Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-07-2019, 05:59 PM - 1 Like   #1
Junior Member




Join Date: Feb 2017
Photos: Gallery | Albums
Posts: 41
Auto focus grabbing wrong spot?
Lens: Pentax 16-85 Camera: K-70 Photo Location: Lore City, OH ISO: 200 Shutter Speed: 1/1000s Aperture: F5.6 

Took this at a horse show in which my daughter was competing. Using 16-85 lens at 85mm (full frame 127.5 equivalent). Daughter and horse are out of focus. Camera shake? Motion blur? Just the lens being soft at its maximum zoom? Or did the autofocus grab a focus point just out of the depth of field for daughter and horse? Have usually had very good results with the 16-85 through out its range. Any thoughts are welcome. Thanks.

Attached Images
View Picture EXIF
PENTAX K-70  Photo 
07-07-2019, 09:48 PM   #2
Otis Memorial Pentaxian
Loyal Site Supporter
RobG's Avatar

Join Date: Dec 2009
Location: Canberra
Photos: Gallery | Albums
Posts: 4,602
It looks reasonably sharp at this scale. What AF pattern did you use? With a subject that size in the frame, anything more that 9 points might pick up the background.
07-07-2019, 10:16 PM - 2 Likes   #3
Loyal Site Supporter
Loyal Site Supporter
Bruce Clark's Avatar

Join Date: Mar 2010
Location: Brookfield, Victoria
Photos: Gallery | Albums
Posts: 4,090
At 1/1000 sec. I would tend to rule out motion blur.
Auto Focus is possibly struggling to pick out the horse and rider as the main subject. The bright building at the back would possibly dominate the AF system.
F5.6 is possibly not the sharpest aperture for the lens.
85mm zoom is at the maximum and also possibly not the optimum.

Suggestions:
Use f8
Back the zoom off a bit. Get a bit closer if you are able.
Use Back Button Focusing. That way the focus is independent of the shutter. Focus on the target and recompose. Give the focus mechanism a little time to do its thing.
07-07-2019, 10:37 PM   #4
Site Supporter
Site Supporter




Join Date: Feb 2015
Photos: Gallery | Albums
Posts: 6,839
In that photo, auto-focus isn't the primary problem. If the subject is the horse and daughter, they are way too small in the frame. The white building and the grass dominate the scene and there is nothing to lead the eye to the horse, plus the view of the side/back of the horse/rider isn't eye catching either. As for the auto-focus, when the subject is that small in the center of the frame, better use center point only to prevent the camera to focus anywhere on brighter areas such as grass or in that case focus on the white building.

07-07-2019, 10:41 PM   #5
Loyal Site Supporter
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 13,207
Hi, DSingley, use the buttons to choose the focus point that's over your daughter, then take the pic. You'll have to take it off Auto for that, of course.
07-08-2019, 08:48 AM   #6
Junior Member




Join Date: Feb 2017
Photos: Gallery | Albums
Posts: 41
Original Poster
Thank you all for the comments they are greatly appreciated. This was my first attempt at something other than landscapes/city scapes or vacation shots.

Had a longer zoom with me, the “inexpensive” Tamron 70-300, but chose to go with the Pentax 16-85 because (a) didn’t think the venue was that big - it was, which lead to the “small subject - big space” result; and (b) have not convinced myself that the Tamron actually delivers fairly good image quality, even though I have images showing that it does. Assuming I get another crack at this, I’ll likely be using the Tamron - getting closer is not really an option given the layout of the event.

Auto focus mode was AF-A, which was a conscious choice. Thought about going to AF-C, but choose to let the camera figure it out. I’ll spend some time in the manual to learn the back button focusing mechanics. Have heard of the technique, but most of the general “how to” materials are geared to the Nikon/Canon crowd, and Pentax’s K-70 manual is not a model of clarity on this point. Also need to figure out how to chose the focus point on the fly - again, IMHO, the K-70 manual is not a model of clarity on that point.

Again, thanks for the comments and thoughts.
07-09-2019, 10:23 AM   #7
Site Supporter
Site Supporter




Join Date: Dec 2015
Location: Goldsboro North Carolina
Photos: Gallery | Albums
Posts: 509
Check out this thread, specifically for the K-70
How do I set up back button focus on a K-70 - PentaxForums.com
07-09-2019, 06:16 PM   #8
Junior Member




Join Date: Feb 2017
Photos: Gallery | Albums
Posts: 41
Original Poster
Thank you!

07-09-2019, 06:39 PM   #9
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 33,324
I would have used AF.s selective single point. but I select the point before framing. Your Tamron may be OK if you shoot it at 200mm. You Tamron at 200mm and ƒ5.6 will give you much better resolution than any 85mm lens on a distant subject.That type of lens is usually fairly good until getting close to 300mm. Everyone says back button focus. I'm not sure why. I've always used the half depressed shutter button. One button instead of two makes life easier in my opinion. I always find, for action simplify.



That works for me.
07-09-2019, 10:07 PM   #10
Loyal Site Supporter
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 13,207
QuoteOriginally posted by dsingley100 Quote
Also need to figure out how to chose the focus point on the fly - again, IMHO, the K-70 manual is not a model of clarity on that point.
pp62-63 of the manual couldn't be clearer, Dsingley!

But if you're new to photography I can suggest buying Yvon Bourque's K-70 handbook as a useful supplement, it's not just a reference manual.
07-10-2019, 06:51 PM - 2 Likes   #11
Junior Member




Join Date: Feb 2017
Photos: Gallery | Albums
Posts: 41
Original Poster
Thanks Normhead. I was doing the half press to get focus (or at least so I thought) and then compose. That said, I’m thinking I either grabbed the wrong focus point or did not realize where the camera had grabbed. As for the 16-85, experience is a sometimes cruel teacher. 🤣 That sinking feeling you get when you think you got the shot- but didn’t. Good news is manifold. First, if schedules work out, I get another crack at it in August - better prepared I would hope. Second, I did get some good shots and probably should not whine so much about the ones that did not go the way I wanted them too. Third, despite the appalling weather (temps in high 80’s dew point in the upper 70’s) it was fun. Got to spend the day with the heiress, and got to shoot something I’d not previously shot.

And, I get meaningful feedback on the shots in a great community. 😄😄
07-10-2019, 09:16 PM   #12
Loyal Site Supporter
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 13,207
QuoteOriginally posted by dsingley100 Quote
Thanks Normhead. I was doing the half press to get focus (or at least so I thought) and then compose. That said, I’m thinking I either grabbed the wrong focus point or did not realize where the camera had grabbed.
Yep, to cut out those mistakes, set it to a selected single point.

Because the subject is so far away, it is fine to just use the centre point and recompose.
07-11-2019, 07:14 AM   #13
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 33,324
QuoteOriginally posted by dsingley100 Quote
Thanks Normhead. I was doing the half press to get focus (or at least so I thought) and then compose.
The longer lens and bigger in the viewfinder subject will also help keep the focus point on the subject.
07-11-2019, 08:53 AM   #14
Pentaxian
rogerstg's Avatar

Join Date: Oct 2007
Location: Rhode Island
Photos: Albums
Posts: 504
QuoteOriginally posted by normhead Quote
I'm not sure why. I've always used the half depressed shutter button. One button instead of two makes life easier in my opinion. I always find, for action simplify.
My main reason is simplicity. I can take a group of similar distanced shots without the need to refocus/recompose each time. It's especially helpful where the subject and background might not have much contrast; causes AF to hunt. It also effectively lets me use single, continuous or manual focus (with quickshift) without changing any other settings or buttons. And, the way I hold my camera naturally puts my thumb at the back button, so dealing with two buttons is not a hindrance for me.

Like any method, there are pluses and minuses, nothing is the best for everyone.
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!
auto focus, critique, daughter, focus, horse, lens, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K1 spot focus doesn't always spot focus peterh337 Pentax K-1 16 07-16-2018 11:51 AM
Macro Grabbing.............. eaglem Post Your Photos! 10 11-08-2017 05:57 PM
Nature Wrong Lens, Wrong time, Wrong…………. lukulele Post Your Photos! 4 05-08-2014 03:11 AM
Macro Grabbing a quick drink! eaglem Post Your Photos! 7 04-09-2012 03:33 PM
Misc Grabbing the Sun -- Happy Solstice! Tamia Post Your Photos! 4 12-22-2010 11:17 PM



All times are GMT -7. The time now is 12:34 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