Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-13-2018, 05:33 AM - 1 Like   #1
Pentaxian




Join Date: Dec 2011
Posts: 1,867
AF Spot mode: hidden fact revealed - AF point is 30% smaller than in "select"

I have been using Pentax cameras for a while, but today I stumbled upon a piece of information which actually is news to me:

QuoteOriginally posted by Pentax:
Highlight: The advantage of Spot setting in AF mode

The Spot setting is an autofocus mode that detects the in-focus point using a single AF sensor positioned at the center of the image field.
For PENTAX digital SLR cameras marketed after the PENTAX K-3, the Spot setting detects an area approximately 30 percent narrower than that of the Select setting, which uses a set of middle AF sensors in autofocus operation.
Source: How to optimize focusing accuracy with large-aperture lenses / Beautiful Photo-life | RICOH IMAGING

I do consider this quite valuable information which I think was completely undocumented so far.

09-13-2018, 05:41 AM   #2
Pentaxian




Join Date: Mar 2009
Location: Rome, Italy
Posts: 337
SPOT or Select on central point are equal, at least on k-1, I checked. it's a bad translation or a wrong sense of the phrase.

There are some evidence that the statement on RICOH site are correct even if doing some tests the two modes look the same.

Last edited by Andrea K; 3 Days Ago at 10:51 AM.
09-13-2018, 05:46 AM - 3 Likes   #3
Pentaxian
Site Supporter
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 29,965
You guys read manuals? Impressive...
09-13-2018, 06:06 AM   #4
Site Supporter
Site Supporter
jpzk's Avatar

Join Date: Jan 2009
Location: Québec
Photos: Gallery | Albums
Posts: 7,604
QuoteOriginally posted by beholder3 Quote
For PENTAX digital SLR cameras marketed after the PENTAX K-3
Seriously ? I thought this was also a feature on the K3.
What exactly does this difference in AF area would imply?

09-13-2018, 06:37 AM   #5
Pentaxian




Join Date: Dec 2011
Posts: 1,867
Original Poster
QuoteOriginally posted by Andrea K Quote
SPOT or Select on central point are equal, at least on k-1, I checked. it's a bad translation or a wrong sense of the phrase.

Read more at: Make the Most of Your Pentax Camera: a Series of Articles Provided by Ricoh - Page 2 - PentaxForums.com
I would agree, that on the K-1 the area doesnt seem to be smaller (I just checked the central point though and dont know if the others in select might be larger).
09-13-2018, 08:12 AM   #6
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 30,492
QuoteOriginally posted by beholder3 Quote
I do consider this quite valuable information which I think was completely undocumented so far.
QuoteOriginally posted by beholder3 Quote
I would agree, that on the K-1 the area doesnt seem to be smaller (I just checked the central point though and dont know if the others in select might be larger).
Fake news? I wonder how the Japanese version of the article reads. I had heard that the center spot was more selective, but not that it depends on how it is selected.


Steve
09-13-2018, 08:20 AM   #7
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 30,492
QuoteOriginally posted by stevebrot Quote
I wonder how the Japanese version of the article reads.
Google translate of the Japanese version (LINK) reads like this:

QuoteQuote:
Tips. Features of the AF point "Spot" "Spot" is a mode to focus on only the 1 point focus point.
For digital SLR cameras after K - 3, we are focusing by detecting a narrow range of about 70%, compared with the case of selecting the central focus detection point in the "select" mode.
It appears that they really mean a diameter 70% of what it would be if using "select". Any native Japanese speakers here?


Steve

Last edited by stevebrot; 09-13-2018 at 08:20 AM. Reason: Forgot to include URL for LINK
09-13-2018, 08:39 AM   #8
Pentaxian




Join Date: Mar 2009
Location: Rome, Italy
Posts: 337
70? 30?

perhaps the sense is that after the k-3 the central point is smaller than the k-3 central point in select?

09-13-2018, 09:23 AM   #9
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 30,492
QuoteOriginally posted by Andrea K Quote
70? 30?

perhaps the sense is that after the k-3 the central point is smaller than the k-3 central point in select?
70% of vs. 30% less.

I would think that difference would be quite obvious with a simple test.*


Steve

* Still find it hard to believe that the center point sensor supports two FOV on top of the physical complexity of supporting cross-point and f/2.8 sensitivity.
09-13-2018, 09:40 AM   #10
Senior Member




Join Date: Mar 2013
Location: So-central, MI / Central, IN
Posts: 174
Hmm, I interpret the original posted statement very literal... that the single middle sensor is used in Spot setting and this equates to a measurement area approximately 30% of that resulting from a set (plural) of sensors about the middle used in Select setting. Unspecified in this particular paragraph is which set of sensors are involved in the Select setting. The OE information being stated for the sake of relative comparison in the areas being measured.
09-13-2018, 09:49 AM   #11
Site Supporter
Site Supporter
MossyRocks's Avatar

Join Date: Nov 2017
Location: Minnesota
Photos: Gallery | Albums
Posts: 372
QuoteOriginally posted by normhead Quote
You guys read manuals? Impressive...
I read the one that came with my K-3 and then promptly forgot most but hey at least now I can say I had forgotten about most of the features.
09-13-2018, 09:58 AM   #12
Pentaxian




Join Date: Dec 2011
Posts: 1,867
Original Poster
QuoteOriginally posted by stevebrot Quote
* Still find it hard to believe that the center point sensor supports two FOV on top of the physical complexity of supporting cross-point and f/2.8 sensitivity.
As physically there are no separate horizontal or vertical focus "points" at all (both f5.6 and F2.8) but only one long line of pixels from which a deliberate decision in software takes a certain part (two parts actually, one on the left side and one on the right side), that is very easy. Firmwarewise they could easily offer 5 or 10 or 20 different AF point sizes.
09-13-2018, 10:01 AM   #13
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 30,492
QuoteOriginally posted by One3rdEV Quote
Hmm, I interpret the original posted statement very literal... that the single middle sensor is used in Spot setting and this equates to a measurement area approximately 30% of that resulting from a set (plural) of sensors about the middle used in Select setting. Unspecified in this particular paragraph is which set of sensors are involved in the Select setting. The OE information being stated for the sake of relative comparison in the areas being measured.
Yes, the ambiguity of the English version may support your reading. What is less flexible is the Google translation of the Japanese site. The Japanese text, being assumed to be the basis for the English version, would indicate the authors intent. With any luck there will be clarification from Ricoh/Pentax at some point. At the very least, this tidbit will likely be part of the Pentax mythos for some time.


Steve
09-13-2018, 10:09 AM   #14
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 30,492
QuoteOriginally posted by beholder3 Quote
As physically there are no separate horizontal or vertical focus "points" at all (both f5.6 and F2.8) but only one long line of pixels from which a deliberate decision in software takes a certain part (two parts actually, one on the left side and one on the right side), that is very easy. Firmwarewise they could easily offer 5 or 10 or 20 different AF point sizes.
One array in two sections can service both f/2.8 and f/5.6, but with separate microlens/prism. It takes two arrays of this type to do crosspoint.


Steve
09-13-2018, 10:23 AM   #15
Pentaxian




Join Date: Mar 2009
Location: Rome, Italy
Posts: 337
QuoteOriginally posted by stevebrot Quote
70% of vs. 30% less.

I would think that difference would be quite obvious with a simple test.*


Steve

* Still find it hard to believe that the center point sensor supports two FOV on top of the physical complexity of supporting cross-point and f/2.8 sensitivity.
I done the test.
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!
af, af spot, autofocus, camera, cameras, dslr, information, mode, pentax, photography, spot
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-1 is noticeably smaller than D850 in most measures but .. Mikesul Pentax K-1 145 06-16-2018 06:24 PM
Select AF point(s) vs. single (spot) point ... any difference in accuracy? jpzk Pentax K-3 35 05-06-2016 05:31 AM
Pentax Full Frame Crop Mode Revealed PF Staff Homepage & Official Pentax News 2 01-13-2016 09:19 PM
[K-30] Strange "thing" appears in smaller apertures Markovo Pentax K-30 & K-50 11 10-05-2014 10:24 PM
Spot AF vs Select AF szmatefy Pentax K-30 & K-50 3 01-20-2013 12:20 AM



All times are GMT -7. The time now is 08:18 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