<p>Part of the confusion stems from the words used.  "higher" resolution doesn't mean better, it means only bigger objects can be resolved; but we want to be able to resolve small objects, such as the angular distance between a pair of double stars.  So small is better in this situation.</p>

CC BY-SA 4.0
2018-05-23T20:46:17.733Z
"Higher resolution" usually *does* mean better. (If you want a plausible way to think about it, "higher" resolution means you can resolve *higher spatial frequencies*, which means smaller angular sizes.)
Peter Erwin
CC BY-SA 4.0
2018-05-23T21:49:42.273Z
Peter Erwin:  well I think that given how the word is commonly used, it’s not a surprise that the OP found the use of “higher” in this context confusing.
Dr Chuck
CC BY-SA 4.0
2018-05-23T12:31:51.303Z
2018-05-23T12:31:51.303Z
Dr Chuck
<p>The angular resolution only tells you your ability to distinguish ("resolve") two separate points of light. For example, your ability to distinguish the two distinct headlamps on a car from being a single light in the distance. </p>

<p>The angular <em>magnification</em> has nothing to do with the angular resolution: it is determined by the focal lengths of your primary and objective, and the eyepiece if applicable. </p>

CC BY-SA 4.0
2018-05-23T02:34:23.617Z
2018-05-23T02:34:23.617Z
zh1
<p>Your formula is correct. In the absence of instrumental effects or blurring of the atmosphere, it gives (approximately) the minimum <em>angular separation</em> between two objects that can be resolved. The larger this is, the <em>worse</em> your telescope is. You want the resolution to be <em>small</em>.</p>

CC BY-SA 4.0
2018-05-23T06:12:06.777Z
2018-05-23T19:30:34.180Z
2018-05-23T19:30:34.180Z
ProfRob
<p>The angular resolution of a telescope is given by $\frac{1.22\lambda}{D}$.</p>

<p>This should mean that the smaller the aperture D, the higher the angular resolution. But it is exactly the opposite - why?</p>

<telescope><fundamental-astronomy><telescope-lens>
Relation between angular resolution and aperture?
Ekansh Agarwal
# Relation between angular resolution and aperture?

(Asked by: username_0 on 2018-05-23)

The angular resolution of a telescope is given by $\frac{1.22\lambda}{D}$.

This should mean that the smaller the aperture D, the higher the angular resolution. But it is exactly the opposite - why?

**Tags:** telescope, fundamental-astronomy, telescope-lens


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## 3 answers

### Answer by username_1 on 2018-05-23. Score: 2 | Accepted answer

Part of the confusion stems from the words used. "higher" resolution doesn't mean better, it means only bigger objects can be resolved; but we want to be able to resolve small objects, such as the angular distance between a pair of double stars. So small is better in this situation.

> **Comments:**
> **username_2**: "Higher resolution" usually *does* mean better. (If you want a plausible way to think about it, "higher" resolution means you can resolve *higher spatial frequencies*, which means smaller angular sizes.)  
> **username_1**: username_2:  well I think that given how the word is commonly used, it’s not a surprise that the OP found the use of “higher” in this context confusing.  

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### Answer by username_3 on 2018-05-23. Score: 6

The angular resolution only tells you your ability to distinguish ("resolve") two separate points of light. For example, your ability to distinguish the two distinct headlamps on a car from being a single light in the distance.

The angular *magnification* has nothing to do with the angular resolution: it is determined by the focal lengths of your primary and objective, and the eyepiece if applicable.


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### Answer by username_4 on 2018-05-23. Score: 6

Your formula is correct. In the absence of instrumental effects or blurring of the atmosphere, it gives (approximately) the minimum *angular separation* between two objects that can be resolved. The larger this is, the *worse* your telescope is. You want the resolution to be *small*.


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