I think that I want to quantify insects color including UV.
I’m going to using this PTFE seat as a white standard.
However, I don’t have gray standards.
It is difficult to buy off-the-shelf them (ex. Labsphere etc.) because they are very expensive.
So, I think that using gray PTFE tape.
In this way, is it not suitable to use gray PTFE tape as with white standards?
If it is suitable to use gray PTFE tape, could you tell me the product name that can be use analyzing and its reflectance?
Sorry for my bad English.
Thanks in advance.
You don’t always need a grey standard if you have a suitable white standard. PTFE plumber’s tape is extremely cheap, and can work well if you wrap it carefully around e.g. a black plastic base to create a uniform, diffuse white. It won’t be perfect, but will be pretty good and consistent between your photos. That PTFE sheet you show might work quite well, though it’s not clear whether this is solid PTFE or sintered. You need lots of layers of air-PTFE boundary to get it really white, which is why spectralon works well (PTFE powder that is sintered to stick it together, with some black thrown in to make it grey).
Another option is powder such as barium sulphate, which is fairly good in UV. You can just compress the powder to create a standard (though any wind or rain would instantly mess it up). You can mix in black carbon powder to make different grey levels.