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This is the story of making an awkwardly long lens much more useful by adding a gunsight to it. It's the evolution of a DIY gear project.
My biggest difficulty with this long lens was aiming it, which is exaggerated on a crop sensor camera like mine. It's like a powerful telescope or pair of binoculars. If the landscape in which the tiny distant subject is situated has large strong features which can be used to help navigate the lens towards the target it's not hard to find the target. For example, if a ship is on the horizon then aim to one side of the ship, wave the lens up and down until you hit the horizon, and then slide along the horizon until you see the ship. But if the subject is in the middle of something with no easily identifiable guiding features, such as a plane in a blue sky, or a rabbit in a grassy field, it can take an annoying amount of time to find it. And forget birds in flight! I once spent half an hour surrounded by wheeling seagulls and only managed to catch only one.
It was good for easy long shots such as relatively stationary birds posing.
Preening Heron by Chris_Malcolm, on Flickr
Planes in a featureless blue sky would sometimes disappear before I could find them in the viewfinder. I only just managed to find the plane and get this twilight shot of red and blue contrails just after sunset, when one contrail was shading the other from the last rays of the sun. Seconds later the plane had disappeared behind house roofs.
Pink and blue contrail pair by Chris_Malcolm, on Flickr
The decisive moment came when I stood in front of a huge flowering rhododendron bush, and wanted to use the 500mm lens to pick out a particular rather amazing looking cluster high up the bush. That cluster was surrounded in all directions by similar looking clusters of flowers. I tried panning in from various distant easily found features, but got lost in the flowers. I had the camera on a tripod and tried very carefully sighting along the barrel on the lens. Nothing worked. An impatient friend pointedly asked what was the point was of a lens so powerful that you couldn't find anything with it. I decided I had to devise a sighting aid for the lens. Googling for telescope sights and gun sights I came across the red dot gun sight. You use it with both eyes open, one eye looking through it. You place the central red dot over the subject and the gun or lens is aimed. Very fast and easy. No, it doesn't fire a laser spot at the target, it's an optical illusion fabricated in the optics. They come cheap from Hong Kong with standard gun sight mounts. I guessed it wouldn't hard to find a way of attaching it to the flash mount on the camera.
That turned out to be a bad idea for two reasons. The first was wobble. The flash mount had too much play in it for accurate calibration. The second was parallax error, which got worse the higher above the lens the thing was. So I decided to mount it directly on the lens.
500mm reflex with red dot sight (angle) by Chris_Malcolm, on Flickr
I just glued it to a slightly too narrow bit of cardboard tube with a slit in it. Opening up the slit provided the frictional grab, and gave space for the focus hold button. That worked pretty well. The lens axis is parallel to the sight axis, so there's a constant parallax error of a couple of inches, i.e. when the red dot is placed a couple of inches above the target the target is smack in the middle of the central autofocus spot. It lets me find tiny small craft so far out at sea that to the naked eye they are just little flecks of colour in the water. It looked like that little kayak below was pretty invisible to the naked eyes on the bridge of that big ship too! (In fact the helicopter platform in front of the bridge stopped them being able to look down and see it.)
kayak & big ship in Firth of Forth: skandi arctic keeps turning by Chris_Malcolm, on Flickr
The red dot sight also made catching seagulls in flight, even close and fast, trivially easy. In fact just for aiming the lens in the sense of getting the target in the viewfinder you don't need the red dot, or the optics. Just a simple tube will do. Sight through the tube and then while being careful not to move the camera lower the eye to the viewfinder (or the LCD).
MF 2012 Flying Seagull 6 by Chris_Malcolm, on Flickr
It looks a lot nicer now that I've painted it all black.
Red Dot gun sight on 500mm reflex lens by Chris_Malcolm, on Flickr
Yes, the camera's been improved as well. The lens is the 500mm f8 Sony reflex, the only AF reflex in captivity. It's delightfully short and light because there's not much glass in it (mirrors instead of lenses) and the light path is folded. It's the only kind of 500m lens that you can easily bung in your gear bag and carry around just on the off-chance that a long lens photo oppprtunity might turn up. But because it's so small and light it has a very low moment of rotational inertia compared to a conventional refractor 500mm prime. That makes it peculiarly prone to shutter shake from the slam of the focal plane shutter opening up. In my case I found shutter shake starting to blur my shots at shutter speeds less than around 1/300th sec.
The camera has been upgraded to the Sony A77. That solves the problem of shutter shake by having an electronic front curtain shutter. With a static target and a stable tripod I can now get really sharp shots down to seconds of exposure now. That makes it much easier to keep the ISO low. That's very useful with a fixed aperture of f8. The A77 also has better high ISOs than earlier Sony DSLRs. Here's a recent kingfisher shot at ISO 6400. The clouded sun was setting and the bird was in deep shade. I only had time for a quick handheld shot before he flew away. It's heavily cropped and noisy, but to the naked eye the kingfisher was barely visible as a bird. It was just a tiny orange patch in the green foliage which might have been a dead leaf.
Kingfisher at Botanic Garden pond by Chris_Malcolm, on Flickr
The next improvement to the lens will be making up a tripod mount under the centre of windage of the lens plus camera. A long mounting plate would do. Not the centre of gravity, the weight isn't a problem. The problem is gusts of wind catching it. With such a long lens the tiniest movement smears the image. Of course IS is available, but the sharpness is never quite as good as being on a stable support with IS turned off.
I think this kingfisher is one of a pair, and the location is fifteen minutes walk from my home. I'm looking forward to some better low ISO shots, and some baby kingfishers!
My biggest difficulty with this long lens was aiming it, which is exaggerated on a crop sensor camera like mine. It's like a powerful telescope or pair of binoculars. If the landscape in which the tiny distant subject is situated has large strong features which can be used to help navigate the lens towards the target it's not hard to find the target. For example, if a ship is on the horizon then aim to one side of the ship, wave the lens up and down until you hit the horizon, and then slide along the horizon until you see the ship. But if the subject is in the middle of something with no easily identifiable guiding features, such as a plane in a blue sky, or a rabbit in a grassy field, it can take an annoying amount of time to find it. And forget birds in flight! I once spent half an hour surrounded by wheeling seagulls and only managed to catch only one.
It was good for easy long shots such as relatively stationary birds posing.
Preening Heron by Chris_Malcolm, on Flickr
Planes in a featureless blue sky would sometimes disappear before I could find them in the viewfinder. I only just managed to find the plane and get this twilight shot of red and blue contrails just after sunset, when one contrail was shading the other from the last rays of the sun. Seconds later the plane had disappeared behind house roofs.
Pink and blue contrail pair by Chris_Malcolm, on Flickr
The decisive moment came when I stood in front of a huge flowering rhododendron bush, and wanted to use the 500mm lens to pick out a particular rather amazing looking cluster high up the bush. That cluster was surrounded in all directions by similar looking clusters of flowers. I tried panning in from various distant easily found features, but got lost in the flowers. I had the camera on a tripod and tried very carefully sighting along the barrel on the lens. Nothing worked. An impatient friend pointedly asked what was the point was of a lens so powerful that you couldn't find anything with it. I decided I had to devise a sighting aid for the lens. Googling for telescope sights and gun sights I came across the red dot gun sight. You use it with both eyes open, one eye looking through it. You place the central red dot over the subject and the gun or lens is aimed. Very fast and easy. No, it doesn't fire a laser spot at the target, it's an optical illusion fabricated in the optics. They come cheap from Hong Kong with standard gun sight mounts. I guessed it wouldn't hard to find a way of attaching it to the flash mount on the camera.
That turned out to be a bad idea for two reasons. The first was wobble. The flash mount had too much play in it for accurate calibration. The second was parallax error, which got worse the higher above the lens the thing was. So I decided to mount it directly on the lens.
500mm reflex with red dot sight (angle) by Chris_Malcolm, on Flickr
I just glued it to a slightly too narrow bit of cardboard tube with a slit in it. Opening up the slit provided the frictional grab, and gave space for the focus hold button. That worked pretty well. The lens axis is parallel to the sight axis, so there's a constant parallax error of a couple of inches, i.e. when the red dot is placed a couple of inches above the target the target is smack in the middle of the central autofocus spot. It lets me find tiny small craft so far out at sea that to the naked eye they are just little flecks of colour in the water. It looked like that little kayak below was pretty invisible to the naked eyes on the bridge of that big ship too! (In fact the helicopter platform in front of the bridge stopped them being able to look down and see it.)
kayak & big ship in Firth of Forth: skandi arctic keeps turning by Chris_Malcolm, on Flickr
The red dot sight also made catching seagulls in flight, even close and fast, trivially easy. In fact just for aiming the lens in the sense of getting the target in the viewfinder you don't need the red dot, or the optics. Just a simple tube will do. Sight through the tube and then while being careful not to move the camera lower the eye to the viewfinder (or the LCD).
MF 2012 Flying Seagull 6 by Chris_Malcolm, on Flickr
It looks a lot nicer now that I've painted it all black.
Red Dot gun sight on 500mm reflex lens by Chris_Malcolm, on Flickr
Yes, the camera's been improved as well. The lens is the 500mm f8 Sony reflex, the only AF reflex in captivity. It's delightfully short and light because there's not much glass in it (mirrors instead of lenses) and the light path is folded. It's the only kind of 500m lens that you can easily bung in your gear bag and carry around just on the off-chance that a long lens photo oppprtunity might turn up. But because it's so small and light it has a very low moment of rotational inertia compared to a conventional refractor 500mm prime. That makes it peculiarly prone to shutter shake from the slam of the focal plane shutter opening up. In my case I found shutter shake starting to blur my shots at shutter speeds less than around 1/300th sec.
The camera has been upgraded to the Sony A77. That solves the problem of shutter shake by having an electronic front curtain shutter. With a static target and a stable tripod I can now get really sharp shots down to seconds of exposure now. That makes it much easier to keep the ISO low. That's very useful with a fixed aperture of f8. The A77 also has better high ISOs than earlier Sony DSLRs. Here's a recent kingfisher shot at ISO 6400. The clouded sun was setting and the bird was in deep shade. I only had time for a quick handheld shot before he flew away. It's heavily cropped and noisy, but to the naked eye the kingfisher was barely visible as a bird. It was just a tiny orange patch in the green foliage which might have been a dead leaf.
Kingfisher at Botanic Garden pond by Chris_Malcolm, on Flickr
The next improvement to the lens will be making up a tripod mount under the centre of windage of the lens plus camera. A long mounting plate would do. Not the centre of gravity, the weight isn't a problem. The problem is gusts of wind catching it. With such a long lens the tiniest movement smears the image. Of course IS is available, but the sharpness is never quite as good as being on a stable support with IS turned off.
I think this kingfisher is one of a pair, and the location is fifteen minutes walk from my home. I'm looking forward to some better low ISO shots, and some baby kingfishers!
