Maybe if you never shoot digital you don't understand the superiority of multi-coated lenses. When you have a digital sensor, it will tend to reflect back out the lens; if your filter is not multi-coated, then it will cause ghosting on a digital camera. This is very real and I, and many others, have seen it many times.
Then again, do you own a Leica? And you honestly are coming here asking if we can't tell the difference between cheap and expensive filters? Why not just take the conversation to its logical extreme and start asking if Leica users can tell the difference. Or if Zeiss lenses are really better than Leica. Or Canon. Start a Canon vs. Nikon debate while you're at it. Or, hell, aks if we wouldn't all be better off shooting Holgas!
But I almost never use filters for film, and the few times that I have I used the expensive multi-coated filters I already own. So . . . I guess I can't say for sure beyond the one or two cheap filters I bought early on in my photography that ghosted and flared on my digital sensor, driving me to the more expensive stuff.
Where do I start?
Yes, I own Leicas. I've been using them for about 40 years. I currently use M8.2, M8, MP, M4-2 (all from new) and 2x M2. Over the years I've had quite a lot of others. Also, I have several Leica-fit lenses: currently 15, 18, 21 (x2), 28, 35 (x3), 50 (x several), 75, 90 (x2), 135, from Leica, Voigtländer and Zeiss. Most are from new. That's apart from the ones I get for review. And yes, I'm honestly coming here to ask what difference you see between cheap and expensive filters. Otherwise I'd not have asked.
I have written for the photographic press for the last 30 years or so, including lots of books; visit my site to see a list of them. I've also formally tested filters to see if they have any effect on resolution (bear in mind what I do for a living -- I get paid to do tests like this), and short of using window glass, have found no loss of resolution with different filter quality using resolution charts, film and lenses in the 35-90mm range. I've not tested wider lenses or longer, though theoretically, longer lenses may be more sensitive to filter quality. Ctein, a better experimentalist than I, has found exactly the same thing. Because I've tested only for resolution, I was asking what people had seen which leads them to believe that cheap filters are inferior.
You, on your own admission, "can't say for sure beyond the one or two cheap filters I bought early on in my photography that ghosted and flared on my digital sensor." In other words, you have almost no experience and you haven't conducted any formal (or even informal) tests. Can you provide an example of this 'ghosting'? Veiling flare, I can just about believe. Images of the diaphragm, conceivably. But 'ghosting' in the sense of a secondary image, I find hard to believe. Perhaps I am misunderstanding you.
As for the rest of your post, about Zeiss and Leica and Nikon, this is nothing to do with the question I asked, but I'll address your concerns anyway.
My own belief -- based on over 35 years of professional work and over 40 years since I started as an amateur -- is that there is a 'quality plateau'. Above it, the camera (or filter, or lens) makes a minimal technical difference: the photographer matters more. Below it, a better camera or lens will make a difference.
The 'quality plateau' is incredibly low, but some cameras and lenses (e.g. Prakticas fitted with Primoplans) fell well below it when new. Others are below it after decades of use/abuse: some of my Pentax lenses aren't too impressive, though others are excellent.
The 'quality plateau' moves steadily but slowly upwards as the photographer gets better, until it reaches a point where all that really matters is that you're happy with the camera: you could use any one of a dozen or more cameras and get good results, but you'll get the best pictures with the ones you're happiest with.
Cheers,
Roger
