Hi guys,
Any of you guys ever used an eyepiece or optical equipment let say binoculars with 17mm eye relief? Is it enough to see the field stop with spectacles on? I know that 20mm eye relief is more than enough having some gap between the eyepiece's eye lens and my spectacles but I just don't know how much gap is that. Any ways of measuring how much eye relief one needs with spectacles on? Thanks.