The Super Blue Blood Moon syzygy – lunar eclipse from Melbourne with the Olympus 300mm lens

Written by Gary on February 1st, 2018

As the much hyped syzygy of a lunar eclipse occurring during a Blue Moon (a 2nd full moon in a calendar month) at a close distance to earth (hence a “supermoon”) continues and provides us with a lovely long eclipse, it is now well past my bed time at after 1.30am so here is a quick post from around 30 minutes ago as totality had just ended:

 

lunar eclipse

Taken with the Olympus OM-D E-M1 Mark II mounted on a tripod with the Olympus mZD 300mm f/4 lens 1/15th sec, ISO 3200 at f/4, sunny WB – image has been cropped and some NR applied in LR.

12 sec delay with electronic 1st shutter to reduce camera and shutter shake.

Live Boost OFF to avoid the moon becoming too over-exposed in EVF. (For astro work without a moon, Live Boost ON is useful).

IS ON to allow magnified manual focus then I turned it off – probably don’t need to do this with the E-M1 Mark II in IS auto mode though.

I use a single spot to focus and assign Fn 2 button to magnified view then move the spot around with the arrow keys to choose some craters with details and with the IS on, the image is more steady as I focus manually.

Here are a couple of earlier shots while I was trying to dodge fast moving clouds:

Umbral totality – the red colour is in effect from a circumferential “sunset” glow around the earth as the earth’s atmosphere diffracts the longer reddish wavelengths of light as it does for our sunsets. If there was no atmosphere on earth, the moon would have been black. This image was taken at 1/10th sec f/4 and ISO 3200.

lunar eclipse

Just before umbral totality with some bluish diffraction rays of earth’s penumbra still present, this image was taken at 1/40th sec f/4 and ISO 3200 and may have had some cloud cover obscuring bottom right:

lunar eclipse

Why didn’t I drop the ISO and use a longer shutter speed?

This has to do with earth’s rotation (which is why you get star trail images with longer exposures) and also the moon’s orbit speed around earth, both of which will result in blurred craters if your shutter speed is too long for the magnification you want to achieve.

In this case I was wanting lots of magnification hence I was using a 600mm focal length lens in full frame terms and then cropping it substantially. In an ideal situation, one would want to keep the shutter speed around 1/125th sec, but even at f/4, this would require a very high ISO during umbral totality, so I compromised and went for ISO 3200 and a slower shutter speed.

Why didn’t I use the 1.4x teleconverter?

Using the teleconverter would mean I would not have to crop as much, however, it would cost me 1 stop of light and that means either doubling the exposure duration with possible movement blur, or doubling the ISO with increased noise and less dynamic range.

In my tests of with and without the teleconverter previously, there is little to be gained in this scenario in using the teleconverter, particularly, as one may need to also drop the aperture down a half stop or so to maintain the optical image clarity and thus further increasing the need to increase exposure duration or ISO – both of which you don’t want to do during totality.

Why are some of your eclipse images blurry?

The main aims of close up shots of the moon are:

  1. get as much detail as possible – get it as critically sharp as possible with no motion blur
  2. get the exposure correct
  3. and when it is not totality, get some interesting shadows on craters.

I have seen a LOT of images posted by people of the eclipse and the far majority are blurry or poorly exposed.

Photographing totality is DIFFICULT but although it is NOT a point and shoot subject, it is not rocket science either.

1. You used the wrong equipment.

Sorry guys, your iPhone or Samsung smartphone is just not going to cut it to get shots of totality with any sort of detail – UNLESS – you somehow connect it through a telescope – but this is not a simple task.

If you want sharp, close up images of totality, you need a telephoto lens of at least 400mm in full frame terms (preferably 800mm) with a wide aperture of around f/4-f/5.6.

2. You didn’t achieve critical focus.

It is very easy to not gain critical focus when you are manually focusing your telephoto lens – use Live View with image stabilisation ON, even when on a tripod, combined with magnified view or focus peaking – this is so much easier with mirrorless cameras with built-in sensor based image stabilisation.

The Olympus mZD 300mm f/4 lens I used is superb, and has a lovely manual focus clutch mechanism to allow more precise manual focus, but even with this, it takes a very slight movement of the focus ring to lose critical sharpness, and without image stabilisation to help, it is not easy – so turn the IS ON and magnify away!

3. The camera or lens shook too much.

You need a sturdy tripod out of the wind.

If using a dSLR, you should be using mirror lock up – obviously you don’t need to worry about this on mirrorless cameras.

You need to use a self timer or a remote timer to allow the camera and lens to stop vibrating after you trigger the exposure.

You need to use electronic 1st shutter in this shutter speed range to minimise shutter shake.

4. The earth moved for you.

As mentioned earlier – too long a shutter speed and you get star trailing effect which will blur the moon – better to have high ISO noise and a shorter shutter speed than subject movement blur.

The optimum longest shutter speed depends upon how magnified you will be viewing the moon in the final image – if it is a wider angle landscape shot with minimal details of the moon visible the you can get away with exposures longer than 1 second, but if you are going for the tight crop then 1/10th sec is about the longest you would want to be, and preferably faster than that.

5. Refraction of earth’s atmosphere.

If you are shooting through miles of earth’s atmosphere with a telephoto lens, there is a lot of variation on how the atmosphere bends the light each microsecond, and you can get precise manual focus one second and when you take the shot it can still be a bit blurry.

Solution, take lots of shots.

This is why the best planetary images taken from earth are down as a stack of hundreds of stills shot as a video – one gets to weed out all the blurry ones (those that look like you are looking a a plane landing on a hot tarmac down the runway – same problem, but exaggerated) and just use the sharper ones.

6. What is NOT a factor – the moon is round and depth of field is an issue for close up photos.

I have seen people talking nonsense that you need to close down your aperture to get sufficient depth of field on the moon because it is a round ball and the centre is closer to us that the edges.

OK, I agree the moon is not flat, but let’s do some maths on depth of field.

Say we are using a 1200mm telephoto lens in full frame terms and we are lucky enough to be able to use such a lens at f/4.

The moon is some 384,000km from earth and the centre is some 850km closer to us than the edges, and when we focus the lens on the moon, the DOF equations state that subjects at distances from 12km to infinity will be in “acceptable” focus – now that gives a LOT of latitude IF you have indeed focused on the moon.

Moral of this story – don’t worry about DOF, use the widest aperture your lens will give acceptable image quality – on the Olympus 300mm f/4 that is wide open at f/4, if you are using a lesser quality telephoto lens, you may need to stop it down by one stop and increase ISO by one stop.

 

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