der Finder
finder
A person who discovers something by chance, especially something that has been lost.
Der ehrliche Finder gab die gefundene Brieftasche im Fundbüro ab.
The honest finder handed in the found wallet at the lost property office.

finder / viewfinder
Loading your saved state.
finder
A person who discovers something by chance, especially something that has been lost.
Der ehrliche Finder gab die gefundene Brieftasche im Fundbüro ab.
The honest finder handed in the found wallet at the lost property office.

The word 'Finder' (finder) is derived directly from the verb 'finden' (to find). The ending '-er' forms, as with many German verbs, the masculine person who performs the action.
Wer etwas findet, ist der Finder.
Whoever finds something is the finder.
The combination 'der ehrliche Finder' (the honest finder) is very common and describes a person who returns a found object. Legally, the finder often has a claim to a 'Finderlohn' (finder's reward).
Der ehrliche Finder brachte das Portemonnaie zur Polizei.
The honest finder took the wallet to the police.
The meaning 'Sucher' (viewfinder) is used exclusively in the context of cameras and photography. Words such as 'Kamera' (camera), 'Objektiv' (lens), or 'Bildausschnitt' (image frame) in the sentence make it clear that this technical part is meant.
Bei meiner alten Kamera muss ich durch den optischen Finder schauen, um das Motiv zu sehen.
With my old camera, I have to look through the optical viewfinder to see the subject.
loser
'der Verlierer' and 'der Finder' both name people according to an outcome. 'Der Verlierer' is someone who does not win in a game, fight, or competition. 'Der Finder' is someone who discovers something, especially something lost. The contrast lies mainly in the idea of losing and finding: with 'Verlierer', the focus is on a negative outcome; with 'Finder', on a successful find. But importantly: in a competition, the direct opposite of 'Verlierer' is normally 'Gewinner', not 'Finder'.

Der Finder der Geldbörse gab sie im Bürgerbüro ab.
The finder of the wallet handed it in at the citizens' office.
Nach dem Finale gratulierte der Verlierer dem Sieger fair.
After the final, the loser fairly congratulated the winner.