<p>The focal reducer doesn't do that. In order to build an apochromatic refractor , that has minimal chromatic aberration, you need an objective lens assembly composed of 3 lenses. In order to reduce the spherical aberration and have a flat field, you need an additional lens element called field flattener. Hope this helps a bit</p>

CC BY-SA 4.0
2021-12-29T20:15:25.080Z
2021-12-29T20:15:25.080Z
Adrian
<p>I am using 75/1000 Plano convex lens to build telescope. Can I use an achromatic focal reducer to reduce chromatic aberration?</p>

<observational-astronomy><telescope><amateur-observing><telescope-lens><refractor-telescope>
Can I use an achromatic focal reducer to reduce chromatic aberration?
Girish Wadkar
# Can I use an achromatic focal reducer to reduce chromatic aberration?

(Asked by: username_0 on 2021-12-29)

I am using 75/1000 Plano convex lens to build telescope. Can I use an achromatic focal reducer to reduce chromatic aberration?

**Tags:** observational-astronomy, telescope, amateur-observing, telescope-lens, refractor-telescope

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## 1 answers

### Answer by username_1 on 2021-12-29. Score: 1 | Accepted answer

The focal reducer doesn't do that. In order to build an apochromatic refractor , that has minimal chromatic aberration, you need an objective lens assembly composed of 3 lenses. In order to reduce the spherical aberration and have a flat field, you need an additional lens element called field flattener. Hope this helps a bit


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