23 Replies to “July 12, 2014 Supermoon”

  1. Hey Bryan,

    The spotting scope is an interesting concept. Nice pictures by the way.

    I have been thinking about something even lighter and smaller for bird and other wildlife photography. Do you have any experience or opinion about any of the 300mm lenses for micro 4/3 format that would give the equivalent of 600mm focal length when the crop factor is considered? The Panasonic 100-300 seems like it would make a nice compact package when combined with a Panasonic or Olympus body. If you have a camera recommendation I would prefer a viewfinder in addition to the viewing screen.

    The other thing I have been trying to find is a 1.4x teleconverter for micro 4/3. It seems like the 300 with a 1.4 would be a good compromise for a light weight long telephoto package to do some bird or wildlife photos. Olympus makes a 4/3 teleconverter but I wasn’t sure if that would work well with micro 4/3. My budget is limited so I am trying to find the best compromise between light weight, long focal length and price. I’m not a pro so I don’t need huge images but I do appreciate reasonably good quality images.

    Thank you for any advice you can give me on compact long lens photography.

    1. Hey Bill,

      Thanks for the note. Yeah, so I’ve been looking at a few solutions including small telescopes by a company called Borg. They have a series of astrograph telescopes that are fast, use fluorite glass from Canon and seem to have excellent performance: http://sciencecenter.net/hutech/catalog/Binder1.pdf The are manual focus only, but so is the spotting scope approach. As far as autofocus lenses for for compact/mirrorless interchangeable lens cameras, I’ve been kinda disappointed that there are not more alternatives out there. Next year there is supposedly a long telephoto equivalent coming for Fuji cameras, but I don’t know what is out there for Olympus. The other thing I have entertained is picking up a converter and buying used, old manual telephoto glass for Nikon/Canon/etc… There are some amazing deals out there.

  2. Thanks for the information and the link Bryan. I have also looked into used older manual lenses but I really like the compact size and auto-focus of the MFT systems. The new long Fuji sounds interesting if it will fit into my budget.

    1. Note: The older manual focus lenses are smaller than the current autofocus lenses. That was actually one of the surprises when I picked up my old 35mm film camera. It was about the same size as the Fuji X-T1.

  3. I have another question for you Bryan if you don’t mind. Two of the pictures on this blog were of hummingbirds, I’ve seen a figure of 4-5mm for the diameter of the eye of the ruby-throated hummingbird. Do you have any research information about hummingbird eyes or about retinal sizes or weights in the hummingbird?

  4. Thanks for the answer Bryan. I couldn’t find any figures for the hummingbird either but I have no research experience so I thought you might have some information.

    The 4-5mm diameter was from actual field measurements. When I couldn’t find research figures and was trying to estimate the weight of the eye and retina of the ruby-throated hummingbird I used the water weight of a sphere 5mm in diameter to approximate the weight of the eye. That figure was a little over 65mg. Based on that figure, if it is reasonable to use, I estimated that the retina would weigh 10mg or less. Does that sound like a reasonable estimate to you or am I way off base. Math was never my favorite subject.

    I have seen figures of 8 to 10mg or ul for the weight of a rat retina. The rat eye has a slightly larger diameter so I thought the 10mg figure would probably be a maximum retinal weight for the hummingbird. It was the maximum retinal weight for the Ruby-throated hummingbird with a 5mm diameter eye that I was most interested in trying to figure out. Thanks again for your help with my questions.

    1. That is probably a good estimate approach, though the mass may vary some +/- 10-20%. But it should get you in the ballpark.

      I’ve never tried weighing a rat eye either. But the same approach should work.

  5. Thanks for the information Bryan. If we add 20% to the 10mg estimate for the hummingbird retina the weight would be 12mg. That means it would take four hummingbird retinas to approximately equal the weight of a drop of water (20 drops/ml). I find it amazing that a biological structure so small is still capable of functioning with the speed and precision necessary to produce excellent vision. The processing speed to weight ratio of the hummingbird retina must be phenomenal.

    1. Interesting… I just weighed a human eye and its around 6 grams. A mouse eye is about 1% the size/mass of a human eye. How that correlates to a hummingbird, I am not sure. Though for their size, hummingbird eyes are larger than most creatures. I think their eyes are larger than the brains…

  6. If the eye you weighed was a fresh sample it would be interesting to measure the length and width of the eye then average them. Based on the volume of a sphere I would expect an average of length and width to be about 22.5 mm for a fresh 6 gram eye. If the sample was fixed or dehydrated I would expect it to be smaller because it would be more dense.

    I also have read that the brain of the hummingbird is smaller than the eye and that the cerebellum is larger than the cerebrum. The 1% weight of the human eye for the mouse eye would make the mouse eye about 60mg in comparison to the 6 gram eye you weighed. That is very close to the weight I estimated for the hummingbird eye. The ruby-throated hummingbird is only about 1/3 the weight of a mouse so the eye of the hummingbird would be proportionally larger as you noted. In the case of the mouse comparison it would be proportionally about three times larger if my figures are correct.

    Thanks again for your help with my questions. I also found your recently posted abstract very interesting. Keep up the good work.

  7. Just thought I would let you know that I recently obtained a chicken head from a local butcher shop that had been processed that same morning. When I dissected out the eye I found it to measure 17mm in diameter with a depth of 11mm. About a 65% aspect ratio. The eye weighed about 2150mg when all extraneous tissues were trimmed off. I was surprised at how large the eye was when I first started to remove it. I took some pictures with a dime in the picture because the diameters of the eye and the dime were the same.

    I have a question based on removing the eye about 6 hours postmortem. The eye was very slightly soft. Do you know if intraocular pressure drops rapidly post mortem and if that pressure drop affects the weight of the eye. Thanks again for all your help.

    1. Birds eyes take up quite a bit of the area of the skull and chicken eyes are quite interesting indeed.

      Chicken eyes are less rigid than human eyes are and the sclera is less thick. Therefore, maintaining intraocular pressure is pretty important. The weight should not change too much.

  8. To clarify the prior post, I wanted to examine a bird eye so I could make a more accurate estimate of the weight of a hummingbird eye. The interesting thing about the chicken eye is that it looks very much like one half of a sphere. There is a slight bulge at the cornea but the surface of the eye is otherwise fairly flat. You could put both eyes together cornea to cornea and they would almost form a sphere.

  9. Thanks very much for the information. After I posted I was curious how much water weight it would take to firm up the eye. I had an extra head from the butcher so I dissected out another eye and injected it with water. It took 0.25 ml or slightly less to firm up and round out the eye nicely. If the live bird eye is moderately firm and well rounded that would mean another 250mg to add to the 2150 for a live weight of approximately 2400mg.

    Using the formula that eye weight of a bird equals 4 times the radius cubed a 17mm diameter bird eye would weigh about 2457 mg which is very close to the live chicken eye weight I determined. If it is reasonable to extrapolate that to the hummingbird then a hummingbird with a known 5mm diameter eye would have an eye weight of 62.5mg, which is close to the 65mg I had previously estimated. Of course the mm dimension of the radius has to be changed to mg for the final weight estimate since 1cubic mm of water weighs 1mg.

    The other interesting thing I thought would work is to measure the eyelid opening between the commissures (open or closed were the same for the chicken) then multiply by 1.7 to get the diameter of the eye for any live bird. Once the diameter was obtained the same formula of 4 times the radius cubed could be used to estimate the live weight of the eye in that particular bird. The chicken had an eyelid opening measurement of 10mm and an eye diameter of 17mm thus the 1.7 multiplication factor.

    Any thoughts or corrections would be appreciated.

  10. Thanks once again, your reference pointed me to some other interesting articles in addition to your link. Part of my difficulty is that I am not involved in research so I only have access to articles available to the general public. My only real interest when I started investigating was the weight of the hummingbird eye and retina. Not being able to find those figures caused me to search for information about other avian species.

    Do you have access to specific eye weights and retinal weights for the chicken that were done by researchers? I would be really interested in finding the weight of the retina if you have it. Both eye weight and retina weight from the same bird would be even better.

  11. Thank you for the reply Bryan. I could not find those figures when I did a general computer search of the literature but I thought you might have them available.

    While researching the chicken eye I came across this abstract (link below) about disordered hyperuniformity with a link to the main article. The main article states the following on page 9. “Importantly, it is highly nontrivial to devise an algorithm that would remove a large fraction of the points from a disordered hyperuniform system while leaving the remaining point pattern hyperuniform, and yet Nature has found such a design.” I assume highly non trivial means it would be something very difficult to accomplish and that they don’t know how it was done by “Nature”.


    You have probably already seen the information, but it might make an interesting future blog post.

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