Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-04-2016, 10:55 AM   #16
Junior Member




Join Date: Oct 2016
Posts: 38
Original Poster
I will not proove myself and say that i dont do mistakes. I do, and that's why you have AF in cameras, for technology to correct human mistakes. Sometimes you do not have a choice, and you had to act wrong, and hope that tech will cover this.
Question is, how far you can go?

10-04-2016, 01:30 PM   #17
Moderator
Loyal Site Supporter
BigMackCam's Avatar

Join Date: Mar 2010
Location: North East of England
Posts: 6,301
QuoteOriginally posted by GraySaint Quote
I've tested all my lenses for focus accuracy, and they all do well, but i did so in good lighting, at almost perfect conditions. Maybe i should test them in dim lighting, not for calibration, but as the test, and see, what results will be. As i mentioned, i've got inconsistent results in hard conditions, so maybe such experiment will teach me how to work around that.
That's great. If you've carried out controlled AF accuracy testing and AF fine tune adjustment for each of your lenses, and you're certain that in good light, the AF is spot on, we can rule that out as a possible issue (as a point of note, out of all the AF lenses I own, about half of them require some AF fine adjustment on my K-3 and K-3II). Fast, third party lenses usually require a little tweaking... not always, but usually. My guess is that both your Sigma 17-50 and Tamron 70-200 required some + or - adjustment, right?

QuoteOriginally posted by GraySaint Quote
I will not proove myself and say that i dont do mistakes. I do, and that's why you have AF in cameras, for technology to correct human mistakes. Sometimes you do not have a choice, and you had to act wrong, and hope that tech will cover this.
Question is, how far you can go?
We all make mistakes, absolutely - but AF won't correct for them. AF is highly dependent on us knowing what it needs to work correctly, as well as it's limitations - it's a partnership between us and the camera The way I see it, most of the camera's systems require me to do something first, and if I don't do it correctly, the camera-automated part of the process will be compromised. I can't think of a single persistent problem I've experienced where my camera was at fault rather than me

By the way, you have some beautiful shots in your Flickr albums. Even considering the AF issues you've been having, most members here would be delighted to have taken some of them. I love the "green bottle" shot
10-04-2016, 02:01 PM   #18
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 41,842
QuoteOriginally posted by GraySaint Quote
Hello.
I'm proud (not really) owner of K-S2. I'm a little bit disappointed (in fact, i'm very disappointed) with its AF performance. It is lacking both speed and accuracy with every lens i have, which are: native 18-135, Tamron 70-200, Sigma 17-50/2.8 and DA-50/1.8
Is the AF performance of K-70 better then K-S2?
Through the viewfinder and in live view (for stills), the AF performance is identical.

The K-70 does have continuous video AF, which works better than the slow on-demand AF we had before, but isn't particularly impressive.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com's high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

10-04-2016, 02:08 PM   #19
Junior Member




Join Date: Oct 2016
Posts: 38
Original Poster
Thank you, you are very kind.
As for lenses, i did not had to make any adjustments, in good conditions focus is ok. Only lens i have problems with, and can not deal with them, is Sigma 18-30/1.8 Art. Such a shame, but for some reason the 50% of shots taken was OOF. Not slightly, but huge. Spent few days with USB-dock trying to adjust, but no success. Had to give it back.
I've been considering K-70 as a replacement, but with no better AF performance, i have to wait for K-3II successor, or maybe look for good proposal of seckond hand one.

10-04-2016, 03:51 PM   #20
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 8,525
QuoteOriginally posted by GraySaint Quote
I will not proove myself and say that i dont do mistakes. I do, and that's why you have AF in cameras, for technology to correct human mistakes.
I'm not sure you've studied AF systems, GraySaint, and if you did, you wouldn't just point a camera at a wall or a bird amongst branches and half-press.

Your Flickr photos are great but that environment has poor light and you're not using flash.

So, it's a big topic, but of relevance to your situation is how PDAF (the very fast method intrinsic to DSLRs) works.

It's a little like the old range-finders on warships ... you're looking to make two segments of a line coincide. Like the Nikon 5300, your K-S2's nine central points can use either a vertical or a horizontal line ... but you need a line of some sort! In a backlit situation where the model is almost a silhouette you're better off choosing the outside edge of the body to focus on.

In Live View mode, the focus method is CDAF, which is the traditional mirrorless technique, and it racks back and forth to find a high contrast area under the focus point. Obviously this would be the worst to try to use on a wall or sky or a backlit subject or in low light.

Knowing the above two systems shapes your shooting strategy. You don't simply point at an object, your keeper rate will drop. If close enough and protocols permit, use the AF LED assist light on your K-S2.

Neither would I trust any camera to choose a focus point for me, it can't read my mind. I usually focus using the centre point (the recommended one to use with a fast lens, BTW) and recompose for the shot.

Some specifics here:

Pentax K-S2 Review - Focusing | PentaxForums.com Reviews


For some K-S2 shots in very challenging circumstances, see these by a forum member:


https://www.pentaxforums.com/forums/184-pentax-k-s1-k-s2/291490-post-your-k-s...ml#post3750887

Last edited by clackers; 10-04-2016 at 04:16 PM.
10-05-2016, 12:48 AM   #21
Junior Member




Join Date: Oct 2016
Posts: 38
Original Poster
QuoteOriginally posted by clackers Quote

For some K-S2 shots in very challenging circumstances, see these by a forum member:


https://www.pentaxforums.com/forums/184-pentax-k-s1-k-s2/291490-post-your-k-s...ml#post3750887
I am sorry, but with F 3.2 shutter 1/125 and ISO 250 it is noone near challenging conditions. Very good shots, though. But you can not compare those with F2.8 shutter 1/320 and ISO 1600 in terms of autofocus performance.
I am aware of "half-press and compose" technique, used it quite a lot on my pervious camera (with 3 af points).
But, as i sayed, sometimes you just have to "spray and pray" and hope that your gear will carry you.
10-05-2016, 04:08 AM   #22
Site Supporter




Join Date: Feb 2015
Location: Avalon Peninsula, Newfoundland
Photos: Gallery | Albums
Posts: 373
One thing going unmentioned that I have noticed going from a K50 to a K70 is the ISO performance difference allows me to stop down to 320 at least without loss of pop or clarity (if any is there to be had--I often shoot in gray, low light situations in Newfoundland). That might make a difference.
10-05-2016, 06:13 AM   #23
Pentaxian
CarlJF's Avatar

Join Date: Sep 2014
Location: Quebec City
Posts: 699
QuoteOriginally posted by GraySaint Quote
But, as i sayed, sometimes you just have to "spray and pray" and hope that your gear will carry you.
For what it's worth, when doing "spray and pray", I found that using "expanded area", or Auto 5, are what works best. The camera has a much better chance of finding an appropriate target if you give it the possibility to use multiple points. Sure, sometime it will focus on something you don't want, but if the AF points mostly or all cover your target, it works relatively well. And certainly better than if you're trying to force the camera, by using only one point, to focus on something without a pattern to focus on.

I know that people say that it's better the selct the point to be sure of where the camera will make focus. But, as you say, sometime it can work better to let the camera find an appropriate target and cross our fingers that this target is somewhere on our target. It's not always possible to efficiently micromanage the focus points in a dynamic scene...

10-05-2016, 04:18 PM   #24
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 8,525
QuoteOriginally posted by graysaint Quote
i am sorry, but with f 3.2 shutter 1/125 and iso 250 it is noone near challenging conditions.

??


Iso 3200!
10-06-2016, 12:40 AM   #25
Junior Member




Join Date: Oct 2016
Posts: 38
Original Poster
QuoteOriginally posted by clackers Quote
??


Iso 3200!
Disturbed | backbeatseattle.com/2016/08/25/photos-kisws-pain? | Flickr

EXIF says - 250
10-06-2016, 01:13 AM - 1 Like   #26
Moderator
Loyal Site Supporter
BigMackCam's Avatar

Join Date: Mar 2010
Location: North East of England
Posts: 6,301
QuoteOriginally posted by GraySaint Quote
That's just the first photo. If you look at some of the others, the EXIF shows ISO 3200...
10-06-2016, 02:12 AM   #27
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 8,525
QuoteOriginally posted by BigMackCam Quote
That's just the first photo. If you look at some of the others, the EXIF shows ISO 3200...
Correct.

@GraySaint, you might be a very good photographer for all I know, but there's something wrong with you if you look at the lighting conditions in those photos and conclude it's normal to shoot concerts at "f3.2 shutter 1/125 and iso 250."

I actually think the first photo was the hardest to get focus on, because the subject is backlit - perhaps that partly explains why it's the softest image. The others all have good contrast in the performers from top and front lighting - we can see many lines.

Last edited by clackers; 10-06-2016 at 02:24 AM.
10-06-2016, 02:19 AM   #28
Junior Member




Join Date: Oct 2016
Posts: 38
Original Poster
my bad, i was just looking at EXIF at first photo, and assumed, they are the same, if they are from same event.
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, k-70, k-s2, k70, pentax k-70, performance
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Overdue Upgrade: *istD to K-S2 or K-70? Rich_S Pentax DSLR Discussion 18 12-07-2016 07:15 AM
Pentax K-1 Continuous AutoFocus Performance Quark Pentax K-1 135 07-20-2016 07:08 PM
Need to look for those subtle changes in K-70 from K-S2 & K-50 anu l Pentax K-70 13 06-12-2016 10:44 AM
K-S1 - K-S2 Bounce Flash Performance johnbachel Pentax K-S1 & K-S2 5 03-21-2015 06:30 PM
K-5 vs K-r autofocus system and performance loco Pentax DSLR Discussion 5 02-28-2012 01:31 AM



All times are GMT -7. The time now is 05:41 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