<p>Hi All,<br> I bought a used Gossen Luna Pro f light meter. It's a newer version that uses a 9v battery. I'd like to use it as a flash meter. Reading the PDF of the manual is a little confusing and I think I get what they mean, but the numbers don't seem to work out right.</p> <p>The meter is set in flash mode, ISO 400, the VFx/EF is set exactly at 1, with the incident light dome in place and pointed back at the SB-26 flash. The flash is off camera but on the same level as the meter (both on the floor). My Nikon D3300 with the 55-200mm f/4-5.6 lens is set for ISO 400, is on a tripod and is about 4' high. I've checked the meter battery using both the battery test button and a battery tester. Both indicate the 9v battery is just fine.</p> <p>The Nikon SB-26 flash is set to Manual 1/1, Zoom 24mm and is exactly 8 feet away from the Gossen Luna Pro f. I use a wireless flash trigger which is non-TTL. The camera's calculated effective distance is 10.8' away. I fire the camera and flash, and null the Gossen by turning the dial until the meter reads "0".</p> <p>According to the manual, the red zero mark on the dial should be between the two red triangles on the scale and it is. So the flash should not be either under or over powered for the meter. The red flash mark on the calculator dial (looks like a Z symbol) points to 1/3 stop below f/64 which is f/57. Um, huh? LOL.</p> <p>My D3300 is set to Manual with a shutter speed of 1/60. If I understand flash lighting correctly, the flash exposure is only affected by the f stop. The shutter speed is used to adjust for ambient light. If I have the aperture wide open for that lens (f/4@55mm), I get an image that is maybe 1-1 1/2 stops under exposed. So I'm not sure why the Gossen reading, using the red flash mark, would indicate f/57 which would be a gross under exposure.</p> <p>If I point the camera at the overhead fluorescent lights, so it's about a foot or so away, and use f/4, I need a shutter speed of 1/500 for the camera to indicate a "perfect" exposure. I set the meter for ambient reflected light reading at the same height, and it also says to use 1/500 at f/4. so it seems like the meter is reading okay, at least for reflected ambient light.</p> <p>Any ideas as to what I'm doing wrong and why I'm getting such a weird reading in flash mode? Could the meter be okay for ambient light readings but broken for flash?</p> <p>TIA,<br> Mark</p>