Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-21-2009, 03:41 PM   #16
Veteran Member
netuser's Avatar

Join Date: Oct 2008
Location: Azores Islands, Portugal
Photos: Gallery
Posts: 2,241
Stanjo, can you borrow a k-7 or k20 from someone ?
I have some fast images taken with k20......

( For instance, check the dolphin image on my PPG. The combo used was k20d and tamron 70-200 while on boat, south/southeast of my island.)

12-21-2009, 03:58 PM   #17
Forum Member




Join Date: Nov 2007
Location: California
Posts: 71
Original Poster
QuoteOriginally posted by netuser Quote
Stanjo, can you borrow a k-7 or k20 from someone ?
I have some fast images taken with k20......

( For instance, check the dolphin image on my PPG. The combo used was k20d and tamron 70-200 while on boat, south/southeast of my island.)
Beautiful picture, netuser! There is hope ...
I don't know any other pentaxian in my area, but a whole bunch of Canikons
12-21-2009, 04:04 PM   #18
Veteran Member
netuser's Avatar

Join Date: Oct 2008
Location: Azores Islands, Portugal
Photos: Gallery
Posts: 2,241
Also in my area, only another one, maybe two pentaxians.

Since the kid was going from left to right for instance I think that with AF-C you could lock lock lock (following) and finnally shoot 2/3 images keepers. (instead of lock/shoot, lock/shoot etc)
Give it a try.
12-21-2009, 04:13 PM   #19
edl
Veteran Member




Join Date: Dec 2007
Location: San Francisco
Posts: 457
QuoteOriginally posted by stanjo Quote
The rink is oval. My son was coming to me from the left - moving on both directions - forwards and sideways.

My real questions:
- I know from experience that the Tamron 28-75 did not cut it, can I expect the Tamron 70-200 to be better?
Don't expect it to be any better. You'll be driving more glass so it'll be slower.

QuoteQuote:
- Would a new body make a big difference?
A new Pentax body will make a slight difference. But a Canon body with 70-200/4 will be faster than Pentax + Tamron 70-200/2.8 simply due to the lighter weight of the F/4 glass and the in-lens USM versus screwdrive. I also believe some of the Canon bodies may have better AF tracking then Pentax, if that's what you're asking.

You should be able to get a better keeper rate than 3 per 100 though, especially with short glass like the Tamron 28-75 - are you using the AF button to focus or is it tied to the shutter release? Pre-focusing?

QuoteQuote:
- Is it the screw-drive that is inherently slow (with heavy tele lens) ?
Generally speaking, screw-drive is slower on long heavy glass then Canon USM or Nikon AF-S. If you're talking about short/normal primes there isn't much difference.

QuoteQuote:
- Are AA batteries (vs Li-Ion) inherently not strong enough to quickly move the heavy lens?
I don't think that's the issue here. But I could be wrong.

12-21-2009, 04:43 PM   #20
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,679
You will find a significant improvement in AF speed and accuracy with the K-7/K-x over the K100DS.
The lens should give you some stellar results, but each camera has its own nuances and learning to master them will go a long way in maximising fast-action keepers.
12-21-2009, 05:02 PM   #21
Forum Member




Join Date: Nov 2007
Location: California
Posts: 71
Original Poster
QuoteOriginally posted by edl Quote
are you using the AF button to focus or is it tied to the shutter release? Pre-focusing?
Auto-focus is tied to the shutter release button. How would using the AF button to autofocus help in this case?

Tried pre-focusing in manual, but the subject never appears in the same place after a full circle of the rink.

I also need to note that a 4 year old, first time on skates, is not a very fast moving subject, so this is not a "sports shooting" situation.
12-22-2009, 01:51 PM   #22
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,679
The K100DS does not have a dedicated AF button.
The AF function is not altered by which button is used anyway - it's just a personal preference.
Try your hands on a K-7 or K-x with your lens and viva la difference!
12-22-2009, 02:23 PM   #23
Forum Member




Join Date: Nov 2007
Location: California
Posts: 71
Original Poster
K-7 vs Canon 7D focus test

http://www.youtube.com/watch?v=ngUcQUchHEU

The Canon focuses much faster even in low light.
I realize that the 7D is an expensive camera, but my short experience with the Rebel was that the auto focus was comparable to 7D in speed.

I have been content with the Pentax AF for many years, but that was before I got kids. I'm sorry to say, but Canikons are a better set up for taking pictures of your kids - priorities in life do matter !

Thank you all for responding to my questions.
Happy holidays best wishes for a better 2010 !

12-23-2009, 01:26 AM   #24
edl
Veteran Member




Join Date: Dec 2007
Location: San Francisco
Posts: 457
QuoteOriginally posted by Ash Quote
The K100DS does not have a dedicated AF button.
The AF function is not altered by which button is used anyway - it's just a personal preference.
Try your hands on a K-7 or K-x with your lens and viva la difference!
I don't completely disagree with your statement, but if you shoot using the AF button you're free to release the shutter whenever you want rather than waiting for AF to figure out what's going on.

In my personal experience this makes a HUGE difference shooting anything that moves. I wouldn't use an SLR that didn't have a dedicated AF button.
12-23-2009, 01:38 AM   #25
edl
Veteran Member




Join Date: Dec 2007
Location: San Francisco
Posts: 457
QuoteOriginally posted by stanjo Quote
http://www.youtube.com/watch?v=ngUcQUchHEU

The Canon focuses much faster even in low light.
I realize that the 7D is an expensive camera, but my short experience with the Rebel was that the auto focus was comparable to 7D in speed.

I have been content with the Pentax AF for many years, but that was before I got kids. I'm sorry to say, but Canikons are a better set up for taking pictures of your kids - priorities in life do matter !

Thank you all for responding to my questions.
Happy holidays best wishes for a better 2010 !
I don't think that test was conducted too well, but of course it's true that Nikons and Canons generally focus faster than Pentax. I haven't used the 7D yet, but I know the D700 AF is stellar. It's made shooting everything much easier. (Before anyone says anything, yes I know a D700 costs a lot more than a K7.)

If you can afford it and need it, then go for it.

To answer your other question, using the AF button to focus allows you to do a few things - zone focus the camera, choose to release the shutter independently of focus point and focus activity, shoot photos completely out of focus, etc. Basically it gives you full control over the AF system and the shutter release.
12-23-2009, 02:25 AM   #26
Pentaxian
LeDave's Avatar

Join Date: Jun 2009
Location: Minneapolis - St. Paul
Photos: Gallery
Posts: 2,896
I think in that AF video, they were focusing both the K-7 and 7d against different things. I used to have the 50-135 for my K-7 and it spins once and locks focus dead-on just like that 70-200 USM on the 7D. I also think whoever made the video didn't like their K-7.
12-23-2009, 12:03 PM   #27
Pentaxian
philbaum's Avatar

Join Date: Oct 2007
Location: Port Townsend, Washington State, USA
Posts: 3,659
My take on this is that if the OP says he's using an f2.8 lens, and the combo is performing that badly, then upgrade the camera. I never had an SLR before the K10, but when i upgraded to the K20, i noticed a large improvement in how all of my lenses locked focus. It was like having a new set of lenses. My tammy 18-250 was suddenly fun to use again.

I shoot publicity photos for an amateur playhouse, along with a friend that uses a Canon 40D, now a 50D. We always sit down afterwards and agree on which photos to send out to the directors and/or for printing. It seems like we are always shooting in less than optimum conditions, but my acceptance rate is usually as good as his, except in specific instances where his experience won out, like using flash instead of natural light in one example.

I did stop using my 18-250 and moved to f2.8 lenses for indoor work, primarily the 50-135 for long and some primes for wide. I was outside one night using some dark trees/branches for framing. There wasn't enough light to AF or MF. Then i switched to the FA 50 f1.4 and it got the AF job done. Reason: more light to focus with before stopping down to the desired aperture.

As someone mentioned, most of the time, i'm using the AF button and i focus on a specific section of the stage that i know will be used time and again. Then i'll use that focus for several shots before using the AF button again.
12-29-2009, 03:30 PM   #28
edl
Veteran Member




Join Date: Dec 2007
Location: San Francisco
Posts: 457
QuoteOriginally posted by philbaum Quote
My take on this is that if the OP says he's using an f2.8 lens, and the combo is performing that badly, then upgrade the camera. (snip).
The other possibility is that his lens is defective. I came to that conclusion after looking at some of the OP's earlier posts.

I had a Tamron 28-75/2.8, it was tack sharp at all focal lengths wide open. But there's a lot of sample variance, so the OP might benefit from having the lens checked out.

Last edited by edl; 12-29-2009 at 03:36 PM. Reason: grammar
12-29-2009, 03:51 PM   #29
Veteran Member




Join Date: Jul 2008
Location: Var, South of France
Photos: Albums
Posts: 1,071
Well, the K2xxx bodies focused faster than the K1xx bodies, and the last K7 and Kx are really faster...
So, yes, the main difference would be the body...

I shot some pics of my 7 years-old nephew today, coming towards me at full speed on a bike, and the K7 + Tamron 70-200 grabbed quite a few good frames I wouldn't have had with my k20...
12-29-2009, 05:22 PM   #30
Pentaxian




Join Date: Oct 2006
Location: Chicago suburb, IL, USA
Posts: 1,535
One point that needs to be made is that in AF C, you need to get an initial focus confirmation to have a chance to allow the AF get subsequent shots in focus. The K20 does pretty well, but the K-7 pushes the bar quite a bit higher still. The faster VF blackout times of the K-7 also makes following action considerably easier for fast moving objects -- this is a factor that I hadn't really appreciated until I shot some BIF with the K-7..

Scott
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!
f/2.8, f/2.8 auto focus, k-mount, lens, pentax lens, slr lens, tamron, tamron 70-200 f/2.8
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tamron 17-50mm Focus Question jeff knight Pentax SLR Lens Discussion 23 08-09-2010 12:26 PM
Question about K-7 auto-focus issue... Sleepy Pentax DSLR Discussion 2 08-05-2010 08:43 PM
Auto focus Extention tube question. uloo Pentax SLR Lens Discussion 8 05-18-2009 09:27 AM
Why wil my sigma 18-200 not auto focus? zak Pentax SLR Lens Discussion 7 05-13-2009 01:50 AM



All times are GMT -7. The time now is 10:29 PM. | See also: NikonForums.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