---
title: "Thumbnails, and why some accounts show plain icons"
url: https://storagestudio.us/wiki/thumbnails-in-finder
category: "The Finder location"
tags: ["finder", "cloud accounts", "thumbnails"]
summary: "The Storage Studio location shows picture, video and document thumbnails on accounts where reading a little of a file costs nothing. On storage that charges for each request it shows plain icons, so browsing never runs up a bill."
updated: 2026-10-01T05:37:33.000Z
---

# Thumbnails, and why some accounts show plain icons

The Storage Studio location shows picture, video and document thumbnails on accounts where reading a little of a file costs nothing. On storage that charges for each request it shows plain icons, so browsing never runs up a bill.

When you browse the [Storage Studio location](https://storagestudio.us/wiki/the-storage-studio-location-in-finder), Finder can show small previews of your photos, videos and documents, just like it does for files on your Mac. Storage Studio draws them by reading only a small part of each file, and only for the files Finder is about to show. On storage that charges you for every request, it shows plain icons instead, so browsing a folder never costs you money.

## Which accounts show thumbnails

| Thumbnails | Plain icons |
| --- | --- |
| Google Drive, Dropbox, OneDrive and Box | S3-compatible storage |
| iCloud Drive, and the Photos folder of an extra Apple ID | Any storage that charges for each request |
| SFTP and FTP servers, and paired devices | Any account type Storage Studio doesn't recognise |
| The **Home** folder on your external drive | |

The rule is simple: thumbnails are drawn only where reading part of a file is free. Anything else gets plain icons, even if that means fewer pictures. Plain icons don't affect your files in any way; open a file and it downloads and opens as usual.

## What gets a thumbnail

- **Photos and pictures**, including common camera raw formats. Most cameras and phones store a small preview near the start of the file, and Storage Studio reads just that part. A small picture with no built-in preview is read whole.
- **Videos** from phones and cameras. Storage Studio reads only the start and the end of the file, which is enough for the first frame, instead of downloading the whole video.
- **Documents**, such as PDFs, Word, Excel and PowerPoint files, Pages, Numbers and Keynote files, text and web pages. Small ones are read whole; for a large PDF only the parts needed for the first page are read. If that isn't enough, the plain icon stays.

```mermaid
%% caption: How Storage Studio decides whether to draw a thumbnail
flowchart TD
  A[Finder is about to show a file] --> B{Is the account free to read from?}
  B -->|No| P[Plain icon]
  B -->|Yes| C{Picture, video or document?}
  C -->|No| P
  C -->|Yes| D[Read only the small part needed]
  D --> E{Could a preview be drawn?}
  E -->|Yes| T[Thumbnail]
  E -->|No| P
```

*Flowchart — How Storage Studio decides whether to draw a thumbnail. Outline:*

- Finder is about to show a file
  - leads to Is the account free to read from?
- Is the account free to read from?
  - No: leads to Plain icon
  - Yes: leads to Picture, video or document?
- Picture, video or document?
  - No: leads to Plain icon
  - Yes: leads to Read only the small part needed
- Read only the small part needed
  - leads to Could a preview be drawn?
- Could a preview be drawn?
  - Yes: leads to Thumbnail
  - No: leads to Plain icon

## Gentle by design

- Thumbnails are made only for files on screen. Scroll, and the next ones are fetched as they come into view.
- Only a few are fetched at a time, to stay light on your Mac and on the account.
- Any temporary file used to draw a thumbnail is deleted straight away. Drawing a thumbnail doesn't leave a downloaded copy of the file on your Mac.

## Why not just show everything?

Some storage, including S3-compatible services, charges for every request, however small. Scrolling once through a folder of photos would mean a billed request for every icon. Storage Studio would rather show a plain icon than run up a bill you didn't ask for.

See also: [Large folders appear a page at a time](https://storagestudio.us/wiki/large-folders-in-finder) · [S3-compatible storage](https://storagestudio.us/wiki/s3-compatible-storage) · [Cloud accounts](https://storagestudio.us/wiki/cloud-accounts)

- **Can I see all my cloud accounts in Finder on a Mac?** Yes. Storage Studio adds a "Storage Studio" location to Finder's sidebar, with each connected cloud account and paired device as a folder inside, and a Finder button in the app's main window opens it. Files stay in the cloud until you open them. Folders you have visited open straight away and… (https://storagestudio.us/faq)
- **Will opening cloud files in Finder fill up my Mac?** No. Only files you actually open are downloaded, and you choose how long they stay on your Mac once you stop using them — from not at all up to a week, 24 hours by default (and longer when the drive keeps its copies on your external drive). After that they go back to being online-only and the… (https://storagestudio.us/faq)
- **Is a locked Delta Drive folder the same as Finder's Locked checkbox?** No. Finder's own Locked checkbox (in Get Info) only stops a file being changed or deleted by accident, and anyone using your Mac can untick it — it doesn't keep anyone out. A locked Delta Drive folder does: it opens only in Storage Studio on your Mac, with your 6-digit PIN and a one-time code we… (https://storagestudio.us/faq)

## What links here

- [Large folders appear a page at a time](https://storagestudio.us/wiki/large-folders-in-finder)
- [The Storage Studio location in Finder](https://storagestudio.us/wiki/the-storage-studio-location-in-finder)