Archivos de diario de septiembre 2017

11 de septiembre de 2017

Labophot Microscope

I noticed a long time ago that the fact I am an engineer shows in my iNaturalist submissions. I have always managed to make it an excuse to play with some gadget or another. So of course, I have wanted a phase contrast microscope since I first learned it was needed to identify many aphids.

Reading up a bit on the topic it was clear that there are two reasonable routes there. First is the low end modern microscopes. Trinocular phase contrast microscopes from Omax, Amscope, or National Optical are available and probably good for any purpose I am likely to use them. The other option is 1980s era entry level research microscopes. Of those the Olympus BH2 and Nikon Labophot seem the most popular. Both these routes seem similarly priced and at least on paper give similar function.

After giving it some thought, going the old microscope route makes a lot more sense to me. Having an above average ability to tinker, it just seems like I can squeeze more out of them than the average user. Also, the microscope has survived thirty plus years and has a large market for used parts so it seems like I should be able to keep one running indefinitely.

After shopping around, I picked up a Nikon Labophot, a condenser, and a 10x objective off of ebay. This seemed to be the cheapest way possible to phase contrast. While the Olympus BH2 is similar price, it seemed that condensers with phase contrast, bright field, and dark field as well as trinocular heads are half the price on the Labophot system. Also, the better CF objectives on the Nikon system can be directly mounted to a camera and used with my stackshot setup.

I was too cheap to get a trinocular head initially. I figured I would just get one a few months in the future. That quickly drove me nuts. I work by creating photos which are identifiable. Having a device which could identify species but could not share that information just would not work.

First I tried using my camera by pointing it into the eyepiece with a macro lens on it. This was a horrible disaster, completely unsharp images. Then I tried using my cell phone to take images. A step up, but still frustrating:



That image showed some details correctly, but compared poorly to the Miutoyo 5X and stackshot setup I was using previously. That setup gave somewhat less detail than the cell phone in the objective, but certainly produced cleaner pictures:



After a few days of thinking about the problem, I realized it was possible to take the head off the microscope and project an image above it. Then, if I held the camera there without a lens I could see something. The first try was a failure, but then I realized that a stack of extension tubes allowed me to hold the camera still:



This did the trick! Now I can take reasonably good photos on the microscope. It even allowed me to make focus stacks by taking a couple photos of an area I am interested in. Even for dark field images it appears to be stable enough to work with the 10X objective:






With phase contrast and a little focus stacking though, it is pretty clear I finally have the magnification to identify most aphids or similar size arthropods. This is a lot more detail on hairs and other small features than I previously had. Eventually I will get a 20X, 40X, and 100X objective to go with the 10X, but this setup does appear to work well as is:







Now I am questioning whether I even want to bother with the trinocular head. A cheap adapter or two could get me from the 48.5mm dovetail connector on the microscope to the setup I am holding on the microscope right now. Would be slower to transition from eyepieces to camera, but I probably will just leave the camera on whenever I use it.

Ingresado el 11 de septiembre de 2017 por glmory glmory | 1 observación | 2 comentarios | Deja un comentario

06 de septiembre de 2017

Locally Common but Rare on iNaturalist

The new algorithm identifying species is amazing with weeds. It seems to get the correct species in the top 3 almost all the time and usually picks it as the top species.

For arthropods, no such luck. I just had it try to identify a springtail. First option was an Oleander aphid, second a fruit fly, third a velvet mite, fourth a psyllid, and none of the suggested top ten was a springtail. This is a bit of an extreme example, it correctly identified a spider I found today, but still the system clearly needs some help.

The problem isn't the algorithm, or at least isn't only the algorithm. A quick search for springtails shows that only four species have more than twenty observations. If I limit myself to research grade submissions not a single one has the twenty observations it takes to be looked for by the algorithm. So springtails are completely invisible to it.

The problem isn't limited to springtails, 23 species of leafhopper, 18 species of isopod, 8 species of aphid, 7 species of psyllid and one species of thrip make the cut. So with taxa like this the algorithm could be dramatically better if a few species were put over the 20 submissions mark.

So I have decided to start resubmitting more often for species which are locally common but do not make the cut for the algorithm. Hopefully I can get someone to hit the agree button enough to make it more useful.

I am also going to look for species with 20+ Total observations, but less than 20 research grade observations. Adding identifications to those species could make a big difference.

Ingresado el 06 de septiembre de 2017 por glmory glmory | 3 comentarios | Deja un comentario