How to get K-r to focus in the dark?

stern said:

I had a Kr which would NEVER focus properly under any low light (always > frontfocus).

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But that is not the problem discussed here.

The problem discussed here is that the K-r is not focusing in the dark. Not "low light" but "in the dark" = "no light at all, not even low light."

And not even front focusing, we are talking about the K-r not focusing at all in the dark.

To have a front focus problem, the camera must have focused first and achieved a focus lock. But we are discussing that the K-r has not achieved a focus lock in pitch dark.

Mainly because the focus assist beam is too weak.

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Take care
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jungleexplorer said:

I just got off the phone with Pentax and they claim there is no lowlight focusing problem and that they are not working on a fix for it. Now what?

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So now you've been told something you've never seen doesn't exist, I'd be really pleased especially as they didn't soft soap you.

You'll worry yourself into n early grave , you can find issues with everything if you really believe hard enough, it doesn't mean they exist.

Many years ago I had a 35mm pocket camera that had no AF (as designed) yet it could take sharp pictures in any light.

It didn't make it a better camera it was just a wide angle lens so didn't need to focus as a digital compact with it small sensor doesn't need to focus.

You may have brought a type of camera that is not suitable for your style of photography as the narrow DoF may be a a hindrance rather than advantage.

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Just select center AF point, place it on the most lit and contrasty part of the subject (ex: top of the right post, at the edge between a black (unlit) and white (lit) part) , and perform the AF there by half pressing the shutter. keep the shutter half pressed, recompose and shoot.

Now this being said, cheap compact cameras may very well choose maximum depth of field if they cannot achieve focus. Because of the great depth of field PS cams have, even an approximate focus is usually good enough, and PS shooters may not be very fussy on focus accuracy anyway. (That's why they're called point and shoot, as opposed to point, focus, (recompose if central AF), and shoot...) This being said, no camera can auto focus in complete darkness.

With an SLR, you have much more Depth of field control, but you also need to know how to use it. You can achieve max depth of focus with your SLR by manually focussing at the hyperfocal distance for a given zoom (mm value) and F/Stop. This is how I shoot fireworks for instance. (You can surely read on on this on the web...)

Cheers!

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The depth of field in all the shots you posted is very large, which is a function with the small sensor of point and shoot cameras. Therefore, to have shots in focus is very easy. For example, the first shot of the two guys, the area of acceptable focus i(assuming the two guys are 10 feet away) is from about 6.5 feet to 22 feet, meaning anything within that range will appear in focus. See http://www.dofmaster.com/dofjs.html for more info on this.

I don't have the Kr, but I've used Pentax dSLRs from the *ist DL up to the K5 over the past 5 years and I believe you can coax the AF to lock if you try a few things. First, make sure you're only using the center AF point, and you have it on single AF (not continuous AF). Next, if it won't lock on the specific target you want, look for a portion of the subject where the contrast changes, such as the edge of subject, abrupt changes in color, or reflective items (glasses, belt buckle, whatever). If those don't work, take advantage of the same DOF physics as above. Set the aperture a little smaller, use a wider focal length, and shoot from about 10 feet away. You want the hyperfocal distance for your aperture and focal length. That's the point beyond which everything is in focus. This has been used by photojournalists for years to make sure they get acceptable shots before AF even existed.

Where in TX are you? Are you in Houston?
--
Russ
http://www.flickr.com/photos/rfortson/
http://www.pentaxphotogallery.com/russfortson
Even bad photography can be fun

I own the Kr and have no problem with AF in low light I can not however use AF in Darkness and especially at 25ft away. I also have no problem with front or back focus in poor lighting or tungsten.

The photos you show are taken at a distance far less less than 25ft, they also have something to focus on like the white or blue shirt, not to mention the larger aperture.

the gazebo itself is neutral in color (brown) additionally you're outside the flash assist range.

According to your first post you couldn't manually adjust the lens because it was to dark and you couldn't see. How then is the camera to AF (see) if you're outside the range of the focus assist light?

I've shot in dark conditions by shining a flash light on the subject to get focus but I'm not sure it would work on a gazebo.

This isn't a low light problem it is a no light problem. Don't waste your time chasing the FF issue, it is taking you up a blind alley. It is like complaining to Ford that your SUV can't do 200mph.

It is also totally irrelevant what any other camera does in this situation, they have a different design and specification. As I said you are trying to go far beyond the automatic capabilities of your camera here. Your camera manual will warn you that AF has it limits and your example is surely beyond that point.

That is when understanding and experience come into play. Others have covered how p&s cameras deal with this and you can easily emulate this by learning a few tricks like hyperfocal focusing technique. It isn't exactly a new technique either, hyperfocal prefocusing was a staple of photojournalism for decades, long before AF was available. That is what I learned to do with film SLRs over 30 years ago and it still works with DSLRs. Actually it is slightly easier with the greater depth of field the smaller APS-C sensor gives and the benefits of quality high ISO are beyond compare with what could be achieved in my film days.

You have a great tool at your disposal which will deliver the goods for you but it can't do it all on automatic. The camera specifications tell you this and it needs input from you to go beyond the auto settings. Work with it and you will get great results.

Many here will be delighted to help you get the best from your kit, just ask and you will get good advice.

--
Steve

http://www.pbase.com/steephill

steephill said:

This isn't a low light problem it is a no light problem. Don't waste your time chasing the FF issue, it is taking you up a blind alley. It is like complaining to Ford that your SUV can't do 200mph.

It is also totally irrelevant what any other camera does in this situation, they have a different design and specification. As I said you are trying to go far beyond the automatic capabilities of your camera here. Your camera manual will warn you that AF has it limits and your example is surely beyond that point.

That is when understanding and experience come into play. Others have covered how p&s cameras deal with this and you can easily emulate this by learning a few tricks like hyperfocal focusing technique. It isn't exactly a new technique either, hyperfocal prefocusing was a staple of photojournalism for decades, long before AF was available. That is what I learned to do with film SLRs over 30 years ago and it still works with DSLRs. Actually it is slightly easier with the greater depth of field the smaller APS-C sensor gives and the benefits of quality high ISO are beyond compare with what could be achieved in my film days.

You have a great tool at your disposal which will deliver the goods for you but it can't do it all on automatic. The camera specifications tell you this and it needs input from you to go beyond the auto settings. Work with it and you will get great results.

Many here will be delighted to help you get the best from your kit, just ask and you will get good advice.

Click to expand...

Well stated Steve

Cheers,

Jack

steephill said:

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Click to expand...

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Raphael Mabo said:

falcon_wizard said:

-You can also try with the flash popped up. It may use it as flash assist. (not sure > though, as I always use an offboard flash)

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No, the k-r does not use the flash as focus assist beam. It uses a special focus assist beam with green light. This is not as powerful as the flash, but it was choosen because there was too much complaint in this forum about using flash as the focus assist because it wasn't discrete enough. But then, if you have a more discrete focus assist - the thing is that it is not as helpful for the AF system...

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Take care
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Click to expand...

Well, I would agree with you in general, but I have used two cameras (Mavica CD-500 and DSC-V1) that used a Hologram AF assist and it was extremely effective and discrete. The hologram AF assist is so discrete that most people never notice it. So there is at least one technology that exist to accomplish this task, and I am sure there are others. The question is, why Pentax does not use one of them?

Russ Houston said:

The depth of field in all the shots you posted is very large, which is a function with the small sensor of point and shoot cameras. Therefore, to have shots in focus is very easy. For example, the first shot of the two guys, the area of acceptable focus i(assuming the two guys are 10 feet away) is from about 6.5 feet to 22 feet, meaning anything within that range will appear in focus. See http://www.dofmaster.com/dofjs.html for more info on this.

I don't have the Kr, but I've used Pentax dSLRs from the *ist DL up to the K5 over the past 5 years and I believe you can coax the AF to lock if you try a few things. First, make sure you're only using the center AF point, and you have it on single AF (not continuous AF). Next, if it won't lock on the specific target you want, look for a portion of the subject where the contrast changes, such as the edge of subject, abrupt changes in color, or reflective items (glasses, belt buckle, whatever). If those don't work, take advantage of the same DOF physics as above. Set the aperture a little smaller, use a wider focal length, and shoot from about 10 feet away. You want the hyperfocal distance for your aperture and focal length. That's the point beyond which everything is in focus. This has been used by photojournalists for years to make sure they get acceptable shots before AF even existed.

Where in TX are you? Are you in Houston?

Click to expand...

Thanks for the advice. I almost always use center focus. I am still learning the K-r menu and the Pentax naming conventions for things, so I am not sure where to find the multipoint focus menu, what it is called and how to modify it. There are many deferent areas on the K-r menu that I ran across last night that have to do with AF. I tried a lot of settings, but I am not sure if the single AF was one of them. I will look for it.

Also thank you for explaining the depth of field thing to me. I am still blurry on this subject though. This is my first SLR and I have a lot to learn about lenses and how they work.

Raphael Mabo said:

Mainly because the focus assist beam is too weak.

Click to expand...

Are you suggesting the Pentax focus assist beam was too weak? I refuse to believe.
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jungleexplorer said:

The question is, why Pentax does not use one of them?

Click to expand...

even shxt came out of Pentax must be perfect, to some anyway. Pentax AF is weak and remains weak for 2 decades, and no amount of BS will create miracle. Either the R&D is too expensive or the bean counter doesn't give a shxt.
--
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geru said:

I own the Kr and have no problem with AF in low light I can not however use AF in Darkness and especially at 25ft away. I also have no problem with front or back focus in poor lighting or tungsten.

The photos you show are taken at a distance far less less than 25ft, they also have something to focus on like the white or blue shirt, not to mention the larger aperture.

the gazebo itself is neutral in color (brown) additionally you're outside the flash assist range.

According to your first post you couldn't manually adjust the lens because it was to dark and you couldn't see. How then is the camera to AF (see) if you're outside the range of the focus assist light?

I've shot in dark conditions by shining a flash light on the subject to get focus but I'm not sure it would work on a gazebo.

Click to expand...

I tried focusing from 5 feet away, but even then it would not work even though the AF assist light brightly illuminated the structure. The problem may actually be the color of the structure which is light green because it is made of treated lumber. The AF assist light is also green (why? I have never seen a green AF assist before). Green is a dumb color to make an AF assist because green is the most common color in the nature world.

steephill said:

This isn't a low light problem it is a no light problem. Don't waste your time chasing the FF issue, it is taking you up a blind alley. It is like complaining to Ford that your SUV can't do 200mph.

It is also totally irrelevant what any other camera does in this situation, they have a different design and specification. As I said you are trying to go far beyond the automatic capabilities of your camera here. Your camera manual will warn you that AF has it limits and your example is surely beyond that point.

That is when understanding and experience come into play. Others have covered how p&s cameras deal with this and you can easily emulate this by learning a few tricks like hyperfocal focusing technique. It isn't exactly a new technique either, hyperfocal prefocusing was a staple of photojournalism for decades, long before AF was available. That is what I learned to do with film SLRs over 30 years ago and it still works with DSLRs. Actually it is slightly easier with the greater depth of field the smaller APS-C sensor gives and the benefits of quality high ISO are beyond compare with what could be achieved in my film days.

You have a great tool at your disposal which will deliver the goods for you but it can't do it all on automatic. The camera specifications tell you this and it needs input from you to go beyond the auto settings. Work with it and you will get great results.

Many here will be delighted to help you get the best from your kit, just ask and you will get good advice.

--
Steve

http://www.pbase.com/steephill

Click to expand...

Thank you Steve. Please pardon my ignorance. I am reading every response and try my best to learn and get up to speed. Could you please explain how to do this hyperfocal thing you talked about?

Thanks to all for your help in enlightening me. I am beginning to understand that the problem is with my ignorance of how dslr's work and not so much with the camera. I think the camera could have a better AF assist system though. The bottom line for me is that I can't afford any more then the K-r, which was a stretch for me to begin with. My only choice if I can't live with this camera, would be to downgrade to the K-x, but I am not sure it has a better AF assist system. So education for myself must be the solution of the day. Thanks for all the help.

Don't give up. There's a little bit of a learning curve, especially in challenging situations like this. But I'm confident you can figure it out.

Bottom line, it's easier for a P&S to take what looks like an in-focus shot due to much larger depth of field. You can do it with the dSLR as well, just need a little practice. Once you figure it out, you'll be much happier overall.

Good luck!
--
Russ
http://www.flickr.com/photos/rfortson/
http://www.pentaxphotogallery.com/russfortson
Even bad photography can be fun

Hey, education works. Look on the bright side. There's a funny story about an old friend: He walks into a camera store one day and says to the salesperson "I'm stupid. What's a good camera for me?" Then, he walked out with a camera he really liked. Cheers,
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Lipo

jungleexplorer said:

geru said:

I own the Kr and have no problem with AF in low light I can not however use AF in Darkness and especially at 25ft away. I also have no problem with front or back focus in poor lighting or tungsten.

The photos you show are taken at a distance far less less than 25ft, they also have something to focus on like the white or blue shirt, not to mention the larger aperture.

the gazebo itself is neutral in color (brown) additionally you're outside the flash assist range.

According to your first post you couldn't manually adjust the lens because it was to dark and you couldn't see. How then is the camera to AF (see) if you're outside the range of the focus assist light?

I've shot in dark conditions by shining a flash light on the subject to get focus but I'm not sure it would work on a gazebo.

Click to expand...

I tried focusing from 5 feet away, but even then it would not work even though the AF assist light brightly illuminated the structure. The problem may actually be the color of the structure which is light green because it is made of treated lumber. The AF assist light is also green (why? I have never seen a green AF assist before). Green is a dumb color to make an AF assist because green is the most common color in the nature world.

Click to expand...

Because like green screens it the farthest from human skin so will be most affective when shooting people in low light.

What do you think is the number one subject for low light shooting guess not so dumb after all.

I guess shooting green gazebos wasn't high on their test criteria.

Seriously though the AF assist light is only usefull for close in work and even then I find it nominal.

The red light on external flashes is much better as it deliver its own contrast lines (which I guess your hologram light did) This means you can achieve AF of low contrast subjects.

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My Photo Stream
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Sorry to hear about your disappointment. And it brings back the days of my huge frustration with my first DSLR (back in 2007) which had me return it after about 2 weeks (I was coming from a superzoom camera). Still, I ended up buying a DSLR in 2010, and have kept it.

As I'm sure you're aware, a DSLR has a tiny, dedicated AF sensor. This sensor receives light that has to go through the semi-transparent main mirror before it reaches the sensor. In other words, it starts with two handicaps: (1) tiny size, and (2) does not receive all the light available.

This is a much weaker solution than on cameras without a mirror (be they compacts, superzooms, micro four-thirds, etc) where the main imaging sensor is also the focus sensor. It thus is large, and gets all the light. Even the tiny sensors of compact cameras, are of a size comparable to that of the tiny AF sensors of DSLRs.

And what's the result of that? Most DSLRs will NOT focus when it gets dark.

The "solution" that was invented, was the AF-assist light. But most AF-assist lights have been designed for short ranges and thus struggle to assist when the distance is a bit too large as in your example.

Now here's my experience, with Nikons not Pentaxes, but similar observations:

• the D300 I owned for 2 weeks back in 2007, and the D7000 I own now, both have quite powerful AF-assist lights. Powerful enough to save the day (or night, ha ha) in most situations, even when the subject is at some distance
• however if the subject is not a wall but something more diffuse such as trees, my DSLR WILL struggle for sure, and possibly not achieve focus at all. And indeed manual focus is no help if I can't see
• by comparison, either my compact superzoom, or my larger superzoom, will both often easily focus in such situations (say, night landscape, trees at night) where the DSLR is struggling and often fails

I guess this doesn't solve your problem: but hopefully it helps you decide whether a DSLR is for you, if you do a lot of shooting at night on distant subjects that don't reflect enough light to help the AF-assist lamp.

I've included some samples below. These were "easy" subjects ie surfaces that were regular and would reflect enough light. They're ranked from brightest to darkest.

Hope this helps.

clock tower at night. helped by some lighting on the building itself.
http://www.flickr.com/photos/antoinebach/5679731816/in/photostream

church at night. helped by lighting on building but not helped by distance. camera struggled a bit but mostly managed
http://www.flickr.com/photos/antoinebach/5515553235/in/photostream

church at night. reality was darker than this 0.7s 1600 ISO shot suggests. camera would not focus if I tried turning the AF-assist light off
http://www.flickr.com/photos/antoinebach/5284072449/in/photostream

Well, I tried the flashlight trick and it worked. It took a bright light though to focus on the gazebo. I did some test shots of my son in the dark with a black jacket on. The camera could focus lock on him at 5 feet away with only the AF assist but not 10 feet away. I had him hold a white T-shirt in front of him at 10 feet and the camera could focus lock with only the AF assist light. I think the problem is the color of the AF assist not the brightness.

Well I guess if I were going to shoot models with a lot of skin showing in low light, then a green assist light would make all the sense in the world. But I think most people like myself are not thinking about shooting half naked models. I think most people will be shooting fully clothed people and nature scenes. Just my opinion though.