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07-20-2015, 01:32 PM   #1
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K-3 How is the high speed profile and ISO auto programmed to work ?

Over the weekend I went to an airshow and thought I would experiment with some of the settings.

First I selected the High speed priority profile and used the default ISO auto setting of 100-3200 together with the fast increase option.
The weather was cloudy and dull so I was surprised to see that the camera continually selected ISO 100 with a shutter speed of 1/250 or 1/320.

So even with the ISO auto option set to fast the camera seemed reluctant to increase it above ISO 100.
I would have thought, with the improvements in noise performance with modern cameras, the firmware should have been programmed to increase ISO earlier, especially with the fast setting selected and the standard and slow options are available.

I also don't consider the camera selecting 1/250 and 1/320 as being much of high shutter speed priority.
I would have expected, with those two settings combined, the camera to always adjust for a minimum shutter speed of 1/500.

So I am not sure what the firmware developers instructions/remit was ?

07-20-2015, 01:39 PM   #2
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QuoteOriginally posted by Stumpy Quote
Over the weekend I went to an airshow and thought I would experiment with some of the settings.

First I selected the High speed priority profile and used the default ISO auto setting of 100-3200 together with the fast increase option.
The weather was cloudy and dull so I was surprised to see that the camera continually selected ISO 100 with a shutter speed of 1/250 or 1/320.

So even with the ISO auto option set to fast the camera seemed reluctant to increase it above ISO 100.
I would have thought, with the improvements in noise performance with modern cameras, the firmware should have been programmed to increase ISO earlier, especially with the fast setting selected and the standard and slow options are available.

I also don't consider the camera selecting 1/250 and 1/320 as being much of high shutter speed priority.
I would have expected, with those two settings combined, the camera to always adjust for a minimum shutter speed of 1/500.

So I am not sure what the firmware developers instructions/remit was ?
High speed priority profile? What is this and where are you seeing it?
07-20-2015, 02:31 PM   #3
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QuoteOriginally posted by enoeske Quote
High speed priority profile? What is this and where are you seeing it?

I think the OP is referring to the Program Line in the Camera #2 menu. It has an option Hi-speed priority said to "Prioritize[s] high shutter speeds". Actually, combining this with option Fast in the Auto-ISO settings makes kind of sense. I have used these options myself, but only as a starting point from where I make Hyper Program tweaks as the need arises.

In my experience, the shutter speeds selected by these auto settings are often not fast enough to freeze even moderately fast action. So I tend to set specific ISOs to get the shutter speeds I want.

What I find a little odd, though, is that in the OP's case ISOs beyond 100 get rarely selected, given that my K-3 will jump quite readily to higher ISOs with those settings.
07-20-2015, 02:49 PM   #4
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QuoteOriginally posted by Stumpy Quote
Over the weekend I went to an airshow and thought I would experiment with some of the settings.

First I selected the High speed priority profile and used the default ISO auto setting of 100-3200 together with the fast increase option.
The weather was cloudy and dull so I was surprised to see that the camera continually selected ISO 100 with a shutter speed of 1/250 or 1/320.

So even with the ISO auto option set to fast the camera seemed reluctant to increase it above ISO 100.
I would have thought, with the improvements in noise performance with modern cameras, the firmware should have been programmed to increase ISO earlier, especially with the fast setting selected and the standard and slow options are available.

I also don't consider the camera selecting 1/250 and 1/320 as being much of high shutter speed priority.
I would have expected, with those two settings combined, the camera to always adjust for a minimum shutter speed of 1/500.

So I am not sure what the firmware developers instructions/remit was ?
That is about right... the program line symbol for 'speed' is a runner. It will start with around 1/250 or so. Depending on what shooting mode you use, ie. Av, Tv or TAv mode, the camera will base it on 1/250 as starting point. If you were to use TAv mode or Tv mode, you would have no problem adjusting shutter speed to your desired level.

07-20-2015, 04:31 PM   #5
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QuoteOriginally posted by Madaboutpix Quote
What I find a little odd, though, is that in the OP's case ISOs beyond 100 get rarely selected, given that my K-3 will jump quite readily to higher ISOs with those settings.
Me too. I have the defaults set on my K-3 and it is more than willing to bump ISO.


Steve
07-20-2015, 04:34 PM   #6
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QuoteOriginally posted by aleonx3 Quote
If you were to use TAv mode or Tv mode, you would have no problem adjusting shutter speed to your desired level.
This is probably the best solution over attempting to work with program line settings.


Steve
07-20-2015, 05:29 PM   #7
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Thank you for your replies.

I prefer to manually select my ISO too, I was just trying things out.

I just found it odd that in a camera that has low noise at ISO 400 and goes to 1/8000 it would limit itself to ISO 100 and 1/320. It is like that part of the firmware is still set up for a 10 year old sensor and technology.

It would have made more sense to me if the camera had at least selected ISO 200, I can't think of many sports etc. shooting where 1/250 would be of much use at 200mm.
I would have thought that it would not be too difficult for the camera algorithm to also take the focal length setting of the lens in to consideration.

The other thing I forgot to mention is that I was using the DA* 60-250 at the time and, when the sun did come out, rather than adjust the shutter above 1/750 the camera preferred to close the lens aperture down, which I suppose is a bit more sensible.

QuoteOriginally posted by Madaboutpix Quote
What I find a little odd, though, is that in the OP's case ISOs beyond 100 get rarely selected, given that my K-3 will jump quite readily to higher ISOs with those settings.
QuoteOriginally posted by stevebrot Quote
Me too. I have the defaults set on my K-3 and it is more than willing to bump ISO.

Steve
It doesn't seem to make any difference in my K-3 if I select the slow, standard or fast option. Maybe I have a camera fault!

Last edited by Stumpy; 07-20-2015 at 05:44 PM. Reason: add info
07-20-2015, 09:27 PM - 1 Like   #8
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QuoteOriginally posted by Stumpy Quote
It doesn't seem to make any difference in my K-3 if I select the slow, standard or fast option. Maybe I have a camera fault!
No need to assume a camera fault.

The setting you are using (High-speed priority) only applies to P shooting mode.

If you want a fast shutter speed to be the priority, just set one in Tv mode. Auto-ISO and auto-aperture will still work.

07-21-2015, 02:17 PM   #9
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QuoteOriginally posted by rawr Quote
The setting you are using (High-speed priority) only applies to P shooting mode.
That and the default behavior for green button in M mode.

I just did a little walk through the feature jungle on my K-3 and discovered that the "fast" program line is most evident when auto-ISO is turned off. Crank the ISO up manually and watch the camera ramp the shutter speed in favor of the aperture.

I have run into this sort of behavior before and it is puzzling until you think of the program line as being defined in terms of EV (Exposure Value), that being a look-up table of shutter/aperture combinations for each EV step. It operates independent of the auto-ISO feature and (from my observation) is applied only after the ISO is set. (Remember that EV is not a measurement of light per se; rather, it is a way of expressing how much of the available light hits the sensor. It is completely independent of ISO.*)

The camera is generally pretty conservative about bumping ISO unless the available light is pretty dim. In bright conditions the ISO stays low and only a little higher when the "fast" option is chosen. As a result, shutter speeds tend to remain low despite using the action setting. Turn auto-ISO off and crank up the ISO and the action program line comes on nice and strong.

I hope this makes sense.


Steve

* That is EV in the pure sense. Coupling the concept to ISO provides a means to suggest subject luminance. A good example would be camera low-light AF ability which is often expressed in EV. In that case, ISO 100 is the convention, but it is usually necessary to qualify by stipulating the working aperture of the mounted lens (e.g. -3 EV(100) @ f/1.4)

Last edited by stevebrot; 07-21-2015 at 02:28 PM.
07-21-2015, 04:56 PM   #10
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As I said I was only experimenting with the auto capabilities of the camera, which would appear to be so conservative to be of little or no use for action shooting.
I only tried the P setting I did not try the "Green" full auto setting to see how that would cope

I then reverted to manually setting the ISO as you suggest.
I just thought a modern firmware should/would take the lens focal length into account within its look up tables.
07-21-2015, 05:15 PM - 1 Like   #11
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QuoteOriginally posted by Stumpy Quote
I just thought a modern firmware should/would take the lens focal length into account within its look up tables.
Ok...I guess that would make sense for some users.

It would appear that the auto-ISO behavior is biased in favor of minimizing high ISO artifact and accommodating high ISO for low light. High ISO with high shutter speed in bright light is a legitimate use case, but is not covered with the existing auto-ISO behavior. I agree that the the "fast" setting is misleading. The most it will give you is about 1-2 stops faster and then only in low light. I suppose Ricoh/Pentax could offer a high 'n bright setting to cover this case in some future firmware.


Steve

Last edited by stevebrot; 07-21-2015 at 05:23 PM.
07-21-2015, 07:52 PM - 1 Like   #12
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QuoteOriginally posted by Stumpy Quote
I then reverted to manually setting the ISO as you suggest.
I just thought a modern firmware should/would take the lens focal length into account within its look up tables.
You can set a range for the auto-ISO to operate in when shooting in shutter-priority (or M, or some other modes).

If you want the camera to work the higher ISO's more, just set a higher floor and ceiling for the auto-ISO range while in (for example) shutter-priority or TAV mode - eg 400-6400 ISO, instead of 100-3200 ISO.

Lens focal length is accounted for in the program line calculations, but the influence on ISO comes from adjustments made to the shutter speed. A direct lookup of what ISO is appropriate for what lens focal length wouldn't make sense.
07-22-2015, 06:12 AM   #13
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Thank you all for your useful input.

I was just trying to gain a little insight in to how the camera "thinks"; your posts have helped me with this and extra.

I continued to use the camera in a more manual way, for the rest of my shots, and it did not disappoint

I have been more than happy with this camera, having come from a K10D/GX-10. It does everthing I want+ for my style of photography.

So much so that I have today raided the piggy bank and ordered another K-3. Good price here in the UK at the moment (still more thany you in the USA have to pay ) and with the Pentax/Ricoh cashback offer it comes in at less than 500.

Though, as an example, here is one the camera did get with "auto" settings. No processing, straight out of the camera.
https://www.pentaxforums.com/forums/172-pentax-k-3/241198-k3-sample-shots-pos...ml#post3319295

Last edited by Stumpy; 07-22-2015 at 06:35 AM.
07-22-2015, 10:11 AM   #14
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QuoteOriginally posted by rawr Quote
Lens focal length is accounted for in the program line calculations
I just tried this, but got the same P mode shutter/aperture at 17mm, 50mm, 70mm and 200mm.


Steve
07-22-2015, 12:02 PM   #15
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QuoteOriginally posted by stevebrot Quote
I just tried this, but got the same P mode shutter/aperture at 17mm, 50mm, 70mm and 200mm.
Maybe I got that partly wrong. You are right if everything else stays the same. Maybe it depends in part on SR being turned on or off? SR and the program line will likely directly interact with each other as the lens focal length varies.

The chart below for the K10D shows the program line at work with the 18-55 kit lens and the FA 50 1.4. It kind of adds to the confusion a little bit about focal length and the program line though.


A an aside, it's interesting to see how much 'neater' a Nikon normal program line looks, especially when you compare the two 50mm f1.4 program lines:

Last edited by rawr; 07-22-2015 at 12:22 PM.
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