The Science of Sunrods (Part 2 – A New Sunrod)

In my last post I broke the sunrod down into scientific terms and (as I figured) it ended up being ridiculous.  The contention (2 out of 4 players didn’t like it) came to the “new” sunrod I had made.  So, I’m going to try again, but this time I’m not nearly as tired.

Behold, the sunrod.  This device over at Amazon sells for only $150 and delivers 10,000 lux through three 4,000 kelvin flourescent lights (recommended daily dosage, 20 minutes).

I’m tempted to get it and turn it on the player with the sunrod, that’d solve this problem real quick 🙂  Of course, that’s mean, and DM’s aren’t mean.  So that means I have to make a new sunrod, hopefully one that “makes sense” according to what we now know.

  • Dilemma 1 – The sunrod lasts too long.  If each starting character gets three sunrods, and each sunrod lasts for four hours, then a virgin party of five has 60 hours worth of light,

Solution:  Have you ever seen them use a glowstick in a movie?  Those people are going through them like candy.  I want that in my game, so if I turn the sunrod into encounter usage it reduces their 60 hours down to one hour and fifteen minutes.

  • Dilemma 2 – A light sheds it’s light at a ratio of about one to ten.  So “bright light” one hundred feet (twenty squares) from it’s source means two things.
    • The light source itself is 10x brighter than the 20th square.
    • The light of the 20th square sheds dim light at the same ratio, away from the source.


Common Light Levels Outdoor

Common light levels outdoor at day and night can be found in the table below:

Condition Illumination
(ftcd) (lux)
Sunlight 10,000 107,527
Full Daylight 1,000 10,752
Overcast Day 100 1,075
Very Dark Day 10 107
Twilight 1 10.8
Deep Twilight .1 1.08
Full Moon .01 .108
Quarter Moon .001 .0108
Starlight .0001 .0011
Overcast Night .00001 .0001

Solution:  We’re going to have to chalk this one up to, as Matt said, rule zero (a wizard did it).  The sunrod has a magical aura of light that does not reach beyond the twentieth square.  If it were alchemical, the rod would have to shed light itself, rather than an aura of light.  Being a magical aura allows the light to be a static brightness, without a centralized ball of brilliance, meaning we can go at the minimum of 100 lux for the whole area.

In-game word usage would read,

“The burst creates a zone of bright light that lasts until the end of the encounter. When the sunrod moves, the zone moves with it, remaining centered on the sunrod.”

  • Dilemma 3 – 60 lumens is “enough to temporarily blind and disorient a person by impairing his night-adapted vision.”  Bright light (photopic vision) is 100 lux minimum, which is about 1000 lumens.

Solution:  I don’t think there’s anyway around this one.  A creature who relies on sight and currently has “night-adapted vision” would be affected by a sunrod, but to what degree?  If it has an effect beyond just light, how do you keep it from becoming a flashbang grenade (as Ben said).

Well for one, a flashbang grenade sheds 6-8 million candela of light.  One candela source emits 12.6 lumens, so a flashbang is somewhere around 75,600,000 lumens.  A lot more than our 1000 lumen minimum.  This means a sunrod probably wouldn’t stun, or even daze a creature, but it would blind them.  (Save ends) would be too harsh for a cheap item, so I think it should just last a single round.

In-game word usage would read,

“Creatures within darkness who are caught within the burst when the sunrod is activated are blinded until the end of their next turn.”

This keeps creatures safe as long as there is some light around.  The “Alpha Strike” phenomena requires teamwork and rewards the “thinking” motivation for players, so I’m all for it.

  • Dilemma 4 – The sunrod is too cheap.

Solution:  I think the revisions made so far help to rectify the pricing.  That, and the fact that our current science can get us one for $150, makes me think it’s actually fine at 2 gp.

I think that’s it for dilemma’s, so now the sunrod should make sense.  Right?

What do you think?  You can be honest.


About j0nny_5

Mid-thirties and work a full-time job in beautiful northern Colorado. In my free time I play D&D, video games, and walk my two beautiful Bouvier des Flandres.
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5 Responses to The Science of Sunrods (Part 2 – A New Sunrod)

  1. Michael Lee says:

    I’m betting that you do those item cards in Word, as I do, but do you have a template?

    • j0nny_5 says:

      Actually I stumbled across It’s a web based program that’s free and has all sorts of cool 4e tools, including power cards of all types. The only way I found to copy them though, was after you’re done creating it use the toolbox to “print” it. This will render some .png’s of all cards you’ve created in a new tab. Then, just like any image, right click and save it (printing not necessary).

  2. Matt says:

    Everything sounds pretty reasonable to me. On the other hand, if you wanted to avoid both the time and the flashbang dilemmas, I think the easiest way would be to have the light non-motive. Break a sunrod = 6 hours of light in an area (fits the release-of-magic idea too, I think.) Then players can use them for camping, or use them for combat, but you can keep exploring shady and dark. Also, if the light lasts for the full time, they have to decide if they -should- use it in combat. After all, 6 hours is a long time to leave a 20 square “IVE BEEN HERE” footprint.

    Then, if they break them all the time, you can punish them with monsters following their candy trail (sorry, I got a bit distracted/confused after you said”DM’s aren’t mean”…

    • j0nny_5 says:

      Not a bad idea, though the footprint would be 41 squares. As I was making the item, I realized it would be easy to make different “versions” of the sunrod for the different tiers, or for different uses…

  3. Akmenos says:

    My question is that should this qualify for everyone? Those with dark vision may be able to easily adjust on the fly. Those with low light and regular might need a certain amount of adjustment and therefore more susceptible. Also what about length of time in the dark. If I have only been in the dark for six seconds, I’m less likely to be blinded than some one who has been in thirty or more second. I dunno. There is a lot of potential variables.

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