1. Any tips to focus manually in low light situation where camera struggles or refuses to focus?
Yesterday, i was taking portraits of my family in dusk with orange sky as the bg. The subjects looked almost black in view finder and live view. I am using fill in flash and the test image showed that they will be properly exposed. But, it was quite a challenge for me to focus accurately for the group photo. The kit was Nikon D3100 + 35mm F1.8 + Promaster flash.
2. When using FF lens in crop sensor, will we get a 1.5x additional zoom?. Will the magnification of a 200mm FX lens will be similar to a 300m DX lens?