I've just received a used Nikon FM body with a 105mm f2.5 non Ai lens that I auctioned off for about 170 USD. But the lens is so heavy and the camera balance is pretty awful. So, I might just get a 50mm f1.8 pancake lens for the body and save the 105mm until I get a Nikkormat or something that weighs for the good balance.

Meanwhile as a alternative lens, I've been thinking about a Cosina's Ultron 40mm F2 pancake lens, which is not really cheap (at least 250 USD) since it's new in the market. Has anyone had any experience with this lens? I want to hear some opinions about this product, but there are very few reviews available online. They are mostly saying that it's not a great lens, a bit too heavy to be a pancake lens, and the bokeh is harsh because of its aspherical design, etc.