I have just read a review of the movie Son of Saul which tells about photos, taken at Auschwitz-Birkenau, by the Sonderkommando Jews; the photos show the gassing of the Jews at Auschwitz-Birkenau.
These photos are shown in the background in the movie as the main characters in the movie are shown in the foreground.
You can read about the movie at
The following quote is from the article in the link above:
The film is based on actual accounts of the Sonderkommando’s gruesome role, its members forced to collaborate with the killing machine or be killed, and marked for extermination themselves every three months as “bearers of secrets” who could not be allowed to survive. The photographer was an actual person, identified only as Alex from Greece, who took four images that were smuggled out to the Polish underground.
You can see these photos on Wikipedia at https://en.wikipedia.or/wiki/Sonderkommando_photographs

Photo taken by a Sonderkommando Jew shows prisoners being herded toward a gas chamber

Photo taken from the doorway of a gas chamber at Auschwitz-Birkenau shows the burning of bodies
The photos shown above were allegedly taken with a 35 millimeter Leica camera by Sonderkommando Jews.
Four of the gas chambers at Auschwitz-Birkenau were underground, but there were two gas chambers that were above ground: Krema IV and Krema V.

Krema IV at Auschwitz-Birkenau had a gas chamber that was above ground
This quote is also from the news article:
Begin quote
In Laszlo Nemes’s remarkable Holocaust drama, Son of Saul, there’s a minor character who risks his life secretly taking photographs of the corpses.
[…]
Watching it [the movie] is a harrowing experience, and the first 20 minutes or so are particularly difficult. The film is shot from the narrow perspective – and the narrowness is the only thing that makes it bearable – of Saul Auslander, a Hungarian Jew who works in the Sonderkommando that herds new prisoners into the “showers,” collects the victims’ clothing, moves the bodies to the crematorium and scrubs out the gas chamber before the next transport arrives. We see the reality of this gruesome job slightly out of focus, as though in Saul’s peripheral vision, as the camera always stays tight on Saul’s face. Often the sounds around him, and our own foreknowledge of the place, are what make the half-glimpsed scenes particularly wrenching.
End quote from news article
Note that those mean ole Nazis forced the Jews to “scrub out the gas chamber” after each gassing. I don’t think that scrubbing the gas chamber was necessary, but this just shows you how depraved the Nazis were.
The following quote is from my scrapbookpages.com website:
Krema IV was located just north of the clothing warehouses, which were in a section that the prisoners called Canada. Across the road from Canada was the Central Sauna which had a shower room and disinfection chambers where the prisoners’ clothing was deloused. Krema IV had a fake shower room which was actually a gas chamber.
According to Michael J. Neufeld and Michael Berenbaum, in their book entitled “The Bombing of Auschwitz: Should the Allies Have Attempted It?” the Krema IV and Krema V buildings were 220 feet long by 42 feet wide.
The Krema IV building was completely demolished, blown up with dynamite which several women prisoners stole from the factory where they were working. All the bricks were removed by Polish civilians after the war, and the ruins that visitors see today are a reconstruction, according to the Auschwitz Museum.
The prisoners who worked in the crematory buildings, removing the bodies of the victims who had been gassed, were members of a special group called the Sonderkommando. According to Dr. Miklos Nyiszli, a prisoner who did autopsies at Birkenau, each Sonderkommando group was killed after a few months and replaced by a new crew.
Knowing that they were soon going to be killed, the members of the next-to-last Sonderkommando revolted and blew up the Krema IV building. A sign at Krema IV says that there were 450 prisoners who were killed by the SS during the revolt or afterwards in retaliation.
The men in the last Sonderkommando were not exterminated. Around 100 of them were marched out of the camp when it was abandoned by the Nazis on January 18, 1945. Several members of the Sonderkommando survived and three of them gave eye-witness testimony at the 1947 trial of Auschwitz Commandant Rudolf Hoess, about how the prisoners were gassed at Birkenau.