I've wondered about one rather minor detail regarding the cameras. How did the astronauts change the film in these cameas without signifigant dust contaimination? Were the cameras just loaded with some obscene amount of film so they wouldn't have to be opened at all? Different camera for each roll? Or did they have some kind of auto-load feature?

NASA contracted for the development of special film cartridges that could take about 70 photos each, so they wouldn't have to be changed as often (and, I assume were easier to change than conventional film).

Keep in mind that on the Moon there's no dust hanging in the air because there's no air. As long as the astronaut isn't kicking up dust, and his gloves are clean, dust shouldn't be a big problem.

PDF file with more than you will want to know about NASA cameras

__________________
Everything I need to know I learned through Googling.

The cameras were magazine-loaded. This is no surprise to professional photographers -- Hasselblads are magazine-loaded as part of the manufacturer's design. Many high-end cameras use magazine-loading, as opposed to the threading little bits of film that we consumer have to deal with.

Put simply, the film is loaded into these magazines on earth, and then a "darkslide" is placed on the front of the magazine to prevent light leaks. You lock the magazine onto the back of the camera body. There's a mechanical interlock which doesn't let you remove the darkslide until the magazine is secure on the back of the camera. (Hasselblad did modify some of the interlocks for use on the lunar surface, in deference to the clumsy gloves.)

Because the Estar base is obscenely thin (think Saran Wrap), the magazine did in fact hold an obscene amount of film -- about 180 frames. But it was quite possible to change the film on the lunar surface using the magazines.

__________________
"Facts are stubborn things." --John Adams
Clavius Moon Base

Did they replace the darkslide when the magazine was finished?

__________________
Freedom For Fission A breath of fresh Iodine-131

Did they replace the darkslide when the magazine was finished?

No. They simply wound the tail of the film strip into the magazine. This is why many of the last few frames on each roll are sunstruck. Check out the LPI photo archive for the best examples.

__________________
"Facts are stubborn things." --John Adams
Clavius Moon Base

Thanks, that is sorta what I expected, but I'd seen so much written that the cameras were basically modified versions of the earth-based cameras that I wasn't sure what had been done.

As for my reasons of thinking about dust contamination, I was recalling a bit from a book about Apollo where Armstrong and Aldrin were covered in lunar dust from head to toe when they got back to the LEM. One of them mentioned that there had been some who wondered if lunar dust might spontantiously combust when exposed to air, and that they were about to find out.

Besides, you have to plan for dust if you simply acknowlede that the moon-walkers might simply fall down and get dust on the camera.

Well...a little clarification: You cant remove the cartidge from the back of the Hasselblad body without replacing the dark slide. The dark slide is simply a thin piece of aluminum, painted matte-black, which fits into a slot covering the opening through which light passes when you make an exposure. You slide it out, make your exposures, then slide it back in to remove the cartidge.

The cartridges are comprised of 2 spools, one having the film and the other being the take-up spool. As you take pictures, the film gets rolled off the film spool and onto the take-up spool. When you're done with the film, you still have several inches of paper backing to advance onto the take-up, which effectively shields your film from light. Then, you open the cartridge, remove the take-up spool, place a strip of adhesive tape (modern films actually use a self-adhesive strip similar to envelopes and lick-able stamps) around it to hold the protective paper on the spool. Then, you take the spent film spool, place it where the take-up spool was and it becomes the new take-up spool...a new film spool is inserted, the protective paper becomes the leader - you have several inches ahead of the film as well as behind - like the leader bit of film in your 35mm which allows the camera to begin spooling, cartridge is closed, reloaded onto the camera body...rinse and repeat

Often a cloth tab is placed on the little handle of the dark slide to facilitate easier removal. Insertion is easy and I have little doubt the astronauts could accomplish this even with clumsy gloves. I'm guessing the sun-struck tail exposures were due to it being difficult to secure the adhesive strips with those gloves before sunlight penetrated the protective paper layers and the spool was placed into a light-safe container.

Hope it's as clear as mud now...

edit: the most annoying thing about these systems is user-error...forgetting to remove the dark slide, winding the entire roll of film onto the take-up spool, THEN realizing the dark slide was in and that whole roll of film is un-exposed...I put florescent colored tabs on my darkslides because I'm rather prone to this particular mistake. Also, since you never actually handle the film, only the paper backing, dust is a greatly minimized concern here.

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

Again, as noted in my previous post, the Hasselblads dont release their film backs unless a dark slide is in place. The only exception I know of to that system is the Polaroid backs which use a disposable paper darkslide and have a slot for an optional metal slide for framing (it has a rectangular cut-out that is the same size as a conventional 120 film frame because Polaroid frames are much larger). Of course, if they modified the bodies so that the dark slide safety was disabled, I would be completely wrong here.

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

Thanks, that is sorta what I expected, but I'd seen so much written that the cameras were basically modified versions of the earth-based cameras that I wasn't sure what had been done.

Visit Hasselblad's web site. They're very proud of the cameras that went to the moon.

As I said, many professional cameras use magazines. Think of the typical motion picture camera, say a Panaflex. There's the black, anodized body to which the lens is attached. And then there is the large white container above for the film. That's a magazine. That whole assembly comes off, to be replaced with another one. Because time is money in that business you want to start your day with a whole box full of loaded magazines so that you won't have to make everyone wait while you load thousands of feet of film.

Hasselblads already used magazines, and they still do. It's standard.

Besides, you have to plan for dust if you simply acknowlede that the moon-walkers might simply fall down and get dust on the camera.

Getting dust on the camera is different than getting dust in the camera. You definitely don't want to drop one of those magazines in the dust, although I recall that someone did.

__________________
"Facts are stubborn things." --John Adams
Clavius Moon Base

I know that, but if I take my 35mm camera and drop it into a pile of Portland Cement, then pop open the back and load a new roll, while wearing oven mitts, I'm likely to get some of said dust that is on the camera into the camera. :wink:

Was the same Hasselblad model used for the Skylab EVAs?

JSC photographic technician Terry Slezak gained some fame after the return of Apollo 11:

http://images.jsc.nasa.gov/images/pao/AS11/10075320.htm
Another point on the darkslide: IIRC, due to the reseau plate on the EVA-cameras, you had to remove the darkslide from the mag before attaching it to the camera. That's why they always had to advance a few frames before and after changing a mag.

Harald

Comixx, you are discussing loading the film into the magazines. The astronauts did not load film in and out of magazines. They just carried dozens of preloaded magazines. They used them, then put them aside and returned them to JSC for development.

Some links on Apollo cameras

http://www.hq.nasa.gov/office/pao/Hi.../a11-hass.html

http://www.hasselblad.com/company/HB....asp?secId=584

http://www.mir.com.my/rb/photography...res/moon/1.htm

I see by Kucharek's post that the cameras were indeed modified to remove the darkslide safeties so they could be removed before the backs were mounted. I assume because the reseau plate obstructed removal of the darkslide. Not handling the film at all, and not affixing the adhesive strips would indeed have caused significant light leaks without the darkslide in place. I guess that was deemed acceptable, overall. I would have thought they would have found a way to make the darkslide operate normally and not risk losing any exposures...

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

I guess, they had the choice between developing a complicated, new mechanism to allow darkslide handling as usual with the reseau plate attached, or simply change procedures by advancing the film a few frames before and after magazine change. They had plenty of film.
What would you choose?

Harald

Well, they already had done plenty of modifications to the camera. They even had to find a way to discharge static because of the film being guided by glass instead of the usual metal. I also saw in the links that they loaded the film on Earth and didnt use any of the paper backing so that they'd be able to load more footage in each film back.

In all, these Hasselblads are completely different animals than the ones I'm used to using, so I'm woefully wrong in most of my suppositions. Sorry to have cluttered up this thread with my ideas And here I thought being a photographer myself would lend me something to add...oh well.

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

Don't belittle yourself, Comixx. I know more about the Apollo Hasselblads than I do about the normal off-the-shelf Hasselblads. And that is a handicap because I can't accurately describe how the cameras were modified. The expertise of a practicing photographer is indescribably important here.

I know the reseau plates had to be coated with a very thin layer of metal to bleed off the static charge. This, in my opinion, would have increased their halation effect and probably caused the "ghosted" fiducials in the Apollo 14 up-sun photos. While they are some of the most beautiful photos taken on that mission, they exhibit some interesting behavior.

I know the magazines had to be modified in order to deal with the interference between the darkslide and the reseau plate. This is a bit surprising because the reseau plate was not an Apollo-specific addition. It's a standard feature of the "Data" model Hasselblad. But if this is the case, you can see why they opted to handle the magazines as they did on Apollo. Omitting the darkslide and providing light protection by rolling the film into the magazine is probably a procedure Hasselblad had developed for dealing with reseau-equipped cameras on earth.

I know the magazines themselves were beefed up to provide extra protection against heat and sunlight.

I know the casing was modified to provide better thermal heat rejection.

I know that tabs were added to the rings in order to make them easy to operate in gloves.

I know some optional equipment (motor winder, exposure meter) was removed or omitted to save weight and reduce complexity.

We may never fully know why the Apollo Hasselblads were modified or used differently, but it's certainly helpful to have a baseline understanding of this type of equipment.

__________________
"Facts are stubborn things." --John Adams
Clavius Moon Base

Well, thanks Jay, I appreciate the sentiment

As for the darkslide modification: I think it was more to seal out dust than because of the reseau plate interfering. The more I examined those pics of the Apollo Hasselblad Data camera, the more it looked to me that they tried to limit clearances between the film back and the body. With a darkslide removed, you have a slot the width - while thin, it's thick enough that you cant casually bend it when it encounters some resistance as it pushes the light seals aside upon insertion - of the darkslide which is, basically, open to dust invasion. While the darkslide slot is designed in such a way as to limit light from entering the camera, I dont think the same is true for dust. I couldnt find any mention of why the darkslide was removed prior to attaching the film back in any of the links provided.

Of course, without getting my hands on one, this is all more conjecture on my part.

__________________
~Brad - Astropaparazzo
http://signaturedigitalimages.com

My name is Lauren. My grandfather is Terry Slezak, first man to touch moondust. They didnt change the film. Its NASA duh. Google him and you'll see.

My name is Lauren.