The Legacy Lens - Pat It At Your Peril
Legacy Lens is a great phrase - it makes you think that you have encountered something wonderful and precious. And all for free. This illusion rapidly vanishes as you try to adapt it to your modern digital camera - you discover that you'll need to spend more again to get an adapter - and in some cases we're talking more than the price of the lens itself - and the result can be sad. If you have purchased the Legacy rather than found it in a box under a bed, that is so much further you have gone from free and wonderful.
Point the finger of hypocrisy at me if you like - I have a Tokina 35mm Macro that was intended to sit in front of a Nikon camera but now links via a Kipon adapter on a Fujifilm X-E2. And does very well - it was the shortest 1:1 macro lens I could find at the time for an APS-C camera and delivered/delivers exactly the point of view and focusing distance I need for tabletop shots. The adapter is well enough built to keep it in good alignment and I am always working at manual aperture and manual focusing anyway. I'd chuck the lash-up in a second if Fujifilm would put out a 34mm Macro in their native X mount, but until they do I am going to take toy car pictures with the Tokina.
Did I wish to retain auto-focus or auto-exposure I would be nursing a dog bite. Legacy lenses were made for the days when you were expected to make your own focusing errors - not entrust them to the AF program on the computer. You throw away all modernity when using them.
Are they better than new lenses? No. Stop squawking, it's true. In every case where modern manufacturers have replaced their 1957 Whateveromatic lens with the 2015 AF ASPH Whateveromatic lens they have multicoated it and recalculated the optical formula to present the ray paths at a better angle to the receptors in the sensor.
Let's face it - when you agonise for months about the latest and greatest camera body of whatever make, and then throw yourself around the town trying to cheapen it with every dealer, and then sit sweating in front of every internet forum to see if strangers agree that you made a wise choice...wouldn't it be nice to know that you have the optical design that was actually intended for that body? Whether it is made in Bangkok, Saigon, Yamagata, or Wetzlar ( or made in Yamagata and shipped to Wetzlar... ) it is a fair bet that the optical designers ate their rice noodles or bratwurst with their camera body colleagues in the staff canteen and that there is likely to be a close agreement on what the glass does to the silicon.
Closer than anything you, your aunt, or that damn dog can think up.
* Poodle. Suzette. Like a dyspeptic rat, but meaner.