Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-09-2011, 03:34 PM   #31
Site Supporter
reivax's Avatar

Join Date: Jun 2011
Location: California
Posts: 730
Original Poster
QuoteOriginally posted by RioRico Quote
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.
What happens if you shoot and your shutter speed is too high, but you've adjusted the aperture and ISO to balance?

In other words, can the shutter speed be too high?

08-09-2011, 03:37 PM   #32
Veteran Member
Philoslothical's Avatar

Join Date: May 2011
Posts: 1,723
If your shutter speed is too high, you'll get either a wide open aperture (potentially soft, and definitely a shallow depth of field), or high ISO that adds noise, or both.

Faster shutter means less light reaching the sensor, just as small aperture (high f number) does. I think of ISO as baseline of 200, but available to amplify the signal from the sensor when needed (at cost of noise).
08-09-2011, 04:03 PM   #33
Inactive Account




Join Date: Sep 2008
Location: Gold Coast, Qld
Photos: Gallery
Posts: 95
QuoteOriginally posted by Swapnil Quote
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
Whats wrong with 12800 ?

http://i448.photobucket.com/albums/qq204/TGPhotography/High%20ISO%20Shots/2011Jude0842-2.jpg

The link is to a shot I took as an experiment to see how bad it is at 12800 and I was shocked at how GOOD it was .
Exif should be intact but in case Photobucket has removed it, details are.
Camera ; Pentax KR
Lens; Sigma 28-105 F2.8 zoom
Mode; RAW
ISO 12800
F Stop; F/8
Speed; 1/13th sec hand held
Focal Length 63mm
No Flash
Metering ; Centre weighted
All I have done is convert to jpeg to upload to Photobucket because it will not take the RAW file, so if anything it should have lost some detail.

This is the same photo after 1 pass of Topaz Denoise RAW Medium and obviously resized to post here.


As for the 100 Vs 200 ISO, 100 wins hands down, If I could afford a K5 I would be using 80 ISO.
Using the same lens as I took this shot which is a film not Digital era lens, on some shots especially landscapes the colours are not as vivid at ISO200 as they are at ISO100.
08-09-2011, 04:51 PM   #34
Site Supporter
mattt's Avatar

Join Date: Feb 2011
Location: Niagara
Photos: Gallery | Albums
Posts: 2,742
This discussion is revolving around Understanding Exposure (B. Peterson) well worth the $25... go for it.

08-09-2011, 06:01 PM - 1 Like   #35
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
For those without the book (or access to a public library, hint hint) here are the basics, and a trick.

Every photo to be taken is a problem to be solved. The factors that can be varied are:

1) ISO setting
2) shutter speed
3) lens aperture
4) lens focal length
5) subject-to-lens distance
6) subject-to-background distance

The first three determine the exposure, the amount of light that is recorded. The last four determine the DOF (depth-of-field), the region of an image that is acceptably sharp. We'll skip DOF now (except to say that wider aperture and/or longer focal length give thinner DOF, and vice-versa) and just concentrate on exposure.

An exposure value (EV) is some combination of shutter and aperture at a given ISO. We can keep the same EV if we vary the shutter and aperture in opposite directions. We measure these variances in stops. One stop is a doubling or halving in the amount of light. So if we double the shutter speed from 1/5 to 1/10 second, that's one stop. Or if we halve the aperture from f/2 to f/2.8, that's one stop. As long as we balance those changes, the EV remains the same.

So maybe we've metered a scene (at any given ISO) as requiring f/2.8 at 1/5 second. But we think that we'll get a blurry picture with the shutter that slow. So we can go to 1/10 second, and open the aperture to f/2. Maybe that's still too slow. So we set the exposure to 1/20 at f/1.4. In each case, we've captured the same amount of light.

Maybe we tried those at ISO 200, and we shot and chimped, and the picture is too dark. Maybe we can't open the aperture any further (darn that slow 50/1.4 lens!) and we don't want a slower shutter. So we can increase sensitivity by a stop, boosting ISO to 400, and now maybe the exposure looks good. But maybe the DOF is too thin, we want a bit more sharpness, so we close the aperture back to f/2 and bump the ISO to 800. Hmm, still not sharp enough -- close the aperture to f/2.8 and push ISO to 1600. Oops, shutter is still too slow -- bump it to 1/40 or 1/50 second, boost the ISO to 3200. What happens now?

Well, depending on the camera, we'll likely see some image noise, which will be most evident in the darkest areas of the image. And here's the trick, which is evident in the picture above of the snoozing doggie: YOU DON'T SEE NOISE IN A WELL-LIT IMAGE! We too often boost ISO to shoot in dimmer light, but that's where the noise is worst. I can shoot my K20D at ISO 6400, its absolute max, which in a dark scene would be super noisy -- but if everything is brightly lit, the noise is only objectionable at great enlargement.

There's lots more, but there's where to start. Learn about how these factors interact to produce different effects. That's the technical aspect of photography. The rest is vision and imagination.
08-09-2011, 09:37 PM   #36
Site Supporter
reivax's Avatar

Join Date: Jun 2011
Location: California
Posts: 730
Original Poster
QuoteOriginally posted by Nobbys Nuts Quote
Whats wrong with 12800 ?
Well that just makes everything a little more complicated. Way nicer than I would expect 12800 to look.

I guess it's just going to come down to a "it depends on the situation..."

Was the room you took this picture in well lit?
08-09-2011, 10:10 PM   #37
Veteran Member




Join Date: Mar 2011
Location: Eastern Kentucky
Posts: 416
QuoteOriginally posted by RioRico Quote
For those without the book (or access to a public library, hint hint) here are the basics, and a trick.

Every photo to be taken is a problem to be solved. The factors that can be varied are:

1) ISO setting
2) shutter speed
3) lens aperture
4) lens focal length
5) subject-to-lens distance
6) subject-to-background distance

The first three determine the exposure, the amount of light that is recorded. The last four determine the DOF (depth-of-field), the region of an image that is acceptably sharp. We'll skip DOF now (except to say that wider aperture and/or longer focal length give thinner DOF, and vice-versa) and just concentrate on exposure.

An exposure value (EV) is some combination of shutter and aperture at a given ISO. We can keep the same EV if we vary the shutter and aperture in opposite directions. We measure these variances in stops. One stop is a doubling or halving in the amount of light. So if we double the shutter speed from 1/5 to 1/10 second, that's one stop. Or if we halve the aperture from f/2 to f/2.8, that's one stop. As long as we balance those changes, the EV remains the same.

So maybe we've metered a scene (at any given ISO) as requiring f/2.8 at 1/5 second. But we think that we'll get a blurry picture with the shutter that slow. So we can go to 1/10 second, and open the aperture to f/2. Maybe that's still too slow. So we set the exposure to 1/20 at f/1.4. In each case, we've captured the same amount of light.

Maybe we tried those at ISO 200, and we shot and chimped, and the picture is too dark. Maybe we can't open the aperture any further (darn that slow 50/1.4 lens!) and we don't want a slower shutter. So we can increase sensitivity by a stop, boosting ISO to 400, and now maybe the exposure looks good. But maybe the DOF is too thin, we want a bit more sharpness, so we close the aperture back to f/2 and bump the ISO to 800. Hmm, still not sharp enough -- close the aperture to f/2.8 and push ISO to 1600. Oops, shutter is still too slow -- bump it to 1/40 or 1/50 second, boost the ISO to 3200. What happens now?

Well, depending on the camera, we'll likely see some image noise, which will be most evident in the darkest areas of the image. And here's the trick, which is evident in the picture above of the snoozing doggie: YOU DON'T SEE NOISE IN A WELL-LIT IMAGE! We too often boost ISO to shoot in dimmer light, but that's where the noise is worst. I can shoot my K20D at ISO 6400, its absolute max, which in a dark scene would be super noisy -- but if everything is brightly lit, the noise is only objectionable at great enlargement.

There's lots more, but there's where to start. Learn about how these factors interact to produce different effects. That's the technical aspect of photography. The rest is vision and imagination.
Am I reading this right that if one took a picture at 800 that was under exposed
then raised to 3200 and got a proper exposed picture it should have less noise?
Jake
08-09-2011, 10:57 PM   #38
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
QuoteOriginally posted by bjake Quote
Am I reading this right that if one took a picture at 800 that was under exposed
then raised to 3200 and got a proper exposed picture it should have less noise?
Jake
No, there won't be less noise. But if the scene is adequately lit, the noise shouldn't be obvious. And it depends on your camera. With a K10D, the noise will likely be quite obvious. It also depends on how large you display the image, how closely you inspect, how it is presented. But again, look at the dog picture above, shot at ISO 12800 on a Kr. Better yet, try it: Shoot a sunlit scene without shadows at lower ISO, deliberately underexposed. Then boost ISO and shoot with proper exposure.


Last edited by RioRico; 08-10-2011 at 06:26 AM.
08-10-2011, 12:27 AM   #39
Senior Member
Swapnil's Avatar

Join Date: Apr 2011
Location: Bellevue
Photos: Gallery | Albums
Posts: 138
QuoteOriginally posted by Nobbys Nuts Quote
Whats wrong with 12800 ?
In the dog image. it looks great for 12800 ISO and will be just fine for small prints. Again said that, it all depends upon lighting condition. Increasing ISO amplifies the signal and it will amplify noise too.
Just keep 12800 ISO for rainy days
08-10-2011, 12:57 AM   #40
Senior Member
Elva's Avatar

Join Date: Sep 2009
Location: Grahamstown in the Eastern Cape province of South Africa
Photos: Gallery
Posts: 126
200 for me in nearly all situations, sometimes 400 in low light conditions.
08-16-2011, 12:33 PM   #41
New Member




Join Date: Jul 2011
Location: Philippines
Photos: Gallery | Albums
Posts: 6
1200 is ok with... and yeah it depends on the situation...
08-16-2011, 01:25 PM   #42
Pentaxian
v5planet's Avatar

Join Date: Jan 2010
Location: Seattle
Photos: Albums
Posts: 1,911
QuoteOriginally posted by RioRico Quote
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.
I am confused by this. The way you have it written suggests that the requirements for sharpness are 4-5 times less stringent than the common 1/FL rule.

ex:

100mm lens:

Acceptable for casual = 1/FL = 1/100 sec
Standard for real sharpness = 4/FL = 4/100 = 1/25 sec

Do you mean 1/(4*FL)?
08-16-2011, 02:22 PM   #43
Veteran Member
Philoslothical's Avatar

Join Date: May 2011
Posts: 1,723
Yeah, that's what he meant. 4*FL rather than 4/FL.
08-16-2011, 03:19 PM   #44
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
QuoteOriginally posted by Philoslothical Quote
Yeah, that's what he meant. 4*FL rather than 4/FL.
Duh, yeah, I was thinking in shortcuts again. 1/(4*FL) not 4/FL.
08-16-2011, 10:42 PM   #45
Site Supporter
Chaos_Realm's Avatar

Join Date: Feb 2011
Location: Melbourne, Australia
Photos: Gallery | Albums
Posts: 1,249
QuoteOriginally posted by reivax Quote
What happens if you shoot and your shutter speed is too high, but you've adjusted the aperture and ISO to balance?

In other words, can the shutter speed be too high?
In short, Yes.

You may be using flash and be beyond sync speed so the shutter could have opened and closed before your flash even fires. So you have to reduce your shutter speed to meet the sync speed of your camera/flash.

Secondly shutter can determine the look of the photo. Sports photographers sometimes use a slower shutter and the panning technique to blur the background but keep the subject in focus.
Similarly to smooth out water (creeks rivers beaches etc) you would aim for a slower shutter speed. But this is dependent on the effect your are after.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, iso, k-r, kr, noise, pentax k-r
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
I am getting a lot of noise at ISO 800 and ISO 1600.... Abstract Pentax K-5 19 11-30-2010 10:48 AM
[Auto-ISO] so, is the K5 and Kr brave enough to use max iso? Reportage Pentax K-5 13 10-24-2010 03:30 PM
K-5 vs K-7 First ISO performance testing (ISO-6400) starscream Pentax News and Rumors 95 09-25-2010 07:02 PM
Default ISO 200 vs ISO 100 joodiespost Troubleshooting and Beginner Help 6 01-09-2010 05:50 PM
ISO ranges and low iso, techies please look. Gooshin Photographic Technique 7 09-09-2009 07:37 PM



All times are GMT -7. The time now is 05:31 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top