This pair, that seems to have closed in a lot since mr. Struve observed it, was observed in mid-twilight. The ArgoNavis DSc's on my G-11 let the way nicely otherwise it would have been difficult to locate the pair.

The sky was still light-blue and only the brightest stars, like Arcturus, were visible to the unaided eye. Struve 1816 was observed and split with a magnification of 480x, and even at that high magnification the sky-background was still bluish.
The split was not very difficult, only the seeing made it impossible for most of the time.

I hope someone can measure this pair, I'm curious what the current separation is. According to the information I have it was 1.9" in 1831, 0.67" in 1991 and 0.6" in 1997. So it could be around 0.5" nowadays, but it could as well be opening up again. 

Complementary comments: Yesterday, around sunset, the sky cleared up completely. I took the change and put the C11 up in my backyard. The bright Moon made serious deepsky observing impossible so I dedicated the session to doubles. Most interesting was the split of two close doubles, STF1816 (0.6" according to WDSC) en Eta CrB (0.8" according to WDSC). The last one was
absolutely the toughest, probably because of the brightness of both components, which results in larger airy disks. Eta CrB was split @ 620x. Most of the time the pair was seen elongated to snowman-shaped and only few and short moments the airy disks popped into focus and showed up separated.

1.9"!? I'm in presence of one 0.5" - 0.6" separation!! Very nice close pair but not too difficult during the rare quiet moments. It's interesting that I can perceive the duplicity also with plossl 15 mm at 238X! The couple is composed by two stars pretty bright and pretty balanced enclosed in a unique oval ring. Their colour is white-bluish. Extimated PA about 80
degrees. A noticeably fine and interesting double. A good test for 25 cm telescopes and for 15 to 20 cm instruments looking for elongated pairs. The last measure in WDS is 0.6" in PA 94 degrees (2001). Now the PA seems decreasing.