На мольберте этот оттенок на холсте кажется темнее, чем на картинке в альбоме.

На мольберте means on the easel.

• на
  • prepositional case is commonly used for location.
• мольберт becomes мольберте in the prepositional singular.
• Putting this phrase first sets the scene: As for the version on the easel...

So the sentence starts by establishing the location before talking about the shade itself.

Yes, but they refer to slightly different things.

• На мольберте = on the easel
  This tells you where the canvas/work is physically placed.
• на холсте = on the canvas
  This tells you where the shade appears.

So the sentence is basically layering locations:

• the canvas is on the easel
• the shade is on the canvas

Russian often allows this kind of stacked location description very naturally.

Because этот оттенок is the grammatical subject of the sentence.

The core structure is:

• этот оттенок = this shade/hue
• кажется темнее = seems darker

So оттенок is in the nominative case, and этот agrees with it:

• masculine
• singular
• nominative

Кажется is the 3rd person singular present tense of казаться, which means to seem or to appear.

So:

• кажется = seems / appears

The -ся is part of the verb’s dictionary form: казаться. In this verb, it is not something you should try to translate literally word-for-word. You can just learn казаться as a complete verb meaning to seem.

In this sentence:

• этот оттенок ... кажется темнее
  = this shade seems darker

Yes. Темнее is the comparative form of тёмный (dark).

So:

• тёмный = dark
• темнее = darker

Russian very often uses this simple comparative form after verbs like казаться:

• кажется темнее = seems darker

This is very natural Russian.

Also note the spelling change:

• тёмный
• темнее

The ё often becomes е in related forms when the stress changes.

Because the simple comparative is shorter and more natural here.

• темнее = darker
• более тёмный = more dark

Russian usually prefers the simple comparative when possible, especially in a sentence like this:

• кажется темнее sounds smooth and idiomatic.

Using более тёмный is possible in some contexts, but here it would sound heavier and less natural.

Чем means than in comparisons.

So:

• темнее, чем ... = darker than ...

In this sentence:

• кажется темнее, чем на картинке в альбоме
• literally: seems darker than on the picture in the album

Russian often leaves out repeated words after чем if they are already obvious. A fuller version would be something like:

• кажется темнее, чем кажется на картинке в альбоме

But repeating кажется would sound unnecessary, so Russian omits it.

This is a very common preposition difference between Russian and English.

In Russian, when talking about what is shown or appears in an image, people often use на:

• на картинке = in/on the picture
• на фотографии = in/on the photograph
• на рисунке = in/on the drawing

Russian treats the image more as a surface. English usually says in the picture, but Russian normally says на картинке.

So this is not something to translate literally word-for-word; it is just the normal Russian pattern.

Because the picture is understood as being inside the album, not on top of it.

• в альбоме = in the album
• на альбоме would mean on the album, for example on its cover or on top of it

So:

• на картинке в альбоме = in the picture that is in the album

That is a good vocabulary question.

• картинка usually means picture, image, illustration
• картина usually means painting or a more formal picture/work of art

In this sentence, картинка в альбоме suggests a reproduced image in an album, not the original painted work. That is why картинка is more natural here than картина.

Yes. Russian word order is flexible, and changing it changes emphasis more than basic meaning.

For example, you could also say:

• Этот оттенок на холсте на мольберте кажется темнее, чем на картинке в альбоме.

That would still be understandable, but the original sentence sounds more natural if you want to begin with the setting:

• На мольберте = on the easel, in the real setup in front of us

So the original word order highlights the real physical object first, then compares it with the album image.

Because Russian has no articles.

English distinguishes between:

• a shade
• the shade

Russian usually does not mark that difference with a separate word. Instead, context does the job.

Here, этот already helps specify the noun:

• этот оттенок = this shade

So there is no need for an article.

It can often be translated as either, depending on the context.

Here:

• кажется темнее could be translated as seems darker
• or more naturally in some English contexts, looks darker

Russian казаться is broader than just visual appearance. It can mean seem in a general sense, but in a sentence about color, English may prefer looks.

So the Russian is perfectly normal, and the best English translation depends on style rather than grammar.