[Our today's guest blogger is a German RODOH contributor who prefers to be known simply as Hans. He is a very able debunker of Holocaust deniers' claims with a keen eye for small but significant details and he employs what I would call an "exactitude" in his contributions.]
A photograph taken by the SS presumably in summer of 1943 shows the sewage treatment plant of Auschwitz-Birkenau (fig.1, 2).
In the background of the photograph the southern side of crematorium II can be seen, and according to late Jean-Claude Pressac "the gas chamber with its Zyclon-B introduction chimneys [is] scarcely visible" under the seventh window of the crematorium building (seen from right). He probably refers to the more or less straight lines below the window, which could outline the south facade of the gas-chamber and which are indicated on figure 3.
There are also some more or less straight lines below window 6, if these are included in the structure it may look like figure 4. In addition, the outline of the eastern facade of the gas chamber has been drawn in and the point where it would meet the crematorium main building.
According to the blueprints, the half-underground gas chamber was covered by earth banks. Another photograph of the southern side of the crematorium (fig. 5), presumably taken in February 1943, shows an already half-completed earth bank at the western side of the gas chamber.
At the time the photograph showing the Birkenau sewage treatment plant was taken, in summer 1943, the earth banks should have been completed. So it is likely that the gas chamber itself wasn't visible, merely the earth banks. The February 1943 photograph shows that the "bare" gas chamber was about as dark as the crematorium roof. The structure Pressac identified as the gas chamber in the summer 1943 photograph is much brighter than the crematorium roof, which indicates that even if we are supposed to see the gas chamber location, we don't see the concrete structure itself but only the earth banks.
Pressac's explanation that the gas chamber is visible on this ground photograph recently has been challenged by Holocaust deniers at RODOH discussion forum. These particular deniers engage in crematoria denial, which is a marginal position even among Holocaust deniers.
These deniers have argued that the gas chamber is not visible, but should be visible (and thus it did not exist). The conclusion that the crematoria or their basements didn't exist is, of course, nonsensical in the light of the physical, documentary and testimonial evidence, but a closer examination suggests that doubts about Pressac's interpretation of the photograph seem to be justified. Since the area immediately below windows 6 and 7 is so blurry, probably neither the claim that the gas chamber is visible, nor the claim that it is not visible can be proven or rejected just by looking at this blurry area.
The question of what we actually see on the photograph is best answered by analyzing whether the gas chamber was visible from the point of view from which the photograph was taken. If it was, the blurry structure is obviously related to the homicidal gas chamber and its earth banks. If not, it must be of different origin.
The foreground of the photograph helps to identify the location of the photographer. It shows the sewage treatment plant south of crematorium II. It consisted of three basins running from east to west. All three basins are visible (labeled 1 - 3 in fig. 6), so the photographer is standing in front of the southernmost basin 1 of the sewage plant. The basins were crossed by footbridges, which subdivided them into four parts, labeled I to IV in the aerial photograph.
The photo shows the handrails of two footbridges to the right of the photographer and this indicates that the photographer was standing in front of the section III. If he were standing in front of the section IV, a third handrail would be visible. It could be argued that there was no handrail at the easternmost footbridge. But there is further confirmation, for if we continue the handrail located just to the right of photographer, it meets the crematorium building approximetely between windows 6 and 7 as illustrated on fig. 7. When compared to the aerial photograph, this corresponds to the position in front of the section III, not the one in front of the section IV.
So now that we have established the aproximate position of the photographer, his visual field is shown in fig. 8. The photographer stood at such an angle that he could see only a very small fraction of the gas chamber. The photo certainly cannot show any of the Zyklon B introduction chimneys.
This is not compatible with Pressac's interpretation. According to him, the photographer needs to stand at least in front of the section IV in order to have caught such a large part of the basement on camera, which however doesn't seem to be the case. In fact, in order to see the Zyklon-B introduction chimneys where Pressac marked them, the photographer would have had to stand even farther west, as approximately indicated on fig. 9, which is also not the case, since that part of the sewage treatment is clearly not visible.
The location of the gas chamber and its earth banks - after we take the actual position of the photographer into account - is shown on fig.10, created by RODOH contributor "MaximusOlson".
So this time the deniers were correct to some extent in pointing out the flaws in Pressac's interpretation - although their conclusion, that the homicidal gas chamber did not exist is of course not supported by the photograph.