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Can I create a lens that will function as a magnifying glass or spyglass with Minor Illusion by using the illusion as a focus to warp or bend light as a lens might?

Alternatively, can Prestidigitation create a spyglass or magnifying glass?

You create a nonmagical trinket or an illusory image that can fit in your hand and that lasts until the end of your next turn.

Thomas Markov
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Sam Lacrumb
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2 Answers2

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Permanently replacing these valuable objects is beyond the capabilities of these spells.

Minor illusion says:

If you create an image of an object--such as a chair, muddy footprints, or a small chest--it must be no larger than a 5-foot cube. The image can't create sound, light, smell, or any other sensory effect.

I'd rule that magnification is an "other sensory effect", so this doesn't work. See this great answer for further details. Further, minor illusion stipulates:

Physical interaction with the image reveals it to be an illusion, because things can pass through it.

It seems to me that because it is an illusion and things pass through it unimpeded, light would pass through the glass unmodified, so it would not function to magnify what you are looking at - magnification requires the light to interact with the medium it passes through, which is not how minor illusion works.

Prestidigitation says:

You create a nonmagical trinket or an illusory image that can fit in your hand and that lasts until the end of your next turn.

A spyglass is not a trinket. It's worth 1000gp. Examples of trinkets can be found on this table in the basic rules. None of these come even close to the value of a spyglass (their values aren't even listed - they aren't worth much at all).

This ruling is further supported by the Sage Advice Compendium when it says:

What kinds of things count as “nonmagical trinkets” for prestidigitation?

Prestidigitation can create a little bauble, the nature of which is up to the spellcaster and the DM. See the Trinkets table in the Player’s Handbook for examples.

That's the closest thing to a RAW answer we have here, and I think it's pretty clear, especially with the explanation from Sage Advice. Further, there's a pretty clear (to me at least) sense in which these spells are not meant to create things of significant value, and magnifying glass and a spyglass are valued at 100 gp and 1000 gp, respectively. Why does this value matter? A cantrip than can be cast at will with no cost serves as a functional permanent replacement for these items if they are allowed to create them.

Thomas Markov
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    I didn't feel the value of the item mattered since the items disapeared quite quickly and were mainly for roll playing. – Sam Lacrumb Jul 25 '20 at 23:03
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    The issue is that an at will cantrip that can produce these item is a functional permanent replacement for having them. I’ll make that clearer in the answer. – Thomas Markov Jul 25 '20 at 23:04
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    Good answer upvoted for the detail in response to what a "trinket" means. However, magnification should not fail because it is a "sensory effect" - how does one sense magnification? Rather, it should fail because "Physical interaction with the image reveals it to be an illusion, because things can pass through it." That is, the real light would pass through the illusory lens unmodified rather than being bent (magnified). This reasoning is used in several of the answers given to the question you link as a "great answer". – Kirt Jul 26 '20 at 08:20
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    To be clear, one senses magnification with the eyes. – Thomas Markov Jul 26 '20 at 08:23
  • @ThomasMarkov One senses anything visual with the eyes-- by this reasoning, Minor Illusion can't create anything visible (or perceptible in any way). I think that the answer overall is correct, but that reasoning seems thin. – Upper_Case Jul 26 '20 at 23:42
  • @Upper_Case I’ve been think a lot today about how to best nail down the details on this one. Still working on it, Kirt’s insight helps. I’ll keep working to improve this one. – Thomas Markov Jul 26 '20 at 23:44
  • @Thomas Markov (&Upper_Case). It's difficult to parse the magicscience in terms of the image not creating the sensory effect of light. I think the image cannot produce light independent of the image itself (you could make a minor illusion of a torch, but it would not illuminate a room). However, I still don't think you 'sense magnification with your eyes'. Rather, looking at an image you can sense with your eyes, the pattern recognition parts of your brain deduce that the shapes represented imply that the image has been magnified compared to how similar images have appeared in the past. – Kirt Jul 27 '20 at 00:41
  • (con't) But you are not directly sensing the magnification. You cannot present someone with a photo at 100x and another at 500x and have them "feel" the greater magnification. Likewise, the illusion cannot actually bend the rays of light in the way that would actually produce magnification. – Kirt Jul 27 '20 at 00:46
  • @Kirt Thanks, I finally got around to adding in your suggested improvements nearly two years later. – Thomas Markov Feb 11 '22 at 13:02
  • I think without counter-evidence, this would be a great answer, but the other answer cites the explicit and specific mentioning of a spyglass and a lens in trinket tables. So assuming the principle that specific and explicit beats general, I'll grudingly -1 this. One question could be if a spyglass is a trinket that fits into a hand. It might be too large for this, if it is not a mini-spyglass – Nobody the Hobgoblin Feb 12 '22 at 06:59
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Yes. Both of these items are listed on lists of Trinkets, with drawbacks attached.

One of the Gothic Trinkets listed in Curse of Strahd is the following:

A spyglass that always shows the world suffering a terrible storm

Thus, using Prestidigitation to create a spyglass should be possible, but it'll always show the view of an area being battered by a terrible storm, regardless of the actual weather.

Similarly, Mordencainen's Tome of Foes lists the following as an Elven Trinket:

A crystal lens made of ivory and gold that causes anything observed through it to appear to be surrounded by motes of multicolored light

Thus, it should be possible to use Prestidigitation to create a magnifying glass, as long as it causes all objects or creatures observed by it to be surrounded with motes of multicoloured light.

nick012000
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