Стоит только изменить экспозицию, как кадр выглядит иначе.

Here стоит comes from стоить, not from стоять.

• стоять = to stand
• стоить = to cost / to be worth

In the pattern стоит только + infinitive, it means something like:

• one only has to...
• it takes only...
• as soon as...

So Стоит только изменить экспозицию... means One only has to change the exposure... or As soon as you change the exposure...

It is an idiomatic construction, so it should be learned as a whole.

This is a very common Russian structure.

Стоит только X, как Y means:

• One only has to do X, and Y happens
• As soon as X happens, Y happens
• It takes only X for Y to happen

So in your sentence:

• Стоит только изменить экспозицию, как кадр выглядит иначе.

the idea is:

• Just change the exposure, and the shot looks different.
• As soon as you change the exposure, the frame looks different.

This pattern often expresses a quick or automatic result.

Examples:

• Стоит только начать, как становится легче.
  Once you just start, it becomes easier.

• Стоит только спросить, как он сразу помогает.
  You only have to ask, and he helps immediately.

Because стоит только is followed by the action that is enough to trigger the result.

Here the action is:

• изменить = to change

So:

• стоит только изменить = one only has to change

This is similar to English you only need to change...

Russian often uses the infinitive in impersonal constructions like this.

Изменить is perfective, and that fits the meaning well here.

Compare:

• менять = imperfective, to be changing / to change repeatedly / in general
• изменить = perfective, to change once / to make a change

In this sentence, the point is that a single completed change in exposure causes a visible result. So perfective is natural:

• Стоит только изменить экспозицию...
  You only need to change the exposure once...

If you used менять, it would sound less natural here because the sentence is about the result of making a change, not the process of changing.

Because it is the direct object of изменить.

• изменить что? → экспозицию

The dictionary form is экспозиция.
Its accusative singular form is экспозицию.

This is regular for a feminine noun ending in -ия:

• экспозиция → экспозицию

No. Here как does not mean how.

In this sentence, как is part of the fixed construction:

• стоит только ..., как ...

So it works more like:

• and then
• when suddenly
• and immediately
• as soon as

It introduces the result clause:

• как кадр выглядит иначе
  and the frame looks different

So you should not translate this как literally as how.

Because the sentence has two parts:

1. Стоит только изменить экспозицию
2. как кадр выглядит иначе

The second part is introduced by как in this correlative construction, so Russian writes a comma between the two clauses.

This punctuation is standard in the pattern:

• Стоит только..., как...

Because кадр is the subject of выглядит.

Ask the question:

• Что выглядит иначе?
  What looks different?

Answer:

• кадр

So кадр is nominative singular.

Russian often uses the present tense for general truths, typical results, or what regularly happens.

Here the sentence does not describe one specific past or future event. It describes a general principle:

• if you change the exposure, the shot looks different

So выглядит = looks is perfectly natural.

It is similar to English:

• Change the lighting, and everything looks different.

Even though it refers to a possible action, the result is stated as a general fact.

Иначе means differently / otherwise.

So:

• кадр выглядит иначе = the frame/shot looks different

It emphasizes that the appearance changes.

A close alternative would be по-другому:

• кадр выглядит по-другому

Both are possible, but иначе is shorter and slightly more compact in style.

It depends on context.

Кадр can mean:

• a frame in film or video
• a shot
• sometimes an image or photo frame in a visual/technical context

Because the sentence mentions экспозиция, it sounds like photography, film, or image-making. So English might translate кадр as:

• frame
• shot
• sometimes image

The best choice depends on the context you were given.

Yes. For example:

• Если изменить экспозицию, кадр выглядит иначе.
  If you change the exposure, the frame looks different.

• Стоит изменить экспозицию, и кадр выглядит иначе.
  Change the exposure, and the frame looks different.

But the original:

• Стоит только изменить экспозицию, как кадр выглядит иначе.

has a stronger sense of all it takes is... or the moment you do it...

So the original is a bit more expressive than the simple если version.