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Pentax DSLR DiscussionTalk about Pentax Digital SLR modes, technique, operation, and problems here (K-7, K-x, K series, and *ist D series). This is a discussion on K10D. Bug with Auto ISO in P mode?, part of the Pentax DSLR Discussion category, related to auto, bug, iso, k10d, mode: Hi,
Yesterday I was experimenting with my K10D and ran into one thing.
ISO was Auto, between 100 and 800. K10D was in P mode. Aperture was 1,8. Shutter speed ...
Yesterday I was experimenting with my K10D and ran into one thing.
ISO was Auto, between 100 and 800. K10D was in P mode. Aperture was 1,8. Shutter speed 1/45. I decided to go for faster shutter speed. So, I turned shutter speed dial, it became f1,4 and 1/60 and that's it. K10D did not allow me to make shutter speed faster than 1/60. I've checked ISO -- it was 100. So, it means that ISO100 f1,8 1/45 became ISO100 f1,4 1/60.
While such behaviour would be perfectly OK with fixed ISO value, I expected different behaviour in Auto ISO mode.
ISO100 1,8 1/45 -> ISO100 f1,4 1/60 -> ISO200 f1,4 1/125 -> ISO400 f1,4 1/250 -> ISO800 f1,4 1/500 and just after that K10D should have hit the limit and should have not allow me to make shutter speed faster.
I can't see any problem for what you've mentioned and I think there is NO bug for what you describe.
Auto ISO will only kick in when there the Av and Tv have both reached their limits, physically for the Av and Tv (for out of range) and handheldable for Tv (at low speed).
What the case you mentioned, there is simply half stop Av room for the camera to adjust, so there is no need to change the ISO. If you need to raise the Tv together with ISO speed by keep the Av, I think the best way to do is to put your cam in Av mode and to select ISO manually.
Originally posted by Edvinas
Hi,
Yesterday I was experimenting with my K10D and ran into one thing.
ISO was Auto, between 100 and 800. K10D was in P mode. Aperture was 1,8. Shutter speed 1/45. I decided to go for faster shutter speed. So, I turned shutter speed dial, it became f1,4 and 1/60 and that's it. K10D did not allow me to make shutter speed faster than 1/60. I've checked ISO -- it was 100. So, it means that ISO100 f1,8 1/45 became ISO100 f1,4 1/60.
While such behaviour would be perfectly OK with fixed ISO value, I expected different behaviour in Auto ISO mode.
ISO100 1,8 1/45 -> ISO100 f1,4 1/60 -> ISO200 f1,4 1/125 -> ISO400 f1,4 1/250 -> ISO800 f1,4 1/500 and just after that K10D should have hit the limit and should have not allow me to make shutter speed faster.
I can't see any problem for what you've mentioned and I think there is NO bug for what you describe.
Auto ISO will only kick in when there the Av and Tv have both reached their limits, physically for the Av and Tv (for out of range) and handheldable for Tv (at low speed).
What the case you mentioned, there is simply half stop Av room for the camera to adjust, so there is no need to change the ISO. If you need to raise the Tv together with ISO speed by keep the Av, I think the best way to do is to put your cam in Av mode and to select ISO manually.
I see problem. K10D manual says that in P mode (Hyper program) turning front wheel sets my camera into Shutter speed priority mode (i.e. into Tv mode). Therefore I expect it to work the same way as Tv mode works.
In Tv mode I was able to set shutter speed faster than 1/60. Aperture was set by camera to 1,4 and because it reached its limit, K10D increased ISO with each increase of shutter speed.
However in P mode I turned front wheel, according to manual camera went into Tv mode, but it did not allow me to set shutter speed faster than 1/60 and kept ISO at 100 (although ISO was set to Auto between 100 and 800).
Originally posted by peted
Were you in P mode or Green mode and what program line are you using?
I rechecked again. Definately there's a problem in Hyper program.
Example. Low light conditions, K10D in P mode, green button pressed: f1.4, 1/30 sek. and ISO800.
I turn fron wheel (for Tv) for two clicks counter clockwise. I get f1.4, 1/15 and ISO200. Then I turn front wheel clockwise (to go back to f1.4, 1/30 and ISO800 -- K10 doesn't do that. It just stays f1.4, 1/15 and ISO200.
OK, I again turn front wheel counter-clockwise for two clicks. It becomes f1.4, 1/8 and ISO100. Turn front wheel clockwise and K10D does not allow to make shutter speed faster, camera just stays in f1.4, 1/8 and ISO100.
Then I press green button and camera jumps back to initial f1.4, 1/30 and ISO800...
edvinas, I tried my k10 just now and it did the same sort of thing in low light so I tried asa 1600 (not auto) and I could get the shutter to go both faster and slower hope this helps! I like the hyper manual mode ,but I might start trying this one for a while. good luck,
borno
I joined this forum just to get into this discussion
I noticed "problem" this just after buying my K10 and after many tests have come to the conclusion that this occurs when the camera reaches the lower end of it's metering capabilities (I should point out that this conclusion may not be correct). If I'm right, it sort of defeats the object of having this facility.
Well, as what EV compensation defeats Auto ISO for all other Pentax DSLRs, what you can do is to fall back to use Manual ISO. This is the only way to go!
Originally posted by K10D
I joined this forum just to get into this discussion
I noticed "problem" this just after buying my K10 and after many tests have come to the conclusion that this occurs when the camera reaches the lower end of it's metering capabilities (I should point out that this conclusion may not be correct). If I'm right, it sort of defeats the object of having this facility.
I noticed some irregularities with Hyperprogram too but until now I didn't quite see what exactly it was doing. It appears that decreasing shutter speed with HyperProgram allows the ISO to decrease but will not allow you to increase the shutter speed (and raise ISO) even though the aperture is wide open. This does seem to be undesireable behavior--it stinks that you can't reverse your last change with a click back in the other direction.
Behavior like this has been making me want to abandon HyperProgram, possibly enable P-Shift rather than HyperProgram for the e-dial when using Program mode. I'm not holding my breath for a fix even though this seems to be within the realm of what is likely possible to change with a firmware fix.
Isn't TAv mode desgined for this? It's exactly what you want - you set desired Aperture and/or Shutter and ISO gets adjusted for you (if you set ISO step to 1/3 stops you'll get it more precise).
To me using Auto ISO in Hyperprogram without some user definable rules seems like the most impossible algorithm that really doesn't have the correct (or at least predicatble) behavior. Just think of it. You have 3 variables but change at a time only one of them (e.g. Shutter). As a result you expect the other 2 variables (Aperture and ISO) to auto change in some predictable manner which's impossible unless you put obvious, simple (remember you're in a heat of taking a shot) and reasonable constraints on behavior of the other two variables.
Changing ISO only when AE reaches the metering limits isn't very usefull. Much better, is how Nikon wisely have done this on D200 (I believe) by allowing user to define Auto ISO constraints in terms of shutter speed, e.g. "Bump ISO when shutter slows below 1/60, decrease ISO when shutter gets faster than 1/60"." That's what you really want - bump ISO to mainatin handholding sharpness. Same can be applied to maintain DOF or lens best aperture, e.g. bump ISO only when aperture opens up past F4.5. I think Pentax on K10D tried to achieve something like this with this vague Hyperprogram Lines. They should've done this the Nikon way- let user control Auto ISO by explicit shutter or aperture threshold values.
Too bad Pentax didn't do this. TAv mode seems like a next best thing.
Originally posted by trog100 
