Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-28-2014, 06:56 PM   #1
Veteran Member




Join Date: Nov 2008
Location: Melbourne, Australia
Photos: Gallery | Albums
Posts: 385
Sigma 85mm F1.4 on K3 or K5ii

Can anyone using this lens please tell me how well it focusses at F2 or faster on the K3 or K5 ii.

I am mainly interested in focus accuracy but comments on focus speed would also be appreciated.

Howie B

03-28-2014, 07:57 PM   #2
Pentaxian




Join Date: Sep 2009
Location: Southern California
Photos: Gallery | Albums
Posts: 3,181
I'm curious, are you seeing photos that show any problems here?
03-28-2014, 09:23 PM   #3
Forum Member
wolfworx's Avatar

Join Date: Feb 2010
Location: East London
Photos: Gallery | Albums
Posts: 60
Correct me if I am wrong, focusing is always done with an (automatic aperture) lens wide open, never stopped down.
So f/2 vs f/1.4 won't make any difference in focusing speed.
Accuracy is another story, I do not have your your combination, but my K5 + Sigma 70-200 have been really troublesome in this regard.
03-28-2014, 10:08 PM   #4
Pentaxian
fgaudet's Avatar

Join Date: Oct 2013
Location: Ontario
Posts: 726
Are you looking for a general opinion of the lens + camera combo? Because focus accuracy will depend on a lot of other factors, the subjects (flat surface, human face...), the lighting (bright, dark, flash), the distance to your subjects and your AF mode... It's very hard to be specific.

I don't know about the 85 but my 35 f/1.4 on my K5 or Kr is pretty much 100% accurate when shooting portraits. For shooting wider shots, like an outdoor scenery it's been very decent. But those are usually shot at much smaller aperture (i.e. f/5.6-f/11)

Wide open, the DoF is so shallow that any lens is bound to show any slight misfocussing, the 35 DoF is shallow and the 85 will only be shallower. I tried some close up shots of someone's eye at f/1.4 there is now way I could get the whole eye in focus, especially if at an angle. AF was pretty consistent at locking focus at the same point however.

As it is often the case, each lens will also be different.

03-29-2014, 02:30 AM   #5
Veteran Member




Join Date: Nov 2008
Location: Melbourne, Australia
Photos: Gallery | Albums
Posts: 385
Original Poster
Okay, my interest is in using it as a portrait lens.

I specifically want comments on F2 or faster as I don't want to have to stop down to overcome focus error.

I know that F2 or faster will have shallower depth of field hence my question at accuracy as that's obviously more critical at faster f stops.

I also typically select the af point when I do portraits.

Anyway, more comments on the af accuracy would be appreciated.

Howie B
03-29-2014, 05:44 PM   #6
Pentaxian




Join Date: Sep 2009
Location: Southern California
Photos: Gallery | Albums
Posts: 3,181
While I don't recommend the center AF point for most shooting, how does the AF perform when you do? The reason I ask is this lens' resolution is heavily biased toward the center. And many lenses struggle with resolution throughout the widest stop - Sigma sometimes more than others. So I'm wondering if this is a factor here.
03-29-2014, 06:18 PM   #7
Veteran Member




Join Date: Nov 2008
Location: Melbourne, Australia
Photos: Gallery | Albums
Posts: 385
Original Poster
Thanx DSims but I am trying to gauge opinion before a possible purchase.

For my intended purpose of portraits, centre only af point is not feasible.

Thanks for your reply.
03-29-2014, 07:06 PM   #8
Pentaxian




Join Date: Sep 2009
Location: Southern California
Photos: Gallery | Albums
Posts: 3,181
QuoteOriginally posted by howieb101 Quote
Thanx DSims but I am trying to gauge opinion before a possible purchase.
In that case, I stay away from Sigma most of the time. I got an FA77 instead, and later replaced it with an FA*85/1.4. It focuses very well - so well that I often use it to shoot fast action sports. Plus IQ and sharpness is very strong at f/1.6 to f/1.8. And even for action I avoid center point AF, because it would ruin my composition most of the time.

I highly doubt the IQ of the Sigma can match either the FA77 or FA*85 if all are shot at f/1.8.

03-30-2014, 07:19 PM   #9
Loyal Site Supporter




Join Date: Apr 2010
Location: Tennessee
Posts: 5,416
QuoteOriginally posted by howieb101 Quote
Can anyone using this lens please tell me how well it focusses at F2 or faster on the K3 or K5 ii.

I am mainly interested in focus accuracy but comments on focus speed would also be appreciated.

Howie B
My Sigma 85mm is probably my most accurate lens. Speed isn't super fast, but its as fast as my 31mm LTD. I probably shoot my 85mm at F/2.8 -F/4.0 the most, by I have no problem with F/2. IQ of the Sigma 85mm is fantastic.
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!
f1.4 on k3, focus, k-mount, k3, pentax lens, sigma 85mm f1.4, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
DA* 55mm f1.4 with K5ii or K3 (AF speed) horc00 Pentax SLR Lens Discussion 9 12-18-2013 11:52 AM
For Sale - Sold: Sigma 85mm f1.4 MBT74 Sold Items 24 12-05-2013 07:15 AM
Portait lens - Pentax 50mm f1.2 (K version) or Samyang 85mm f1.4 Damon Pentax SLR Lens Discussion 17 01-21-2013 01:35 AM
77mm f1.8 or Sigma 85mm f1.4 for outdoor portraits? crossover37 Pentax SLR Lens Discussion 60 05-12-2011 11:04 AM



All times are GMT -7. The time now is 07:20 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