Saturday, 7 September 2013

snaps and traps


questions, questions, questions... if it were possible to benefit from any expertise or experience on the following, that would be much appreciated:

firstly, i'm planning a portable moth trap. (so far i've only ever used a 15w trap, run off the mains.) i'm not sure what wattage of light to go for. i had been considering the circular 22w bulbs but now wonder if that would be a mistake in terms of the battery ampere-hours required. how successful are 8w bulbs at bringing in the moths? (15w bulbs seem problematic as an 18 inch long bulb doesn't seem easy to carry around, or to mount on a portable trap.) if i used a 12 inch 8w bulb, what sort works best, and is it best to mount it vertically or horizontally? has anyone ever used a suspended trap with the light, and trap entrance, underneath? on occasions it would be useful to be able to run the trap for more than one night without having opportunity to recharge the battery in between. is that hoping too much, in terms of a practical power supply? does anyone have experience of how different types of batteries perform/last? are there any easily portable lead acid batteries? are there drawbacks to li-ion batteries in addition to the cost?

secondly, i'm wondering about buying a better camera. i've been using a compact point and shoot camera but the autofocus technology doesn't allow the lens to get close to the moth and it's difficult to avoid chromatic aberration around any edges. for micros, it's all but useless (and it's not great with macros, particularly if the light is anything less than bright). i don't have much technical knowledge of photography. does anyone know if any of the newer compact cameras are up to the job?

7 comments:

  1. Hi Peter, we use Anglian Leps Heath traps (easy to carry short distancesin a bag)and a wooden skinner, not very portable mainly because of the weight of the trap box, with 15w actinic tubes.
    Never had a poblem with the Heath blowing over but don't put it out in v high winds, we peg it down with tent-pegs and have the battery leaning against one side.
    Both use 18Ah batteries,(two can be carried easily in a ruck sack) suitable for summer months only. Winter battery is a 33Ah, only manage one in a rucksack.
    The length of the tube may be a problem if you intend walking a long distance, but we have not broken one yet.
    The 33Ah battery will last two nights in the summer, but not a good idea for winter as a low battery can damage an actinic tube.
    No experience of li-ion batteries.
    Liz has tried lots more traps than we have so may be able to answer more of your questions.

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  2. Peter, When considering the wattage of lamp in relation to the battery use the formula Watts = Voltage X Amps (I). Therefore I = W/V. A 15 watt tube would consume 1.23 amps. Round that up to 1.5 amps to cover for conduction loss in the wire etc.

    When it comes to batteries you should only use 50% of its charge if you want the battery to last a long time. Exceeding that will rapidly kill the battery and also decrease the life of the tube.

    Evan

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  3. I did write a screed but managed to lose it before it was published. I'll contact you by e-mail Peter as there is a lot of info available plus you could try out various traps if we loan them to you.

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  4. Peter, We have taken all our pictures with either a Nikon P150 and the smaller Panasonic DMC-TZ30. Have a look at them to see if they come up to your needs. Remember that on the blog all the pictures have been compressed losing some quality. Evan

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  5. thank you for all the, very helpful, information. maybe i should try out a couple of different traps, and see how it feels carrying them in a backpack, before i decide.

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  6. Hi, I am a visitor from Pembs.
    Regarding cameras, I take pretty good pictures with an old Panasonic DMC-FS7. The important thing is that the camera has a "macro zoom" or "tele macro" facility whereby you can take close-up pictures with magnification (mine is about 3.5 x) This enables me to get almost full frame pictures of micros which is essential for me to identify them as my eyesight is not very good especially in poor light. It is also a small light camera which is very handy for the occasional one-handed shot and easy to carry. The Panasonic DMC range has moved on apace and provides all sorts of things you don't need but I am sure you could get something suitable. (see comment above)
    Rosemary

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  7. Peter, If you are going to carry the trap in a rucksack it might be an idea to put the tube inside a plastic drain pipe for protection.

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