diff --git a/python/desc/imsim/atmPSF.py b/python/desc/imsim/atmPSF.py
index 03334a2f..e28c999c 100644
--- a/python/desc/imsim/atmPSF.py
+++ b/python/desc/imsim/atmPSF.py
@@ -46,11 +46,13 @@ class AtmosphericPSF(PSFbase):
     @param exptime      Exposure time in seconds.  default: 30.
     @param kcrit        Critical Fourier mode at which to split first and second kicks
                         in units of (1/r0).  default: 0.2
+    @param screen_size  Size of the phase screens in meters.  default: 819.2
+    @param screen_scale Size of phase screen "pixels" in meters.  default: 0.1
     @param doOpt        Add in optical phase screens?  default: True
     @param logger       Optional logger.  default: None
     """
     def __init__(self, airmass, rawSeeing, band, rng, t0=0.0, exptime=30.0, kcrit=0.2,
-                 doOpt=True, logger=None):
+                 screen_size=819.2, screen_scale=0.1, doOpt=True, logger=None):
         self.airmass = airmass
         self.rawSeeing = rawSeeing
 
@@ -62,6 +64,8 @@ def __init__(self, airmass, rawSeeing, band, rng, t0=0.0, exptime=30.0, kcrit=0.
         self.rng = rng
         self.t0 = t0
         self.exptime = exptime
+        self.screen_size = screen_size
+        self.screen_scale = screen_scale
         self.logger = logger
 
         self.atm = galsim.Atmosphere(**self._getAtmKwargs())
@@ -139,7 +143,7 @@ def _getAtmKwargs(self):
 
         return dict(r0_500=r0_500, L0=L0, speed=speeds, direction=directions,
                     altitude=altitudes, r0_weights=weights, rng=self.rng,
-                    screen_size=819.2, screen_scale=0.1)
+                    screen_size=self.screen_size, screen_scale=self.screen_scale)
 
     def _getPSF(self, xPupil=None, yPupil=None, gsparams=None):
         """
diff --git a/python/desc/imsim/imSim.py b/python/desc/imsim/imSim.py
index 3bbe69cd..0764b026 100644
--- a/python/desc/imsim/imSim.py
+++ b/python/desc/imsim/imSim.py
@@ -859,7 +859,7 @@ def FWHMgeom(rawSeeing, band, altitude):
     return 0.822*FWHMeff(rawSeeing, band, altitude) + 0.052
 
 
-def make_psf(psf_name, obs_md, log_level='WARN', rng=None):
+def make_psf(psf_name, obs_md, log_level='WARN', rng=None, **kwds):
     """
     Make the requested PSF object.
 
@@ -875,6 +875,9 @@ def make_psf(psf_name, obs_md, log_level='WARN', rng=None):
         Logging level ('DEBUG', 'INFO', 'WARN', 'ERROR', 'CRITICAL').
     rng: galsim.BaseDeviate
         Instance of the galsim.baseDeviate random number generator.
+    **kwds: **dict
+        Additional keyword arguments to pass to the AtmosphericPSF,
+        i.e., screen_size(=819.2) and screen_scale(=0.1).
 
     Returns
     -------
@@ -901,7 +904,7 @@ def make_psf(psf_name, obs_md, log_level='WARN', rng=None):
                              rawSeeing=rawSeeing,
                              band=obs_md.bandpass,
                              rng=rng,
-                             logger=logger)
+                             logger=logger, **kwds)
     return psf
 
 def save_psf(psf, outfile):
diff --git a/tests/test_psf.py b/tests/test_psf.py
index 6e013029..bf638357 100644
--- a/tests/test_psf.py
+++ b/tests/test_psf.py
@@ -46,7 +46,7 @@ def test_save_and_load_psf(self):
                                'tiny_instcat.txt')
         obs_md, _, _ = desc.imsim.parsePhoSimInstanceFile(instcat)
         for psf_name in ("DoubleGaussian", "Kolmogorov", "Atmospheric"):
-            psf = desc.imsim.make_psf(psf_name, obs_md)
+            psf = desc.imsim.make_psf(psf_name, obs_md, screen_scale=0.4)
             psf_file = os.path.join(self.test_dir, '{}.pkl'.format(psf_name))
             desc.imsim.save_psf(psf, psf_file)
             psf_retrieved = desc.imsim.load_psf(psf_file)