Το κλείστρο αλλάζει φωτογραφική έκθεση· το διάφραγμα αλλάζει φωτεινότητα.

Το is the neuter singular definite article, so it means the.

It appears twice because Greek normally uses the article separately with each noun:

• το κλείστρο
• το διάφραγμα

So the structure is basically:

• the shutter changes...
• the aperture changes...

Also, Το is capitalized here only because it is the first word of the sentence.

Because both subjects are third person singular:

• το κλείστρο = singular
• το διάφραγμα = singular

So the verb stays in the same form each time: αλλάζει.

This is the present tense form of αλλάζω. The ending -ει here corresponds to he/she/it changes.

So:

• το κλείστρο αλλάζει = the shutter changes
• το διάφραγμα αλλάζει = the aperture changes

Because φωτογραφική is an adjective modifying έκθεση, and in Greek adjectives must agree with the noun they describe in:

• gender
• number
• case

έκθεση is feminine singular, so the adjective must also be feminine singular:

• masculine: φωτογραφικός
• feminine: φωτογραφική
• neuter: φωτογραφικό

So φωτογραφική έκθεση is the correct matching form.

Greek often leaves out the article when speaking about something in a general or non-specific way, especially after verbs.

Here the sentence is talking about exposure and brightness as general concepts, not about one particular exposure or one particular brightness. So bare nouns sound natural:

• αλλάζει φωτογραφική έκθεση
• αλλάζει φωτεινότητα

If you added articles, the meaning would usually become more specific or more context-dependent.

In this sentence:

• το κλείστρο = nominative, because it is the subject
• το διάφραγμα = nominative, because it is the subject
• φωτογραφική έκθεση = accusative, because it is the direct object
• φωτεινότητα = accusative, because it is the direct object

A thing that can confuse learners is that some Greek forms look the same in nominative and accusative, especially when there is no article. So you often identify the role from the sentence structure and meaning.

Yes. They are both neuter singular nouns.

Greek has more than one common neuter ending. For example:

• κλείστρο ends in -ο
• διάφραγμα ends in -μα

Both are still neuter, which is why they both take το.

This is very common in Greek: gender is not determined by just one ending pattern.

The sentence uses a very straightforward subject–verb–object order:

• Το κλείστρο / αλλάζει / φωτογραφική έκθεση
• το διάφραγμα / αλλάζει / φωτεινότητα

That is the most neutral order for a statement like this.

But Greek word order is more flexible than English. You can move things around for emphasis, contrast, or style. The original version sounds like a neutral explanatory sentence, which is why it is very suitable for technical or educational writing.

That mark is the Greek ano teleia, often printed as a raised dot: ·.

In modern Greek, it works as a pause stronger than a comma. In many contexts, it is similar to an English semicolon or sometimes a colon.

Here it separates two closely related clauses:

• first clause: Το κλείστρο αλλάζει φωτογραφική έκθεση
• second clause: το διάφραγμα αλλάζει φωτεινότητα

So it is showing a neat parallel between the two statements.

The accent mark shows which syllable is stressed when you say the word.

For example:

• κλείστρο → stress on κλεί-
• αλλάζει → stress on -λά-
• διάφραγμα → stress on διά-
• έκθεση → stress on έκ-
• φωτεινότητα → stress on -νό-

In Modern Greek, this is a stress accent, not a special tone or pitch accent.

Also notice that το has no accent mark. Monosyllabic words usually do not take one.

Two very common Greek vowel combinations appear here:

• ει is pronounced like ee in see
• αι is pronounced like e in met

Examples from the sentence:

• κλείστρο → ει sounds like ee
• αλλάζει → αι sounds like e

So αλλάζει is pronounced roughly a-LA-zee, not with an English ai sound like in rain.

Yes. In many contexts, the Greek present tense can cover both:

• a general truth / habitual meaning → changes
• an ongoing action → is changing

In this sentence, the meaning is best understood as a general statement:

• the shutter changes photographic exposure
• the aperture changes brightness

So English usually translates it with the simple present. But grammatically, Greek αλλάζει does not force the same distinction that English often does.