HP 7858 Printer detecting wrong photo paper size, thinks 4x6 is 5x7

[sumner42]

I have printed photos on this 7858 printer successfully in the past, but today, when I try to print using the same photo paper, and same photo app on my iPhone, the photo is cropped unacceptably. Maybe in the past, the cropping was happening, but I didn’t care, because I had lots of extra space that I didn’t care about being cropped off. For this photo it matters, as I have subject matter close to the edge that I care about, and it is being cropped off.  

After poking around, it appears that the printer is not detecting the 4 x 6 photo paper size, and is instead defaulting to 5 x 7 photo paper, which explains the undesired cropping.

I can override the default photo paper size to 4 x 6, using the web interface to the printer, and I see that 4x6 paper size, when I next attempt to print a photo from the iPhone, and that photo prints OK. However, for the photo after that, the printer defaults back to 5 x 7, which I can see from the iPhone, and also in the web interface, and the resulting print is again cropped unacceptably. 

I tried removing the photo paper from the tray, and sliding the photo paper guide open to 5 inches wide, and then closed to 4 inches wide, to see if the printer would recognize the correct size. I can see some metal buttons, that might be part of the size detection mechanism, which I assume is a magnetic sensor, but I don’t see how that would work, and nothing appears misaligned. 

When I tell it to check for updates, the printer reports that the most current updates are installed. It is set for automatic updates. 

I’m looking for a resolution that doesn’t require me to reset the default paper size in the web interface, before I print every single photo! 

[Echo_Lake]

@sumner42

Thank you for posting on the HP Support Community.
 

Don't worry as I'll be glad to help,  

I appreciate your efforts to try and resolve the issue. I would suggest using the HP Smart app to print photos and changing the print size settings. 
Firstly, let's load photo paper correctly:

1. Open the paper tray door.
2. Grasp the door, and then pull it toward you to extend the paper tray.
3. Slide the paper width guides to their outermost positions. ...
4. Load a stack of photo paper into the tray with the short edge facing toward the printer and the print side down.

Update the printer firmware:

• Click here to download and install the latest printer firmware from your PC.
• Click here to know different methods of updating printer firmware.

Print photos using the HP Smart app on your Android or iOS device.

• Open the HP Smart app, and then select your printer on the home screen.
• Tap the Print photos tile.
• Browse and select the photo you want to print.
• In the Preview window, tap the Edit icon, change any print settings, and then tap Done.
• Tap Print, and then swipe up on the screen to choose the correct paper size and type you loaded into the printer.
• Tap Print to print the photo.

Hope this helps! Keep me posted for further assistance.
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