Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-03-2009, 02:24 AM   #1
Senior Member
paulelescoces's Avatar

Join Date: Sep 2009
Location: Singapore
Photos: Gallery
Posts: 241
Focus Accuracy K 50 1.4

Hi All,

Had my K20D for a few months now (got in May)... is my first DSLR so much of this is quite new to me.

I purchased some time back (from ebay) a Pentax K 50 1.4.... find it a great lens, amazing build quality and have had some great shots in a short time. I typically pull this lens out when lighting conditions mean I use it or use a flash...

I do however have a problem... this lens is manual focus.... and shooting it wide open at 1.4 DOF is very narrow... I really have trouble detecting if I have accurately focussed in the viewfinder. With this I tend to have a high % of shots which are not focussed (e.g. I try and focus on the eyes in a portrait but dont have the focus accuracy to get them sharply in focus)....

My workaround for this till now is to take multiple shots at with small focus adjustments... or Use Liveview where I can use the dial to zoom into the subject... works very well but only works well with very slow moving subjects. Focus confirmation seems to confirm accross a range of focus adjustments... and seems a bit slow to kick in in low light anyway.

Any advice or techniques I can use to try and get more focussed shots?

Thanks
Paul

09-03-2009, 03:18 AM   #2
Veteran Member
Barnster's Avatar

Join Date: Jun 2009
Location: Mid North Coast,Australia
Photos: Gallery
Posts: 1,013
QuoteOriginally posted by paulelescoces Quote
Hi All,

Had my K20D for a few months now (got in May)... is my first DSLR so much of this is quite new to me.

I purchased some time back (from ebay) a Pentax K 50 1.4.... find it a great lens, amazing build quality and have had some great shots in a short time. I typically pull this lens out when lighting conditions mean I use it or use a flash...

I do however have a problem... this lens is manual focus.... and shooting it wide open at 1.4 DOF is very narrow... I really have trouble detecting if I have accurately focussed in the viewfinder. With this I tend to have a high % of shots which are not focussed (e.g. I try and focus on the eyes in a portrait but dont have the focus accuracy to get them sharply in focus)....

My workaround for this till now is to take multiple shots at with small focus adjustments... or Use Liveview where I can use the dial to zoom into the subject... works very well but only works well with very slow moving subjects. Focus confirmation seems to confirm accross a range of focus adjustments... and seems a bit slow to kick in in low light anyway.

Any advice or techniques I can use to try and get more focussed shots?

Thanks
Paul
I don't know about the K20D,but with my K100D,point the camera towards your subject.You then press the shutter down halfway,like you would with a AF lens to focus,turn the focusing ring until you here the beep and the see red light in the viewfinder at the same time.That will indicate when the lens is in focus.That's how it works for me with my K100D & manual lenses.
09-03-2009, 03:20 AM   #3
Veteran Member
mickeyobe's Avatar

Join Date: Dec 2006
Location: Toronto, Ontario, Canada
Posts: 1,762
Paul,

I do not mean to insult you but if you cannot focus at f1.4
I would suggest that you get an autofocus lens.

But try this first.
When you focus you should try to focus on a sharp edge or the junction between two areas of differing contrast.
If the K20D has a split image focussing screen you should align a vertical line.
Do not attempt to focus on large featureless areas.

There is an alternative, however, I am not sure that it would work for you; a magnifier for your viewfinder.

Mickey
09-03-2009, 03:56 AM   #4
Senior Member
paulelescoces's Avatar

Join Date: Sep 2009
Location: Singapore
Photos: Gallery
Posts: 241
Original Poster
Hi Thanks for the responses,
Barnster, I use this technique although find that the focus confirmation "confirms" accross quite a range of focus ring movement, final result is a bit hit and miss on getting the details focussed (e.g. eyes).

Mickey, thanks for the tip, have the original focussing screen with no viewfinder. Also when the bank/fiance allow a AF version is on the cards.

Thanks,
Paul

09-03-2009, 04:06 AM   #5
Loyal Site Supporter




Join Date: Mar 2009
Location: Gladys, Virginia
Photos: Gallery
Posts: 15,770
I don't manual focus much -- mainly in low light where the camera doesn't see contrast. I think what most do who use manual focus a lot is invest in a katz eye or other split screen focus screen.
09-03-2009, 07:00 AM   #6
Pentaxian
jimH's Avatar

Join Date: Apr 2009
Location: South Central Nebraska - USA
Photos: Gallery | Albums
Posts: 1,415
Getting proper focus with manual lens

Paul, I've had similar issues with SMC Pentax-M 50mm f1.4 lens that I was using. Some things to consider: First of all with a manual lens the camera defaults to "center" focus & center metering. You should try to aim as closely as you can with the center of the view finder, on the part of your subject you want in focus.

The red light referred to by Barnster is indicating where the focus point is, so make sure that red light is on the point you want in focus. Secondly the green hexagon focus confirmation light will light when the spot under the red light is in focus. I've had the best luck using "catch-in-focus" to get proper focus, however you really need to "sneak up" on proper focus with the focus ring to avoid triggering the shutter as you go past the correct point of focus. If you aren't familiar with "catch-in-focus" let me know.
09-03-2009, 07:13 AM   #7
Site Supporter
Douglas_of_Sweden's Avatar

Join Date: Apr 2008
Location: Stockholm
Photos: Gallery
Posts: 3,348
This works for me: eBay.ie: Diagonal Split Image Focus Screen Pentax k10D k20D DS (item 110385037541 end time 30-Sep-09 00:53:02 BST)

Does not cost that much so perhaps talking with the bank will be easier...
09-03-2009, 07:43 AM   #8
Senior Member
paulelescoces's Avatar

Join Date: Sep 2009
Location: Singapore
Photos: Gallery
Posts: 241
Original Poster
Jim, thanks for the reply... I will give that a try, just checked the camera manual and think I have not yet enabled it in the K20D Custom Menu (option 34 apparently) I will change that and try it this evening.

Douglas, depending on the success of the above I might try that route.

Paul

09-06-2009, 02:44 AM   #9
Moderator PEG Judges
Kerrowdown's Avatar

Join Date: Aug 2008
Location: Highlands of Scotland.
Photos: Gallery
Posts: 32,226
Try the katzeye route and see how you get on, it helped my old eyes get it right again.
09-06-2009, 11:12 AM   #10
Veteran Member
KungPOW's Avatar

Join Date: Nov 2007
Location: Vancouver, Canada
Photos: Gallery
Posts: 1,702
The modern focusing screen as found in the K20D is VERY inacurate for manual focusing with a large aperture lens.

The screen was designed for use with the smaller aperture zooms that are so common today.

The trade off is that the brighter screens are not as acurate for focusing, but the better screens for focusing, are not bright enough for a 3.5-5.6 zoom.

As sugested, if you are going to do allot of manual focusing, then get a Katz Eye or similar focusing screen.

Here is an write up that explains it:

Manual Focus with AF DSLRs
09-06-2009, 12:11 PM   #11
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,152
QuoteOriginally posted by KungPOW Quote
The modern focusing screen as found in the K20D is VERY inacurate for manual focusing with a large aperture lens.

The screen was designed for use with the smaller aperture zooms that are so common today.

The trade off is that the brighter screens are not as acurate for focusing, but the better screens for focusing, are not bright enough for a 3.5-5.6 zoom.

As sugested, if you are going to do allot of manual focusing, then get a Katz Eye or similar focusing screen.

Here is an write up that explains it:

Manual Focus with AF DSLRs
What KungPOW said...plus my piece...

My experience has been that the focus confirm lacks adequate precision for manual focus with a fast lens. I have the Katz Eye and frequently notice that the green hexagon will be lit both front and back of the actual focus point as determined by the split-image.

So the conclusion is that if you frequently or almost exclusively (me) use manual focus, an aftermarket screen is a good investment. The Katz Eye is the high end solution, but many members of this forum have been satisfied with much less expensive products through eBay or focusingscreen.com.

Steve
09-06-2009, 12:22 PM   #12
Banned




Join Date: Oct 2007
Location: Savannah, U.S./Baguio City, P.H.
Posts: 5,979
split-image sucks, what we need is for someone to put out a nice fresnel screen with a simple microprism center. its a 1000x easier to focus with than a split-image. particularly once you go past f4.
09-06-2009, 01:19 PM   #13
Moderator PEG Judges
Kerrowdown's Avatar

Join Date: Aug 2008
Location: Highlands of Scotland.
Photos: Gallery
Posts: 32,226
QuoteOriginally posted by séamuis Quote
split-image sucks, what we need is for someone to put out a nice fresnel screen with a simple microprism center. its a 1000x easier to focus with than a split-image. particularly once you go past f4.
I had this on my LX's, designed with sharper angles for fast lenses, maybe it would be worth talking to the folk at Katzeye and if there was enough demand, maybe they would manufacture.
09-07-2009, 04:55 AM   #14
Senior Member
paulelescoces's Avatar

Join Date: Sep 2009
Location: Singapore
Photos: Gallery
Posts: 241
Original Poster
KungPOW, excellent article, I think I will go this route.

any other specifics on brands of focus screen, Katz Eye are quite expensive... dont mind paying it if I know there lower cost solutions are not worth it.

Thanks,
Paul
09-07-2009, 05:01 AM   #15
Banned




Join Date: Oct 2007
Location: Savannah, U.S./Baguio City, P.H.
Posts: 5,979
QuoteOriginally posted by paulelescoces Quote
KungPOW, excellent article, I think I will go this route.

any other specifics on brands of focus screen, Katz Eye are quite expensive... dont mind paying it if I know there lower cost solutions are not worth it.

Thanks,
Paul

well thats opinion really. the lower cost can be worth it to some, not to others. I purchased a katzeye for my k-m but purchased a screen from focusng-screen.com and saved 50 buck over the katzeye for my istD. its a good screen, but I have had to do a permanent .5 EV bump to make up for the effected metering of the darker screen. the katzeye is about the same brightness but I haven't had to adjust metering on the k-m.

if you have the money, id say go katzeye, but the other alternatives can be just as good.

if I knew how to cut glass I would pull the screen out of a junked SV and use that. oh man... I should learn. the ony problem that I have with the katzeye is that I just dont care for split-image enough to have made the price worth it. focsuing-screen.com has other types available but the cost gets close to the katzeye. but despite being a Taiwanese based site, they are professional and ship very fast and very well packaged.
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!
accuracy, camera, focus, focus accuracy, lens, pentax help, photography, shots, time
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Focus Points and Accuracy montman Pentax DSLR Discussion 3 06-09-2010 09:48 PM
Focus accuracy krypticide Pentax DSLR Discussion 12 11-15-2009 12:19 PM
K10, split-screen, LF80 & LL60 : Focus and exposure accuracy dlacouture Pentax DSLR Discussion 24 11-18-2008 06:20 AM
K20D AF.C Accuracy Nanthiel Pentax DSLR Discussion 6 09-14-2008 10:13 PM
AF Speed vs Accuracy Workingdog Pentax News and Rumors 9 12-25-2007 08:19 AM



All times are GMT -7. The time now is 04:15 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