I scan these 6x6 negs at 4000 dpi all the time, and yeah they look grainy at
100% even with films like Acros that have fine grain. In prints, however,
the grain isn't visible. I usually don't print huge, 11x11 if I print the
whole square, or around 11x14 if I crop to a rectangle (equal to 14x14
square). I've done a few 16x20s and they looked incredible too, beating any
digital camera I have tried (I'm sure the 50mp medium format systems beat my
results; the 22mp ones based on 35mm slrs might equal it, but are out of
reach financially for me as well).
That wurlitzer building is cool! I like that shot. I actually found out that
GE has a sign similar to the one in Ft. Wayne (but larger) on one of their
buildings in Schenectady! Looks just like the one here though.
I will have to rescan my shot at 1000dpi and see how it looks, I already put
the neg away and went on to scanning some other shots.
--
Chris Crawford
Fine Art Photography
Fort Wayne, Indiana
260-747-3962
http://www.chriscrawfordphoto.com My portfolio
http://blog.chriscrawfordphoto.com My latest work!
On 3/14/09 8:06 PM, "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
> Looks pretty good to me even if it is only 8-10 lp/mm. Ever since
> reading Bruce Fraser's book on sharpening I've learned to evaluate the
> look of a printed image on screen by showing it at 25-40% of actual
> pixel size. The (rule of thumb) percentage is determined by taking the
> pixels per inch of your monitor (93 for mine) divided by the print
> resolution. For a 300 dpi print you'd get 93/300 = 31%. At 240 dpi
> you'd get 93/240 = 39%.
>
> Taking one of the 100% pixel crops (the GE sign) and displaying it at
> 39% (simulating 240 dpi) shows fairly evident grain. But displaying at
> 31% (simulating 300 dpi) makes the grain nearly invisible. On an actual
> print it probably would be invisible. Fraser's full sharpening rule of
> thumb for ink jets was to display the image at the recommended
> percentage and then sharpen until the image looked slightly "crunchy".
> The reason is that an ink jet print will be slightly softer after the
> ink spreads and is partly absorbed into the paper. I think an ink jet
> print would probably do something similar with the small amount of
> residual grain.
>
> I found it very interesting that, despite the theoretically low
> resolution that the real limit in the image appears to be film grain.
>
> Incidentally, I like the shot. It reminds me of my old TOPE image of
> the Wurlitzer (organ) building in North Tonowanda, NY (just a bit south
> of Niagara Falls. <http://www.tope.nl/tope_show_entry.php?event=11&pic=19>
>
> By my calculations you should have an image that's 9449 pixels square
> after scanning a 6x6 neg at 4000 ppi. That should give you a 31.5"
> square print at 300 dpi. But the math seems awry here and I don't
> understand why. If the image resolution was really only 10 line
> pairs/mm that's equal to 20 pixels per mm. The film is 60mm wide so the
> actual image resolution should only be 1200 pixels total or more like
> 500 ppi. I'm wondering what happens to this image if you scan it at,
> say, 1000-1200 ppi or just enough to avoid aliasing. Does it look just
> as good?
>
> Chuck Norcutt
>
>
> Chris Crawford wrote:
>> A couple weeks ago I mentioned my first time using a Vivitar 2X
>> teleconverter with my Hasselblad and the 150mm f4 CF-Sonnar lens to get an
>> effective 300mm f8 lens. I shot it at f22, for an effective aperture of f45.
>> At that aperture, as we noted, even the best lenses are limited by
>> diffraction to a resolution of less than 10 l/mm (Someone, I think it was
>> Chuck Norcutt, said the actual number was only 8!). The image looks pretty
>> good nonetheless! Here's a scan of it, and a couple of 100% crops.
>>
>> http://www.chriscrawfordphoto.com/family-snapshots/vivitar-hassy2x/
>>
>> What do you guys think? I paid very little for the 2x, I think it was $35
>> from eBay. I wonder if the closest Hasselblad lens to this combo, the 250mm
>> f5.6 CF-Sonnar would be any better given that I had to use such a small
>> aperture for the depth of field needed to keep the whole sign and the
>> foreground building facade sharp.
>>
>>
--
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