<p>Supplemental speculation:</p>
<p>In order to produce an image on the sensor from a finite distance, one would have to design and build a special <em>and expensive</em> lens with a conjugate focus close enough to be practical, and a well characterized and flat field (or a curved object plane).</p>
<p>Then one would presumably discard this lens after this simple test.</p>
<p>Instead, the ~200<span class="math-container">$\lambda$</span> pinhole offers the following advantages over developing and adding some kind of projection lens</p>
<ul>
<li>being very easy to model unambiguously with basic optics (MTF, scattered light, etc)</li>
<li>not requiring any focus or introduce any errors if focus isn't correct</li>
<li>automatically produces a fairly low light flux which might be suitable for the array</li>
</ul>
<p>While none of these are mentioned in the linked articles in the other answer, they are sort-of self-evident from basic optics.</p>
<p>Also <em>somewhat</em> self-evident is that the internet can not get enough fractal vegetables (or <em>fruit</em>, see Vi Hart's video below), and that the simple yet beautiful pinhole camera + fractal vegetable demonstration is cool and has some public outreach value.</p>
<p><a href="https://i.sstatic.net/JKVMg.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/JKVMgm.jpg" alt="screenshot from Vera C. Rubin Observatory LSST Camera" /></a> <a href="https://i.sstatic.net/bnpqV.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/bnpqVm.jpg" alt="screenshot from Vera C. Rubin Observatory LSST Camera" /></a>
<a href="https://i.sstatic.net/34yli.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/34ylim.jpg" alt="screenshot from Vera C. Rubin Observatory LSST Camera" /></a> <a href="https://i.sstatic.net/dO9OT.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/dO9OTm.jpg" alt="Romanesco broccoli (Brassica oleracea)" /></a></p>
<p>Click images for full size. The first three are screenshots from the video and the last is from <a href="https://en.wikipedia.org/wiki/File:Romanesco_broccoli_(Brassica_oleracea).jpg" rel="nofollow noreferrer">Wikimedia's Romanesco broccoli (Brassica oleracea)</a>.</p>
<p><div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/ahXIMUkSXX0?start=0"></iframe>
            </div></div></p>

CC BY-SA 4.0
2021-08-08T01:13:34.970Z
2021-08-08T01:13:34.970Z
uhoh
<p>The SLAC National Accelerator Laboratory video <a href="https://www.youtube.com/watch?v=qc_iscV1uA0" rel="nofollow noreferrer">Vera C. Rubin Observatory LSST Camera</a> (caution! annoyingly loud music, lower volume before playing) shows a <a href="https://en.wikipedia.org/wiki/Romanesco_broccoli" rel="nofollow noreferrer">Romanesco broccoli</a> (which I'd assumed was a 3D printed mathematical surface of that name until I checked and found out that this is the name of an actual vegetable i.e. <em>Brassica oleracea</em>) as the object of a pinhole camera projecting its image on to the astoundingly large CCD array.</p>
<p>There are likely several advantages to using the pinhole rather than a well-corrected projection lens, is it possible to say what they are?</p>
<p>Is it also possible to elaborate on the choice of object for the camera?</p>
<p>See also:</p>
<ul>
<li>slac.stanford.edu <a href="https://www6.slac.stanford.edu/news/2020-09-08-sensors-world-largest-digital-camera-snap-first-3200-megapixel-images-slac.aspx" rel="nofollow noreferrer">Sensors of world’s largest digital camera snap first 3,200-megapixel images at SLAC</a></li>
<li>BBC: <a href="https://www.bbc.com/news/science-environment-54066586" rel="nofollow noreferrer">Vera Rubin: Super telescope's giant camera spies broccoli</a></li>
<li><a href="https://astronomy.stackexchange.com/q/34647/7982">What is the LSST now? Where does LSST end and Vera C. Rubin Observatory begin?</a></li>
</ul>
<p>Caution! annoyingly loud music, lower volume before playing:</p>
<p><div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/qc_iscV1uA0?start=0"></iframe>
            </div></div></p>

CC BY-SA 4.0
2020-09-09T15:38:46.463Z
Broccoli is fractal.  No, really, it's a decent physical object with repetitive, high-detail structures.   Lots of stuff to try to resolve in the image.
Carl Witthoft
<observational-astronomy><photography><observatory><vera-c-rubin-observatory>
Why was the Vera C. Rubin Observatory LSST Camera tested with a broccoli and a pinhole?
uhoh
# Why was the Vera C. Rubin Observatory LSST Camera tested with a broccoli and a pinhole?

(Asked by: username_0 on 2020-09-09)

The SLAC National Accelerator Laboratory video [Vera C. Rubin Observatory LSST Camera](https://www.youtube.com/watch?v=qc_iscV1uA0) (caution! annoyingly loud music, lower volume before playing) shows a [Romanesco broccoli](https://en.wikipedia.org/wiki/Romanesco_broccoli) (which I'd assumed was a 3D printed mathematical surface of that name until I checked and found out that this is the name of an actual vegetable i.e. *Brassica oleracea*) as the object of a pinhole camera projecting its image on to the astoundingly large CCD array.

There are likely several advantages to using the pinhole rather than a well-corrected projection lens, is it possible to say what they are?

Is it also possible to elaborate on the choice of object for the camera?

See also:

* slac.stanford.edu [Sensors of world’s largest digital camera snap first 3,200-megapixel images at SLAC](https://www6.slac.stanford.edu/news/2020-09-08-sensors-world-largest-digital-camera-snap-first-3200-megapixel-images-slac.aspx)
* BBC: [Vera Rubin: Super telescope's giant camera spies broccoli](https://www.bbc.com/news/science-environment-54066586)
* [What is the LSST now? Where does LSST end and Vera C. Rubin Observatory begin?](https://astronomy.stackexchange.com/q/34647/7982)

Caution! annoyingly loud music, lower volume before playing:

**Tags:** observational-astronomy, photography, observatory, vera-c-rubin-observatory

> **Comments:**
> **username_1**: Broccoli is fractal.  No, really, it's a decent physical object with repetitive, high-detail structures.   Lots of stuff to try to resolve in the image.  

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## 1 answers

### Answer by username_0 on 2021-08-08. Score: 1

Supplemental speculation:

In order to produce an image on the sensor from a finite distance, one would have to design and build a special *and expensive* lens with a conjugate focus close enough to be practical, and a well characterized and flat field (or a curved object plane).

Then one would presumably discard this lens after this simple test.

Instead, the ~200$\lambda$ pinhole offers the following advantages over developing and adding some kind of projection lens

* being very easy to model unambiguously with basic optics (MTF, scattered light, etc)
* not requiring any focus or introduce any errors if focus isn't correct
* automatically produces a fairly low light flux which might be suitable for the array

While none of these are mentioned in the linked articles in the other answer, they are sort-of self-evident from basic optics.

Also *somewhat* self-evident is that the internet can not get enough fractal vegetables (or *fruit*, see Vi Hart's video below), and that the simple yet beautiful pinhole camera + fractal vegetable demonstration is cool and has some public outreach value.

[![screenshot from Vera C. Rubin Observatory LSST Camera](https://i.sstatic.net/JKVMgm.jpg)](https://i.sstatic.net/JKVMg.jpg) [![screenshot from Vera C. Rubin Observatory LSST Camera](https://i.sstatic.net/bnpqVm.jpg)](https://i.sstatic.net/bnpqV.jpg)
[![screenshot from Vera C. Rubin Observatory LSST Camera](https://i.sstatic.net/34ylim.jpg)](https://i.sstatic.net/34yli.jpg) [![Romanesco broccoli (Brassica oleracea)](https://i.sstatic.net/dO9OTm.jpg)](https://i.sstatic.net/dO9OT.jpg)

Click images for full size. The first three are screenshots from the video and the last is from [Wikimedia's Romanesco broccoli (Brassica oleracea)](https://en.wikipedia.org/wiki/File:Romanesco_broccoli_(Brassica_oleracea).jpg).


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