDAF).

I realize this may be a bit off the full topic but it should be a bit helpful.

05-23-2016, 03:43 PM   #9
Moderator
Loyal Site Supporter
BigMackCam's Avatar

Join Date: Mar 2010
Location: North East of England
Posts: 6,062
That's interesting, @UncleVanya - I missed that Moon post of yours originally. Thanks for the links
05-23-2016, 03:44 PM   #10
Pentaxian
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 10,612
QuoteOriginally posted by BigMackCam Quote
This is a long-debated topic... I wonder if anyone has done any resolution tests on cropped images vs those with the TC? And, potentially, other TCs?
I think there were some threads about this with certain lenses. I think with a good quality TC, the TC was slightly, but not by a lot, better than just cropping in PP. With those no-brand cheap TC, the difference was not apparent by eye, at least not to most people.

Similarly, APSC cameras were slightly better than taking a FF shot and cropping it, at least in regards with super telephoto (the test subjects were birds, if i remember right)

Edit: that said, yes, TC does not technically add detail. It only magnifies the lens in front of it. This also means that the lens you use is very important, specifically the amount of detail it can render
05-23-2016, 04:33 PM   #11
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 9,737
On the plus side you are magnifying the best (central) part of the image and spraying it over a larger number of pixels than you would have put it over had you simply cropped. However that also means that if the detail was never captured then it has less data to work when when interpolating the image so it may end up being moot or not any sharper. To my eye the FA* 300 with the f/1.7 might be a SLIGHT bit sharper but then I look again and reverse myself. I think it's a toss up at least on the K-3.
05-23-2016, 04:53 PM   #12
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 24,662
QuoteOriginally posted by ybo1 Quote
To my knowledge, a TC never adds detail, just increases FL.
That isn't knowledge. That is a wives tale concocted by people who should know better. A very simple easy test deproves it. Honestly, there is no excuse for posting this kind of info without supporting images. If you'd taken a half hour of your life to find out if it was true, you'd know better. Detail is determined by focal length and lens quality, not by whether or not a TC is used. The TC makes practically no difference. A simple test would show this.

Mind you, it could be true, if you shoot with really cheap lenses, like something that was a cheap 3rd party product from 30 years ago. But any modern lens is sharp enough to benefit from a TC.

And even old consumer glass, like my A-400 benefits from a TC.

Last edited by normhead; 05-23-2016 at 05:00 PM.
05-23-2016, 05:00 PM   #13
Site Supporter




Join Date: Feb 2015
Photos: Gallery
Posts: 626
As the Pentax 1.7x was made for full-frame wouldn't it be expected to improve compatibility of attached lenses? I'd expect the Tamron-F 1.4X Pz-AF MC4 is also full-frame but not 100% certain.
05-23-2016, 05:34 PM   #14
Site Supporter




Join Date: Jun 2013
Location: Newcastle
Photos: Gallery | Albums
Posts: 1,463
I did a little testing in this thread (and didn't get too many trolling comments - which often happens when you touch on the TC issue).

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/309566-tele...on-x1-4-a.html
05-23-2016, 05:54 PM   #15
Site Supporter
Shanti's Avatar

Join Date: Jul 2012
Location: Western Denmark
Photos: Gallery | Albums
Posts: 903
The Pentax 1.4 TC works fine on the DA70,on DA*300 vignettes a bit,On DFA150-450 not so good,at least for BIF..must check with the 1.7 AFTC later
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, check, converter, da 1.4 tc, dslr, full frame, full-frame, k-1, k-1 and pentax, k1, lens, pentax, pentax da, pentax k-1, results
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Serialnumbercard of Pentax-DA 1.4 AW AF Rear Converter Tau-Ceti Troubleshooting and Beginner Help 2 03-09-2016 12:30 PM
Is the Pentax HD DA 1.4 Converter truly Full Frame compatible? johnmb Pentax K-1 31 02-27-2016 10:59 PM



All times are GMT -7. The time now is 06:48 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top