Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-21-2009, 12:59 PM   #1
Senior Member




Join Date: Jun 2009
Location: Riverhead, NY
Photos: Gallery
Posts: 150
Manual focus in low light - technique?

Hi Folks -

I've recently come across this forum, have done some reading, and it seems like there's quite a bit of great information here. I have a bit of a noob-ish question and I hope you'll bear with me. Just as a reference, my camera is an early K100D and along with the kit lens, I have a selection of older manual focus lenses from a pair of Pentax SLR's I had used for years (K1000 and KX).

Anyway, I've recently started playing with the camera in low ambient light and have found focusing properly to be pretty tricky. For the photos below, I used an old 50mm manual focus SMC lens. What I did in an effort to minimize error was to use a tripod (obviously) and the timer on the camera because I don't have a remote shutter release. I stopped down the lens to f8 or so, set the shutter speed to 20 seconds, and prayed that the depth of field would be sufficient to get a clear image. I found that the DOF preview was sufficient to get a decent exposure, but really had trouble seeing whether it was well focused. I also found the viewfinder to be tough to see through.

I figure that I could have opened up the lens to use a faster shutter speed, get some test shots off to get the focus close, then stop down the lens, slow the shutter w/o touching the focus, and things should be pretty good...but the camera and I were being snowed upon and it was cold.

What sayeth the photography gurus?




06-22-2009, 09:51 PM   #2
Igilligan
Guest




Well I sayeth that the focus on the house is pretty darn good. I am seeing detail in the Black shutters... with all that snow I think that came out well.

The car has the plane of focus point at the rear tire/center of the hood since the car is at an angle ... you can see the lugnuts are sharp.

Did you leave the shake reduction on? I would keep that off when on a tripod and long exposures.

And you are right, what I would have done would have been to open up the lens to get some more light for focus then stopped it down for the shot. I find a big difference sometimes at f2.8 vs F8 on wear I think the focus point is.
Try it with your lens, get the best focus at F8 then open up the lens and see how far off you are, sometime I am quite a bit off.

But I know it must have been cold!
06-22-2009, 10:53 PM   #3
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
Focus for me isn't about looking at the subject and turning the ring until it is in focus. It is about looking to see what's in focus, and turning the ring until the in-focus zone includes the subject. Note the place on the focus ring where it's a little behind the subject, then a little in front, then split the difference and verify the subject looks good. That's my basic approach.

I personally would have done those shots handheld, wide open or close to it, high enough ISO to make it handholdable - but I'd also have found soemthing to lean against for support. Since the subject isn't moving, I'd have hoped for a sharp enough picture at maybe 1/8. It probably woudn't have come out as well as what you did, though!
06-23-2009, 04:45 AM   #4
Inactive Account




Join Date: Dec 2008
Location: Ames, Iowa, USA
Photos: Albums
Posts: 2,965
Some depth of field focus correction can be done using FocusMagic or similar deconvolution programs. Here is a crude example in which I corrected the focus on the car's front wheel.


I like the photo as-is BTW.

Iowa Dave

06-23-2009, 11:57 AM   #5
Veteran Member
GerryL's Avatar

Join Date: Jan 2009
Location: CA
Posts: 2,731
If you really want to be sure about the focus, is try to focus as nearly as you can see clear then just crank up the aperture opening to the smallest opening you can afford.
Since it is in a tripod something smaller than an f-8 would have made sure everything was sharp (DOF).
Anyway, you did fine so, nothing to worry about!
06-23-2009, 01:00 PM   #6
Veteran Member




Join Date: Sep 2008
Location: Tri-Cities, British Columbia
Photos: Gallery
Posts: 1,784
Yup, sounds like how I do my manual focusing too:

1) know what part of your subject you want to be in focus (eyes, nose, petal, etc.)
2) know what "in focus" looks like for your lens
3) get comfortable with dialing that focus ring to do the front/behind focus tip; someone mentioned in another post that when you hit the focus point, the part you want in focus will "pop" in the viewfinder.

QuoteOriginally posted by Marc Sabatella Quote
Focus for me isn't about looking at the subject and turning the ring until it is in focus. It is about looking to see what's in focus, and turning the ring until the in-focus zone includes the subject. Note the place on the focus ring where it's a little behind the subject, then a little in front, then split the difference and verify the subject looks good. That's my basic approach.

I personally would have done those shots handheld, wide open or close to it, high enough ISO to make it handholdable - but I'd also have found soemthing to lean against for support. Since the subject isn't moving, I'd have hoped for a sharp enough picture at maybe 1/8. It probably woudn't have come out as well as what you did, though!
06-27-2009, 07:17 AM   #7
Senior Member




Join Date: Jun 2009
Location: Riverhead, NY
Photos: Gallery
Posts: 150
Original Poster
Thanks for the thoughts! I'll absolutely keep these things in mind as I move forward, though what I've found most difficult with the low light photos was actually being able to perceive what portion of the photo was in focus and what wasn't. The viewfinder was tough to see through and the DOF preview helps, but doesn't quite get me there.

I've actually found this to be a problem I have with photos in daylight using my old 80-200 lens, too. Looking at the photo below that I took the other day, I think it would be better with a very sharp focus on the reflection from the eye. Perhaps I should install one of those prism thingies as my eyes aren't what they were 20 years ago!
06-27-2009, 04:40 PM   #8
Veteran Member
GerryL's Avatar

Join Date: Jan 2009
Location: CA
Posts: 2,731
Well, you got it perfectly focused and sharp...at the hind leg..

06-27-2009, 05:00 PM   #9
Senior Member




Join Date: Jun 2009
Location: Riverhead, NY
Photos: Gallery
Posts: 150
Original Poster
QuoteOriginally posted by GerryL Quote
Well, you got it perfectly focused and sharp...at the hind leg..
I know! So close, yet so far away.... Arrrrgh!!! I'll keep at it and surely I'll improve; half of solving a problem is knowing what it is. Patience and practice....
06-30-2009, 10:02 AM   #10
Forum Member




Join Date: Jun 2009
Location: Gator Country
Photos: Gallery
Posts: 51
It is a rather shapely hind leg
07-01-2009, 05:18 PM   #11
Veteran Member




Join Date: Jun 2009
Photos: Albums
Posts: 1,679
QuoteOriginally posted by Ccat Quote
It is a rather shapely hind leg
looks tasty too!!
07-02-2009, 10:36 PM   #12
Forum Member




Join Date: Jan 2009
Location: Pleasanton, CA
Posts: 68
Is that Beemer a 325ix? I used to have one a lot like it.
07-18-2009, 08:25 AM   #13
Senior Member




Join Date: Jun 2009
Location: Riverhead, NY
Photos: Gallery
Posts: 150
Original Poster
QuoteOriginally posted by HarryN Quote
Is that Beemer a 325ix? I used to have one a lot like it.
Not quite. It's a lightly optioned '91 318i. It's a base car with a limited slip differential and foglamps that's been cared for since day one and works really well as a daily driver.
07-20-2009, 10:23 PM   #14
Inactive Account




Join Date: Jul 2009
Posts: 11
QuoteOriginally posted by Judd Quote
Perhaps I should install one of those prism thingies as my eyes aren't what they were 20 years ago!
I just replaced my focusing screen with a split circle one (a preference born in my MX days), and I find it makes a huge difference in manual focusing, especially in low light. I've heard KatzEye makes nice ones for $100 or so, but I got a $25 one from VirtualVillage. After a harrowing install process (I'm always nervous going into the mirror/sensor cavern) I'm very happy with the result. There are a number of threads here about people's experiences with these screens, so I'll just say if you want a more exact idea of where your focus is, it's worth the trouble.
07-22-2009, 02:00 AM   #15
Veteran Member
Wombat's Avatar

Join Date: May 2008
Location: South Australia
Photos: Gallery | Albums
Posts: 901
QuoteOriginally posted by Judd Quote
Perhaps I should install one of those prism thingies as my eyes aren't what they were 20 years ago!
You can get 1.5X magnifiers which clip onto the viewfinder. I use one from time to time in difficult lighting and it really helps to sharpen up your focus.
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!
bit, camera, focus, lens, light, pentax help, photography, shutter
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Low Light auto focus JohnKSA Troubleshooting and Beginner Help 6 03-10-2010 04:19 AM
My Technique for Manual Focus Lenses Youngster Photographic Technique 37 12-31-2009 12:01 PM
My technique to focusing in extreme low light vitalsax Pentax DSLR Discussion 21 01-06-2009 01:18 AM
Low Light Manual Focusing? sjl7678 Pentax DSLR Discussion 11 08-15-2007 12:55 PM
Manual focus technique- please help button Digital Processing, Software, and Printing 14 06-19-2007 06:56 AM



All times are GMT -7. The time now is 01:46 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