diff --git a/METIS/METIS_DET_IFU.yaml b/METIS/METIS_DET_IFU.yaml
index c3387675..0297ae02 100644
--- a/METIS/METIS_DET_IFU.yaml
+++ b/METIS/METIS_DET_IFU.yaml
@@ -78,6 +78,12 @@ effects:
       noise_std: "!DET.readout_noise"
       n_channels: 32
 
+  - name: exposure_output
+    description: Return average or sum over NDIT subexposures
+    class: ExposureOutput
+    kwargs:
+      mode: average
+
   - name: ad_conversion
     description: Apply gain and convert electron count into integers
     class: ADConversion
diff --git a/METIS/METIS_DET_IMG_LM.yaml b/METIS/METIS_DET_IMG_LM.yaml
index 55229dc0..e65c2b46 100644
--- a/METIS/METIS_DET_IMG_LM.yaml
+++ b/METIS/METIS_DET_IMG_LM.yaml
@@ -95,6 +95,13 @@ effects:
       noise_std: "!DET.readout_noise"
       n_channels: 32
 
+
+  - name: exposure_output
+    description: Return average or sum over NDIT subexposures
+    class: ExposureOutput
+    kwargs:
+      mode: average
+
   - name: ad_conversion
     description: Apply gain and convert electron counts into integers
     class: ADConversion
diff --git a/METIS/METIS_DET_IMG_N_Aquarius.yaml b/METIS/METIS_DET_IMG_N_Aquarius.yaml
index 9ea8c294..b2b00653 100644
--- a/METIS/METIS_DET_IMG_N_Aquarius.yaml
+++ b/METIS/METIS_DET_IMG_N_Aquarius.yaml
@@ -92,14 +92,11 @@ effects:
       noise_std: "!DET.readout_noise"
       n_channels: 64
 
-  - name: chop_nod
-    descriptions: chopping and nodding
-    class: ChopNodCombiner
-    include: false
+  - name: exposure_output
+    description: Return average or sum over NDIT subexposures
+    class: ExposureOutput
     kwargs:
-      chop_offsets: "!OBS.chop_offsets"
-      nod_offsets: "!OBS.nod_offsets"
-      pixel_scale: "!INST.pixel_scale"
+      mode: average
 
   - name: ad_conversion
     description: Apply gain and convert electron count into integers
@@ -107,3 +104,12 @@ effects:
     kwargs:
       dtype: uint16
       gain: "!DET.gain"
+
+  - name: chop_nod
+    descriptions: chopping and nodding
+    class: ChopNodCombiner
+    include: false
+    kwargs:
+      chop_offsets: "!OBS.chop_offsets"
+      nod_offsets: "!OBS.nod_offsets"
+      pixel_scale: "!INST.pixel_scale"
diff --git a/METIS/METIS_DET_IMG_N_GeoSnap.yaml b/METIS/METIS_DET_IMG_N_GeoSnap.yaml
index d810ab32..12b54723 100644
--- a/METIS/METIS_DET_IMG_N_GeoSnap.yaml
+++ b/METIS/METIS_DET_IMG_N_GeoSnap.yaml
@@ -100,14 +100,11 @@ effects:
       noise_std: "!DET.readout_noise"
       n_channels: 8
 
-  - name: chop_nod
-    descriptions: chopping and nodding
-    class: ChopNodCombiner
-    include: false
+  - name: exposure_output
+    description: Return average or sum over NDIT subexposures
+    class: ExposureOutput
     kwargs:
-      chop_offsets: "!OBS.chop_offsets"
-      nod_offsets: "!OBS.nod_offsets"
-      pixel_scale: "!INST.pixel_scale"
+      mode: average
 
   - name: ad_conversion
     description: Apply gain and convert electron count into integers
@@ -116,6 +113,15 @@ effects:
       dtype: uint16
       gain: "!DET.gain"
 
+  - name: chop_nod
+    descriptions: chopping and nodding
+    class: ChopNodCombiner
+    include: false
+    kwargs:
+      chop_offsets: "!OBS.chop_offsets"
+      nod_offsets: "!OBS.nod_offsets"
+      pixel_scale: "!INST.pixel_scale"
+
   - name: det_n_fits_keywords
     descriptions: FITS keywords specific to N detector
     class: ExtraFitsKeywords
diff --git a/METIS/tests/test_readout_exptime.py b/METIS/tests/test_readout_exptime.py
index f8183fab..a9d461e1 100644
--- a/METIS/tests/test_readout_exptime.py
+++ b/METIS/tests/test_readout_exptime.py
@@ -1,3 +1,4 @@
+"""Test whether giving exptime in readout() is respected."""
 import copy
 import os
 from matplotlib import pyplot as plt
@@ -34,6 +35,7 @@ def test_readout_exptime():
 
     # The first readout might ignore the exptime.
     metis_l = sim.OpticalTrain(cmd_l)
+    metis_l["exposure_output"].set_mode("sum")
     metis_l.observe(star, update=True)
     result_first = metis_l.readout(exptime=0.1)[0]
     # We need to copy the first readeout, because
@@ -42,6 +44,7 @@ def test_readout_exptime():
 
     # The second readout might not properly have the detector reset.
     metis_l = sim.OpticalTrain(cmd_l)
+    metis_l["exposure_output"].set_mode("sum")
     metis_l.observe(star, update=True)
     result_temp = metis_l.readout(exptime=.1)[0]
     result_temp_copy = copy.deepcopy(result_temp)