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08-08-2011, 09:49 PM   #16
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Isn't the native ISO for the K-x/r 200? And reducing it to 100 also reduces the dynamic range? Or something...

08-08-2011, 10:04 PM   #17
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Normally keep it at 200 on my K-X but will go to where it needs to be for speed and aperture.Being used to manual cameras I tend to not use a lot of the aut functions on the camera but will try the auto iso settings to see how things come out.Still trying to figure out why some shots at 3200-6400 come out good or acceptable while others at 800-1600 are terrible.Normally I am fascinated by how well the K-X does at higher iso.My Panasonic FZ that I have been using since 2004 didn't do too well at 400.
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08-08-2011, 10:23 PM   #18
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QuoteOriginally posted by crf529 Quote
Isn't the native ISO for the K-x/r 200? And reducing it to 100 also reduces the dynamic range? Or something...
Correctly said. Expanding ISO to 100 will reduce the DR. Lowest ISO in K-r and K-x is 200 whereas ISO 12800 is totally not usable.
Try taking few sample shots to set high ISO limit
08-08-2011, 10:39 PM   #19
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Actually ISO100 on the K-x gives more DR than ISO200. Just like ISO80 is what gives the max DR for the K-5. Check the DXO charts, it's there for all to see, no need to wonder or guess at all.

The common wisdom that you get more noise and less DR at the low expanded ISO setting is no longer true, whether it was once true I don't know, but for all the recent Pentax DSLRs the lower the ISO, the more DR and the less noise.

08-08-2011, 10:59 PM   #20
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Cheers for that. I've had my lower limit fixed at 200 on the K-r because I read a few threads on here that concluded 200 was superior due to its greater DR. Good to know!
08-08-2011, 11:18 PM   #21
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Expanded ISO is digital alteration of signal to produce underexposed images and compensating either with increasing exposure or increasing aperture. Every camera has native ISO range and anything beyond that is digital manipulation. As per the DXO i totally agree that it boosts DR but all the articles that I have read so far says, Its always better to shoot in native ISO range. If shot in expanded ISO mode they usually result either drop in DR or more noise
08-08-2011, 11:28 PM   #22
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Well in this case conventional wisdom about expanded low ISO is simply wrong, maybe a few years ago it was correct, but that ship has sailed and the software engineers have won out. More power to them
08-08-2011, 11:33 PM   #23
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Yes I understand the native ISO thing but I have looked at many photos at both 100 and 200 and I prefer 100 by far.
I have photos on a tripod, with same exposure and just different ISO and I can see a significant difference in darker areas - particularly in blue and no degradation in other areas (colour etc) at 100.

Maybe its just my K-x but I certainly prefer it anyway.

08-09-2011, 12:18 AM   #24
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QuoteOriginally posted by mattt Quote
IMO, leaving Kr in ISO 200 negates one of the greatest feature of this camera, and will cause undesirable slow shutters to become a problem in low light situations.
I'll respectfully disagree with the first part of your statement, but the second can be true. I'm not advocating that the required balance for a good exposure be ignored. I'm saying that by keeping the ISO low by default, you (if you're paying attention) will know pretty quick when there's no other way to get a suitable shutter speed, and can bump it up manually for that shot.

I found my K-r using ridiculously high ISO levels in broad daylight, just because it could. It would set the shutter to 1/1000 second, totally unnecessary for shooting what I was (immobile plants and such), and introducing totally unnecessary noise in the process. After a few sessions of this I said to hell with it, I know better than the camera what ISO I need, and I know my preference towards keeping it as low as possible - hence, defaulting it to 200, and increasing it sparingly if needed.

That said, I'm shooting mostly daytime stuff in adequate light these days, or at night with a flash, so I can also see how my plan wouldn't work for a lot of people, who may shoot primarily in dim light.
08-09-2011, 04:17 AM   #25
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For me it depends on available light, type of action (fast or slow) and require aperture.

For sunny outdoors I generally use ISO 200 or sometimes 100 where necessary. I'll then either have to use a high shutter speed or stop down to f/8 or more.

Once it clouds over I typically bump it up to ISO 400 especially when shooting with the DA55-300 (higher shutter speed for longer lens). I typically try and follow the rule where shutter speed should be ~2x focal length. I'll also have to open up to say f/5.6 (max aperture for 55-3000 @ 300). Exceptions to this is if I'm using say the 50mm f/1.7

If I'm shooting fast action outside I'll typically go between ISO 400 and 800 while adjusting shutter speed for the action and focal length.

Once I go inside my base is usually 800 (unless it is really bright) and the go up to 1600. Sometimes I'll also go into the 3200 range if relatively dim. Exception again if I use the 50mm f/1.7. For my other lenses it is usually f/4 for the minimum with some attempts at f/2.8 (generally soft).

For fast action indoor I did do some shots at ISO 10000 and 12800 with some good results. See my post here: 2nd Attempt at Photographing Kick Boxing: Pentax SLR Talk Forum: Digital Photography Review for some kickboxing shots I did.

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08-09-2011, 09:30 AM   #26
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QuoteOriginally posted by twitch Quote
Actually ISO100 on the K-x gives more DR than ISO200. Just like ISO80 is what gives the max DR for the K-5. Check the DXO charts, it's there for all to see, no need to wonder or guess at all.

The common wisdom that you get more noise and less DR at the low expanded ISO setting is no longer true, whether it was once true I don't know, but for all the recent Pentax DSLRs the lower the ISO, the more DR and the less noise.
Sorry, still new to all of the terminology.

DR? DXO? What are they?

Thanks.
08-09-2011, 09:36 AM   #27
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QuoteOriginally posted by ablundon Quote
I typically try and follow the rule where shutter speed should be ~2x focal length.
I read about this rule recently. I tried it out and seemed to get good results.

One thing I was wondering about was, do you have to increase the shutter speed even higher when using older lenses?

I have two DA lenses and on FA lens. I don't know if this also happens with DA lenses, but on a pick taken with my FA lens, it reads:

Focal Length: 50 mm
35mm focal length: 75


Does that mean my shutter should have been 1/150 instead of 1/100? Or is 1/100 good enough (not fast action shooting).
08-09-2011, 09:51 AM   #28
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Good question... I think the rule originated that with full frame cameras the denominator of the shutter speed should be equal to the focal length. See Introduction to Shutter Speed in Digital Photography. On a crop sensor that would mean that the shutter speed should be 1.5x the focal length...I guess it is just easier to multiply by 2. This is for an unstabilized camera.

For camera stabilization I've read that it can gain you a stop or so. Perhaps using the rule that denominator of the shutter speed = focal length would be OK for even a cropped sensor when using stabilization.

I really haven't been able to test this a lot. On my list of things to do.
08-09-2011, 01:40 PM   #29
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QuoteOriginally posted by reivax Quote
Sorry, still new to all of the terminology.

DR? DXO? What are they?
DR is Dynamic Range, the gradations of light that a sensor (or film or whatever) can record. Greater DR means the camera can capture a greater range of light intensities with more accuracy -- fewer blown highlights, and details lost in the shade.

DXO is an imaging organization that tests optical quality and provides correction software, among other stuff: Image Science by DxO Labs

QuoteOriginally posted by ablundon Quote
I typically try and follow the rule where shutter speed should be ~2x focal length.
The handheld 1/FL rule came from FF film days. But in THE CAMERA, Ansel Adams showed that for REAL sharpness, you need more like 4/FL or 5/FL. With a crop-sensor camera without image stabilization / shake reduction, those would be more like 2/FL (acceptable) or 8/FL (sharp). Ah, but SR gives about 2-3 stops gain in the 100-400mm range IIRC. Thus we can live with the 1/FL rule for casual shooting, and 4/FL for SHARP handhelds.

But just as the usable ISO rule is as low as necessary, the usable shutter-speed rule is as fast as necessary. Kind of like the common-law speed limit: no faster than is safe.

Last edited by RioRico; 08-09-2011 at 01:48 PM.
08-09-2011, 01:52 PM   #30
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It's a good rule but I break it frequently. In the real world, it's not always possible to follow all the rules: you often have to make trade-offs between shutter speed, aperture and ISO. Pick your poison (but get the shot.) The photo police may nail you, though--the penalty is a crap photograph.
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