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發表於 2014-3-18 09:45:03
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A important note, I think when you check a lens. You check it as an entire package. For example, a perfectly looking scratchless lens may be because it is over cleanned and a lot of coatings are off! I rather buy one with more coating intact and more small scratches. You can tell how thick the coating is from the colour of the lens and if you know what colour the coating is for each lens.
Scratches can be cleaned most of the time by removing a very few layer of coating.
Also take a few pictures and see if the lens look like pics from that lens. Some very old 8 elements, for example, rumoured to have the 2 inner elements replaced and the pics will look less sharp.
On other areas, I will check seperation first as this is something that cannot be fixed easily. I will check if the lens's picture taken are what it supposed to be. Seperations can be fixed, but will often change the character of the lens and it might not be as sharp as well.
Second will check if have mold, because if not cleaned propably, will spread across to all other lens in your dry cabinet. Not worth the risk. For any new lens purchased, best not put in the same dry cabinet as your most treasure lens. It might content mold that you are not aware of.
Haze really depends on which lens. Some I am pretty sure can clean by good cfu, some is hard to clean completely (Like old V1 rigid).
Cleaning marks etc. really depends on cost of lens and how rare the lens is. Again, look at it as a package. Some lens looks perfect without any scratches but some haze and you might think it is a good deal. But actually the haze covered the scratches and once cleaned it is no longer as perfect.
For a collector grade lens. I will also check if the lens have been opened before. Some lens might be tight and dry and have some naturally developed marks on lens (This is less of a concern). For a lens that is virgin and rare, I prefer not to clean it if have some minor haze. Check the screws if have any marks, check other areas to know if it is a never opened lens. |
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