Wednesday, April 25, 2018

Flies in flight


The hoverfly Epistrophe eligans male in flight (F11, 1/1000s, ISO 1600, 100mm Macro)
Taking pictures of flies in flight is rather challenging. Hoverflies are a little easier than some others because they hover in one place for a few seconds at a time. Males are territorial and tend to repeatedly return to a similar air space. Epistrophe eligans is a common, early spring species in which the males lek. A group of males tends to form a loose cluster around the end of a branch and jostle for position. These were taken at a reproduction ratio between 1:1 and 1:2 so, even with a 100mm macro, it is still necessary to get pretty close to the fly to focus. Auto-focus is of little use in this situation. It is better to switch to manual focus and focus by rocking backwards and forwards. A small aperture is necessary to get enough depth of field. These wee taken at F11. A fast shutter speed is also necessary to stop motion of both the fly and the camera. Even in bright sunshine, a high ISO will be necessary. So the camera (Canon 80D) was set in manual mode (M) with 1/1000s and F11 dialled in and the ISO set to "Auto". I used high speed shooting mode to take brief bursts of shots when the fly came into focus through the viewfinder.

The Beefly, Bombylius major, is another common early spring species that hovers, although not as persistently as a hoverfly. The following shot was taken using similar techniques.

Bombylius major (F8, 1/1000s, ISO 2500, 100mm macro)

Friday, April 20, 2018

Kowa TSN-PA8 for DSLR digiscoping

I have previously written about digiscoping using a 50mm lens on the DSLR camera body. However, an alternative is to mount the camera body directly on the telescope, using the telescope's optics as the lens system. My scope is a Kowa TSN-823M, which is a fairly old scope that is no longer in production. Kowa have offered an adapter of this type (TSN-PA7) for their current 'scopes, but their adapter for the legacy range of 'scopes - including mine, is a bit more recent. This is the TSN-PA8.
TSN-PA8 mounted on the 'scope eyepiece with Canon 60D fitted.
The adapter is in two parts: a collar that screws on to the accessory mounting thread around the eyepiece aperture of the telescope and a tube which fits over the eyepiece, slips onto the collar and is held in place by a pair of screws. The camera is mounted using a T2 mount which screws on to the outer end of this tube.
from left to right, telescope with the eyepiece removed, collar, tube and the Canon T2 mount at the bottom
The outer end of the tube is closed by a piece of coated, optical glass which covers the eyepiece and prevents any muck, dust or moisture which might be on it from getting into the mirror box of the camera and hence on to the sensor. This was added to the PA7 adapter about 2015 (and it became the PA7A) but, as far as I know, has always been a feature of the PA8.
The assembled mount in position over the eyepiece. Note the optical glass covering the end of the eyepiece to prevent anything getting into the mirror box of the camera.
The cut-outs on the side of the tube allow access to the eyepiece's zoom ring so that you can still operate the zoom whilst the camera and adapter are in place.
Ports in the side of the tube allow access to the eyepiece zoom ring.
Overall, it is a well made and well designed, if rather expensive, piece of kit and does the job of mounting a DSLR on the 'scope very well. It is fairly quick and easy to fit. Swap the camera lens for the adapter, slip it over the eyepiece and do up the two securing screws and you are ready to go. The camera can be oriented either horizontally, in landscape mode or vertically, in portrait mode, just by loosening the screws and twisting and, unlike my previous DSLR digiscoping setups, the zoom function is accessible whilst the camera is mounted.

In use, the usual problems of digiscoping remain. Firstly, the field of view is very small, so finding your target is often quite difficult and it can be rather tricky to keep a moving subject in view. Secondly, the magnification is considerable and the whole setup rather cumbersome, so camera shake is a big problem. It needs a pretty fast shutter speed and you really want to trigger the shutter without touching the shutter button. I usually use either the 2 second delay timer or the Canon RS-60E3 remote shutter release. I find one difference with my previous digiscoping attempts is that I don't get any vignetting, even at the lowest zoom magnification setting.

According to info on the Kowa web site, at minimum magnification this set up is roughly equivalent to a 1200mm, F12 lens on a 35mm camera and a maximum zoom a 2900mm lens at F34. On an APS-C sensor camera like mine, you need to multiply these focal lengths by 1.6x to appreciate the sort of reach you get.

Exposure Settings

At these very small apertures, even on a bright day, a pretty high ISO is needed to get a decent shutter speed. I usually try to stick to 1/1000s to counter subject movement and camera shake, so the ISO rarely goes below 1600. I put the camera in manual mode (M), set the shutter speed to 1/1000s and select Auto ISO. I generally find I have to dial in between minus one and minus one and two third stops compensation to get a correct exposure, otherwise the metering system seems to over-expose everything. I am not sure why this should be so.

Focusing is, of course, manual and done with the telescopes focus knob. If the subject is fairly static, live view is very useful for adjusting the focus accurately. I use as much magnification as I can get on live view to critically set the focus. Otherwise, make sure that the dioptre setting on the viewfinder is properly adjusted for your eyes before you start and focus as best you can visually, through the viewfinder. You don't get a lot of depth of field, so I generally take a series of shots, adjusting the focus each time - unless I have been able to set it up accurately on a static subject using live view.

Results

These examples are derived from straight RAW shots taken using my Canon 80D on the setup described, at minimum zoom unless otherwise stated.
Gadwall female, 1/1000s, ISO 2000, -1⅓ exposure compensation

Great Spotted Woodpecker on feeder, 1/1000s, ISO 6400, -1⅓ exposure compensation
These two shots of a coot were taken seconds apart, the first at minimum zoom and the second at maximum.
Coot at minimum zoom, , 1/1000s, ISO 1600, -1⅓ exposure compensation
same Coot at maximum zoom, , 1/1000s, ISO 5000, -1⅓ exposure compensation
I find that shots taken at higher zoom levels are always rather soft. I think this is because diffraction becomes a very significant issue at such tiny apertures.

This shot of a  Heron catching a fish illustrates the problems of capturing action with such a cumbersome setup and without the benefits of auto-focus. Here, I haven't got the focus quite right - I think the plane of maximum sharpness is just in front of the bird and, despite the fast shutter speed,  camera movement is obvious (I think I jabbed at the shutter button with my finger to try and capture the moment!).
Heron catching a fish, 1/1000s, ISO 2000, -1 stops exposure compensation

Thursday, April 19, 2018

Long term review of Manfrotto 701RC2 fluid video tripod head

I bought my 701RC2 on 8th Feb 2006 for £83.94. A quick web search shows that, whilst it is no longer listed on the Manfrotto web site and is, therefore, presumably no longer in production, there are still sites offering it for sale new (and at prices less that I paid for it 12 years ago).
Manfrotto 701RC2
I have used it both for my birdwatching telescope and for photography continuously and it does the job well. The movement is smooth, it locks into place easily and tightening the pan and tilt screws do not alter the 'scopes position appreciably. It is rated for 4kg, so it has no problem with either my 'scope or camera with a long lens.

One of the features I like is the built in spirit level. Whilst it has obvious benefits for photography, I also find it quite useful when birdwatching. If I am sea watching or at somewhere like a large reservoir, I like to level up the tripod so that I can pan the 'scope round in a wide arc without having to constantly readjust the tilt. Having a spirit level built into the base of the tripod head is therefore, very handy.

Spirit level
Another feature which I have more mixed feelings about is the sliding top plate. This allows the quick release plate to be moved backwards and forwards by +/- 20 mm. You loosen off a screw and the whole plate slides backwards and forwards.

Scale for the sliding quick release plate.
In theory, this is a nice idea. It allows you to balance the head nicely for different gear so that the tilt mechanism stays where you put it without having to tighten it up hard. In practice, it is not so good. Firstly, the travel is not sufficient to properly balance the gear I normally use. My telescope (Kowa 823) tends to be a bit back heavy - so it will tend to tip backwards unless the tilt screw is well tightened. So, I slide the plate all the way forwards - which is nearly enough to balance it but not quite! In contrast, my Canon 80D with the 100-400mm lens at full zoom is decidedly front heavy and the plate won't slide back nearly far enough to counter this. Secondly, it is impossible to tighten up the locking mechanism on the sliding plate sufficiently to stop it sliding. Tighten it up as much as you can and it will still moves relatively easily. The reason is easy to see: the tightening mechanism consists of a little rectangular plate which is pressed against the side rail of the sliding plate by tightening the screw. But the area of contact is only 20mm long and it is metal on metal, so not much friction.

Tightening mechanism: top - the screw removed, bottom - the plate and screw.

This can get quite annoying since, I have it set up as best I can for whatever gear I am using, but as soon as you carry it about for a bit, the plate slides to one end or the other and isn't in the right place for the next time you stop.

It has been a fairly robust piece of kit and is still in good, functioning condition after 12 years, if with a bit of chipped paint here and there. Spares are available from the Manfrotto spares web site and I have had to avail myself on a couple of occasions. I managed to lose the long handle on my way back from one trip abroad (it was disassembled for carriage) and I managed to break the head off the pan tightening screw on another occasion. In both cases I got the necessary parts with no problem, but they are rather pricey!

All in all, it has been a very good tripod head and I continue to use it. The one thing I would change is the sliding quick release mount. It needs the locking mechanism modifying so that it locks in place positively and, ideally, needs a bit more travel.

Tuesday, November 01, 2016

Mandarin

Mandarin drake, Eye Green LNR, 31/10/2016, taken with Canon 80D, Canon 100-400mm f4-5-5.6L MkII at 300mm, f5.6, 1/1000s, ISO 800
Mandarins have been reported from time to time at Eye Green LNR (a disused clay pit just east of Peterborough) over at least the last year and I have seen two males there on several occasions. But whenever I have taken a camera, they have failed to appear! This was the first occasion I have found them when I had a camera with me and it so happened that the light was rather nice with hazy, low afternoon sunshine lighting up the autumn colours of the trees around the lake and reflecting in the water.

The Mandarin is considered to be an introduced species in Western Europe, including the UK, although, according to Sir Christopher Lever's monograph on the species (Poyser, 1990), there is evidence that it occurred in this part of the world in the past - i.e. 600,000 years ago in the Cromerian Inter-glacial! The species was widly sold in the far east and many were probably brought back to Britain, especially in the 19th and early 20th Centuries. The first known reference is to birds displayed in the gardens of Sir Matthew Becker at Richmond Green, Surrey in 1745. He was a director of the East India Company so it is easy to understand how he obtained them. By 1834 they were breeding in the gardens of the Zoological Society at Regent's Park, London and the first mention of a wild breeding bird was one shot at Cookham on the River Thames in Berkshire in 1866. By the First World War, over 300 were reported to be breeding in and around the Duke of Bedford's park at Woburn Abbey and by the second World War there were strong populations breeding wild especially at Windsor Park, the Forest of Dean and around Woburn. As a young bird watcher, I saw my first one at Virginia Water around the mid 1970s.

The native range of the species is in the far east with a migratory population that breeds in the east of Russia and China and winters in Korea and Vietnam, and a resident population in Japan. The Russian/Chinese population is believed to have declined substantially over recent decades and may now number less than 1,000 pairs, but the Japanese population is believed to be stable at around 7,000 pairs. An estimate published in the BTO's journal, Bird Study, in 1988 by A.K.Davies put the UK population at around 7,000 individuals with about 2,500 breeding pairs, but there is some evidence it has spread further since that time. There are other, smaller introduced populations in Europe, especially around Berlin and a couple of small populations in the USA. The IUCN has assessed the species as "Least Concern", so it is not currently though to be threatened, despite the declines in China and Russia.
Mandarin drake against autumn colours reflected on the water - details as above.

Tuesday, October 11, 2016

Focal length of digiscope revisited


I wrote a blog post about attempting to calculate the focal length of my digiscoping setup some time ago (here) for the DSLR setup I described in this blog post. I came to the conclusion that, with the telescope's eyepiece on its minimum magnification of 20x, it was acting as about a 1,000mm F12 lens (and since the camera - a Canon 60D - has a 1.6 crop factor, the 35mm equivalent focal length would therefore be 1,600mm).

Back in February, I was preparing a talk on digiscoping for a local camera club and decided to tackle the same question a different way. I went to the Rothschild's Mere hide at Woodwalton Fen and spent a couple of hours taking pictures of the same subjects with various digiscoping setups and also with my Canon 300mm F4 prime lens which I could then use as a standard for comparison.

Here are some Cormorants sat on the tern raft in front of the hide taken using the Canon 60D with the 300mm F4 lens.
Scaled down image from full frame: 300mm, F8, 1/1000s, 400 ISO
100% crop showing the measurement I made from the beak tip to the back of the head on a line projected through the point of the yellow triangle on the face
Whilst viewing the image at 100%, I measured the width of the head of the adult Cormorant on the right, from the tip of the bill to the back of its head along a line projected through the point of the yellow triangle below its eye. This line was 263 pixels long in this case. 

To check that this worked reasonably well, I put my 1.4x converter on the lens and took, as near as possible the same shot (bearing in mind that this all takes time and birds move!).
Scaled down image from full frame: 300mm with 1.4x converter, F8, 1/1000s, 800 ISO
100% crop. Same measurement - 374 pixels
Note I had to bump the ISO up by a stop (from 400 to 800) to get the same exposure as you would expect. As near as possible the same measurement of the same bird (but of course there is some error because it may well have its head in a slightly different position) was now 374 pixels. 374/263 = 1.42, so pretty close to the 1.4x I would expect from the converter.

Here is a digiscoped picture of the same bird with my telescope's eyepiece on its minimum magnification of 20x.
Scaled down image from full frame: Digiscoped image, Kowa 823 with 20-60x eyepiece on minimum, Canon 60D with an Olympus 50mm F1.4 lens wide open at 1/320s, 800 ISO mounted on the eyepiece.

100% crop, Same measurement: 925 pixels
The whole head no longer fits in my 100% crop shown here, but the same measurement on the original image now comes out at 925 pixels. 925/263=3.509 suggesting the focal length equivalent of 1,053mm (300 x 3.509). This is pretty close to the 1,000mm I calculated in my previous blog post. Note also I have gone from an exposure of 1/1000s at F8 to 1/320s with the Olympus 50mm F1.4 wide open to maintain the same ISO setting.

With the telescope's eyepiece bumped up to its maximum magnification of 60x here is what I got.
Scaled down image from full frame: Digiscope at 60x, 1/60s, 800 ISO
100% crop, same measurement 3052 pixels
Now we can only get the eye in on a 100% crop, but the same measurement across the head comes out at 3052 pixels. 3052/263=11.583 suggesting a focal length of 3,375mm. The exposure had to go from 1/320s to 1/60s (which is probably one reason why it is not very sharp and shows signs of camera shake!) - another 2.5 stops. Given that this is a 1.6x crop factor camera, the 35mm focal length equivalent is a whopping 5,560mm!

Saturday, October 08, 2016

Phoneskoping

I have an HTC one-V smartphone which runs Android 4.0.3. It has a 5 Mp camera (1552 x 2592 pixels) - which is not of tremendously good quality! Nevertheless, since I usually carry it when I am out birding, the idea of simply being able to slip it on to the eyepiece of my telescope for a quick record shot, is quite attractive.

I came across Phoneskope adapters at the Bird Fair at Rutland Water some years ago. At the time, they made a universal adapter that attached to a 'phone cradle using self-adhesive Velcro (I am not sure whether they still do this model). I paid £28.80 for the version of the adapter made specifically for my telescope eyepiece (Kowa 20-60x zoom) and about another £3 for a hard shell case for my 'phone from eBay. The cost of the adapter seemed a bit high for a simple plastic cup with a hole in the bottom - but I can understand that tooling up to make these is probably quite expensive and there are a lot of different eyepiece models out there. So the market for each type of adapter to fit a particular model is probably quite restricted!
The phneskope adapter attaches to a hard shell case for the phone by a self-adhesive ring of Velcro.
The Phoneskope adapter came with a self-adhesive Velcro ring. It was straightforward to stick one half to the back of the adapter and the other half to the hard shell case, centred around the camera holes. The tricky part is getting the two parts attached together by the Velcro so that the camera is exactly centred over the eyepiece of the telescope. This required very precise positioning and took a lot of trial and error. Once I got the two halves together in the correct alignment however, the Velcro formed a pretty strong and robust join, so I haven't had to do it again. Here it is in place on the eyepiece of my telescope:
The photo shows the Android stock camera app. There is a zoom bar up the left hand side the shutter button is the blue circle at the lower-right. Use is very straightforward (assuming the telescope is focused on the subject before mounting the phone):
  1. You need to zoom in a bit to reduce the vignetting at the top and bottom corners by tapping the zoom bar,
  2. Tap on the image where you want the camera to focus (usually the bird's eye),
  3. Tap the shutter button to take the picture
This is easy and quick, but the downside is step 3 - tapping the shutter button. One of the biggest problems with digiscoping is camera shake, so the last thing you want to do is to tap the camera at the moment you take the photo! I found a free Android app called "Say cheese camera" which essentially adds voice activation for the camera. According to Google Play, it works with Android 2.2 and upwards and there is also an iPhone version available. As the name suggests, what this does is to trigger the camera when you say "cheese" - or any other distinct and isolated word (or even clap your hands - not a good move in a bird hide though). I find "Go!" or "take" work well and are less embarrassing when other people are nearby! The advantage, of course, is that you can trigger the camera without touching it.

I have to say that the results I get are not brilliant, but I think that is down to this particular phone model which has a pretty indifferent camera. The HTC one-V was launched in 2012 and clearly the technology has moved on. The current generation of phones have much better cameras and there are some pretty decent bird images to be found on Flickr, forums, etc. taken using mobile phones. There is certainly nothing wrong with the Phoneskope adapter. The whole this is quite robust, and small and light enough to be conveniently carried in my anorak pocket. It slips on easily and quite firmly and I can quickly grab a record shot with the minimum of fuss. These are good enough to convince my birding friends that I have actually seen what I say I've seen., which is the main point of the exercise for me.
Red-necked Grebe at Rutland Water

Thursday, October 06, 2016

Manfrotto 349 hide clamp

I am not sure exactly when I bought my hide clamp, but I think it was probably in the early 2000s. It is a Manfrotto 349 and is still available (for about £60 on Amazon - I think I paid £42 for mine, which indicates how long ago it was).
It is a pretty simple device: a tube which fits the centre column from my tripod forming the stem of a G-clamp which allows it to be firmly mounted on the edge of the shelf in a hide, or even on something like a fence rail or tree branch. The jaws of the clamp open up to about 60mm and the whole thing weighs 400g. Here it is in position, clamped to the shelf in a bird hide and supporting my telescope:

Of course, it can just as easily be used to support a camera with a long lens. What I like about this design is that it utilises the centre column and pan-tilt head from my tripod - which I am carrying anyway. Some other designs, like the Opticron Universal or the RSPB's hide clamp, effectively have their own centre column and head built in, so if you are carrying a tripod, you end up with two similar bits of kit and have to carry both!

I have found it to be very well made and robust. The cross bar on the screw which tightens the clamp is big enough so that you can clamp it pretty firmly and the centre column can be securely fastened over range of heights to cope with hides with the shelf at varying distances below the viewing window. Swapping the centre column between the tripod and the clamp is very easy and quick. I have only come across one hide where I couldn't get the clamp over the shelf and that is the Jordan Hide at Holkam - which has an edging strip attached to the shelf which is too wide for the jaws to fit over. However, somebody has thoughtfully cut notches in this strip, so there are just a few place where the clamp will fit. Frustrating if the hide is full and you can't get a seat in the right spot!

I find I use a hide clamp less often these days. Hide designs have moved on and it is not infrequent to find hides where you can use a telescope or camera standing up with your tripod fully extended. For example the Island Mere Hide at Minsmere or the Parrinder Hide at Titchwell are designed to allow this. Another design I like is the hides at the RSPB's Frampton Marsh reserve where the benches are not fixed down. This allows you to move the seat far enough away from the hide wall so that you can sit behind a partially extended tripod. Nevertheless, many more traditional hides have a fixed bench and a single, narrow window designed for those sitting on the bench. In these cases, the space between the bench and the shelf is too narrow to use a tripod (I really have tried!) and a hide clamp is the solution for me.

The only downside to a hide clamp (apart from remembering to take it) is that any vibration in the hide caused by people moving about and getting up and down is transmitted to your telescope or camera through the building's structure. Of course this happens to some extent however you use your optical gear, but it is exacerbated by having your equipment firmly clamped to the structure. This can get annoying when hides are busy, but I don't usually find it to be more than a momentary issue.