K3 questions.
Best regards, John

So the little preview button (on the OFF/ON dial) is it just to save the hassle of deleting a photo if it wasn't how you'd like it to be?
If you just do a preview the image isn't automatically saved at all - it's for testing your settings, only you get the option to save it which is sometimes handy - imagine only having a preview image that was unrepeatable but couldn't be saved! It is possible to customize that in the menu options to give an optical preview instead so you can see the depth of field through the viewfinder before taking the shot like some old film cameras used to have.
John K
So the little preview button (on the OFF/ON dial) is it just to save the hassle of deleting a photo if it wasn't how you'd like it to be?
If you just do a preview the image isn't automatically saved at all - it's for testing your settings, only you get the option to save it which is sometimes handy - imagine only having a preview image that was unrepeatable but couldn't be saved! It is possible to customize that in the menu options to give an optical preview instead so you can see the depth of field through the viewfinder before taking the shot like some old film cameras used to have.
I know it doesn't save until I tell it to. I just wasn't sure what the point of it would be if you're already shooting RAW. As in, if I took a picture I could just redo it if I don't like the way it looks, not needing a preview button. I can see where I'll be very thankful for it at random times I am sure, such as a high shutter speed shot. I have my K3 set to the digital preview. I know it sounds like I'm complaining about the function, but I'm really thankful for it. I'm just making sure I understand how it works and what advantages it has so I use it correctly.
Suppose it was a great shot, and then another great shot comes along, but you miss it because you have to save the earlier image first.
It's not as if the size of SD cards is limiting.
TBH I've never seen the point of the optical preview either. By the time it stops down significantly, the viewfinder is so dark and grainy that seeing the DoF accurately is impossible.
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Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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You can't even see the parts through the viewfinder that are IN FOCUS never mind the change from in-focus to out-of-focus

It's also unlikely that the small viewfinder image would have the same DOF as the one calculated for say an 8x10 print.
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Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
http://www.slrgear.com/articles/focus/focus.htm
As this graph shows, manual focusing through the viewfinder was indeed a complete non-starter of an idea.
As I said earlier if you can't see where the point of focus is. you won't see where it goes out of focus. If you could all the people asking for full frame just so that they can have OOF/Bokeh backgrounds could just put the back of the subject at the change point from focus to OOF making the background very blurred...... Just not possible partly because DOF in practise doesn't follow the theory.
Even electronic AF systems struggle to detect a difference at f/5.6 and smaller.
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Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
Regards, Christopher
ChristopherWheelerPhotography
The DoF preview may not offer precision, but it is usually enough to give reassurance that the OOF object you have in the foreground of your pic as seen through the viewfinder using a lens's widest aperture will in fact be acceptably focused at the smaller aperture you've selected. It's obviously not of use on every shot, but it's helpful on some.
More theory

In the darkroom days it was well known that the only accurate method of focusing a negative was by looking at the grain through a grain magnifier.
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Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
You may want to tell me I'm wrong to do so, but I can at least tell you that I am not talking theoretically.
Regards, Christopher
ChristopherWheelerPhotography

In practise you can't actually tell where a camera is focussed and where it is out of focus either through the viewfinder or on the screen as in this typical 50mm at f/5 shot. That's why most lens tests you see on the web aren't of any use. Each shot is actually focused on a different spot in most of them.
Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
Believe that if you want to

In practise you can't actually tell where a camera is focussed and where it is out of focus either through the viewfinder or on the screen as in this typical 50mm at f/5 shot. That's why most lens tests you see on the web aren't of any use. Each shot is actually focused on a different spot in most of them.
With my superninja powers (and with a little help from the Canon EE-S) I can often tell what is going to be in focus and what isn't. Even if the thing I want in focus is outside the puny central phase detect autofocus area of a DSLR. On a good day I can even judge the depth of field


Post by kh1234567890, on Flickr
Pentax M 50mm f1.4 at probably f1.8 or thereabouts.
Flickr Stream
cutting it down for a K-5 yet.
Looks like RH could do with one in his Canon.......
Took all the trouble to do a 17 shot test with two
expensive 50mm f/1.2 - f/1.4 lenses and was about
5 -10 metres different with the distances as mentioned in
the comments. You can see it on the paving flags.
Sadly most Internet lens tests are like that

http://ricehigh.blogspot.com/2013/01/luxury-50mm-lens-fight-ef-5012l-vs-cz.html
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Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
aadixon
Member
So the little preview button (on the OFF/ON dial) is it just to save the hassle of deleting a photo if it wasn't how you'd like it to be? When doing that I see it saves it as a JPEG, but then gives the option to save it as a RAW after the JPEG is saved. So, does the K3 store the RAW information temporarily or what? Just wondering how it can save RAW if it shot JPEG, or if there is a difference in quality of that RAW file compared to if I shot RAW without the preview function.
-Aaron