Re: [OM] IMG: Sunrise, Moonset

[John Hudson]

Does "embiggen" convey any greater meaning than "enlarge" in the context 
of the subject under discussion ?
jh


On 10/20/2014 8:09 AM, Chuck Norcutt wrote:
> I'm sorry you cant embiggen it because there's no larger image behind 
> it available to the general public.  And showing you (in particular) a 
> full pixel version wouldn't prove or disprove anything.  That shot was 
> done handheld with the 5D and no IS on the lens.  What's its actual 
> resolution?  I have no idea.  I only know that it meets my own 
> criteria for a shot planned to be printed at 8-10" high at full frame 
> size.  It wasn't intended to be cropped to show the detail of the 
> foreground flowers (although it might suffice for that).  If I really 
> wanted to do that I'd have taken a different photo... just as you did 
> with the weather vane.  I consider a hyperfocal shot to be a 
> purposeful, landscape shot.  It's meant to be displayed as I framed it 
> in the viewfinder.  If it serves a second purpose that's fine but was 
> not the intent.
> Your comments about hyperfocal distance and CoC lead me to believe 
> that your understanding of such is only partial.  You say: "ALL DoF 
> calculations and tables rely on assumptions about the CoC..." Your 
> comment about the use of tables making assumptions about CoC is quite 
> correct.  The same holds for DoF markings on lenses and, 
> unfortunately, most DoF calculators.  They all assume a CoC of about 
> 30 lines/mm for 35mm size images.  However, a good DoF calculator 
> makes no such assumptions.  It allows you to define the desired CoC.  
> I find that 30 lines/mm is adequate for my own usage when working with 
> the 5D.  But working with the E-M5 with its 4/3 sensor requires 60 
> lines/mm to account for the 2X print magnification over 35mm.  Maybe 
> your own criteria require 40 lines/mm for 35mm size and 80 lines/mm 
> for 4/3. Whatever it is can be readily determined with a good DoF 
> calculator that allows entry of the CoC as a parameter.
> The following DoF/hyperfocal calculator will allow entry of a specific 
> CoC if you scroll all the way to the bottom of the list of cameras.
> <http://www.dofmaster.com/dofjs.html>
>
> For my own use I don't carry a calculator but do carry a small card 
> with hyperfocal distances that I have calculated for just a couple 
> wide angle focal lengths.  The characteristic of these little custom 
> tables is that they use only one aperture (the diffraction limit for 
> the sensor size)... about f/11 for a 5D and about f/5.6 for an E-M5.  
> Then I calculate the hyperfocal distance.  The parameters that I used 
> for the 24mm shot on the 5D would have been f/11 and hyperfocal 
> distance of 5.65 feet.  But I make no attempt to be that precise in 
> setting the focus distance. What I do know is that, if I focus at less 
> than 5.65 feet I will miss infinity.  I don't depend on focusing 
> scales since most lenses don't have them and those that do may be hard 
> to interpret with any precision.  But I can estimate 6 feet fairly 
> accurately and then add a foot or two to be on the safe side.  If I 
> end up focusing at 8 feet the near focus will be 4 feet instead of 1/2 
> of 5.65.  But that rarely matters whereas missing infinity does.
> This is not really finished but I've got to end it here now. We're 
> traveling to Florida after having sold our New York place to await the 
> completion of the South Carolina house.  This laptop is shared with 
> SWMBO and it's now her turn.  :-)
> Chuck Norcutt
>
>
> On 10/19/2014 6:22 PM, Moose wrote:
> > On 10/19/2014 1:02 PM, Chuck Norcutt wrote:
> > > Here's a little hyperfocal math at work showing the you can trust them
> > > numbers.  The closest plants in this photo are about 3 feet away from
> > > the camera.  Note that "infinity" is in focus.  Canon 5D, 24mm at f/11
> > > with lens focused at 6 feet.  This is actually a 2-image pano.
> > > <http://www.chucknorcutt.com/Mt%20Rainier/pano%208552-8553er.htm>
> > Lovely @ 5x10" on my screen. But of course, being Pixel Peeper Moose, I
> > kept looking for where to click to embiggen it.
> >
> > ALL DoF calculations and tables rely on assumptions about the CoC, as
> > you know well. And they all have their roots in opinion polls. Folks
> > showed a bunch of prints to another bunch of folks, asked which were
> > sharp and tallied the results. That's why you set the viewing size in
> > making the calculations.
> >
> > Here's why I don't have and/or don't trust them numbers.
> >
> > 1. Right off the bat, I'm in trouble, because my 20/10 vision is an
> > outlier; I don't have the same opinions about what is sharp as the 
> > average.
> > 2. The world has changed. We, at least the pixel peepers among us,
> > routinely view images at magnifications never dreamed of in film days
> > (the movie Blowup not withstanding), if only because grain the size of
> > golf balls isn't that interesting.*
> >
> > I rather routinely take crops of rather small parts of an image and
> > present them at 8.5x11" on my screen, larger or smaller for various
> > viewers on their screens.
> >
> > Take the example I just used. Lets say I decide to do a gallery or book
> > of the weather vanes I shot over the years. (Farfetched for weather
> > vanes, but two of my three books have come from images collected from
> > over the years.) I have a good shot of this one, in focus. I've added it
> > to the existing comparison.
> > <http://www.moosemystic.net/Gallery/MPhotos/BayArea/Miscellaneous/AngelMoon.htm> 
> >
> >
> > Had I used hyperfocal for 'good enough' focus, it would be soft at this
> > size. Taken with the 14-150 @ 150. Had I had the 70-300 at the time, I
> > wouldn't have needed such a crop, but that's part of the point: I
> > didn't, but shot for the best result, no matter what as yet unknown use
> > I might put it to.
> >
> > 3. I said it before. My µ4/3 lenses don't have DoF markings, anyway, nor
> > do any zooms I know of. This shot was taken casually, when I parked in a
> > tiny village and was about to walk to a store to pick up a custom order.
> > How am I to make all these calculations in any reasonable time frame? I
> > don't even know for sure how far away the vane is.
> >
> > I've tried using manual focus to find the middle between extremes, but
> > the results have been mixed, at best. Usually to my eye, not right for
> > either end.
> >
> > A couple of shots in a few seconds, and I'm done and on my way.
> >
> > Directly On Focus Moose
> >
> > * OK, another disclaimer, if only for me. Kodak made a special reversal
> > film, originally for spy planes, I believe. We used the commercial
> > version back when. It seemed grainless and somehow like the subject ran
> > out of detail before it did. :-)   Slow, very tricky to process, etc. As
> > far as I know, no one was using it for regular photography. But for huge
> > enlargement on a rear projection screen, amazing.
--
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