[kyoto kid]

...so if a character already has natural low light vision, are they one step better against darkness modifiers if they also have the Tetrachromatic Vision Gene mod or does his/her low light vision cancel that out?

[Marcus Gideon]

They're essentially the same thing, although Tetrachrome is worse...

Core pg 175, Environmental Compensation chart

Low-Light Vision = Treat Partial Light (-1) and Dim Light (-3) as Full Light (-0)

Chrome Flesh pg 162, Tetrachromancy

Tetrachromancy lets you treat Partial Light (-1) conditions as Full Light (-0) and grants +3 dice pool modifier to visual Perception tests.

So it's kind of a toss-up. Low-Light lets you see better in Partial or Dim, while Tetra only works in Partial. But Tetra also gives you +3 to Perception, which Low-Light does not.

Be aware, Genetech does look to be in the same boat as Cybertech. Where the Core book warns people with inherent abilities from getting replacements that may end up taking those abilities away... such as natural born Low-Light and then getting Cyber-Eyes that do not. In this case, Chrome Flesh pg 155 talks about Man vs Nature, and how Genetech is altering your body in somewhat radical ways. Since it takes 2 weeks of treatment to apply and hits you for 0.1 Essence, I would say that getting Tetra done will end up replacing your Low-Light. Your eyes used to have certain rods and cones that let you see in a certain way. But now the gene therapy has made them grow into something totally different.

[Novocrane]

I'd disagree with Marcus on whether it replaces natural enhancements, though it's really going to be up to each GM. Tetrachromacy stacks with Hawkeye by strict RAW, though.

Thermographic Vision: Visibility and Light conditions shift one row up

This combined with Tetrachromacy, on the other hand, would be slightly better than LLV.

[Medicineman]

I tend to disagree with Marcus too
What You see is what you get  is a default line in SR5 (ImO)
Only when CGL explicetily writes  that one Item replaces some other (like here that Tetrachromatic Vision would replace LLV) than you loose the later. Only then ! (ImO)

with a Lost Dance
Medicineman

[kyoto kid]

...so basically it would not improve one's vision beyond hiss/her natural LLV, though it would still grant the Bonus to perception. 

[Marcus Gideon]

Like Novocrane said, it's going to depend on the GM at the table. Or once we get errata (there's always errata).

If you have Low-Light and Thermo on your Eyeware, you can't run both at the same time. You have to pick one or the other and go with it.

This is getting multiple forms of vision implanted... no, not even implanted. This is genetically altering your eye so that it naturally perceives light in some form or fashion. So it's not something you really get to switch off like an implant would.

If the GM lets you stack Low-Light with Tetra, then the only benefit is +3 Perception. Both already give you help in Partial Light, and Low-Light gives you help in Dim Light as well. Neither one says "move up 1 category" like Novocrane pointed out Thermo does. So there's no reason (in my mind at least) to think that adding some light sensitivity to some more light sensitivity is going to let you see in the complete absence of light. Since it goes Partial, Dim, Total Darkness. There's no light, which is why you can't see.

[Whiskeyjack]

If you have Low-Light and Thermo on your Eyeware, you can't run both at the same time. You have to pick one or the other and go with it.

Was this actually said somewhere in a book?

[adzling]

I'm not sure how you would run both lo-light and thermo at the same time...I mean how could that be possible (they would block each other out)?

We play you have to use a free action to shift back and forth.

[Hobbes]

I'm not sure how you would run both lo-light and thermo at the same time...I mean how could that be possible (they would block each other out)?

We play you have to use a free action to shift back and forth.

Run separate sensor feeds in a separate AR (or projected) windows.  Enough justification for a perception check anyway.  Multiple sensors incur the distracted penalty for AR at GMs discretion.

So, seeing through low light, but a small Thermo window in your peripheral vision that'll show heat signatures. 

[Marcus Gideon]

We're having this exact same convo in another thread

The point is, from both a fluff perspective, and from a game mechanic perspective, it's best if they don't stack.

Low-Light is amplifying ambient light. Which is why it says it brings Dim (-3) or Partial (-1) all the way up to Full (-0). However, it would be useless in Total Darkness (-6) b/c there is zero light to amplify.

Thermo is imaging based off near infrared, and even works in Total Darkness, but it only moves you up 1 category.

If you allow them to stack, players are going to toss both into their Eyeware. Then when you hit them with Total Darkness situations, they'll say the Thermo moves it up from Total Darkness to Dim Light, and then Low-Light takes over and moves it the rest of the way to Full Light. Suddenly the room has gone from zero light whatsoever, to looking like daytime. Even though there isn't actually any light for Low-Light to amplify, from a purely game mechanics perspective it fits. Move up 1 category, at which point you qualify to move the rest of the way up the chart for free.

As for shifting... technically it would be a Change Device Mode action. Which is a Free Action if you're using DNI and wireless, or a Simple Action if you are not.

[PJ]

Although RAW do not say they cannot combine, the wording for Low Light is distinct from Thermographic.

Thermographic makes mention of shifting up a category; Low Light says something like 'treat Dim and Partial as Full.'  Nitpicky, but the difference in wording lends support to not stacking the two (as technically, Full Darkness shifted up one is still not a Partial Light condition).

Also, Tetrachromatic says it adds a fourth cone, so I don't see why you'd lose Low Light (or any other natural) vision.  You're not replacing the eyes, just adding a set of cones.

This is why I love this game; plenty of room in the rules for interpretation multiple ways.

[Marcus Gideon]

Although RAW do not say they cannot combine, the wording for Low Light is distinct from Thermographic.

Thermographic makes mention of shifting up a category; Low Light says something like 'treat Dim and Partial as Full.'  Nitpicky, but the difference in wording lends support to not stacking the two (as technically, Full Darkness shifted up one is still not a Partial Light condition).

Also, Tetrachromatic says it adds a fourth cone, so I don't see why you'd lose Low Light (or any other natural) vision.  You're not replacing the eyes, just adding a set of cones.

This is why I love this game; plenty of room in the rules for interpretation multiple ways.

It's referring to the Environmental Modifiers chart on Core pg 175.

Light / Glare
Full Light (-0)
Partial Light (-1)
Dim Light (-3)
Total Darkness (-6)

If you plunge the character into a room of Total Darkness, and they click on their Thermo, it will move them up the chart 1 category, into Dim Light.
Then they click on their Low-Light, which says that it automatically moves Dim or Partial all the way up to Full.

Which means, despite the setting for the scene not having any light whatsoever, the game mechanics of it say that stacking the two leads to 0 penalties.

[Herr Brackhaus]

How does enhancing ambient light have any effect on thermographic vision, or vice versa?

At my table, no stacking allowed. I feel relatively confident that that is what the rules intend. YMMV, so ask your GM because the books won't tell you one way or another.

[gradivus]

How does enhancing ambient light have any effect on thermographic vision, or vice versa?

At my table, no stacking allowed. I feel relatively confident that that is what the rules intend. YMMV, so ask your GM because the books won't tell you one way or another.

I could be wrong but I think Marcus point is that if you allow stacking then there is no point to lighting penalties, ergo, they should not stack.

At least that's how I read what he wrote.

Of course, I'm no expert at what people intended when they say/write something. If I was, I might still be married.

[Marcus Gideon]

I just wish people would clarify whether they're responding to the overall question, or the last post before them. That way I know whether they're trying to contribute to the convo, or argue with me (for instance).

For my input... the question of whether Thermo and Low-Light should stack, comes down to whether you look at it from a cinematic storyline perspective, or from a purely game mechanic RAW perspective.

Storywise, Thermo doesn't use ambient light. Which is why it still functions in Total Darkness. But it only moves you up the chart 1 category, which means you'd still have a -3 to everything unless you have a Thermo flashlight handy. Low-Light would not function at all in those conditions b/c there is no ambient light whatsoever for it to amplify. Which means it's effects would not stack.

Game mechanics wise, Thermo's RAW effect raises the penalty 1 category, which brings it to Dim Light category. From there, Low-Light's RAW effect raises Dim or Partial all the way up to Full, which means no penalties. So from a purely game mechanics perspective, ignoring the scene or any of the roleplay aspects and just staring at a character sheet and dice... if you allow them to stack then you make the Total Darkness scene irrelevant. The two effects cancel out the initial -6 penalty, and your characters are free to act unhindered.