I am looking for a possibility to survey insects in the field using video cameras, possibly also at night. Does anybody have some good or bad experience with this kind of survey and some indications about possible material to use?
Camera with high resolution and wide angle lens will be much better than ordinary camera. Also using ultraviolet photography (UV lens ) will give you different details of an image compared to non-UV lens.
Camera with high resolution and wide angle lens will be much better than ordinary camera. Also using ultraviolet photography (UV lens ) will give you different details of an image compared to non-UV lens.
Before we can make any recommendation about UV or other filters, it would be helpful to know what you mean by "survey." Do you mean that you want to non-destructively "census" insects at a feeding stations or a light source (or a white sheet with a light behind it)? That is, are you wanting an automatic camera taking shots at regular time intervals? Or do you mean that you are walking transects, using spotlights, and then taking photographs?
Some thoughts:
- If using simple spotlighting to census insects (at night) and then repeating the transects during the day, a good wide-angle lens will no doubt be necessary. For small insects, you may want to build a rig with a reverse-mounted lens with a flash diffuser (on a bracket). (To save money, don't buy a macro lens. Just take your regular 18-55mm--or shorter--lens and turn it around. You need a cheap mount adapter to do this.) You can add to this setup using extension tubes.
- For daytime shots, you may avoid getting close to your subjects altogether. I suggest trying a larger lens (say, a 70-300mm) with a set of extension tubes. You'll be able to stay far enough away to prevent insects from flying but get high enough magnification to capture the insect well.
- Concerning UV lens (@Madan Gautam) : You probably don't need this if you just want to identify the insects. If you do want to get into animal visual modeling (there's a great new literature out there for using standard DSLR cameras for detecting UV), be warned that this is an expensive prospect. The associated equipment can be very expensive. One of the standard ones (Nikon Nikkor UV lens) runs about US$8000. Of course, the lens is only the beginning. Because the camera sensor elements sensitive to UV are also the ones sensitive to other dominant wavelengths (in the human visual range), it is necessary to block out the visual-range wavelengths. So, you need a UV-pass filter. Of course, because you want to discriminate between UV and visual, you also need a filter that cuts out UV and isolates the visual range. These filters are expensive. So, let's hope you're only doing this for survey purposes.
Thank you very much! I would like to video-tape interactions among insects at fixed sites (non-destructive, continuous record for some hours). UV-device is appealing, sadly much to expensive for my limited budget. I might consider the idea of taking regular shots instead of continuous filming, if this would allow a better picture quality and possibility of better identifying the insects, but I fear to miss some part of the "story".
I did not know about the possibility to turn the lens around, that's a nice advice!
Best
Hi Valerie,
Ha! I did read your original question but I apparently missed the phrase "video cameras." My apologies. Since you are attempting to record at night, you of course have the choice of using a light trap OR not using a light trap. The second option will no doubt require the use of an infrared light source. One worry is that this will attract certain species differentially.
In other words, though I'm no ecological entomologist, I think you're right about combining methods. That said, I think it would also be worth explicitly modeling the detection probability (independent of abundance) as a function of night/day, survey/capture method, and other variables you deem important (e.g. temperature). Hierarchical mixture models might end up being your friend, in this case. This might be overkill, but it might be a good way to truly separate pattern (abundance) from process (researcher bias).
Does this help at all?
Hi! Thank you very much. Yes I think infrared is what I need. Would you have any advice about material? I experienced some infrared security camera, but was disappointed by the poor image quality. I could hardly find any study using video camera for field survey, but with the quick development of technology, it should be possible to get some nice film sequences.
That's very good that you make me aware of the possibility that it may attract some species. I'll have to think seriously about it and the possibility to correct bias.
Cheers
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