Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-17-2012, 09:25 PM   #1
Veteran Member
FrancisK7's Avatar

Join Date: Sep 2007
Location: Montreal
Photos: Gallery
Posts: 474
VL 58/1.4 - focus adjustment needed?

I was playing with my VL58/1.4 today and experienced focusing issues that seemed to have cropped out of nowhere. I was in MF mode, single point (center) focus. The subject's eyes were in the dead center of the viewfinder. Each time I got focus confirmation. I know single point isn't really a point but a small area. Pic #1 wasn't too bad but in pic #2 focus completely missed.

I realize MF lens are hard to focus properly when wide open, but I didn't experience so much trouble two months ago when I was at the botanical garden shooting butterflies. I had forgotten to change the AF mode and was in AF.S for the butterfly shot. Is there a difference in the way the K5 handles focus confirmation in these two modes? It's weird. I'd like to play more with the lens in the studio but can't afford my lack of experience hindering my work.

They look acceptable when resized but I'm wondering whether I need AF adjustments? I've never done this for any lens before.

Maybe I just suck with MF glass and need more practice? I thought of that possibility.

K5 f/1.6 ISO100 1/125s - 100% crop


K5 f/1.8 ISO100 1/125s - 100% crop


K5 f/1.8 ISO100 1/125s


K5 f/1.6 ISO100 1/125s


K5 f/1.4 ISO100 1/250s (don't have a 100% crop at this time but it was better)



Last edited by FrancisK7; 06-17-2012 at 09:32 PM.
06-17-2012, 10:04 PM   #2
Veteran Member
sterretje's Avatar

Join Date: Dec 2008
Location: Roodepoort, South Africa
Photos: Gallery | Albums
Posts: 3,534
I guess that you need more experience with MF glass. What do you use to decide if something is in focus? The image in the viewfinder or the green hexagon. I assume the latter as you ask about difference between MF and AFs and hence focus confirmation.

As you might have noticed, there is a range in which the green hexagon indicates that the subject is in focus; you have to figure out how much you have to adjust inside that 'range' and if you get better results focusing from infinity or from nearby. If you used the green hexagon as the indication, I guess that you approached the butterfly with the lens starting at infinity and turning the focus ring to closer focusing distance; and you stopped when the green hexagon came up. With the slight OOF shoots. I guess you came from close focus and adjusted to longer focusing distance and hitting the other side of the range.

Difference between MF and AFs on the camera is that in AF the camera does not take a picture if it thinks that the image is out-of-focus.

I don't have a VL, but I assume it does not identify itself. In which case the only focus adjustment is a global adjustment that affects all lenses (including AF ones).

If you rely on the image in the viewfinder, make sure and double sure that your diopter settings are correct.

Good luck
06-17-2012, 10:05 PM   #3
Veteran Member




Join Date: Aug 2009
Location: New England
Photos: Albums
Posts: 691
Perhaps focus shift is a factor? Could also be a low light/tungsten light issue, not uncommon with phase detect AF sensors (used in MF confirmation). Try using live view instead.
06-17-2012, 10:13 PM   #4
Pentaxian
twitch's Avatar

Join Date: Nov 2009
Posts: 4,571
The most reliable way of focusing MF lenses is either live view or an aftermarket screen like this one which I put in my K-5. I can routinely nail focus wide open with my 50/1.2 with this screen. It sucks for the DA 55-300 though.

06-17-2012, 10:13 PM   #5
Veteran Member
FrancisK7's Avatar

Join Date: Sep 2007
Location: Montreal
Photos: Gallery
Posts: 474
Original Poster
QuoteOriginally posted by sterretje Quote
I guess that you need more experience with MF glass. What do you use to decide if something is in focus? The image in the viewfinder or the green hexagon.
Green hexagon 100% of the time. Relying on the viewfinder is a recipe for disaster in my experience. Too easy to miss focus.

I never really thought of using LV. I shot with a K10D for five years and have had the K5 for a few months. I never used LV yet, I'm not accustomed to it. It's not a bad idea to rely on LV to get a better focus but it's not as practical or possible (especially outside, on bright days).
06-17-2012, 10:14 PM   #6
Veteran Member
FrancisK7's Avatar

Join Date: Sep 2007
Location: Montreal
Photos: Gallery
Posts: 474
Original Poster
QuoteOriginally posted by twitch Quote
The most reliable way of focusing MF lenses is either live view or an aftermarket screen like this one which I put in my K-5. I can routinely nail focus wide open with my 50/1.2 with this screen. It sucks for the DA 55-300 though.
Very interesting. I'll check that screen out. Thanks!
06-17-2012, 10:15 PM   #7
Pentaxian
twitch's Avatar

Join Date: Nov 2009
Posts: 4,571
QuoteOriginally posted by FrancisK7 Quote
Very interesting. I'll check that screen out. Thanks!
THere's a very long thread about that screen here https://www.pentaxforums.com/forums/pentax-k-5/142241-best-screen-ever-manual...anon-ee-s.html
06-18-2012, 05:40 AM - 1 Like   #8
Pentaxian




Join Date: Nov 2011
Photos: Gallery | Albums
Posts: 3,762
There is very little depth of field at f/1.4, so unless you're using live view on a tripod,
it would seem to be unreasonable to expect perfect focusing every time.
The Nokton doesn't exhibit focus shift the way lenses like the ZK 85/1.4 do,
but my own recommendation would be to rely on focus bracketing for hand-held shots anyway.
Try shooting a continuous burst as you move the whole camera through the focus zone
(rather than rotating the focus ring).

06-18-2012, 06:33 AM   #9
Pentaxian
jeffshaddix's Avatar

Join Date: Jun 2010
Location: Albuquerque, NM
Posts: 1,371
I shoot the VL58/1.4 wide open quite a lot, and even after two years of practice and an Ee-S screen it isn't easy. The DOF is tiny wide open, and sharpness drops off rapidly if the focal plane isn't spot on (seems more pronounced in this lens than others). I know my green hexagon front focuses in dim light, so I've gotten used to only relying on my eye + screen for nailing focus. The best practice is like lytrytyr mentioned, shoot many shots sweeping the focus slightly. I agree that LV typically isn't practical, but for non-rushed static scenes it's worth a try.
06-18-2012, 09:26 AM   #10
Veteran Member
FrancisK7's Avatar

Join Date: Sep 2007
Location: Montreal
Photos: Gallery
Posts: 474
Original Poster
QuoteOriginally posted by lytrytyr Quote
Try shooting a continuous burst as you move the whole camera through the focus zone
(rather than rotating the focus ring).
That is so completely and entirely logical! Never occurred to use burst shots. I suppose learning to handle MF glass takes some getting used to after being spoiled by AF glass for so long.

Only other MF lens I owned was the VL 125mm APO Macro (which I REALLLLY regret selling) years ago and never got into using MF lens since I found a niche in studio work early and the FA77 was one of my earliest good glass acquirement. I was never motivated to discover great MF glass until recently.

I ordered the screen and thank you all sincerely for your help, it will be very helpful for the future!
06-18-2012, 08:15 PM   #11
Pentaxian
littledrawe's Avatar

Join Date: Jan 2010
Location: Red Rock
Photos: Gallery | Albums
Posts: 2,454
QuoteOriginally posted by twitch Quote
The most reliable way of focusing MF lenses is either live view or an aftermarket screen like this one which I put in my K-5. I can routinely nail focus wide open with my 50/1.2 with this screen. It sucks for the DA 55-300 though.
This screen is awesome!! Works better than the stock screen with all my lenses!
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!
crop, f/1.6, f/1.8, focus, focus adjustment, iso100, k-mount, k5, lens, mf, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
AF adjustment debugging needed dave2k Pentax SLR Lens Discussion 4 10-31-2011 04:29 PM
Focus Adjustment JohnKSA Pentax DSLR Discussion 2 08-22-2011 07:10 AM
Focus Adjustment milesy Troubleshooting and Beginner Help 8 07-12-2011 09:40 PM
k-x focus adjustment fafo13 Pentax DSLR Discussion 2 04-21-2011 06:48 AM
Lens focus adjustment on k20/k7 - help needed netuser Troubleshooting and Beginner Help 3 03-12-2010 12:26 AM



All times are GMT -7. The time now is 01:34 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