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Grant
05-25-2010, 11:17 AM
This may be of interest to some:



Before I fell in love with photography I was in love with Astronomy. In fact I still am.

Today I gave advice about shooting the moon. This image was shot on film using an old Pentax, and it was even old when I took this image. The camera was directly connected to a telescope but a coupler called a T-mount and therefor there was no camera lens involved.

Most people tend to over expose the moon. The easiest way to expose for the moon is to use the Sunny 16 rule. When you think of it the moon is directly light by the sun. There will may be a slight discrepancy caused by atmospheric extinction and a light grazing effect when the moon is past first or last quarter this may require a stop adjustment.

The sunny 16 just states set your shutter to the reciprocal of the ISO and shoot at f/16.

http://farm4.static.flickr.com/3410/4638997280_15728aeb9f_o.jpg

I took this image at 1/250, f/10 at ISO 100 and there is no vertical crop.

Marko
05-25-2010, 11:26 AM
Hi Grant,

Thanks so much for sharing this knowledge. MUCH appreciated.

Mad Aussie
05-25-2010, 06:14 PM
Very cool.

I've seen some awesome images of space taken by people with very std cameras but using a complex set up. Shots of Nebula's etc. Amazing stuff. You're not into that are you Grant?

Grant
05-25-2010, 09:58 PM
You're not into that are you Grant?


I was very much into that from about 1980 to 1995, but that was another life.

.

Mad Aussie
05-26-2010, 04:52 AM
That stuff fascinates me .. .but I simply couldn't sit up all night to get these shots.

Here's a sample from another website ... by another photographer called Nighthound ...

http://i3.photobucket.com/albums/y67/Nighthd/Astrophotography/test/m101x.jpg


Is that the sort of stuff you took Grant?

Iguanasan
05-26-2010, 08:37 AM
...snip...
Most people tend to over expose the moon. The easiest way to expose for the moon is to use the Sunny 16 rule. When you think of it the moon is directly light by the sun. There will may be a slight discrepancy caused by atmospheric extinction and a light grazing effect when the moon is past first or last quarter this may require a stop adjustment.

The sunny 16 just states set your shutter to the reciprocal of the ISO and shoot at f/16.

(image removed for brevity - it's up above)

I took this image at 1/250, f/10 at ISO 100 and there is no vertical crop.

Hey, Grant, thanks for sharing the explanation of how to shoot the moon. I've had a number of successful moon shots myself once I realized that the moon was reflected sunlight and exposed properly. I am wondering if you can explain for "the folks at home" why you suggest f/16, ISO 100, 1/100 but then show an image where the settings you used were f/10, ISO 100, 1/250?

Marko
05-26-2010, 10:02 AM
Just jumpin in here... those two exposures are almost identical.

The aperture is about 1 stop larger on the F10 shot so the shutter needs to be faster by roughly the same amount.

I' m guessing that this may have been shot handheld so the faster shutter speed is for sharpness...?

Fortytwo
05-26-2010, 10:46 AM
That stuff fascinates me .. .but I simply couldn't sit up all night to get these shots.

Here's a sample from another website ... by another photographer called Nighthound ...

http://i3.photobucket.com/albums/y67/Nighthd/Astrophotography/test/m101x.jpg


Is that the sort of stuff you took Grant?

I'd just love to be able to take shots like that. But that'll require a motorised tripod and a very good (and expensive) telescope. Still saving...

Grant
05-26-2010, 11:12 AM
Marko has the math right.

There reason for f/10 is only obvious if you are deep into astronomy The image was taking using a 200 mm catadioptric telescope that had a 2000 mm focal length, hence the f/10. The telescope and camera were mounted on a motor driven yoke mount. This type of equipment requires the camera to be directly attached to the telescope so there is no choice of f/stop. Well, not strictly true as you can decrease the f/number by optically increasing the focal length, but then the magnification would go up and I would only have part of the moon on my film. The optics were made by Meade Optics.

Astrophotography is a whole world onto itself and somethings in general photography don’t apply to it and certain things very important to astrophotography would be very new to an everyday photographers.

For everyday exposures of a full moon just use the sunny 16 rule for full moon and for other phases start with this rule and adjust if needed. For the techno guys the Moon average reflectivity called albedo is 12% which is close to the18% grey a meter is set for. That being said you need to use a narrow spot meter on the moon or you will be averaging in a lot of black sky in your exposure.

Mad Aussie I did do things like that but with film not digital. The arrival of digital has made the whole field a lot easier but a lot more interesting. Now “easier“ is relative as it is a very demanding procedure. In the days of film I was in seventh heaven if I had made 3 exposures in an evening.

Marko
05-26-2010, 12:56 PM
but i missed the line where you said the camera connected to telescope DOH!

Thx for the fuller explanation!

Mad Aussie
05-26-2010, 06:13 PM
It's an amazing genre of photography for sure and I'm often amazed by how somne great images are captured these days on what amounts to basic equipment for this type of work.

The patience alone is beyond me!!