How to avoid reflections on glass pane in museum? [duplicate]

Question

I want to photograph objects exhibited behind a glass pane in a museum. How can I avoid the annoying reflections on the glass pane?

The example shown here is from the Kunstkammer of the Kunsthistorisches Museum in Wien, a large collection of valuable artwork belonging to the Habsburg dynasty. This one is a lead statuette of about 0.5 m size from 1759, titled Gefesselter Prometheus (Prometheus Bound), by the sculptor Johann Baptist Hagenauer (1732–1810). The sculpture is behind a glass pane, and you can see that other objects in the same room are reflected on the glass pane. See on Prometheus's right arm for example. I'd like to reduce the annoying reflections as much as possible. Click on the pictures to get the full versions.

That museum allows photography, as long as you don't use a flash or tripod. This is great for visitors like me, and certainly refreshing compared to the strict attitude of some museums around here. But I'm still just an ordinary visitor, so I can't put up curtains or change the lighting of the room. But I hope you can still give me hints I can use even with these constraints.

I know that the single most important way to avoid reflections on glass is to change the position of the camera. Indeed, if I were to lower the camera, I'd get even worse reflections as you can see on the photo below. The above photo is after choosing the position of the camera the best I can, while still showing the eagle eating Prometheus's liver.

I will note also that the above photograph is a bit blurry from motion. I know I can avoid that by retaking the photo until I manage to hold the camera more steady, or using a larger lens. That is not the topic of this question, I'm asking how to reduce the reflections. The above photo is cropped, I took it with a Panasonic DMC-TZ70 compact camera at 1/2 s exposure time, f/3.3 aperture (the largest for this camera); the photo below uses 1/3 s exposure time.

Answer 1

Your only remedy will be careful selection of the camera position and mounting a polarizing filter. As you are composing and focusing, you rotate the polarizing filter for maximum reflection mitigation. If the reflections remain, select another viewpoint. Rotating the polarizing filter as you compose is the key to finding a setup with minimum reflections.

Answer 2

Your best bet is likely a Circular Polarizer Filter. You can twist the filter to try and reduce as much reflection as possible.

There are small lens tents that you can put to the glass and do even better, but I'll assume touching the glass is not allowed.

Finally, a Circular Polarizer Filter isn't "free". Expect to lose about 2 stops, and crank up your ISO. Bonus, if you are getting a lot of blur handholding, you should probably bump up your ISO anyway.