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07-12-2012, 12:03 AM   #1
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Strange auto-ISO behavior with flash ?

I got my blue K-30 delivered today. Just put in the strap. eneloops with the AA adapter that I already had, and the DA 18-250, and started taking a few pictures indoors, in lowlight, in green mode.

Pleasantly surprised to see that the flash did not automatically pop-up by default. Factory setting was auto ISO 100-3200 . It just raised the ISO and pictures were fine without the flash.

However, when I manually popped up the flash, the behavior was very strange : ISO was lowered dramatically, and the shutter speed decreased dramatically.

Without flash, at 18mm, I get f3.5, 1/15 and ISO 3200 .
With flash popped up, I get f3.5, 1" and ISO 100 ! 1" is not handholdable of course.
What's weird is that the viewfinder just shows "auto-ISO" when the flash is popped up, and don't see the actual ISO until after the shot is taken and I review it. If the flash is down, I see "3200" in the viewfinder.

I thought shutter speed was supposed to be 1/180 for flash ? So why is it 1" ?

This isn't making any sense to me, coming from the K200D and K-r.

I will post some shots with the EXIF.

When I look at the shots on the LCD in detailed mode, everything is the same except the ISO, shutter speed and the flash icon being absent or present.

The auto "scene" mode shows that "night scene" was selected for both.

Firmware is 1.00 .

User error or bug?

07-12-2012, 01:02 AM   #2
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Mine does the same, its standard behaviour.

It appears to automatically select a scene - pointing it at my cat went into "face" mode and 1/40th sec iso 3200 - pointing it towards the dark grey carpet changed the scene guess to night scene like yours - without flash 1/25th second iso3200, with flash 1/4sec iso 400.

I'm taking a guess here that it's attempting to keep some of the background exposed by lengthening the shutter?

No idea, odd - manual will no doubt explain it. I never use auto anyhow.

*EDIT*

From the manual:

Night Scene Portrait: For capturing images of people in low light conditions, such as dusk or night. Even though flash is used, the camera will use slow shutter speeds so background areas beyond the flash will also appear correctly exposed in the picture (Slow-speed Sync p.236). To prevent camera shake, either turn on the Shake Reduction feature, or mount the camera on a tripod.


Sweet, good guess then

Last edited by FruitLooPs; 07-12-2012 at 01:10 AM.
07-12-2012, 01:05 AM   #3
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QuoteOriginally posted by madbrain Quote
auto "scene" mode
Seriously...
07-12-2012, 01:18 AM   #4
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QuoteOriginally posted by rawr Quote
Seriously...
it's entry-level

Also look at the setting for flash, it could be second curtain.

07-12-2012, 01:35 AM   #5
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QuoteOriginally posted by RonHendriks1966 Quote
it's entry-level

Also look at the setting for flash, it could be second curtain.
I've posted the explanation from the manual above. And yes I agree, some people who purchase this camera will probably stick to Automatic modes so it isn't a silly question - I won't be one though
07-12-2012, 02:22 AM   #6
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QuoteOriginally posted by FruitLooPs Quote
Mine does the same, its standard behaviour.

It appears to automatically select a scene - pointing it at my cat went into "face" mode and 1/40th sec iso 3200 - pointing it towards the dark grey carpet changed the scene guess to night scene like yours - without flash 1/25th second iso3200, with flash 1/4sec iso 400.
I was pointing the camera at furniture in this case.

QuoteQuote:
I'm taking a guess here that it's attempting to keep some of the background exposed by lengthening the shutter?

No idea, odd - manual will no doubt explain it. I never use auto anyhow.
I don't normally use auto either, I just did as I came home very late, just unboxed it, and didn't feel like messing with the settings yet -I wanted to shoot right away. I suppose lowlight indoor shots are the hardest to get right. Sadly, green mode with flash is not up to the task on the K-30.

QuoteQuote:
Night Scene Portrait: For capturing images of people in low light conditions, such as dusk or night. Even though flash is used, the camera will use slow shutter speeds so background areas beyond the flash will also appear correctly exposed in the picture (Slow-speed Sync p.236). To prevent camera shake, either turn on the Shake Reduction feature, or mount the camera on a tripod.

Sweet, good guess then
Good find. I just don't remember this behavior happening with my previous Pentax cameras at all. My mother now has the K200D, and a member of this forum now has the K-r.

Shake reduction was on, but with the camera selecting a 1 second shutter speed, it is not all that helpful.

I find it quite confusing that raising the flash causes the shutter speed to go down, especially to a full second duration that requires tripod use.
Couldn't the camera lower the ISO to something a bit higher than 100 so the camera is still hand-holdable ? I realize green mode default is always going to be a compromise in one situation or another, but this just doesn't seem very reasonable.

I find it even more disconcerting that the ISO value is not displayed in the viewfinder when flash is raised - so I can't see what ISO value the camera actually chose before I shoot. In the viewfinder, it shows "ISO AUTO" on the left and then on the right the word " Auto" where the value should be. With flash down it shows "ISO AUTO" and "3200" next to it. Surely the camera must have already decided on the low ISO since it decided on the shutter speed of 1 second ?

I compared this with my Canon T3i with a very similar lens, Tamron 18-270 (with VC on) . I set it on 18mm, and shot the same furniture with it in the house.

In the auto mode with no flash, the T3i selected f3.5, 1/15 and ISO 3200 . Exactly the same exposure choice that the K-30 made.
In green mode, the T3i automatically raised the flash, and selected f3.5 , 1/60 and ISO 400.
That is easily hand-holdable. It is much more reasonable than f3.5, 1" and ISO 100 . It's likely that the power levels of the two cameras' flashes are different.

If I put the K-30 in P mode instead of green, it selects f3.5 1/15 and ISO 400 .
07-12-2012, 02:23 AM   #7
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QuoteOriginally posted by rawr Quote
Seriously...
Thanks, that was very helpful.
07-12-2012, 02:25 AM   #8
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QuoteOriginally posted by RonHendriks1966 Quote
it's entry-level

Also look at the setting for flash, it could be second curtain.
What do you mean by that ?
The camera was just out of the box, I hadn't messed with any settings yet except set the language/date.

07-12-2012, 07:14 AM   #9
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QuoteOriginally posted by madbrain Quote
Thanks, that was very helpful.
You got off lightly. I come from /p/.
07-12-2012, 07:33 AM   #10
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QuoteOriginally posted by madbrain Quote
I find it even more disconcerting that the ISO value is not displayed in the viewfinder when flash is raised - so I can't see what ISO value the camera actually chose before I shoot. In the viewfinder, it shows "ISO AUTO" on the left and then on the right the word " Auto" where the value should be. With flash down it shows "ISO AUTO" and "3200" next to it. Surely the camera must have already decided on the low ISO since it decided on the shutter speed of 1 second ?
I believe it needs to fire a pre-flash to meter before it decides on the ISO.

I never use Green mode since RAW isn't available, only jpeg. Well, I switch it to Green mode sometimes if I'm handing the camera over to someone to take a picture or two. Have you tried using the flash in P mode? I use Hyper-Program (P mode) quite often as it gives me the best of both worlds: auto when I'm lazy or in a hurry and Av or Tv when I have certain depth of field or motion freezing requirements. You have to set up your e-dials correctly though. I don't recall what the factory default is. Plus you can can shoot RAW or RAW+jpeg in P mode.
07-12-2012, 07:38 AM   #11
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Honestly, auto iso doesn't work very well with the flash (either pop up or external) on Pentax cameras. Setting your iso to, say, 400 really seems to make a big difference.
07-12-2012, 07:42 AM   #12
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QuoteOriginally posted by madbrain Quote
I thought shutter speed was supposed to be 1/180 for flash ? So why is it 1" ?
That's just the fastest shutter speed available. The flash duration is very short so even with slow shutter speeds you can freeze motion. How slow the speed can be and still produce acceptable results depends on what you're shooting.

Again, I recommend using Program any time you want auto settings while maintaining a degree of control so you can partially override the camera's poor decisions in odd shooting situations like the one you are describing. I keep my front e-dial set to control the shutter speed when in Program and you could simply dial the shutter speed up a little bit to get into a better range when you aren't happy with the camera selecting a slower speed.
07-12-2012, 08:10 AM   #13
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Does the K-30 have any auto iso settings that include minimum shutter speed etc?
07-12-2012, 08:38 AM   #14
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IF this is the default for green mode, I would suggest a lot of people buying a K-30 as their first DSLR will be dissatisfied.

I just tried a similar exercise in my K-x in a darkish room. No flash: 55mm, 1/40, f4.0, ISO 3200. With flash: 55mm, 1/40, f4.0, ISO 1600. So evidently the K-x is keeping a handholdable shutter speed.

I was just helping an acquaintance with their K-x recently. They had NO idea how it worked and used only green mode.

I would suggest that green mode needs to be programmed like a P&S, as this is how those using that mode will probably use it. A 1" shutter speed with flash will frustrate many.
07-12-2012, 08:59 AM   #15
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This isn't just Pentax with this sort of wonky Auto-mode. The Nikon D3100 and even the D5100 exhibit some pretty stupid behavior in terms of balancing Apterture, Shutter speed, and ISO. There simply is no good way to program the camera to always have the correct balance so instead the manufacturer finds a "good enough" balance so the people using these cameras as point and shoots, they will not appear to notice. You guys will seriously be shocked to learn how many people with sub-$1,000 DSLRs take them to Walgreens or CVS or whatever drug store to get the images printed.

Essentially, Auto-mode isn't for us.
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