|
It was an unusually clear night on the 5th of
January 2007, and there was a wonderful full moon, so I thought
I'd have a go at photographing it.
I do not own and have never so much as looked through an astronomy
telescope, so these pictures might be easy to obtain with such
a beast - but my goal was just to capture as decent a picture
as my camera gear could obtain.
If you own one of the super telephoto lenses of 500mm plus, you
might like to have a go.
Equipment
I brought out the big guns on this one. My longest lens - the
Canon 500mm f4 IS with a 2x Canon teleconverter. I used the 20D
rather than the 1D mk2 as it has a higher pixel density on it's
1.6x sensor.
As I wanted to ideally fill the frame with the moon if I could,
I quickly added my other teleconverter - a 1.4x and stacked this
on top of the 2x to get even more magnification. The total focal
length was now 500mm x 2 x 1.4 = 1400mm. With the 1.6x factor
of the 20D this equated to a staggering effective focal length
of 2240mm ! That's more like it.
First experiences
I mounted the lens onto my sturdy Gitzo 1548 tripod with Kirk
ball head and took a look through the viewfinder - I was met by
....a totally bright out of focus blur ! Ah. Ok, the autofocus
doesn't work on the 20D when the 2x extender is used, so manual
focus it had to be. That was easier said than done - I had to
be so careful with the focussing, as moving the focus ring by
the slightest amount had a huge effect.
The next issue was that as soon as I so much as touched the lens,
the image vibrated terribly in the viewfinder. I could see that
technique at these magnifications was going to be critical if
I was going to get a sharp image. So next precaution was to set
the camera to mirror-lockup (using custom function 12 on the 20D).
In this mode, the first press of the shutter-release button flips
the mirror up (and the viewfinder therefore goes black). The second
click opens the shutter and the mirror returns down. The idea
is to reduce vibration due to mirror-slap.
I also then used a remote cable release - as I couldn't even touch
the shutter button without seeing the image vibrate in the viewfinder.
Ok - getting there, but not taken a single picture yet ! Look
through the viewfinder again to check focus and - blast it - the
moon has moved ! Who said it could do that ! reframe and try again.As
I stared through the viewfinder, I could actually see it moving
- wow.
To IS or not IS ? - that is the question
The advice on second generation telephotos such as the 500mm
f4 is to keep the image stabilisation switched on when a tripod
is used, but to switch it off on a first generation IS lens (such
as the 100-400 IS). So IS was switched to on.
But - whoa - the image leapt up in the viewfinder as the IS kicked
in and didn't return, so I had to reframe again. As I watched,
I could see that the image was still just waving around very slightly,
so I had to turn the IS off - contrary to the usual advice ! Whether
this happened because I had stacked the converters (which is not
a practice endorsed by Canon) I don't know. But the IS had to
stay off on this occasion.
Exposure and ISO setting
I could see that this was going to be tricky, I knew that the
bright moon would fool the camera's metering system - and so it
did. I ended up using manual exposure for ultimate control.
I set the aperture to f8 - if in doubt use f8 ! This happened
to also be the maximum aperture achievable with the stacked converters.
I really didn't need much depth of field - the moon is essentially
a flat disc to photograph, so f8 it was.
To get the correct shutter-speed I simply used trial and error
- consulting the camera's histogram each time to keep the "mountain
range" as far to the right of the graph as I could without
sending the highlights off the scale into clipping. If you under-expose
the image you will see a lot of noise in the black night sky behind
the moon when you brighten it up in the RAW converter later -
so exposure had to be spot on.
ISO setting was the one easy choice - ISO 200 gives pretty well
maximum quality and dynamic range - so that is what I used.
White balance was just set to auto - I don't faf around with trying
to get it right - that is the beauty of shooting RAW - just set
it as required in post-processing later.
I settled on 1/80 second at f8 as being about right. I then just
reframed the shot again for the umpteenth time and finally took
a few shots and scuttled off to bed as it was getting pretty late.
- About 2:00 am to be precise. Had I really been at it for over
two hours ? Wow - time flies when you are having fun!
Next Day
Next day I got up and eagerly inspected my previous night's
work on the computer. How would the pictures look at 100% on the
screen - and has stacking the converters killed image quality
?
I processed the raw images in the usual way (see my tutorial
on raw conversion) , opened it in Photoshop, adjusted the levels
(autolevels worked fine for once), sharpened with unsharp mask
and then took a hard,critical look. Wow - the image quality was
fantastic - but never mind that - just look at the surface of
the moon !
I spent the next 15 minutes just pouring over the surface of
the moon like a voyeur-explorer ! Look at those craters - look
at those skid marks where a meteorite must have hit ! what are
those lines ? What are those funny circles ? Absolutely fascinating
!
So there we are - how to photograph the moon. Unfortunately I
used a lot of mighty expensive equipment to achieve this result
- but hey - it was just lying around doing nothing anyway !
So if you just happen to have a super-telephoto lens yourself
- why not have a go ?
One last crop of the big crater at the top - can't see any cheese
though.
|
