Crab spider II. Up close with 65mm MP-E

Charles Krebs · Post by **Charles Krebs** » Sat Jul 14, 2007 9:42 pm

This afternoon I looked for the crab spider I had photographed and posted yesterday, and found it close to where it had been left off. The air was dead calm so I knew I would be able to take some long exposures. I coaxed the spider onto a white daisy and got out the Canon 65 MP-E. These three images were made using "natural" light (in the shade), with exposures of about 1.6 second at a "marked" f8. The spider would sometimes stay motionless in the same position long enough for me to shoot several exposures changing the focus slightly (to get extended DOF). The top two images are each composed of 3 frames combined in Helicon Focus. The bottom is 5 frames. (The bottom image is with the MP-E set at 5:1, the closest it will go. The other two are probably about 3.5 or 4:1.).

After my brief photo session I placed the spider back on the lavender where I had initially found it. When I checked back a short time later is had already caught its next meal... another honeybee!

rjlittlefield · Post by **rjlittlefield** » Sat Jul 14, 2007 10:22 pm

Wow! A virtuoso display of aesthetic beauty and technical prowess.

1.6 seconds per frame with a live specimen outside.

This is just awesome, Charlie. "Crab spider with pollen" ?

--Rik

Mike B in OKlahoma · Post by **Mike B in OKlahoma** » Sat Jul 14, 2007 10:51 pm

Not only 1.6 second exposures with a wild specimen, but STACKED groups of 3 to 5 shots! Wow.

beetleman · Post by **beetleman** » Sun Jul 15, 2007 6:00 am

Simply incredible Charles. #3 is awesome

Ken Ramos · Post by **Ken Ramos** » Sun Jul 15, 2007 6:32 am

Beautiful as usual Charlie. I am assuming that the two red eyes are actually the primary eyes of the spider while the rest are nothing more than mere ocelli.

DaveW · Post by **DaveW** » Sun Jul 15, 2007 7:13 am

"I am assuming that the two red eyes are actually the primary eyes of the spider while the rest are nothing more than mere ocelli"

Nah, it's red eye from flash on camera !

Seriously, great shots, photostacking of a live subject is really pushing the boundaries. Good job spiders don't blink. Or do they?

DaveW

Charles Krebs · Post by **Charles Krebs** » Sun Jul 15, 2007 9:23 am

Those two eyes were interesting. No flash was used. While taking the photos it was apparent that the spider could "rotate" or ""move" something under the surface that made the eye appear either red, black, or partially red/black when viewed from the same position. These two enlarged (consecutive) frames show what I mean. (They are at slightly different focus points so try to ignore the softness). Of particular interest is the "lower" red eye. If you look at about the 2:30 to 3 o'clock position off to the side of the eye socket you can see that it is darker in the right frame. I could observe this darker section moving about below the surface and as it moved about the eye would show various stages of red, black, and "partial". I didn't notice this with the other eyes.

Here is a quote from a web page dealing with jumping spiders. While it is a different species, and the two "AMEs" are much larger, perhaps something similar to what is described occurs with the crab spider.

From: http://tolweb.org/accessory/Jumping_Spi ... cc_id=1946

Jumping spiders have excellent vision, with among the highest acuities in invertebrates. The eight eyes are grouped four on the face (the two big Anterior Median eyes in the middle, and two smaller Anterior Lateral eyes to the side), and four on top of the carapace (two medium-sized eyes toward the back, and two very small eyes in front of them). You can think of the Anterior Median eyes (AME) as acting like our fovea, with high acuity but small field of view, and the remaining six eyes acting like our peripheral vision, with lower resolution but broad field of view...

... the AME's are long and tubular, which helps their resolution (longer focal length, more magnification) but which means they have a narrow field of view. Since the AME's have a narrow field of view, the spider needs to point them in different directions to see different things. To some extent this is done by moving the carapace, but the eyes can move as well. This is not done by moving the whole 'eyeball', since the lenses of the eyes are actually built into the carapace. Instead the retina moves around, while the lens stays fixed. This retinal movement is accomplished by some small muscles...

Ken Ramos · Post by **Ken Ramos** » Sun Jul 15, 2007 11:35 am

We are still getting "Infernal Sevice Errors!"

Pretty neat there Charlie, thanks. I suppose that explains the eye thing pretty much, doesn't it? So if, I am assuming, all eight of them are looking at you then they might all be red and that none of them are quite like ocelli, of which I thought six of them were.

That's what I get for thinking.

Good info, thanks again

Walter Piorkowski · Post by **Walter Piorkowski** » Sun Jul 15, 2007 8:42 pm

Truly beautiful Charles. What stunning backgrounds for this subject.
Walt