I'm new to DSLR cameras; as I love photography, I decided to get a Nikon D7500 with 18-140mm kit lens.

I've just mounted the lens to the camera but when I see through the viewfinder, the image doesn't look bright and seems like the lens or the sensor is dirty, I already checked the camera and lens they are brand new. I haven't put battery yet, could someone please tell me if this is a problem or just because I haven't inserted a battery yet?

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    \$\begingroup\$ Does this answer your question? Why is the battery required to manually focus through the viewfinder? (Different camera, but same type of viewfinder.) \$\endgroup\$
    – Michael C
    Commented Aug 26, 2020 at 11:17
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    \$\begingroup\$ Just wondering, out of pure curiosity: is there any reason you decided to ask here first instead of putting in the battery and trying it? Seems like you could have saved yourself a ton of time here... \$\endgroup\$
    – user91988
    Commented Aug 26, 2020 at 15:01

1 Answer 1


Your camera, like many modern DSLRs, has a “transmissive” optical viewfinder which requires battery power in order to be fully transparent. Here is what Canon says about Transmissive Viewfinders in Digital camera features: Transmissive LCD viewfinders:

This new viewfinder uses a transmissive LCD which, unlike traditional viewfinders, does not feature interchangeable focusing screens but, instead, uses an LCD screen through which light passes, giving an optical view but with the ability to overlay extra information on the screen as required.

In An overview of the Intelligent Viewfinder Display system in the EOS-1D X and EOS 5D Mark III, Rudy Winston writes:

The LCD overlay does require a tiny amount of electrical power to operate. This is obviously no concern when the camera is turned on, but if the battery is removed the transmissive LCD suddenly loses a lot of brightness and contrast. This is perfectly normal and will return to full brightness once a battery is reinstalled in the camera (the camera doesn't have to be turned on; it only requires a functioning battery pack to draw power for proper viewfinder operation).

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    \$\begingroup\$ Thank you very much, I've put the battery on and tested, working fine now. Really appreciate your answer \$\endgroup\$
    – The King
    Commented Aug 25, 2020 at 19:58
  • \$\begingroup\$ Or, it could be the lens cap... =P \$\endgroup\$
    – Stian
    Commented Aug 27, 2020 at 9:07
  • \$\begingroup\$ Yeah, I was also a bit upset when I looked through the VF of my brand new just-opened 80D after having used 1100D a lot (which has clear view even without a battery). But then I quickly read in the manual's Installing and Removing the Battery section: "The camera’s viewfinder becomes bright when a battery is installed, and darkens when the battery is removed. If the battery is not installed, the picture in the viewfinder becomes blurred and focus cannot be achieved." \$\endgroup\$
    – Ruslan
    Commented Aug 27, 2020 at 9:44
  • \$\begingroup\$ Even my ancient D200 needs a battery to get a clear viewfinder picture.... \$\endgroup\$ Commented Aug 27, 2020 at 14:15

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