In the words of a well known large format lens purveyor, lens defects generally affect the user more than the lens. As Erie's example showed, obvious defects can be invisible in the final print.
Two of my lenses have 3-4mm scratches near the center of the rear element with no apparent effect, except on the price. Hence I picked up a 240mm Sironar-S ($2300 new) that was in perfect condition except for the scratch for $500.
I also have a 19" Red Dot Artar with significant cleaning marks on the front element that I picked up quite cheap. It looks like someone cleaned the glass with steel wool. I haven't done a direct comparison to a another lens, but it seems fine. If contrast is reduced, I haven't noticed. Unscientific to be sure (maybe I just have learned to develop longer), but it illustrates the point. Beyond that, common sense prevails. As mentioned previously, the price should reflect the defect, and a good return policy is your friend.
Check out the image quality this damaged lens can produce.
I would not buy a camera with coating issues only because I buy for the long term. I buy used gear in excellent condition and keep it.
If I was on a budget and just wanted something to run 120 film through while I test the MF waters, coating defects wouldn't be an issue. I doubt a beginner would notice. The sheer image size/quality difference from 35mm would be an eye-opener.
I used to use my Dad's 35mm Ciro rangefinder from the 1950s. I always swore it had great optics, and they were indeed good for a low-budget camera. When the shutter died for the final time, I took a close look at the lens, and it looked like a Brillo pad had been used to clean it. The last pictures it made were as good as any others it made during its lifespan.
Had a 200/4 Nikkor AI with a big spot of coating damage on the rear element. Looked like oily film on it. Yet, the photos that came from it were fine. No difference when compared to shots I've made with other 200mm Nikkors that I've owned.
epatsellis, does it work that well stopped down? If so, I'm impressed. Again, I use to be of the 'lens defects are less of a big deal than people think' camp until picking up a few lenses with a bunch of cleaning marks which had extremely poor contrast to the point of being usable for the shots I wanted to get.
The impact on the negatives changes defect to defect. Without the ability to test it and be sure I understand what impact there is if any, I personally wouldn't be comfortable putting down a bunch of money on something blind unless I was confident I could sell it for the same price if it didn't work for me.
Thats just me though. Everyone will have their own criteria.
A lot of my lenses have slight glass defects. Never noticed the difference between them and the mint ones, so I have no problem saving a few hundred.
yes, that 210 Componon was my standard wide 8x10 lens for at least a year, I probably shot 100+ negatives with it jsut fine. I finally gave it to a friend of mine starting in 4x5 and had hit upon hard (harder than me) times, along with a couple of boxes of fomapan that I just couldn't get comfortable with.
Lots of light scratches can reduce contrast, though thorough shading and attention to craft (i.e. knowing you'll have to dev for 20% or 30% more to get the snap back) can offset the effects. I have a 135 Fujinon with significant cleaning marks that is likely my favorite lens on 4x5. Neither of my Hassy lenses are pristine, and shoot just fine. I guess it really depends on an individuals financial situation as well, for the first few years return to photography, I shot with an 8x10 C1 and the aforementioned Componon and a 12" T-R triple in a Betax. Worked just fine for me, even on Ultrafine Dupe Film, which is merciless in revealing image defects in my experience.
I prefer to take the view that it can allow me to spend some time with a lens and decide if I want to find one in better condition if the f.l. or design jives with my aesthetic while passing my good fortune to another person. While most of my LF work is flim/optical printing, with contemporary hybrid approaches, loss of contrast is easily dealt with in post if need be, as long as it isn't veiling flare that obsucres details in the lover zones.
At my level of performance, i can't afford using less-than-mint lenses!!! OTOH, it sure would be nice to have *something, anything* to blame for the crap photos i make! I've seen some great photo's from less-than-great glass (condition or design). As mentioned, it's the brain *behind* the lens not just the lens.