Die sluiterspoed bepaal hoe lank lig die sensor bereik.

Sluiterspoed means shutter speed.

It is a compound noun:

• sluiter = shutter
• spoed = speed

Afrikaans, like Dutch and German, very often writes compound nouns as a single word. So where English has shutter speed, Afrikaans normally has sluiterspoed.

Bepaal means determines.

So:

• Die sluiterspoed bepaal ... = The shutter speed determines ...

It is the present tense form, and in Afrikaans most verbs do not change form depending on the subject:

• ek bepaal
• jy bepaal
• hy bepaal
• ons bepaal

Because this is an embedded clause after bepaal.

The sentence has:

• a main clause: Die sluiterspoed bepaal
• an embedded clause: hoe lank lig die sensor bereik

In Afrikaans, the finite verb often goes to the end of a subordinate or embedded clause. That is why bereik comes last.

So the pattern is:

• hoe lank = how long
• lig = subject
• die sensor = object
• bereik = verb at the end

This is one of the most important word-order differences from English.

The subject is lig.

So in lig die sensor bereik:

• lig = the thing doing the action
• die sensor = the thing receiving the action
• bereik = reaches

So the meaning is light reaches the sensor, not the sensor reaches light.

Because lig here is being used as a general, uncountable noun: light in general.

Afrikaans often leaves out the article with mass nouns or abstract nouns when speaking generally.

So:

• lig = light in general
• die lig = the light, a specific light

In this sentence, the general idea is meant, so lig without die is natural.

It is a noun here, meaning light.

That matters because lig can also be an adjective meaning light as in not heavy.

Here it is definitely the noun, because it is the thing that reaches the sensor.

Bereik means reach here.

So:

• lig die sensor bereik = light reaches the sensor

In other contexts, bereik can also mean things like attain or achieve, but in this sentence it has the physical sense of reach.

It can mean either, depending on context.

Here it means duration, so:

• hoe lank = how long / for how long

Because the sentence is about shutter speed and a camera sensor, it clearly means how long light reaches the sensor, not physical length.

Because sensor is a countable singular noun here, and it refers to a specific sensor: the camera’s sensor.

So:

• die sensor = the sensor
• ’n sensor = a sensor

In this context, die sensor is the natural choice.

Yes. If you wanted to say light sensor as a single compound noun, Afrikaans would normally write it as ligsensor.

That is useful here, because:

• lig die sensor bereik = light reaches the sensor
• ligsensor = light sensor

So in your sentence, lig and sensor are two separate words because they are doing different jobs in the clause, not forming one compound noun.

It is in the present tense.

Afrikaans often uses the present tense for:

• general truths
• scientific facts
• instructions
• explanations

So Die sluiterspoed bepaal ... is a normal way to express a general fact: Shutter speed determines ...

Yes. In this sentence, that is a very good way to understand it.

So:

• hoe lank lig die sensor bereik can be understood as
• for how long light reaches the sensor

Even though Afrikaans uses hoe lank, the English idea for how long is often the clearest match in sentences like this.