Mr Physics

Mr Physics

Lives in United States Volney USA, NY, United States
Joined on Oct 31, 2010

Comments

Total: 24, showing: 1 – 20
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On Inside RA001: World's first Boeing 747 'Jumbo Jet' article (92 comments in total)
In reply to:

beavertown: Airbus is better than Boeing.

I like beavers better than trolls. A lot better.

Direct link | Posted on Sep 29, 2014 at 12:01 UTC
On Inside RA001: World's first Boeing 747 'Jumbo Jet' article (92 comments in total)
In reply to:

Chuck Lantz: I noticed a couple of interesting bits; ... an ashtray at the engineers station, and a panel where "gauge" is spelled "guage." Kinda makes me wonder what else they got wrong in all those goodies.

You wouldn't have trusted a cigarette smoking engineer in 1969?

Direct link | Posted on Sep 29, 2014 at 11:59 UTC
On Nikon D750 First-impressions review preview (1054 comments in total)

This light writing machine sounds like it could be a winner. I'm not trying to make money with my photography but I seem to want to update my "main" camera every 2-4 years. So do I spend $3300 USD or $2300 (each probably very fine machines). The D750 has a couple of extra gadgets that I like to play with: WiFi and the flip screen.
The total allowable exposure value remains equal or to or better than the D700 (i.e. 1/8000s @ ISO200 ISO=1/4000s @ ISO100 and the flashsync speed to the new machine fairs better).
This machine looks like it would be fun to learn to use well.

Direct link | Posted on Sep 12, 2014 at 13:10 UTC as 197th comment
On Readers' Showcase: Nature and Wildlife article (29 comments in total)

Great and lucky captures! All of these are wonderful.

Direct link | Posted on Aug 3, 2014 at 15:44 UTC as 15th comment
On Nikon D810 Preview preview (1533 comments in total)
In reply to:

Mr Physics: I never really had a use for the "Qual" or WB" buttons. If they just had a 2-button thing for metering and ISO, I might get one of these. O.K., I'm not telling the truth. I'll still get one of these, despite too many buttons. :)

The last sentence should imply that I lust the D810 and I'm trying to rationalize the expenditure despite already having very good light writing machines (D700 and D90).

Direct link | Posted on Aug 1, 2014 at 22:36 UTC
On Nikon D810 Preview preview (1533 comments in total)
In reply to:

Mr Physics: I never really had a use for the "Qual" or WB" buttons. If they just had a 2-button thing for metering and ISO, I might get one of these. O.K., I'm not telling the truth. I'll still get one of these, despite too many buttons. :)

I'm a D700 and RAW recording guy so it makes sense for me to be in 14 bit compressed NEF always. I've always tweaked the WB in post processing and generally leave the WB in auto.

I've been wondering if the quality and range of actual light data captured would be better if I'd simply select an appropriate WB at capture time but never had the ambition to study this question in detail. I wouldn't know where to start. We have the options of direct sunlight, shade and cloudy but there doesn't seem to be an in camera compensation to accommodate the difference in the Sun's light from bright mid-afternoon to the red-ish orange of dusk. When I find myself with mixed source lighting indoors (often a combination incandescent and florescent lighting) I don't have a clue what option to pick at capture time. I usually choose "Auto" and sort it out in post processing. So I haven't ever used the WB and QUAL buttons.

Direct link | Posted on Aug 1, 2014 at 22:32 UTC
On Nikon D810 Preview preview (1533 comments in total)

I never really had a use for the "Qual" or WB" buttons. If they just had a 2-button thing for metering and ISO, I might get one of these. O.K., I'm not telling the truth. I'll still get one of these, despite too many buttons. :)

Direct link | Posted on Aug 1, 2014 at 13:52 UTC as 58th comment | 4 replies
On What is equivalence and why should I care? article (2037 comments in total)
In reply to:

chbde: Very good article. It is however slightly incorrect on the topic of diffraction:
"This is because, like depth-of-field, softening from diffraction depends on the actual size of the aperture, not the F-number."

As "Cambridge in Color" (http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm) explains it very nicely, the size of the diffraction pattern on the sensor depends only on the f-number. This is also the reason why diffraction softening is independent of focal length. But one can see the effect of diffraction if the size of the diffraction patterns exceeds the dimensions of a pixel, so it is dependent on pixel density.

"This means diffraction will have the same impact on two images shot at equivalent apertures"

That sentence remains correct, however, for sensors with equal number of pixels.

As a consequence of this, by the way, on a 16MP 2.3" compact the resolution is already diffraction limited at f2.8!

The Airy disk analysis is good to use as a first approximation.But we are only talking about space in between the aperture and the sensor at that point. The focus distance or focal length becomes irrelevant.

Diffraction occurs because of a fundamental uncertainty ( a blurring, if you will) when a packet of light waves pass through an opening of a given dimension. Physic can't explain WHY this happens but can calculate the magnitude to great accuracy. When we observe this packet of light, we are always on the sensor side of the aperture. Thus the same small angle between two blade of grass through a 35mm lens experience the same diffraction as a pair of galaxies through a 1000mm lens (at the same absolute aperture).
It might be interesting for me to go through the derivations from first principals to arrive at this conclusion (and it would take forever) but it would be boring to try and share the results with most anybody else. That why I admire DPR's empirical exposition. :)

Direct link | Posted on Jul 7, 2014 at 18:58 UTC
On What is equivalence and why should I care? article (2037 comments in total)
In reply to:

chbde: Very good article. It is however slightly incorrect on the topic of diffraction:
"This is because, like depth-of-field, softening from diffraction depends on the actual size of the aperture, not the F-number."

As "Cambridge in Color" (http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm) explains it very nicely, the size of the diffraction pattern on the sensor depends only on the f-number. This is also the reason why diffraction softening is independent of focal length. But one can see the effect of diffraction if the size of the diffraction patterns exceeds the dimensions of a pixel, so it is dependent on pixel density.

"This means diffraction will have the same impact on two images shot at equivalent apertures"

That sentence remains correct, however, for sensors with equal number of pixels.

As a consequence of this, by the way, on a 16MP 2.3" compact the resolution is already diffraction limited at f2.8!

For a given wavelength (color), diffraction effects can be completely determined by the actual aperture i.e. FL/f-number. DPR has exposed and illustrated this fact very well. They have created the ultimate FF vs crop vs smaller exposition article. It's the best, clearest and most concise explanation I have ever seen. Kudos to the team that wrote it. It should an excellent reference for years to come to us all. I'm sure there may be some small mistake(s) in it, but if corrected, this one article WILL stand as an authoritative reference.

Direct link | Posted on Jul 7, 2014 at 18:08 UTC
On Nikon D810 Preview preview (1533 comments in total)
In reply to:

mirkoc: I like:
new 'highlight-weighted' metering option (to preserve highlight detail in contrasty scenes)

I'm thinking that it adjusts the exposure independent of the recording mode. But I could use a feature that leverages the great DR of these modern cameras to protect highlights of BIFs when I don't have the time to chimp and adjust exposure compensation.

Direct link | Posted on Jun 27, 2014 at 00:41 UTC
On Nikon D810 Preview preview (1533 comments in total)

Dang. I've been a 12MP guy for quite a while now. It is my fundamental belief that if you can't say it with 12MP then you have a speech impediment. But this light writing machine has me drooling for a number of reasons: they've expanded the range of available (useable?) ISO by 2 stops over the D800 and 4 stops over the D700. If that translates to something noticeable in DR @ base ISO, then that is very big. They have that highlight preserving metering option which is potentially big (for me). I've blown too many highlights from white water fowl to not want this. And what if I'm wrong about 12MP being sufficient to completely record the light from a capture? This machine has me interested in moving beyond the D700 for the first time. Hmmm. I think Nikon hit it out of the ballpark on this one (maybe).

Direct link | Posted on Jun 26, 2014 at 22:53 UTC as 243rd comment | 8 replies
On Flying Penguins: Photography in Antarctica article (43 comments in total)

A very strong collection of beautiful images. Not many of us on this planet get the opportunity and you have made the best of yours.

This gives some weight to your axioms: get out there and stay out there AND treat each sunset like it's your last. These are 2 most important things I learned from reading this that apply to me. Thanks.

Direct link | Posted on May 11, 2013 at 03:13 UTC as 5th comment
In reply to:

sosmix: I still can't get my head around someone going out looking for wildlife with a gun in one hand and a camera in the other.

Photograph them or kill them, it must be quite a dilemma.

Yes, I can't grasp it either. But I don't own a gun but I own more cameras than I like to admit. And my cameras have these HUGE memory disks/cards. HUGE, I tell you HUGE. I'm liable to go out and take pictures of innocent 1st graders at any moment....wait a second, that doesn't sound right. I should just point my big 85mm f/1.4 at my head and end it all. Oops. Wrong format.

If I was a hunter, I would try to "capture the moment" and do both very quickly in sequence. So, it might be both.

Direct link | Posted on Apr 5, 2013 at 12:13 UTC
In reply to:

Thinking out loud: Trophy hunters are serial killers who get great pleasure out of destroying living creatures - the "trophy" is just a convenient excuse for their blood lust. If you doubt this, watch videos of the "hunt". They stalking their prey from a distance (the animals do not sense them) using telescopic sights on their rifles,they slaughter them with a high velocity bullet. The interesting bit is just how excited they get - orgasmic in fact, they rush over to the kill and marvel at just how magnificent the dead animal is. It does not occur to them that it was magnificent until they brutally end its life!
Perhaps the only good thing about this is that these morons are killing animals and not humans - as far as we know.

Every living human would not exist but for the hunters in their ancestry. Hunting is the rule set forth by the Higher Power (whatever your name for him/her) of everyone.

Direct link | Posted on Apr 5, 2013 at 11:59 UTC
On Ethics of prize-winning photo debated article (151 comments in total)
In reply to:

Funduro: Journalist have been busted as plagiarist more often now, thanks to Google. Heck even two consecutive German heads of education have resigned because of plagiarist Doctoral thesis & the like. So it's not surprising this photographer staged this photo and gave false narrative about it.

No. He's simply honoring a photographer of significance.

Direct link | Posted on Feb 26, 2013 at 13:25 UTC
On Pssss psss psss ... ooooh! in the Secrecy challenge (6 comments in total)

Yes, this is one of those "Wow" images. Well done, sir.

Direct link | Posted on Dec 25, 2012 at 01:39 UTC as 1st comment
On Nikon D600 Hands-on Preview preview (713 comments in total)
In reply to:

Dyun27: After looking at the RAWs, frankly I think all these cameras are way too close to call and in the end it's the photographer who will make the biggest difference to the images taken. I gotta say though, the D600 is really holding it's ground among these $3,000.00 + cameras, maybe even surpassing some by a tiny margin! I never dreamed it would come so close to the noise quality of the D3s, at least at ISO 6400 and below. The D3s starts pulling away from the rest at ISO 12,800. They all have some positives and some negatives, but having this kind of noise handling for $2,000.00 is firggin' awesome.

Penelope Crux IS hot. Who is Scarlett Johansson?

Direct link | Posted on Oct 23, 2012 at 17:56 UTC
On - in the Envy challenge (1 comment in total)

Wow. I like this image on many different levels.

Direct link | Posted on Jun 10, 2012 at 01:20 UTC as 1st comment
On roadside cross photo in wgjohnston's photo gallery (1 comment in total)

Simple. Powerful. Beautiful. Wow, I'm in awe.

Direct link | Posted on Mar 11, 2012 at 06:02 UTC as 1st comment
On barns in the Winter 2011-2012 challenge (3 comments in total)

Very good. Good eye.

Direct link | Posted on Mar 11, 2012 at 05:59 UTC as 2nd comment
Total: 24, showing: 1 – 20
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