Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-14-2019, 03:55 PM - 1 Like   #16
Loyal Site Supporter
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 13,338
QuoteOriginally posted by kypfer Quote
so whilst waiting to win the lottery I'll be carrying my 70-200mm f/2.8 + matching 2x, which may become my "default" lens
Well, good luck with that. People like WPresto have shown that the Pentax HD 1.4 TC is outstanding and only degrades the image quality by a tiny amount.

A 2x converter is a mixed blessing. Yes, you have now got in theory a 400mm f5.6, so that's okay by the autofocus module, but that extra bit of unexceptional glass getting in the way of the sensor may mean that it's a tossup whether it was better for you to leave it off and just crop in.

08-15-2019, 12:29 AM   #17
Senior Member




Join Date: Jan 2018
Posts: 293
Original Poster
QuoteOriginally posted by clackers Quote
Well, good luck with that. People like WPresto have shown that the Pentax HD 1.4 TC is outstanding and only degrades the image quality by a tiny amount.

A 2x converter is a mixed blessing. Yes, you have now got in theory a 400mm f5.6, so that's okay by the autofocus module, but that extra bit of unexceptional glass getting in the way of the sensor may mean that it's a tossup whether it was better for you to leave it off and just crop in.
No contest there ... all of my image viewing these days is on a computer screen or TV and a lot of my pictures are 100% cropped for final viewing anyway. I'll agree that some of the older converters, that are manual focus and even manual exposure, can be more of a liability than an enhancement, but my experiences with the matching Sigma EX converter on my Sigma 70-200mm f/2.8, purchased new when I bought my original *ist film camera, has always been very satisfactory!

A Sandpiper or similar at 100 yards is not a big subject, so the more pixels I can get covered by subject matter the better

I'm not shooting for National Geographic or even a local contest, I just want to be able to demonstrate a recognisable image and maybe show the differences between two similar species that were present on a particular day or take a record of something unusual or rare.

Recognising the limitations and requirements of my equipment will help me achieve this a little more regularly
08-15-2019, 01:12 AM   #18
Loyal Site Supporter
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 13,338
QuoteOriginally posted by kypfer Quote

I'm not shooting for National Geographic or even a local contest, I just want to be able to demonstrate a recognisable image and maybe show the differences between two similar species that were present on a particular day or take a record of something unusual or rare.
Just ID pictures or recording the experience? Sure.

I have an older Tamron 2x TC I don't bother to put on my Tamron 70-200 f2.8. The Pentax 1.4 works really well on it, though.

08-15-2019, 01:27 AM   #19
Pentaxian




Join Date: Dec 2011
Posts: 2,322
QuoteOriginally posted by stevebrot Quote
The analogy is useful because of the broad familiarity in photography circles with the spit-image and also because the blackout behavior is similar as the limits are tested. Also demonstrable is the how/why of AF fine adjustment works...too much stuff for discussion here.
I do agree that modern PDAF in essence is very much like the way the human user uses the prism in a split image matte screen. But I do assume few readers here will easily understand why that is.

If one understands the principle similarity it is also easy to understand that the angle at which the two half parts of the split image prisms are made in essence makes them a F5.6 or F2.8 or whatever split image thingy, because it makes them look that far to the edges of the lens.

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!
autofocus, camera, center point af, degree, dslr, field, k-1, k-70, kp, lens, mode, pentax, photography, rate, sensor, shots, subject
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
DFA 50mm 1.4 autofocus accuracy Lev Pentax SLR Lens Discussion 44 12-20-2018 04:04 PM
Autofocus Accuracy across brands - any data? UncleVanya General Photography 5 09-22-2018 11:19 AM
K-01 vs K-5: autofocus speed/accuracy in low light kamisu Pentax K-01 4 03-24-2017 04:26 AM
DA*55 autofocus accuracy robgo2 Pentax SLR Lens Discussion 7 09-02-2013 11:09 PM
Autofocus sensor sensitivity starbase218 Pentax DSLR Discussion 3 12-24-2011 05:02 AM



All times are GMT -7. The time now is 03:14 PM. | 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