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05-25-2010, 10:08 AM   #16
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QuoteOriginally posted by Wheatfield Quote
What makes you decide a lens is worth keeping?
If it does something no other of my lenses do, it's a keeper.

QuoteOriginally posted by Wheatfield Quote
What makes you decide that a lens is junk?

For example, if a lens has good bokeh, but can be forced to show CA/PF, will you keep it for the bokeh or get rid of it for the fringing?
- CA/PF are easily correctable in software (at least with Lightroom it's a breeze) so I don't care too much for that. I've corrected huge CA on DA 12-24 and especially the Tamron 18-250 (which I sold but not for these reason).

- Distortions are a bit more bothering because the current LR doesn't support corrections (but it's going to change with LR 3). Most normal zooms have heavy distortions at the wide end. My DA*16-50mm has certainly too much at 16mm. The
DA 21mm is also an offender. Fortunately it's not concerning on every shot.

- Bokeh cannot be corrected at least not without strong PP (or some specialized plug-ins like Alien Bokeh). I've not enough experience with Bokeh to reject or keep a lens but I can see that my FA77 and FA50 produce nice things in that domain. My DA 55-300mm is awful IMHO unless you put the background completely OOF.

- Flare resistance is very important to me. That's why I consider the DA 15mm even when my DA 12-24mm cover this range particularly well already.

- Vignetting is quite OK. It was only bothering on my old Tamron 18-250mm. It's also easy to correct.

- Sharpness is probably the most important feature of a lens, especially on digital. So if a lens cannot be sharp, it's almost useless. I sold my FA 80-320mm due to its very poor performance at 320mm wide open. It was "junk" at that setting.

BTW, there is a nice article by Thom Hogan about what matters most in a lens: Qualities to look for in a lens.

05-25-2010, 11:00 AM   #17
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Do I enjoy using it?

Is it a useful lens?

Will I possibly regret selling it?

If it doesn't meet those criteria, will selling it allow me to fund more LBA? =)
05-25-2010, 11:30 AM   #18
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There's no logic to it with me--it's just LBA.

Most of my glass is the old stuff, so it's not all that expensive anyway. (My most expensive is the Tak 85, which was $270.)

So I just buy them to have. When I make my decision on the relatively expensive Tammy 10-20 or DA 10-17--and knowing there's that remarkable DA 15 out there--things get more complicated.
05-25-2010, 11:33 AM   #19
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QuoteOriginally posted by Wheatfield Quote
A couple of threads, and a few posts have made me curious about the way people think about lenses.
What makes you decide a lens is worth keeping?
What makes you decide that a lens is junk?

For example, if a lens has good bokeh, but can be forced to show CA/PF, will you keep it for the bokeh or get rid of it for the fringing?
I have yet to get rid of a lens because of CA or PF, although that may have been a deciding factor in me letting my Tamron 70-300 f/4-5.6 go.

I'm a sucker for the various types of bokeh. I often like a little character in the OOF rendering - I rarely find any bokeh that I find totally unacceptable.

QuoteQuote:
Another example: Is it unadulterated sharpness above all else or can a little softness be forgiven if the lens has other attributes that you like?
I can deal with a little softness at the high apertures as long as the lens has good contrast and color transmission.

Here are my main reasons for returning a lens, in order of importance to me:

1) Bad BF/FF issues. (AF)
2) Lack of sharpness (AF or MF)
3) Lack of contrast - even if the lens is sharp (AF or MF)
4) Bad CA/PF
5) Build quality is too low (AF usually)
6) Focal length or overall utility just doesn't 'fit' me
7) Bad bokeh




.

05-26-2010, 09:15 AM   #20
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QuoteOriginally posted by Wheatfield Quote
What makes you decide a lens is worth keeping?
Important factors
  • If it has reasonable optical quality
  • If it does the job it was designed to do and I need something to do that job
  • If it feels good in the hand and handles well
  • If it is pretty (yeah, I am a sucker for good looks)
  • If it has the twin virtues of lightness/compactness
  • If it has excellent build
  • If it has unique optical qualities (pixie dust)
QuoteOriginally posted by Wheatfield Quote
What makes you decide that a lens is junk?
As many forum users know, I am a fan of lesser known, weird, and cult glass. As such, my tolerance for quirks is pretty high. None-the-less, I do have my limits:
  • Obvious defect
  • Poor build/clumsy controls
  • Inconsistent performance
  • Overall poor contrast/sharpness
  • Poor distortion control
  • Gross optical aberrations
  • Unreasonably heavy/bulky paired with mediocre performance


Steve
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