Portrettet blir skarpere dersom brennvidden og lukkertiden er riktige.

Because portrettet is the definite singular form of et portrett (a portrait).

• et portrett = a portrait
• portrettet = the portrait

Norwegian usually adds the definite article as a suffix to the noun, instead of using a separate word like the in English.

Since portrett is a neuter noun, the definite ending is -et.

Blir is the present tense of bli, which often means become, get, or turn.

So Portrettet blir skarpere means something like:

• The portrait becomes sharper
• The portrait gets sharper

If you used er, it would describe a state: the portrait is sharper.
With blir, the sentence emphasizes a change or result.

Skarpere is the comparative form of skarp (sharp).

• skarp = sharp
• skarpere = sharper
• skarpest = sharpest

This is similar to English adjectives like sharp → sharper.

In this sentence, skarpere is used because the portrait is being compared to a less sharp version of itself.

Dersom means if.

It is very close in meaning to hvis, which is also very common and often more everyday in tone.

So these are both possible:

• Portrettet blir skarpere dersom ...
• Portrettet blir skarpere hvis ...

Dersom can sound a little more formal or written, but in many contexts they are interchangeable.

Because they are definite singular forms of common-gender nouns.

• en brennvidde = a focal length

• brennvidden = the focal length

• en lukkertid = a shutter speed / exposure time
• lukkertiden = the shutter speed / exposure time

For many common-gender nouns, the definite ending is -en.

So again, Norwegian usually builds the onto the end of the noun.

Because Norwegian normally marks definiteness with a suffix on the noun itself.

English:

• the portrait
• the focal length
• the shutter speed

Norwegian:

• portrettet
• brennvidden
• lukkertiden

So the noun ending already includes the meaning of the.

Because the adjective agrees with a plural subject.

Here the subject is:

• brennvidden og lukkertiden = the focal length and the shutter speed

Two things joined by og (and) count as plural, so the adjective must be plural too:

• singular: er riktig
• plural: er riktige

Compare:

• Brennvidden er riktig. = The focal length is correct.
• Brennvidden og lukkertiden er riktige. = The focal length and the shutter speed are correct.

Here riktige means correct or appropriate.

In technical contexts, riktig often means that something has the correct setting, value, or choice.

So er riktige here means that the focal length and shutter speed are set correctly / are the right ones.

It does not mean right in the sense of not left.

In Norwegian, the verb-second rule applies to main clauses, but not in the same way to subordinate clauses.

The clause after dersom is a subordinate clause:

• dersom brennvidden og lukkertiden er riktige

In subordinate clauses, the order is typically:

subordinating word + subject + verb

So this is correct:

• dersom brennvidden og lukkertiden er riktige

A main clause, on the other hand, follows the verb-second pattern:

• Portrettet blir skarpere

Yes. Norwegian can put the conditional clause first:

• Dersom brennvidden og lukkertiden er riktige, blir portrettet skarpere.

This is also completely correct.

When a subordinate clause comes first, the main clause still follows Norwegian word order rules, so you get:

• ..., blir portrettet skarpere not
• ..., portrettet blir skarpere

That inversion is very important in Norwegian main clauses after a fronted element.

They are compound nouns, which are very common in Norwegian.

• brennvidde

  • related to brenne / brenn-
  • vidde = width/extent
    In practice, this noun means focal length.

• lukkertid

  • lukker = shutter
  • tid = time
    So it literally means something like shutter time, i.e. shutter speed/exposure time.

Norwegian often forms technical vocabulary by joining smaller words together into one noun.

Yes. Portrettet is singular.

The sentence says that one portrait becomes sharper if two settings are correct.

So the structure is:

• main subject: Portrettet = the portrait
• condition: brennvidden og lukkertiden = the focal length and the shutter speed

The fact that the condition contains two nouns does not change the number of portrettet.

Yes, slightly.

Two things make it sound a bit more formal or technical:

1. dersom instead of the more everyday hvis
2. technical camera vocabulary like brennvidden and lukkertiden

A more everyday version might be:

• Portrettet blir skarpere hvis brennvidden og lukkertiden er riktige.

The meaning is basically the same, but the style is a little less formal.