Aperture for maximum sharpness? at DVinfo.net

Paul Anderegg · November 28th, 2015, 02:24 PM

At wide angle, and then at telephoto, anyone happen to know what the optimum apertures are for best clarity and sharpness, and what the limit would be before diffraction softness begins? I have a resolution chart and the 4K option, I might try to figure it out if no one else has a ready made answer. The biggest tell i know to look for is red/green edge chromatic abberations when you rack focus on a high contrast black/white line.

I typically shoot at night at high gain, so I never really iris down, but if I shoot any daylight stuff, would be good to know.

Paul

Paul Anderegg · November 28th, 2015, 02:54 PM

Made some 4K frame grabs, from f4.0 to f9.6. When testing for slightly out of focus CA, I found that stopping down from f4.0 to f5.2-f5.6 helps a lot, ridding the image of soft red/blue edge hazing in the corners. I can't for the life of me see a difference in center sharpness or CA.......go Zeiss. :)

Was trying to upload the frame grabs, but the site said I am missing a security token, and error'd out. :(

Paul

Tom Grushka · November 29th, 2015, 02:33 AM

Man, I hope the X70 is sharp wide open... it (was) a >$2K camcorder and its only job is to shoot good video. :)

Joachim Claus · November 29th, 2015, 02:48 AM

Hi Paul,

There is a nice internet site, which describes all kinds of optical performance limits. They also have a calculator online, where you can enter your camera data and get the answer of your question.

Digital Camera Diffraction – Resolution, Color & Micro-Contrast

Noa Put · November 29th, 2015, 02:49 AM

All camera's I have owned produced the sharpest image between f4.0 and f5.6, if you shoot wide open and if you pixelpeep you will notice more image softness and it gets worse if you close down the iris completely, especially on small sensor camera's it will give you the impression your shot is out of focus. It's called diffraction and not much you can do about that.

Paul Anderegg · November 29th, 2015, 04:16 PM

Quote:

Originally Posted by Joachim Claus

Hi Paul,

There is a nice internet site, which describes all kinds of optical performance limits. They also have a calculator online, where you can enter your camera data and get the answer of your question.

Digital Camera Diffraction – Resolution, Color & Micro-Contrast

I am a bit skeptical of that chart, it doesn't jive with what I am seeing, nor the large sensor size. I run 1/3' cameras that are good until diffraction at f5.6. The X70 definitely is sharper and less CA stopped down a stop or two.

Paul

Ron Evans · December 6th, 2015, 03:35 PM

I think I get the best results from my NX5, NX30 or CX700 with iris wider than F4. Certainly closed down more than F5.6 and I see the sharpness decrease on my NX5U for sure. I shoot stage so want as much of stage in focus as possible so try to stay close to F4 most of the time. Since it is often dark in the theatre the full stage unattended cameras are usually wide open anyway.

For me the key was to let the cameras shoot in auto and see what the engineers would like the iris to be !! On most of my Sony's it ends up between F2.8 and F4. On the AX100 it is very similar with all of them preferring to increase shutter speed before shutting down the iris beyond F4. With the NX5U having negative gain it does that too before shutting down the iris. With all of them of course the lenses ramp when zoomed so one is stuck with that anyway. In some respects that is why I try to stay close to F4 on the NX5U as I can then zoom around without be bothered about the ramping.

Ron Evans

Noa Put · December 6th, 2015, 03:44 PM

The diffraction effect is much worse when you close the iris down compared to opening it completely up, when you have it wide open, there is some loss in resolution but nowhere near as bad when you close it completely down. I remember when I had my canon xh-a1 I tested this and with the iris almost closed it looked like the image was out of focus. This diffraction effect also seemed much worse on small sensor camera's.

Ron Evans · December 6th, 2015, 03:58 PM

Yes , at F8 my NX5U is not good and a noticeable softness compared to F4. I use gain and ND to try and stay close to F4 for my uses.

Ron Evans

David Dixon · December 6th, 2015, 10:10 PM

I find my X70 is pretty sharp wide open and actually shoot that way about 85% of the time. One of the main reasons I bought the camera is the noticeably shallower depth of field compared to 1/3 inch chip cameras, so I often shoot to maximize that effect.

Jody Eldred says his testing shows 5.6 gives the absolute best sharpness.

Paul Anderegg · December 6th, 2015, 10:27 PM

I would tend to agree with Jody's findings, they match mine. I really do see up to f9.6 in testing seems similarly sharp, and sharper than f4.0 at full telephoto. I am just looking to maximize my 4K resolution, and when you start pushing Ci and digital zoom in 4K, you start magnifying any chromatic abberation of fuzziness in the optics.

f4.0 is slightly fuzzy and softer (enough to notice side by side) than f5.6 when you pixel peep 4K footage. :)

Paul

November 28th, 2015, 02:24 PM	#1
Paul Anderegg Trustee Join Date: Jan 2013 Location: San Diego, Califonia Posts: 1,559	Aperture for maximum sharpness? At wide angle, and then at telephoto, anyone happen to know what the optimum apertures are for best clarity and sharpness, and what the limit would be before diffraction softness begins? I have a resolution chart and the 4K option, I might try to figure it out if no one else has a ready made answer. The biggest tell i know to look for is red/green edge chromatic abberations when you rack focus on a high contrast black/white line. I typically shoot at night at high gain, so I never really iris down, but if I shoot any daylight stuff, would be good to know. Paul

November 28th, 2015, 02:54 PM	#2
Paul Anderegg Trustee Join Date: Jan 2013 Location: San Diego, Califonia Posts: 1,559	Re: Aperture for maximum sharpness? Made some 4K frame grabs, from f4.0 to f9.6. When testing for slightly out of focus CA, I found that stopping down from f4.0 to f5.2-f5.6 helps a lot, ridding the image of soft red/blue edge hazing in the corners. I can't for the life of me see a difference in center sharpness or CA.......go Zeiss. :) Was trying to upload the frame grabs, but the site said I am missing a security token, and error'd out. :( Paul

November 29th, 2015, 02:33 AM	#3
Tom Grushka Regular Crew Join Date: Jan 2015 Location: Denver, CO Posts: 55	Re: Aperture for maximum sharpness? Man, I hope the X70 is sharp wide open... it (was) a >$2K camcorder and its only job is to shoot good video. :)

November 29th, 2015, 02:48 AM	#4
Joachim Claus Regular Crew Join Date: Jun 2006 Location: Seeheim-Jugenheim, Germany Posts: 132	Re: Aperture for maximum sharpness? Hi Paul, There is a nice internet site, which describes all kinds of optical performance limits. They also have a calculator online, where you can enter your camera data and get the answer of your question. Digital Camera Diffraction – Resolution, Color & Micro-Contrast Attached Thumbnails $Aperture for maximum sharpness?-diffraction-x70.jpg$

November 29th, 2015, 02:49 AM	#5
Noa Put Inner Circle Join Date: Jun 2007 Location: Belgium Posts: 9,510	Re: Aperture for maximum sharpness? All camera's I have owned produced the sharpest image between f4.0 and f5.6, if you shoot wide open and if you pixelpeep you will notice more image softness and it gets worse if you close down the iris completely, especially on small sensor camera's it will give you the impression your shot is out of focus. It's called diffraction and not much you can do about that.

December 6th, 2015, 03:35 PM	#7
Ron Evans Inner Circle Join Date: Mar 2003 Location: Ottawa, Ontario, Canada Posts: 4,220	Re: Aperture for maximum sharpness? I think I get the best results from my NX5, NX30 or CX700 with iris wider than F4. Certainly closed down more than F5.6 and I see the sharpness decrease on my NX5U for sure. I shoot stage so want as much of stage in focus as possible so try to stay close to F4 most of the time. Since it is often dark in the theatre the full stage unattended cameras are usually wide open anyway. For me the key was to let the cameras shoot in auto and see what the engineers would like the iris to be !! On most of my Sony's it ends up between F2.8 and F4. On the AX100 it is very similar with all of them preferring to increase shutter speed before shutting down the iris beyond F4. With the NX5U having negative gain it does that too before shutting down the iris. With all of them of course the lenses ramp when zoomed so one is stuck with that anyway. In some respects that is why I try to stay close to F4 on the NX5U as I can then zoom around without be bothered about the ramping. Ron Evans

December 6th, 2015, 03:44 PM	#8
Noa Put Inner Circle Join Date: Jun 2007 Location: Belgium Posts: 9,510	Re: Aperture for maximum sharpness? The diffraction effect is much worse when you close the iris down compared to opening it completely up, when you have it wide open, there is some loss in resolution but nowhere near as bad when you close it completely down. I remember when I had my canon xh-a1 I tested this and with the iris almost closed it looked like the image was out of focus. This diffraction effect also seemed much worse on small sensor camera's.

December 6th, 2015, 03:58 PM	#9
Ron Evans Inner Circle Join Date: Mar 2003 Location: Ottawa, Ontario, Canada Posts: 4,220	Re: Aperture for maximum sharpness? Yes , at F8 my NX5U is not good and a noticeable softness compared to F4. I use gain and ND to try and stay close to F4 for my uses. Ron Evans

December 6th, 2015, 10:10 PM	#10
David Dixon Major Player Join Date: May 2011 Location: Knoxville, Tennessee Posts: 495	Re: Aperture for maximum sharpness? I find my X70 is pretty sharp wide open and actually shoot that way about 85% of the time. One of the main reasons I bought the camera is the noticeably shallower depth of field compared to 1/3 inch chip cameras, so I often shoot to maximize that effect. Jody Eldred says his testing shows 5.6 gives the absolute best sharpness.

December 6th, 2015, 10:27 PM	#11
Paul Anderegg Trustee Join Date: Jan 2013 Location: San Diego, Califonia Posts: 1,559	Re: Aperture for maximum sharpness? I would tend to agree with Jody's findings, they match mine. I really do see up to f9.6 in testing seems similarly sharp, and sharper than f4.0 at full telephoto. I am just looking to maximize my 4K resolution, and when you start pushing Ci and digital zoom in 4K, you start magnifying any chromatic abberation of fuzziness in the optics. f4.0 is slightly fuzzy and softer (enough to notice side by side) than f5.6 when you pixel peep 4K footage. :) Paul