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Lensrentals | all galleries >> photogeek_contest >> hors_category > Macrocomposit.jpg
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sarangiman20-Nov-2013 21:23
Descriptions of the CMYK inkjet printer dots (upper right) and the RGB pixels of the Retina Macbook Pro (lower right):

CMYK Pigment Dots (Epson 9900): I thought it'd be fun to image the CMYK pigment dots in a print (particularly, the moon in a print of this cityscape shot of mine: from the highly-regarded Epson 9900 printer (supposedly capable of 2880x1440dpi). I estimate the dots to be roughly 35µm across, based on my measurements from the 'Ruler' shot above.

Retina Macbook Pro (MBP) pixel-peeping: I've imaged the individual R, G, and B pixels of the high-density Retina MBP IPS (in-plane switching) display. You'll note some sub-pixel features: it seems 5-8 'strips' per color pixel. For ease of visualization, I've desaturated some of the blue pixels & enlarged one such desaturated blue pixel in the inset - here you can easily count 8 such strips. My measurements (based on the 340nm/pixel measurement from the 'Ruler' shot) indicate that each color MBP pixel is approx. 30µm across; that would make each of the 8 sub-pixel strips 30/8 = 3.75µm across. Hence, it would seem that we've resolved ~4µm features here.

Sanity check: Retina MBP panels have a pixel density of 220ppi. That equates to 1 pixel per 115µm; however, since each pixel consists of R, G, B pixels, each color pixel should be at most 115/3 = 38µm across. 38µm is consistent with my measurement of ~30µm based on the magnification I achieved (determined by the 'Ruler' shot above) - so that was a satisfying reality check!
Carlo Vaccari 17-Nov-2013 05:15
It looks like you need a Coastal Optics UV-Vis-IR 60/4...

The chromatic aberration makes the red pixels on the MBP display distinctly out of focus.
Lensrentals16-Nov-2013 18:49
Ruler: This shows that 1mm on a ruler (side note: I need a better
ruler!) is optically magnified approx. 14x on the NEX-6 sensor. A
quick calculation indicates that 1mm, or 1000µm, is represented by
2960 pixels. This equates to 1 pixel representing 340nm of the imaged
object; note, however, the 340nm figure is a bit silly -- 340nm is
smaller than the wavelength of green light, & you can't optically
image features on the order of the wavelength of light (due to
diffraction). Still, it's a rough estimate that will allow us to
assign some sizes to features in the subsequent images shot with this
setup. Photoshop 'ruler' tool was used for all measurements.

Side note: At these magnifications any movement is amplified - from
someone walking in your home or above your condo to a truck driving
down the street near you. An optical bench or some platform with a
high moment of inertia to put the camera/stage on would've helped;
however, in the absence of any such support, I had to make do with
shutter speeds no longer than 1/60-1/125s (despite using a wireless
trigger). Hence, I used the technique of multi-frame averaging to
increase SNR of shots. For the Retina MBP image, 9 shots were aligned
& averaged to increase the SNR approx. 3-fold.

P.S Interestingly, I had a setup with more accessories - e.g. with a
50mm lens reversed on a 70-200 to act as a diopter - but it turns out
I got more magnification & resolution with the setup pictured; hence,
that's what I'm submitting. It turns out you can't reverse a 50mm lens
on the Canon 1-5x macro at 5x magnification (at least in this setup
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