סימן קנ סעיף ג
אָסוּר לְשַׁמֵּשׁ לְאוֹר הַנֵּר, אַף עַל פִּי שֶמַּאֲפִיל בְּטַלִּיתוֹ. אֲבָל אִם עוֹשֶׂה מְחִצָה גְבוֹהָה עֲשָׂרָה טְפָחִים לִפְנֵי הַנֵּר, מֻתָּר (וְעַיֵּן לְעֵיל סִימָן פ סָעִיף עו). וְכֵן אָסוּר לְשַׁמֵּשׁ בַּיּוֹם, אֶלָּא בְּבַיִת אָפֵל. וּבַלַּיְלָה, אִם הַלְּבָנָה מְאִירָה עֲלֵיהֶם, אַף עַל פִּי שֶׁמְּאִירָה לְתוֹךְ הַבָּיִת, מַאֲפִיל בְּטַלִּיתוֹ, וּמֻתָּר. וְכֵן אִם יֵשׁ נֵר בְּחֶדֶר אַחֵר, וּמֵאִיר לְחֶדֶר זֶה, צָרִיךְ הַאֲפָלַת טַלִּית.
The marital act is forbidden in a lighted room, even if the light is dimmed with a garment. But if you make a partition ten tefachim high6See glossary. The partition must also be secured at the bottom to the extent it would not blow to and fro in a usual outdoor wind. (Magein Avraham, Mishnah Berurah 240:40). If the partition completely covers the source of the light, it does not have to be ten tefachim high, but our case refers to where the candle or bulb is visible above the partition. The partition merely creates a separate domain and thus marital relations are permitted, providing the light is dimmed with a garment. (Magein Avraham, Mishnah Berurah 325:10). However, if the light source is in another room, everyone permits it if the light is dimmed with a garment. See Sh’ar Hatziyun 240:24–26. in front of the light, it is permissible. Marital relations are also forbidden by day unless the room is darkened. At night, if the moon is shining directly on you it is forbidden. However if it is not shining [directly] on you, even though it is shining into the room, you may shut out its light with a garment [or window shade], and it is then permitted. Also, if there is a light in another room and it shines into this room, you must shut out this light with a garment.
תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)