KUNST
SCHÖNHEIT & WELLNESS
HANDWERK
KULTUR & GESCHICHTE
UNTERHALTUNG
UMFELD
ESSEN & GETRÄNKE
REVERSE ENGINEERING
WISSENSCHAFTEN
SPORT
TECHNOLOGIE
WEARABLES
Youblob · CC0
Telephoto Lens
To photograph a distant subject large, you need a long focal length - and a long lens means a long camera. In 1891 Thomas Rudolphus Dallmeyer in London, and Adolf Miethe in Germany, independently put a negative lens behind a positive one. The pair acts like a single lens of much longer focal length, yet it is physically shorter than that focal length. That is what 'telephoto' means, and nearly every long camera lens since uses it.
**No patent number is cited here**: Dallmeyer patented it in Britain, and no US patent for his design was verified, so none is claimed.
**You build one on an optical bench**, measure its focal length from the size of a distant image, and let a ray-trace notebook redesign it.
Anfänger
90 minutes
Anweisungen
1
1
Know your lenses
Know your lenses
Focus a distant window onto paper with each convex lens; the lens-to-paper distance is its focal length. Pick one about 100 mm. Take a concave lens about half that (its label gives it; it will not focus alone).
Materialien für diesen Schritt:
Satz Sammellinsen1 Set
Konkavlinse1 StückBenötigte Werkzeuge:
Stahllineal2
2
Set up the bench
Set up the bench
Mount the convex lens in a holder at one end of the bench, pointing out of a window at something far away. Tape tracing paper to a holder as the screen.
Materialien für diesen Schritt:
Rolle Schnittmuster-Transparentpapier1 Blatt
Malerkrepp1 RolleBenötigte Werkzeuge:
Optische Bank mit Schiene
Linsenhalter-Set3
3
Image with one lens
Image with one lens
Slide the screen until the far scene is sharp. Measure the height of one chosen feature on the screen - a window, a chimney.
Benötigte Werkzeuge:
Stahllineal4
4
Add the negative lens
Add the negative lens
Put the concave lens 60 mm behind the convex one. The image is now far behind; move the screen back until it is sharp again and measure the same feature. Try 55 and 65 mm spacing too.
Benötigte Werkzeuge:
Bandmaß (Rollmeter)5
5
Design it on paper
Design it on paper
Jupyter-Notebook wird geladen …
6
6
History & Context
History & Context
**What the 1891 designs did:** a positive front group and a negative rear group, spaced so the system focal length exceeds its length. **Modern build (derived):** two stock lenses on a bench.
Early telephoto attachments screwed behind ordinary lenses; modern long lenses build the idea in. Its limits: spacing is critical, the negative group adds distortion (pincushion), and the image is dimmer at the same aperture diameter because the focal length grew.
Materialien
4- 1 SetPlatzhalter
- 1 StückPlatzhalter
- Platzhalter
- 1 RollePlatzhalter
Benötigte Werkzeuge
4- Platzhalter
- Optische Bank mit Schiene10% ProvisionPlatzhalter
- Linsenhalter-Set10% ProvisionPlatzhalter
- 1 vendor sell this, none ship to you yetPlatzhalter
Verwandte Blueprints
Diese Blueprints teilen Wissen — Techniken, Materialien oder Prinzipien
CC0 Gemeinfrei
Dieser Blueprint ist unter CC0 veröffentlicht. Sie dürfen dieses Werk für jeden Zweck frei kopieren, ändern, verbreiten und verwenden, ohne um Erlaubnis zu fragen.
Unterstützen Sie den Maker, indem Sie Produkte über seinen Blueprint kaufen, wo er eine Maker-Provision von Anbietern festgelegt, verdient. Oder erstellen Sie eine neue Iteration dieses Blueprints und verbinden Sie ihn in Ihrem eigenen Blueprint, um Einnahmen zu teilen.