Does DR affect Aperture?

rlatjsrud · 07-21-2016, 09:06 PM

That's my question.

Adam · 07-21-2016, 09:17 PM

Originally posted by rlatjsrud

That's my question.

DR as in dynamic range or dust removal?

Neither has much to do with the aperture.

alamo5000 · 07-21-2016, 10:20 PM

Originally posted by rlatjsrud

That's my question.

You could ask the question the other way around for something a bit more interesting.

Does aperture affect Dynamic Range?

It is actually a very good question and something that I have experimented with some.

I would recommend trying an experiment though. Get a tripod and find a scene that has controlled Dynamic Range (IE lighting).

Open your lens all the way and take shots at ISO 100 at whatever shutter speeds are needed. Then bump it up to ISO 200 and repeat. then 400 and repeat. At 800 you can stop.

Then close down a stop or two and repeat. And then close down a stop or two again and repeat again.

It wouldn't be hard you just have to be consistent and maybe take notes of what you are doing.

Finding that 'right' ISO/shutter speed/aperture combo isn't always as easy as it looks.

**Digitalis** · 07-22-2016, 12:03 AM

Originally posted by rlatjsrud

That's my question.

Flip that question on its head - how could aperture possibly affect dynamic range?

**Rondec** · 07-22-2016, 02:27 AM - **1 Like**

Aperture does not affect dynamic range, except in as much as it affects your ability to shoot at lower iso. The lower the iso you pick, the more dynamic range you will have. If the only way you can get to iso 200, say, is by opening your aperture up to f2, then if you set your aperture to f4 and iso 800, you will have less dynamic range.

If you are on a tripod and can use iso 100 with impunity, regardless of your shutter speed, then aperture will not affect dynamic range at all.

**WPRESTO** · 07-22-2016, 04:20 AM

OP: You did not by any chance miss-type and mean "HDR?" SFAIK, HDR changes only shutter speed.

photoptimist · 07-22-2016, 07:56 AM - **1 Like**

Originally posted by Digitalis

Flip that question on its head - how could aperture possibly affect dynamic range?

Aperture won't change the sensor's DR capabilities but it can affect the DR of the scene by modulating the amount of diffuse light that pollutes pixels that should be dark.

1. Aperture will affect the amount of diffuse light reflected from lens element edges on to the sensor in the dark parts of the scene. If you hold your lens up to strong light with the aperture fully open, you can see various parts of the structure of the lens reflecting light especially the edges of glass elements and sometimes the metal, too (matte black is never really black). Close down the aperture and many of sources of spurious light will be less visible.

2. Similarly, aperture will interact with any finger prints, dirt, or haze in the lens which can also diffuse light from the bright parts of scene onto the dark parts of the scene.

**clackers** · 07-23-2016, 02:51 AM

DR is a property of the sensor. It closely correlates with pixel size.

photoptimist · 07-23-2016, 05:23 AM

Originally posted by clackers

DR is a property of the sensor. It closely correlates with pixel size.

Indeed! The sensor does play a major role. Yet a fogged, non-multicoated lens can limit the dynamic range of what reaches the sensor just as an 8-bit file format might limit the DR despite the quality of the lens and sensor.

DR is a holistic property of the entire image formation system (lens, sensor, processing pipeline, file format, etc.) any of which can degrade the DR.

07-21-2016, 09:06 PM	#1
rlatjsrud Guest	Does DR affect Aperture? That's my question.

07-21-2016, 09:17 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Originally posted by rlatjsrud That's my question. DR as in dynamic range or dust removal? Neither has much to do with the aperture. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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07-21-2016, 10:20 PM	#3
alamo5000 Pentaxian Join Date: May 2012 Posts: 2,962	Originally posted by rlatjsrud That's my question. You could ask the question the other way around for something a bit more interesting. Does aperture affect Dynamic Range? It is actually a very good question and something that I have experimented with some. I would recommend trying an experiment though. Get a tripod and find a scene that has controlled Dynamic Range (IE lighting). Open your lens all the way and take shots at ISO 100 at whatever shutter speeds are needed. Then bump it up to ISO 200 and repeat. then 400 and repeat. At 800 you can stop. Then close down a stop or two and repeat. And then close down a stop or two again and repeat again. It wouldn't be hard you just have to be consistent and maybe take notes of what you are doing. Finding that 'right' ISO/shutter speed/aperture combo isn't always as easy as it looks.

07-22-2016, 12:03 AM	#4
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	Originally posted by rlatjsrud That's my question. Flip that question on its head - how could aperture possibly affect dynamic range?

07-22-2016, 02:27 AM - 1 Like	#5
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,653	Aperture does not affect dynamic range, except in as much as it affects your ability to shoot at lower iso. The lower the iso you pick, the more dynamic range you will have. If the only way you can get to iso 200, say, is by opening your aperture up to f2, then if you set your aperture to f4 and iso 800, you will have less dynamic range. If you are on a tripod and can use iso 100 with impunity, regardless of your shutter speed, then aperture will not affect dynamic range at all.

07-22-2016, 04:20 AM	#6
WPRESTO Loyal Site Supporter Join Date: Aug 2010 Location: Massachusetts Photos: Gallery \| Albums Posts: 59,108	OP: You did not by any chance miss-type and mean "HDR?" SFAIK, HDR changes only shutter speed.

07-22-2016, 07:56 AM - 1 Like	#7
photoptimist Pentaxian Join Date: Jul 2016 Photos: Albums Posts: 5,126	Originally posted by Digitalis Flip that question on its head - how could aperture possibly affect dynamic range? Aperture won't change the sensor's DR capabilities but it can affect the DR of the scene by modulating the amount of diffuse light that pollutes pixels that should be dark. 1. Aperture will affect the amount of diffuse light reflected from lens element edges on to the sensor in the dark parts of the scene. If you hold your lens up to strong light with the aperture fully open, you can see various parts of the structure of the lens reflecting light especially the edges of glass elements and sometimes the metal, too (matte black is never really black). Close down the aperture and many of sources of spurious light will be less visible. 2. Similarly, aperture will interact with any finger prints, dirt, or haze in the lens which can also diffuse light from the bright parts of scene onto the dark parts of the scene.

07-23-2016, 02:51 AM	#8
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	DR is a property of the sensor. It closely correlates with pixel size.

07-23-2016, 05:23 AM	#9
photoptimist Pentaxian Join Date: Jul 2016 Photos: Albums Posts: 5,126	Originally posted by clackers DR is a property of the sensor. It closely correlates with pixel size. Indeed! The sensor does play a major role. Yet a fogged, non-multicoated lens can limit the dynamic range of what reaches the sensor just as an 8-bit file format might limit the DR despite the quality of the lens and sensor. DR is a holistic property of the entire image formation system (lens, sensor, processing pipeline, file format, etc.) any of which can degrade the DR.