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How do you define "tack sharp"?

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--
Linda R

Photography: Celebrating Life
 
DaSonyGuy said:
The problem with MTF tests is that most only test the lens at f8
and therefore the score does'nt necessarily reflect how well the
lens performs at other apertures.
Click to expand...
Not Nikon. See here: http://nikonimaging.com/global/products/lens/mtf.htm

Here's an example of why I think this is important. Looking at the MTF curves out to about 12 mm (which is most of what matters on a DX camera), Nikon's 50 f/1.4 looks worse than their 50 f/1.8. But that's comparing one at f/1.4 to the other at f/1.8. I'm pretty sure that if both were stopped down to f/2.8, the 30 lines/mm MTF for the f/1.4 would be better than for the f/1.8. (Unless, of coures, most of the comparisons of the sharpness of these two lenses at apertures like f/2.8 are completely wrong, or the relative resolution and sharpness of the two lenses at f/2.8 has absolutely no relation to the MTF measurements, which I doubt.)

But otherwise your point is well taken -- in general, I believe it is true that the MTF of lenses will improve as you stop them down a few stops, so the MTF that is published may not be very predictive of how the lens will perform (in terms of sharpness and contrast) under specific conditions of use.

I believe one should also "expect" better MTFs for telephotos than for wide angle lenses. So if the MTF of a 35 mm lens looks worse than the MTF of a 105 mm lens (even at the same f-stop), I don't think that really says much about the resolution and contrast of those two lenses in relation to other lenses of the same focal lengths. The 35 may still be better in terms of those characteristics than many of the other 35s out there, and the 105 may not be among the better 105s. It should be better to compare MTFs of two 35s with the same maximum aperture and two 105s with the same maximum aperture to judge their quality relative to other lenses of the same FL (and the same maximum aperture). But of course that may not always be possible.

Not that I think MTFs are the be-all and end-all. But although I'm not a lens designer or expert, I've found it helpful to try to understand them a bit in comparing how different lenses perform in real use.
--
Jim Kaye

'I believe that the electronic image will be the next major advance. Such systems will have their own inherent and inescapable structural characteristics, and the artist and functional practitioner will again strive to comprehend and control them.' -- Ansel Adams, 1981
 
Linda . . . before I wrote my original post to you, I looked at your profile and saw you were not a pro photographer so felt I would give a different angle answer, as you 'might' be fairly new to cameras or digital in particular. I knew you would get many specific replies to the definition you were seeking, so I offered a different 'take'. That's all. I stand by my post. I'm not sure if it were Adams or Bresson but one made a comment (to paraphrase IF memory serves) "a sharp photo of nothing in particular means little". I'm sure someone can give the author and quote properly.

Looks like everyone was helpful to you with specific views and opinions. I hope it worked out for you. It's always good to get different viewpoints isn't it? Yet in the end, I always go with my heart in regards to photos not the tech stuff or what others do.

I have a friend that takes such sharp photos of birds that you feel feathers are going to be blowing around your keyboard. I respect it, but it doesn't interest me. At the same time, I know what I do doesn't interest him. That's cool w/ me. He can't understand why my 'somewhat' out of focus, histograms that are pushed to the limits, levels out of whack, shadows enhanced, etc etc (all on purpose) . . alleycat gallery is in the top 20 all time most popular at Pbase. So of course I love pushing his buttons with it. smile We all have different likes and dislikes don't we?

Best,
Knox
rocklin said:
While it's true I simply asked for a definition, and yours is one
of the easiest to implement,Ï'm also interested in any related
comments
--
Linda R

Photography: Celebrating Life
Click to expand...
--
Knox
--
Avatar Photography
http://www.avatarphotoart.com
Alley Cats . . . Urban Tails (the book)
http://www.urbantailsbook.com
http://www.alleycatphotos.com
http://www.pbase.com/streetkid
 
knox said:
Linda . .
Click to expand...
We all have different likes and dislikes don't we?

Yep, it's what makes photography interesting, because our likes and dislikes can change. Thanks for posting

Linda R
 
I really enjoyed getting your tips and ideas. Plenty of food for thought here.
--
Linda R

Photography: Celebrating Life
 
Yep! Sure look tack sharp to me. Unusual coloured eyes. Makes for an interesting pic. Thx for posting
--
Linda R

Photography: Celebrating Life
 
Currently my 300 F4 EF ID for me qualifies as tack sharp on my D1x

I do not use unsharp mask or other sharpening methods anymore on pictures from this lens. My tamron 90 F2.8 macro at f5.6 does not need any sharpening. Both are sharper than my 200 F4 MF nikkor wich is not bad at all.

Compared to these my old 135-400 sigma that was reasonably sharp on an S1pro fuji, but disappointed me a lot on the D1x. That was too much resolution for this lenses blur circle.

--
http://users.pandora.be/dcweb
http://dirk.fotopic.net
dcornelis (@) gmail dot com
 
thanks friend
tfultz said:
I would take the 'feeling' of your photos over a 'tack sharp' image
of any day of the week. Your opinion is spot on and I think a lot
of posters spend so much time worrying about 'sharpness' and
'creamy bokeh' that they end up making a perfectly sterile, boring
shot.

and as my favorite HCB quotes says: 'Sharpness is a bourgeois concept'

--
http://tysonfultz.smugmug.com
http://www.pbase.com/tfultz
Click to expand...
--
Knox
--
Avatar Photography
http://www.avatarphotoart.com
Alley Cats . . . Urban Tails (the book)
http://www.urbantailsbook.com
http://www.alleycatphotos.com
http://www.pbase.com/streetkid
 
--Hey Knox!! I just looked at your alley cat 'book', I love it! Great pix and a super presentation. Whether you're a cat lover (I am) or not, the photos will make one smile and ponder. Love the low point-of-view shots, they really bring one into the cat's world. Strong work!

the photographer formerly known as 'Kallitype'
 
thanks friend . . .many August days spent in a dumpster smile
argyrotype said:
--Hey Knox!! I just looked at your alley cat 'book', I love it!
Great pix and a super presentation. Whether you're a cat lover (I
am) or not, the photos will make one smile and ponder. Love the
low point-of-view shots, they really bring one into the cat's
world. Strong work!

the photographer formerly known as 'Kallitype'
Click to expand...
--
Knox
--
Avatar Photography
http://www.avatarphotoart.com
Alley Cats . . . Urban Tails (the book)
http://www.urbantailsbook.com
http://www.alleycatphotos.com
http://www.pbase.com/streetkid
 
How ironic that you should post this just a few days ago, but it serves as both tribute and proof of the impact a photo can have. It was announced today that Joe Rosenthal passed away at the age of 94. Just this one photo, let alone many of his others, will keep his memory alive for generations.
RBFresno said:
RBFresno said:
Q:Re: How do you define "tack sharp"?
Click to expand...
A: Sharp enought to see a tack accurately represented ;-)

For some pictures sharpness is extremely important, for others it's
not. Here is a picture that's not particularly sharp, lots of
underexposed areas, blurry stars & stripes, etc:



It of course, won a Pulitzer prize for Joe Rosenthal (below):



I'd consider burning all of my supersharp pictures from this year,
if I could come up with just one like this!
There is inevitably a spectrum of discussion on sharpness ranging
from the technical (MTFs, line pairs/whatever, etc, tecnniques
affecting sharpness, etc.), to the artistic (sharp enough to convey
whatever).

Here's a prior thread regarding sharpness:
http://forums.dpreview.com/forums/read.asp?forum=1030&message=16775592

RB

http://www.pbase.com/rbfresno/profile
Click to expand...
--
Whimsy is salvation for a life taken too seriously.
http://www.pbase.com/frankvigil
 
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