About two years ago, I picked up a 50mm f/1.4 for pretty good price ... but, I found that shooting through the lens was ... well, weird. It was soft and worse yet ... incredibly soft at its widest aperture.
So, if you're reading this, your probably asking (and rightfully so) "How bad is this, Don?"
Well, just for fun and no serious set-up, I threw a target (my pen & ink drawing I did of my dog) up against my desktop monitor (that weird blue glow along the upper right hand corner), backed up 18 inches and shot 4 images with each lens (except the last one) ... at the following settings, to demonstrate this issue: f/1.4, f/1.7, f/2.5 & f/2.8
Okay ... here's the quick output of a brand new SONY 50mm f/1.4 PRIME:
Then, here's the older (suspect) Minolta 50mm f/1.4 PRIME:
Yeah, baby ... I think we are looking at a total lens rebuild, here. That color shift is the lens, itself ... so I believe it has been compromised. All settings, except for aperture were the same. (ISO 400, speed 1/50th)
But, in contrast, here's my (new back in 1985) Minolta 50mm f/1.7 lens - there is no f/1.4 shot. It seems to keep the faith ... with a slight tint. There is a golden glow to my "Golden." This lens has been with me since I began shooting the Minolta Maxxum 7000. Tried and true. I take care of my glass. Obviously, the clown who owned this f/1.4 prior wasn't as careful - probably bounced the darn thing. :mad: No wonder I got a "reasonable" price on it, when I bought it.
So ... off to repair, today ... this probably won't be cheap. :(
BTW ... this is a casual, but relatively good demonstration of what a f/1.4 lens gives you over a f/1.7
I mean, look closely at the apparent exposure level change in that first series. Even in the second series. It seems pretty significant with only a 0.3 change in aperture, huh? An f/1.4 can save an image and get you out of the noise. It's rather easy to see why you would want an f/1.4 choice over the f/1.7 or even an f/1.8 by other manufacturers.
Yeah, even the dog agrees ...