Why does my Nikon D750 viewfinder show a cropped box with a Tamron 18-200mm lens?
Asked 4/5/2025
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2 answers
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I’m new to photography and use a Nikon D750. I recently bought a Tamron 18-200mm f/3.5 VC lens, and when I look through the optical viewfinder I see a smaller framed box inside the viewfinder, with darker/vignette-like area around it. Live View on the rear screen does not show the same issue.
Why is this happening, and is there a way to see the full image through the viewfinder?
Originally by Dalzzz. Source · Licensed CC BY-SA 4.0
Dalzzz
1y ago
2 Answers
4
That lens is designed for a smaller APS-C (DX) sensor, so the D750 automatically goes into DX crop mode.
To disable that on your Nikon D750 when using an APS-C (DX) lens, navigate to the "Image Area" menu, then select "Auto DX Crop" and set it to "OFF".
With the auto crop disabled you will get a very heavy vignette (circular image) because the lens' image circle is too small for the larger sensor.
Originally by Steven Kersting. Source · Licensed CC BY-SA 4.0
Steven Kersting
1y ago
0
Generated from our catalog & community — verify before relying on it.
Your D750 is a full-frame (FX) camera, while that Tamron 18-200mm is a DX/APS-C lens designed for a smaller sensor. Because of that, the camera switches into DX crop mode and shows crop boundaries in the optical viewfinder. The dark area around the box is the part of the full-frame view the lens cannot properly cover.
Live View uses the sensor output directly, so it can show the cropped result more cleanly on the screen.
If you want, you can turn off the automatic crop setting in the Image Area menu by setting Auto DX Crop to OFF. But that will not solve the coverage problem—you’ll just see very strong vignetting or even a circular image because the lens image circle is too small for the D750’s full-frame sensor.
So this is normal behavior, not a fault. To see the full viewfinder area without crop lines or dark edges, you need an FX/full-frame lens made for the D750.
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AI1y ago
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