focusing

August 1st, 2015
My question this time is about focusing in relatively dark conditions when not using a flash. Have a look at the two shots below. Both were taken inside my house with no flash. I had the aperture all the way open, which I know will throw part of the shot out of focus, but in the shot where Chico is looking up, I aimed for his eyes, so that's what SHOULD be in focus and clearly is not. I'm using a single AF point which is definitely what works best for me in better light. My lens is doing a lot of searching, though my camera did claim that this shot was in focus before I clicked the shutter. I tried focusing manually, but that didn't help me much as my own judgment isn't very good through the viewfinder. Maybe I would have had better luck using live view, but I was lying on the floor and I'm not sure I would have been able to see the screen. I didn't have a whole lot of time, either, of course -- he wasn't going to stay still all evening! ;-)

In the second shot, I locked my focus on the ball and then waited for him to approach. Here, the focus is slightly better, though still not really sharp (that might be the wide aperture coming into play). Apart from closing the aperture, is there anything I could have done to get his face a bit more in focus?



August 1st, 2015
DbJ
While it's possible the focus wasn't quite nailed, I think what really is impacting the shot is the aperture. Given your focal length of 50mm, I'm guess you were 5 feet or less from your subject? On your Pentax, with a focal length of 50mm and 5ft from your subject, your focal plane is around 1-1/2 inches...or so. It would have even been less if closer. So in the second picture, for example, if you focused on the ball, the dogs eyes would be out of focus because they are more than an inch behind the ball. Using such narrow apertures at close distances is really tough. As far as actual focus method, in poor light a lot of cameras do struggle, some are better than others. Focusing on the closest eye is the right call, I think you did well given the circumstances. When considering the low light along with such a narrow depth of field, it was a very challenging shot.
August 1st, 2015
I'd say it's simply because you shot the images with 1/25th or 1/40th of a second - these slow speeds mean its rather hard not to move, you or the subject, when you press the shutter. I doubt your focus skills were wrong, more that it's on a slow shutter.

As a general rule, less that 1/60th of a second and you will probably show movement in a photo unless well aware of the speed and doing everything you can to keep very still. Lying on the floor and shooting a doggie who'd not understand he has to keep real still for a second isn't going to help!
August 1st, 2015
@dbj Thanks and yes, I was very close. I figured that was the issue in the second photo. Maybe I need to get further away and then just crop the shot.

@blightygal I thought about that possibility, although my camera was pretty well supported -- I think it was at least partly resting on the floor. I can usually manage a pretty sharp shot at 1/40 of a second with my 50mm lens, but the first shot was taken at 1/25 of a second. That said, the dog wasn't moving in that shot, but it's possible that I moved the camera slightly when I clicked the shutter.
August 2nd, 2015
Very cute photos.
Looking at the files close up it's definitely shutter speed.
August 2nd, 2015
@dbj @blightygal What each of these folks said.
August 2nd, 2015
Nothing further to say re aperture/shutter speed/distance etc but - what an adorable doggie! Both shots are very, very cute!
August 2nd, 2015
@nap101 @frankhymus @aranelinya4268 Thanks, everybody (for the compliments on my dog, too! He really is a cutie!). Any suggestions on how to at least get my AF to lock on to something -- it can just hunt and hunt and never focus on anything! I thought of maybe using a flashlight to light up whatever it is I'm focusing on and then turn it off, but I'm not sure that's a good idea when focusing on the dog, who might view it as an invitation to come check out the flashlight!
August 2nd, 2015
@hamora Your autofocus latches onto changes in contrast (or so I am led to believe) so in low light and low contrast situations, you might best be advised to switch to manual focus. In the case of your photos above, I am going to suggest that the lack of sharpness is down to motion blur at the camera end. It is surprising just how even the slightest bit of motion can totally ruin a shot.
August 2nd, 2015
@hamora I forgot to say that if you have Photoshop CC (and possibly Lightroom CC - I'm sure that someone else can tell you that) then there is a blur reduction tool which, whilst it isn't anything more than a blunt instrument at times, can remove small amounts of motion blur quite successfully.
August 2nd, 2015
@creampuff Thanks. My manual focusing skills are not great, especially in low light. I see worse than my camera does! I did try the blur reduction took in Photoshop (I don't think Lightroom has it), but I didn't see much of a difference.
August 2nd, 2015
@creampuff I take that back. I just tried the blur reduction tool again and it actually does make a significant difference, but it sharpens other areas of the photo that I don't want to sharpen. I think that with enough time and patience, I could work that out.
August 2nd, 2015
@hamora I just had another play with your shot in Photoshop. If you create a new layer and reduce the motion blur on that to the level you want and then add a layer mask you can bring through the blur that you like in the areas you want through the layer mask.
August 2nd, 2015
@creampuff Thanks for the tip -- I'll try that!
August 2nd, 2015
For its vintage, circa 2009, the K-x AF system (variants of phase detection) is on a par with the competitors through the viewfinder, the Nikon D5000 and the Canon 500D, but in low light it will hunt and not accurately focus occasionally even though it does register "locked." Don't think to try AF in Live View, the contrast detection AF implementation was significantly inferior to the competition even six years ago. Manual Focus if you have time would, of course, be best in Live View. Here's what DPR said six years ago. Look towards the bottom (disregarding all the comments of course) for its evaluation of the auto focus. http://www.dpreview.com/reviews/pentaxKx/13

There really is little you can do, sorry to say. Current AF technology, six years later, has tremendously improved especially in low light.
August 3rd, 2015
@frankhymus This could be very good news -- it all depends on your perspective. Now I have a legitimate reason to buy a newer camera ;-)
August 3rd, 2015
@hamora Well, good luck to you if you do...
August 4th, 2015
@frankhymus Thanks! Mentioned it to my husband today (again) and the answer was no longer "Why do you need a better camera?" so maybe I'm getting somewhere ;-)
August 5th, 2015
alot of photographers i know that shoot at night carry a torch wiht them so they can illuminate the area they want, focus and then turn off the light to shoot.

Of course theyre generally shooting either landscapes or people who they can tell to stay still... not an animal that can move :)

If you believe its a focus issue (as opposed to one of the two issues addressed above), you could always try turning bouncing the torch light off the wall to illuminate enough to get focus lock and then shooting?
August 5th, 2015
@toast Thanks for the suggestion!
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