Mike Davis

Mike Davis

Lives in United States Dallas, TX, United States
Has a website at http://www.accessz.com
Joined on Jun 12, 2002

Comments

Total: 37, showing: 1 – 20
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On Hasselblad unveils pixel-shifting 200MP H5D-200c MS article (230 comments in total)
In reply to:

Mike Davis: For a print resolution goal of 5 lp/mm (unresampled 360 ppi):

In single-shot mode, with 51.3 MP on a 43.8x32.9mm sensor, diffraction would begin to inhibit a desired print resolution of 5 lp/mm (about 360 ppi) in a 23.0 x 17.2-inch print at f/11.1. (Sensor pixel density is 189 pixels/mm. Enlargement factor for that print size is 13.33x.)

In six-shot mode, with 205.2MP on the same 43.8x32.9mm sensor, diffraction would begin to inhibit a desired print resolution of 5 lp/mm (about 360 ppi) in a 46.0 x 34.4-inch print at f/5.5. (Sensor pixel density is 377 pixels/mm. Enlargement factor for that print size is 26.65x.)

For a print resolution goal of only 2.5 lp/mm (unresampled 180 ppi):

In single-shot mode, with 51.3 MP on a 43.8x32.9mm sensor, diffraction would begin to inhibit a desired print resolution of 2.5 lp/mm (about 180 ppi) in a 46.0 x 34.4-inch print at f/11.1. (Sensor pixel density is 189 pixels/mm. Enlargement factor for that print size is 26.65x.)

In six-shot mode, with 205.2MP on the same 43.8x32.9mm sensor, diffraction would begin to inhibit a desired print resolution of 2.5 lp/mm (about 180 ppi) in a 92.0 x 68.8-inch print at f/5.5. (Pixel density is 377 pixels/mm. Enlargement factor for that print size is 53.3x.)

What size print do you hope to make, at what resolution? Do you need this camera's 6-shot mode and are you willing to shoot at apertures wide enough to exploit the higher pixel density without inhibiting your desired print resolution?

Direct link | Posted on Aug 22, 2014 at 20:25 UTC
On Hasselblad unveils pixel-shifting 200MP H5D-200c MS article (230 comments in total)

For a print resolution goal of 5 lp/mm (unresampled 360 ppi):

In single-shot mode, with 51.3 MP on a 43.8x32.9mm sensor, diffraction would begin to inhibit a desired print resolution of 5 lp/mm (about 360 ppi) in a 23.0 x 17.2-inch print at f/11.1. (Sensor pixel density is 189 pixels/mm. Enlargement factor for that print size is 13.33x.)

In six-shot mode, with 205.2MP on the same 43.8x32.9mm sensor, diffraction would begin to inhibit a desired print resolution of 5 lp/mm (about 360 ppi) in a 46.0 x 34.4-inch print at f/5.5. (Sensor pixel density is 377 pixels/mm. Enlargement factor for that print size is 26.65x.)

Direct link | Posted on Aug 22, 2014 at 20:25 UTC as 47th comment | 2 replies

I suspect the label "Diffraction Correction" exaggerates the effectiveness of this feature. No amount of processing can magically recreate actual subject detail that was lost to diffraction as the light passed through the aperture. It might be able to simulate what appears to be genuine subject detail, but it won't be accurate.

For example, assuming that all other variables affecting resolution are up to the task... If diffraction at a given f-Number is just bad enough to prevent you from discerning the date "2014" on the face of a coin lying on a table several meters from a camera equipped with a normal FL lens when viewing at 100%, "Diffraction Correction" isn't going to reconstruct that data from thin air when the data never got past the aperture in the first place.

You can't make a silk purse from a pig's ear.

Direct link | Posted on Jul 23, 2014 at 12:18 UTC as 7th comment | 12 replies
On Stream your photos... via backpack? article (34 comments in total)

He looks deservedly smug...

Direct link | Posted on May 19, 2014 at 13:49 UTC as 15th comment
On Orion DVC210 DLSR Crane Review article (38 comments in total)

For still shots, I'd rather use my Bogen/Manfrotto 3048 and a step ladder to get my camera to a height of 11 feet.

Direct link | Posted on Mar 30, 2014 at 09:15 UTC as 8th comment | 2 replies
On Nikon D4s First Impressions Review preview (1046 comments in total)

ISO 409,600 is eight stops faster than ISO 1600.

Fairground rides: 1/250 sec. @ f/16
Night street scene: 1/200 sec. @ f/16
Interior by candlelight: 1/60 sec. @ f/16
Landscapes by full moon: 1/2 sec. @ f/16

Direct link | Posted on Feb 25, 2014 at 22:55 UTC as 181st comment | 6 replies
On Cold Hearted Wind in the Bales challenge (4 comments in total)

Trite, but true: I LOVE this!

Direct link | Posted on Nov 8, 2013 at 23:58 UTC as 3rd comment

Sadly, it took 2nd place in this challenge.

Direct link | Posted on Oct 19, 2013 at 12:45 UTC as 1st comment
On Nikon D800 Review preview (17 comments in total)

Regarding the excellent demo of diffraction's impact at various f-stops, on page 25 of this review, where is the photo showing what could have been accomplished using Photoshop ACR sharpening against an f/4 RAW file?

I would very much like to compare sharpening of the f/4 RAW file to sharpening of the f/22 RAW file. Surely, a silk purse made from silk would be more attractive than a silk purse made from a pig's ear.

Link to page 25 of this review: http://www.dpreview.com/reviews/nikon-d800-d800e/25

Mike

Direct link | Posted on Oct 19, 2013 at 12:13 UTC as 11th comment
In reply to:

Humboldt Jim: Can we assume that a 1" sensor system can be stopped down to ƒ16, or even 22 without diffraction problems?

Using the example I've given above, if you're willing to assume that no one will view your prints at distances less than 20 inches (instead of 10 inches), you can double the calculated f-Number, stopping down to f/12.84 - delivering an effective 2.5 lp/mm at 20 inches that will appear every bit as detailed as a 5 lp/mm print at 10 inches.

Please note that there are only two variables in the formula for calculating the f-Number at which diffraction will begin to inhibit a desired print resolution (expressed in lp/mm for a 10-inch viewing distance): Enlargement factor and desired print resolution at a given viewing distance.

Somehow, discussions of resolution (or "sharpness") almost always neglect these critical variables.

Have a look at the equation for calculating the maximum acceptable diameter for a circle of confusion. It includes Enlargement factor and desired print resolution at a given viewing distance.

http://en.wikipedia.org/wiki/Circle_of_confusion

Direct link | Posted on Nov 3, 2012 at 18:28 UTC
In reply to:

Humboldt Jim: Can we assume that a 1" sensor system can be stopped down to ƒ16, or even 22 without diffraction problems?

A desired resolution of 5 lp/mm (which is equivalent to 360dpi, taking into account the 30% loss of resolution imposed by a typical CMOS sensor's Bayer algorithm and AA filter), to support viewing distances as close as 10-inches (25cm), for a 23x enlargement factor (which is required to make an 8x12-inch print from a 1-inch sensor's uncropped capture - an enlargement factor that would require, at 360 dpi, an image resolution of 2880x4320 pixels, or 12.44 MP:

f-Number = 1/ 5 / 23 / 0.00135383 = 6.42

Thus, a one-inch, 12.44 MP sensor cannot deliver more than 5 lp/mm (360dpi) of resolution after enlargement to an 8x12-inch print when using f-Numbers larger than f/6.42.

A one inch sensor is still quite small, compared to a full frame or MF sensor.

Continued below...

Direct link | Posted on Nov 3, 2012 at 18:26 UTC
In reply to:

Humboldt Jim: Can we assume that a 1" sensor system can be stopped down to ƒ16, or even 22 without diffraction problems?

The f-Number at which diffraction will begin to inhibit a desired print resolution (expressed in line pairs per millimeter for a viewing distance of 10 inches), at an anticipated enlargement factor can be calculated as follows:

f-Number = 1 / desired print resolution / anticipated enlargement factor / 0.00135383

A 1-inch sensor would have dimensions 13.2 x 8.8mm.

The possible f-Numbers at which diffraction would inhibit a desired print resolution at an anticipated viewing distance are endless, but here is an example combination:

Continued below...

Direct link | Posted on Nov 3, 2012 at 18:25 UTC

If this catches on, Facebook will have to buy a lot more hard drives.

Direct link | Posted on Sep 24, 2012 at 17:23 UTC as 33rd comment
On HDR for the Rest of Us article (199 comments in total)
In reply to:

jezsik: I hope there's a follow-up to this article. I already know how to bracket exposure, but that's just the raw material. What I struggle with is how to combine them properly. I can't help but feel that this is like a baking tutorial that focuses only on finding the best ingredients for a recipe.

Yeah! That's what I'm talkin' about! The one at bottom right (at your first link) is wonderfully natural, but without HDR, you couldn't have captured that with a single exposure. Nice example! Thanks!

Direct link | Posted on Aug 28, 2012 at 04:49 UTC
On HDR for the Rest of Us article (199 comments in total)
In reply to:

CaseyComo: Call me old-fashioned, but I prefer the look of a single exposure. If the sky is too bright, expose for the shadows and use a grad ND filter.

Well, I'm almost with you, brother, but I say use HDR with even LESS saturation than the author's finished images. Unfortunately, we are in the minority. Walk into any Wal-Mart or Fry's Electronics, go to the rear of the store and check out how all of the television displays are adjusted: unnaturally saturated. Sometimes I think Joe Consumer has lost the ability to even see color. He wants to be slapped in the face with it.

Direct link | Posted on Aug 28, 2012 at 04:42 UTC
On Just Posted: Sony DSC-RX100 preview with sample images article (645 comments in total)
In reply to:

Mike Davis: Sony seems to be making a serious attack on visible diffraction, with this camera.

The f-Number at which diffraction will *begin* to inhibit a desired print resolution in lp/mm, at anticipated enlargement factor can be calculated as follows:

f-Number = 1 / desired print resolution / enlargement factor / 0.00135383

If (notice the word "If") you desire to render subject detail in the final print at a resolution of 5 lp/mm (a fairly aggressive goal), making the largest possible prints at an unresampled, uncropped 29.3x enlargement factor (print size would be 15.2 x 10.1 inches at an image density of 360 dip), the largest f-Number that can be used without diffraction beginning to inhibit your 5 lp/mm resolution goal, would be...

1 / 5 / 29.3 / 0.00135383 = 5.04

I find it noteworthy that Sony chose not to include f/5.6 and larger f-numbers with this lens - given that it stops down no further than f/4.9.

Big sensor and fast lens = less vulnerable to diffraction.

Mike

" but educated users should be able to decide" - and therein lies the deficiency I was hoping they had addressed.

Direct link | Posted on Jun 13, 2012 at 12:16 UTC
On Just Posted: Sony DSC-RX100 preview with sample images article (645 comments in total)
In reply to:

Mike Davis: Sony seems to be making a serious attack on visible diffraction, with this camera.

The f-Number at which diffraction will *begin* to inhibit a desired print resolution in lp/mm, at anticipated enlargement factor can be calculated as follows:

f-Number = 1 / desired print resolution / enlargement factor / 0.00135383

If (notice the word "If") you desire to render subject detail in the final print at a resolution of 5 lp/mm (a fairly aggressive goal), making the largest possible prints at an unresampled, uncropped 29.3x enlargement factor (print size would be 15.2 x 10.1 inches at an image density of 360 dip), the largest f-Number that can be used without diffraction beginning to inhibit your 5 lp/mm resolution goal, would be...

1 / 5 / 29.3 / 0.00135383 = 5.04

I find it noteworthy that Sony chose not to include f/5.6 and larger f-numbers with this lens - given that it stops down no further than f/4.9.

Big sensor and fast lens = less vulnerable to diffraction.

Mike

Ooops! Never mind!

I just saw some sample photos taken at f-Numbers greater than f/4.9.

Wishful thinking...

Mike

Direct link | Posted on Jun 11, 2012 at 18:39 UTC
On Just Posted: Sony DSC-RX100 preview with sample images article (645 comments in total)

Sony seems to be making a serious attack on visible diffraction, with this camera.

The f-Number at which diffraction will *begin* to inhibit a desired print resolution in lp/mm, at anticipated enlargement factor can be calculated as follows:

f-Number = 1 / desired print resolution / enlargement factor / 0.00135383

If (notice the word "If") you desire to render subject detail in the final print at a resolution of 5 lp/mm (a fairly aggressive goal), making the largest possible prints at an unresampled, uncropped 29.3x enlargement factor (print size would be 15.2 x 10.1 inches at an image density of 360 dip), the largest f-Number that can be used without diffraction beginning to inhibit your 5 lp/mm resolution goal, would be...

1 / 5 / 29.3 / 0.00135383 = 5.04

I find it noteworthy that Sony chose not to include f/5.6 and larger f-numbers with this lens - given that it stops down no further than f/4.9.

Big sensor and fast lens = less vulnerable to diffraction.

Mike

Direct link | Posted on Jun 11, 2012 at 18:36 UTC as 14th comment | 5 replies
On Sigma shows latest products at Focus on Imaging article (42 comments in total)
In reply to:

D1N0: for some sample's http://www.flickr.com/groups/sigmadp1/

6 LIKES and counting, on use of the word "bloodbath."

Direct link | Posted on Mar 11, 2012 at 15:40 UTC
On Sigma shows latest products at Focus on Imaging article (42 comments in total)
In reply to:

Salvatore Castrovinci: Very good alternative..... I am waiting the price...... I hope not so exagerate as the First SD1.......

About the viewfinder I can should use, for the DP1m, the OVF of the old DP1.... is not so different as field image....... or not ?

Cheers

Salvatore

I would think that any viewfinder made for a 28mm lens on a fullframe camera would work well with either the DP1 or the DP1 Merrill, given that they both have 28mm-equivalent lenses.

For example: The Voigtlander 28mm Metal Brightline Viewfinder

http://www.cameraquest.com/jpg6/VF%2028%20M%20B%201.jpg

http://www.cameraquest.com/jpg6/VF%2028%20M%20B%202.jpg

Direct link | Posted on Mar 11, 2012 at 15:33 UTC
Total: 37, showing: 1 – 20
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