Vac Sampling

As I mentioned in the last post, yesterday I gave the vac sampler a quick blast (or suck) - albeit just down the lane on a rough verge with grasses, docks, nettles a few thistles and other low-growing vegetation. Given the location I wasn't expecting too much, but I ended up filling pots pretty quickly. Here's a snap of the first sample dumped into a shallow white tray ....

Anyone with a keen eye, or the patience to click for bigger, will note a host of tiny insects and collembola. It doesn't look much, but honestly this was alive with tiny life. I only took four samples in all, but each tray took a fair few minutes to observe and try to wrangle the odd specimen into pots.

I learnt a couple of things that I need to consider on the next go with this. Firstly, with such tiny stuff and associated dust particles and seeds etc, it only takes a very slight breeze to blow everything around or even out of the tray. Even leaning in with the eyeglass and breathing out was enough to shift what you're about to look at. I need to see if I can knock up some sort of wind-shield to sit around the tray whilst staring at it. Also, given that sitting the tray on the floor is easiest, I really need to look at ensuring I'm kneeling on soft ground or get some knee pads (how old does that make me sound!). Thirdly, wrangling tiny weevils and beetles into pots is hard enough, but for Collembola and anything that jumps I may well have to resort to using the pooter that I have and have barely ever used.

So, in four short blasts in unpromising habitat, what did I get? Or I should say what did I retain and identify instead of ignore and leaving for another day:

Five springtail species, including three new for the square yearlist: Orchesella villosa, Pogonognathellus longicornis and (new for me) Entomobrya nicoleti.

Entomobrya nicoleti

A couple of Orchesella villosa alongside one of several species I ignored.

Seven beetle species, including five new for the square yearlist: Hypera rumicis, Cartodere bifasciata, Cartodere nodifer, Perapion violaceum and (new for me) Perapion hydrolapathi.

Cartodere bifasciata

Cartodere nodifer

Perapion violaceum (left) & Perapion hydrolapathi (right)

A bug and a leafhopper new for the square yearlist: European Cinchbug and Eupteryx florida.

European Cinchbug (macropterous)

Oh, and an immature mollusc ....

Kentish Snail

I reckon the bits I identified only account for maybe 50% of the species actually hoovered up. I didn't really check the time, but in all these four samples and poking about in the tray only took c40mins or so. Of the species added, I reckon that all of the springtails and both of the Cartodere spp. would never have been picked up through sweeping. Having said that, the Hypera rumicis is one I've never seen in the square and I can't recall seeing European Cinchbug down here either.

I certainly looking forward to giving this more effort in the square.

Here's a track that is absolutely packed with small unidentifiable samples - like my tray:

Vignette

For several years now (since May 2012 having looked back) I've been using the Raynox DCR-250 macro lens attachment, first on the Lumix FZ-45 bridge I had at the time and since October 2014 on a Nikon Coolpix P600 bridge. I'm not going to ever pretend that it's as good as working with a proper macro DSLR set-up, but I love it and for the cost it is unbeatable. As with any macro lens, depth of field can be an issue when the camera is fully zoomed in but for most inverts and especially reasonable sized micromoths it's great.

Actually the only problem I have endured is when photographing slightly larger moths, especially some of the geometrids if they sit with wings splayed out a bit. The problem is that as with any lens attachment there is an element of vignetting. Depending on the size and posture of the moth, I can either zoom through the vignetting, or crop it out. So for web purposes the only issue really is that sometimes I am having to crop to a size that means I'm losing a fair bit of the original image size. I'm also sometimes constrained on the aspect ratio which is why I tend to use a variety of image sizes on here - it's not all for artistic purposes, sometimes I have no choice but to crop at a 1:1, 3:2 or 3:4 ratio instead of 4:3.

Here's an example ......

Maiden's Blush - full image with no cropping, vignetting in corners

So as you can see with this example, I can easily crop this image to either a 1:1 square or a 3:4 portrait, but in both instances I'm losing half the original image size. Of course in this example it doesn't help that I opted for an arty on-the-skew framing rather than photographing the moth 'straight-on'. Here's a better example ......

Dotted Border - full image with no cropping, vignetting in corners

Same image showing how much I lose from cropping to a 3:2 ratio to lose vignetting

Where it becomes more of a problem is that I am sometimes forced to crop the subject a bit more tightly than I'd like, and this in conjunction with the contraint on cropping ratio means that images might not be great for future publications.

Anyway, you get the gist. So after years of this I suddenly thought this week that maybe I could just get hold of the lower magnification DCR-150 lens which will give more scope for larger/odd shaped moths. So I got one and had a quick play today. Here are two shots of the same Clouded Drab from last nights trap - not an ideal subject but shows the potential. There are subtle focal length and focussing differences between the two lenses, so what I have done is zoomed the camera to the point where I have nearly lost the vignetting effect (just a slight shadow in the corners).

Using DCR-150

Using DCR-250

Neither of the above is what I want. To get a better surround to the subject on the DCR-250 I need to zoom out ... which will increase the vignetting. On the DCR-150, there is plenty of scope to zoom in and improve image size whilst losing any vignetting but I might lose some depth of field. I'm going to have to play around over the coming weeks to see if I can get a nice balance, but I think I'll be using DCR-150 for most macro moths and DCR-250 for most micros and beetles, bugs etc. Anything larger like Hawk-moths, butterflies and dragonflies are best photographed without any attachment.

The other realisation is that the Coolpix P600 is getting on for five years old now, and although I'm still very happy with the image (a lot cleaner sensor than the Lumix) it is starting to play up a bit with some of the button/dial functions being flaky. Quite possibly time for a new camera this year - no idea what but will have to start looking.

Before I go, here's my best effort with that tiny weird beetle from yesterday - a not very compliant subject and hard to get a nice balance between depth of field and image size (I repeat it was very tiny!).

Cartodere nodifer - Narborough Bog 26/03/2019