I use Energizer ultimate lithium batteries and have no problem. If you’re using good batteries there may be an internal problem and you should contact the company 

Yes and no. Using motion detection it doesn't work through a window. However.... using the timer inside it you can record through a window using it. How? Set the timer to record 4 minutes every 5 minutes for 1-5 hours or whatever time you need it to record for. This is what I do- just make sure you have a SD card with enough memory for the videos- I use a 32 GB SD card, I use it though a window as a security camera for my car....I live in an apartment so I can't hard wire anything and this works great for what it is. 

K&F have a list of which adapter will work for each lens to camera combination they support 

Well, i will answer your question. At first, these binoculars have a short eye relief distance that means you can roll down the eye cup to adjust the distance. If your vision is not too bad, i can make sure you will view things clearly if you use them without your glasses, just focus the left eye with the center focus wheel and use the dioptre setting on the right lense to focus the right eye. Of course, if your vision is too bad, it doesn’t matter if you wear glasses. In fact, you can see more field if you wear glass. Hope this helps. 

If your camera indicated "lens is not properly installed", please modify the camera menu settings. Usually called the "release the shutter the lens is not installed", you can modify the settings to allow. Specifically refer to the camera manual.Following are some examples:

1. MFT（M4/3 mount camera）'Lens Not Found' - Warning Message Appears
   For Panasonic Lumix:
   The camera needs to be set to function without a MFT-Mount lens attached. You can do this by changing the following camera setting:
   'Menu' -> 'Custom Menu 5' -> 'Shoot W/O Lens' -> 'On'
   (Exact naming and location of this option may change depending on camera model)
   
2. Fujifilm X mount camera, The camera needs to be set to function without a GFX-Mount lens attached. You can do this by changing the following camera setting:
   'MENU' -> 'SETUP' -> 'BUTTON/DIAL SETTING' -> 'SHOOT WITHOUT LENS' -> 'ON' (Exact naming and location of this option may change depending on camera model) Choose ON to enable the shutter release when no lens is attached.
   
3. Sony E mount camera, 'No Lens Attached' - Warning Message Appears
   The camera needs to be set to function without a E-Mount lens attached. You can do this by changing the following camera setting:'Menu' -> 'Setup' -> 'Release w/o Lens' -> 'Enable'
   (Exact naming and location of this option may change depending on camera model)
   
4. Nikon 1-Series mirrorless camera , 'Check lens. Pictures can only be taken when a lens is attached' - Warning Message Appears
   With a Nikon 1-Series camera (such as the J2), you will need to make sure the camera is in 'Manual' exposure or shooting mode and the focus selection is also set to manual. When in any other mode the camera tries to take control of the lens which is not possible as the adapter does not have any contact with the camera circuitry, so you get the lens check warning as the camera does not think there is a lens attached.
   
5. 'EOS M mirrorless camera ,'No Lens Attached' - Warning Message Appears
   The camera needs to be set to function without a EF-M Mount lens attached. You can do this by changing the following camera setting:
   'Menu' -> 'Custom Menu' -> 'Custom Function 7' -> Select 'Release shutter w/o lens'
   (Exact naming and location of this option may change depending on camera model)
   
6. Konica Minolta:
   For Konica Minolta and "No Lens Attached"
   Custom Menu 3
   First item "Shutter Lock"
   Set it to "Off: no lens"
   (Depending on camera model "Shutter Lock" May be in different menu location)
   
7. 'Samsung NX 'No lens.' - Warning Message Appears
   The adapter is designed to trigger a sensor inside the camera body itself so no setting needs to be changed. If the error message is coming up with one of our adapters attached, then it is possible that the adapter is not hitting that sensor the way that it should. Usually rotating the adapter slightly in the mount, or un-mounting and remounting the adapter clears the problem with no further action needed. If that doesn't solve the problem, then the best course of action would be to swap out the adapter you have with a replacement.