dirty little secret

Is there anyone here who can use a 6 mm ortho without putting lash oil on the lens?
If I blink without pulling my eye back from the ep, I deposit.
It seems to spread out fairly wide and low, because the interference effect color is uniform within the discoloration, which leads to my second question:
Has anyone quantified the performance of an eyelashed ep with great coatings, like the UO 6mm HD Ortho (which is the particular EP that prompts my questions), compared to a clean one, or compared to an EP with more eye relief, but two more clean surfaces, like a barlowed one?
What goes through my brain is I may be better off with extra surfaces and some eye relief rather than a great minimalist ep that is dirty.
Any comments or measurements?
Thanks,
Dan

Is there anyone here who can use a 6 mm ortho without putting lash oil on the lens?

Well, that's what the vulcano top is for - to blink upon, isn't it? At least that works with 4mm ortho.

Dmitri

Roland posted once that the biggest effect on scatter that we will see is from the dirty EP and that he keeps his EPs clean because of this.
I think that a clean EP will perform better because of this.
Can I use a 4-5-6mm UO Ortho without getting eyelash oil on it? Not too well, but I think some of us have longer lashes too! The Volcano Top is easier to keep clean in that respect from what I can tell. I have the UO HD Ortho in the 6mm and it is difficult to not touch with the lashes, the 5mm is almost impossible.
Perhaps our eyes make a difference in this problem too. The closer we need the eye the more prone to eyelash oil?
I do use my 3-4-5-6mm Radians more because of this issue. I find them more comfortable to use, no problem with lashes and the difference in performance is slight at most at least for my eye.

I don't know about quantifying it, but I think I can see a difference. This is one of the two reasons why I don't use short eye relief anymore (the other is fogging), although the eyelash oil problem really depends a lot on the mounting. Usually short eye relief oculars are mounted nearly flush with the surface. This may increase the perception of eye relief, but it worsens eyelash oil problems. It's better to recess the lens slightly.
--
Mike

Hi Dan,
Personally I like the suggestions to burn your eyelashes off or try Duct tape! Maybe Super Glue them to your eye brow?
Just Kidding.

Seriously, decades ago when I was young and had long eyelashes I wondered it the eyelash oil affected the viewing. This was about the time many different multi-coatings were coming out and they were being discussed in detail. I took a pair of matched eyepieces and let one get reasonably well coated with lash oil. Then we took great care NOT to get any oil on the other. 3 of us tried this over a 2 night period at a Star Party. Although not a scientific survey, at the end of 2 nights of viewing we decided the lash oil did effect the Planetary viewing. We all agreed it seemed to have little effect on Lunar viewing (We were using Slow, f/15 scopes then) and I don't remember any of us commenting on scatter. We were split on DSO viewing.
So I guess the answer to your question IMHO is yes it can very well affect your viewing.

That said, I used to cut my eyelashes short to prevent the problem (like John Cassella) until I learned the technique of slowly Closing my eye intentionally which carefully allows the eyelashes to bend/flex and not sweep across the eyepiece. This is easier with a volcanio top as mentioned. The quick, rapid motion of a blink causes my eyelash to swipe the eye lens. A slow careful closing and opening does not when you get the hang of it.
Then again, if your eyelashes are long, use an eyelash curler and that helps. (seriously)
Now a days I find I tend to just slightly rock back, blink, and rock forward without even thinking about it.
This all assumes you're comfortable using an EP with a very short eye relief. Sometimes just having something that close to your eye can bother people.

Hope that helps. Clear Skies, Bill