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-   -   F-stop on the Moon? (http://www.dvinfo.net/forum/photon-management/46721-f-stop-moon.html)

Bogdan Apetri June 24th, 2005 11:00 AM

F-stop on the Moon?
 
Hello!

Anybody knows what was the F-stop on the Moon when the astronauts were taking those pictures/little films? Probably wide open, even wider than F1.0
(with special lenses, like the ones adapted later for Barry Lyndon)? But wide open all the time?...

Matt Gettemeier June 24th, 2005 11:16 AM

The still pictures were probably an F8 (or higher)... film? I dunno'...

If the cams were doing F1.0 I think stars would show up in the background (yeah, yeah I know the debate on that and I've got an F1.0 lens and stars show up)...

The cams were Hasselblads...

Chris Hurd June 24th, 2005 11:23 AM

Absolutely *not* wide open. All of the moon walks were scheduled during periods of lunar daylight. It was pretty bright up there, in fact, the astros had the sun visors on their helmets in place pretty much all the time (that's why you rarely ever see a photo of an astro's face on the moon, due to his sun visor being down all the time). The cameras were specially adapted 70mm medium-format Hasselblads, each with an 80mm lens, although they also had 105mm, 250mm and 500mm lenses available. Most all lunar surface shots were taken "from the chest" without benefit of a viewfinder. But as far as exposure is concerned, stopped down all the time is more like it, due to the intense brightness they were working in.

Bogdan Apetri June 24th, 2005 12:45 PM

Yes, it makes perfect sense. Thanks Chris.

The Barry Lyndon lenses were not at all designed for the "Apollo moon landing program" as they say. It must be untrue. I guess they were designed for photography from space (either satellite pics or just space pics).

Chris, you seem very knowledgeable about it. Do you know what the F-stop they use on Mars? (it seems I am joking, I am not). I'm very curious, with these two rovers, Opportunity and Spirit. Did they know in advance what F-stop would they need, somewhere in the neck of the woods? They must have auto exposure, though. The light on Mars is changing much more often than on the Moon. Plus, they are taking macro pics after grinding a rock.

Also, no night pics on Mars, I think.
Thanks.

Chris Hurd June 24th, 2005 09:11 PM

I am not at all knowledgeable about it, sorry; I'm just an armchair historian with an interest in the Apollo program. You might try a Google search; I'm sure the info you're looking for is publicly available.

Marco Leavitt June 24th, 2005 09:39 PM

I have nothing to add other than to say this is a very cool post. Hasselblads on the moon! I never knew that. Maybe it's because I just finished reading "Rocket Boys." I just find this fascinating. I hope more people have input on how they captured those pictures.

Richard Alvarez June 24th, 2005 10:08 PM

Marco

Hassleblads in orbit... I'm pretty sure one was lost 'overboard' on one of the Gemini missions.

I grew up in Houston, wanting to be an astronaut. Lived in Seabrook, four miles from the manned spacecraft center... I was a BIG space geek. Still am.

John Sandel June 24th, 2005 10:09 PM

"... you rarely ever see a photo of an astro's face on the moon ..."

I don't think I've ever seen one, 'less you count those candid shots inside the LEM, where the guys had their helmets off.

Chris Hurd June 25th, 2005 08:50 AM

I'm not near my resources at the moment, but there is a short film clip from an Apollo 17 moonwalk where either Cernan or Schmitt's face is clearly visible through a raised sun visor. That's the only instance I'm aware of.

Pete Bauer June 25th, 2005 10:32 AM

I was surprised that although there's lots of info about the Hasselblads and the film on the internet, including NASA official sites, I couldn't find anything on the actual exposures used for the photos...eg, the combo of ASA/F-stop/Aperture. So I asked one of the NASA photographers, and he kindly provided this reply:

The exposures varied depending on what the lunar astronauts were photographing (from f5.6 at 1/30 second in the shadow of the LEM to 1/250 second at f/11 in full sunlight.) They shot with two types of 70mm film. A Kodak Ektachrome 64 (ISO 64) and a black & white Kodak 3400 film rated at ISO 40.

A shutter speed of 1/250 second was selected to minimize excessive motion by the suited astronaut during exposure. According to the Apollo 11 post mission report on photography with the Kodak Ektachrome 64, "To simplify camera operations, f-stops of 5.6 and 11 were chosen for exposures in the cross-sun and down-sun directions, respectively."


In more current news, looking good so far for STS-114 to meet its launch window of 13-31 July. Fingers crossed!

Chris Hurd June 25th, 2005 02:35 PM

Thanks for the update, Dr. Pete! My face will be glued to the NASA channel during that entire week.

Bogdan Apetri June 25th, 2005 04:46 PM

Thanks for the update!

Also, the Impactor will soon collide with that comet... should be very interesting. Observed from both close range and all the way from the Hubble.

Bogdan Apetri July 4th, 2005 01:22 AM

Success!
 
Off topic, but Deep Impact just collided with Tempel-1. Nice (almost) live images!


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