This one has me stumped again. My question is about using my electronic flash (S unpak 4000 AF)on my 8x10 HOBO as fill flash. The mounted lens is a Schneider S/A 121 f8 (black version). My exposure for my test shot calls for 1/30th @ f22. I am placing my flash on FULL manual . Remember that I am only concerned with flas h within the flash's capability. About a 10 foot range. The lens has a Synchro-Compur, a sync post, but no markings to indicate which s hutter speed is the sync. This is an outdoor sunny day exposure. I am exposing o ne sheet of film with, and the other without flash. After developing the negativ es and letting them dry,I cannot identify the one that was exposed with the flas h. Yes, I made sure the flash went off . So!, my question to all the large forma t gurus' that have been there and done that is: 1-Is my flash not powerful enough? 2-Is it because of my f stop (f22) 3-What f stop if not all is the sync one? :and just for information sake this home made hobo was designed for street shoot ing, and f22 is a necessity to cover the complete 8X10 format corner to corner. Thank you for any information you can give me.