I just purchased an Explore Scientific FCD-100 102 (4 inch) and I'm looking for a good field flattener and potentially a focal reducer to shoot with an A7S (full frame).
The ones sold by ES won't work for me as they all have a focal plan on 45mm and I need 55mm, which seems to be the standard.
After looking online, it doesn't seems like there are many options that fits the bill and and I somewhat settled one Stellarvue 0.8x FR/FF. That said they don't mention if it will cover a full frame sensor. Anybody has experience?
If not my last option would be their large sensor FF without any FR.
Any other options I should consider?