Variable damselfly (Coenagrion pulchellum)

The Variable Damselfly is an uncommon species which occurs in widely scattered colonies throughout Britain but it can be abundant where it occurs. This picture was taken at Baston Fen in South Lincolnshire - a well known and good site for the species - on 3 July 2018.

Variable Damselfly male (Canon 80D, 100mm macro, F11, 1/250s, ISO 400)

I have seen the species at a few other sites in the region around Peterborough, but most consist and abundant at Baston Fen. In general, I would say it looks a bit daintier and darker than the very common Azure Damselfly (C. puella) with which it tends to occur. Males are fairly easily separated: the mark on the 2nd abdominal segment is typically shaped like a wineglass in C. pulchellum (but like a tumbler in C. puella - i.e. "U" shaped and not connected to the basal black band of the segment); the antihumeral stripes (the pale stripes running longitudinal down the thorax) are interrupted in C. pulchellum (broader and continuous in C. puella) and the 9th abdominal segment is mostly black with only a narrow, basal blue stripe (9th segment half or more blue in C. puella). However these features are quite variable (hence the name - Variable Damselfly!) especially the shape of the mark on the 2nd abdominal segment of the male.

Comparison

High ISO, available light insect shots

Conditions in the garden this afternoon were warm but overcast. I was taking some available light pictures of insects coming to Marjoram flowers (Oreganum vulgare). I was trying to maintain a fairly high shutter speed (1/400 - 1/500) because I was hand holding the camera with a 100mm macro lens and at an aperture of F6.3 or F8. To achieve this, I had to let the ISO go quite high.

Gatekeeper on Marjoram (100mm Macro on Canon 80D, 1/500s, F6.3, ISO 4000)

Here is an example of a shot of a Gatekeeper taken at ISO 4000 (1/500s, F6.3). This is a somewhat cropped version (3675 x 3090) of the RAW file (Canon's .CR2 file format - 6000 x 4000) as rendered into GIMP 2.10.2 by the default settings of nufraw. Whilst noise is evident on close examination, I think the image is quite usable and is pretty impressive for ISO 4000.

Digitising old slides using an Ohnar zoom slide duplicator

I have loads of old 35mm slides, mostly from my days of film photography using the Olympus OM2 system, but also some even older. There are some good wildlife photographs here as well as stuff of historical, family and personal significance. Over the years, I have used a number of means of capturing these including a CanoScan III film scanner, a "Compact Digital Film Scanner" from Jessop's and a 35mm holder for a flatbed scanner. None of these have been particularly satisfactory and none of them work with my current hardware.

Be that as it may, there are times when I want to recover images from my old slide collections. So I have recently tried yet another approach: I have an old device - an "Ohnar Zoom Slide Duplicator" by Bush & Meissner Ltd.

I don't remember when I bought this, but probably in the 1980s. It is designed to fit on a 35mm SLR camera using a T2 mount - and mine has an Olympus T2 mount, so clearly dates from my Olympus OM2 days. The 35mm negative or slide goes in the holder (at the right hand end in the photo above) and the whole device is pointed at some bright light source (e.g. an electronic flash). The holder has a translucent white diffuser built in. The holder allows the slide to be moved from side to side and can be moved up and down and rotated. The device also has a built in 1 - 2.5x zoom. So it is possible to photograph the whole slide or any portion of it.

A problem is that this device was designed for use on a 35mm SLR. I expect that it would deliver an image of the whole 35mm frame when on a full frame DSLR body but, mounted on a crop sensor DSLR such as my Canon 80D, the minimum magnification is effectively 1.6x (the body's crop factor) and it is not possible for me to capture the whole frame.

In practice, it mounted easily enough using a Canon T2 mount. I find that a good exposure is only achieved by trial and error, which when using a DSLR, is not a problem. I simply inserted a slide, pointed one of my Yongnuo 560 III flash guns at the diffuser, put everything on manual, set the ISO to 100, shutter speed to 1./250 (the flash sync speed of this body) and then took a series of trial shots, adjusting the flash power each time until I got an acceptable histogram. I find that the density of slides varies quite a bit, so the flash power needed for a good exposure varies by at least a stop either way between different slides, but typically around 1/16th power.

The main problem I have encountered with all of these devices (and this is no exception!) is that they tend to significantly increase the contrast of the image. Even using the best method and exposure, the resolution and dynamic range of 35mm colour slides are not actually very good compared to what we have become accustomed to with modern digital images, so the resulting images are rather disappointing whatever the capture device.

Courtship of Poecilobothrus nobilitatus (Dolichopodidae)

The Dolichopodid fly Poecilobothrus nobilitatus is a common species which can be abundant in the right conditions. It likes the shallow, muddy edges of pools and streams and even muddy puddles in dappled shade. Dolichopodids (long legged flies) have extravagant external male genitalia, they are typically colourful with metallic green and blue colours and iridescent eyes and the legs of males are often ornamented. In this particular species, the males, which are about 5-6 mm long, have the wings blackened over the outer half and milky white tips.

Poecilobothrus nobilitatus male

 Females are usually a bit duller and lack ornamentation. In this species, the wings are not coloured.

Poecilobothrus nobilitatus female

During courtship, Dolichopodid males semaphore with there ornamented legs, or in this case, their coloured wings. In this species, courtship takes place on the surface of wet mud or water. At the start of a courtship bout, the male approaches a female and and waves its wings in short bursts when a few centimeters away, it then jumps over the female and repeats from the other side. If the female shows any interest, the second phase involves the male hovering in a short, wavering flight, in front of and to either side of the female.

There is a small pond in my garden in the shade of a Scot's Pine tree. This obviously provides the right conditions for P. nobilitatus and large numbers are present at the moment - and courting furiously.

Poecilobothrus on the pond - these are mostly females

 I wanted to try and photograph this courtship behaviour, but I knew it would be difficult. The flies are small and, to get a good image, would need a reproduction ratio close to 1:1, which means getting quite close. At these short distances, the rapid movements involved would make it very difficult to capture. In these circumstances, electronic flash provides sufficient illumination to achieve the small apertures necessary for the depth of field and also the short duration of the flash has a chance of freezing the movements.

Photos were taken using a 100mm macro lens at around f16. The main illumination was from Canon MT-24 dual flash with a Yongnuo 560 III providing background illumination. A Yongnuo RF605C radio unit was used to trigger the background flash. The Canon 80D camera was set in manual mode and the flash power set as low as possible - around 1/8 or 1/16 power. This reduces the flash duration allowing for high speed imaging. The maximum flash sync speed for this camera is 1/250th sec, so the shutter speed was set to 1/250 or 1/200th. At 100 ISO, f16 and 1/250 sec, the available light level would lead to underexposure of about 4-5 stops, so the exposure is totally due to the flash, therefore the camera's shutter speed is irrelevant (providing the shutter is fully open when the flash fires).

Male (right) approaching a female (left) wing waving

Male wing waving

Male leaping over a female