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03-01-2013, 10:47 AM   #46
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QuoteOriginally posted by JonPB Quote
But I'm probably being incredibly na´ve, being that I'm definitely quite ignorant of the relative weight of effort required for each part of the process.
I don't know anything about lens design. I'd love to hear someone at Pentax answer this. Is updating an old lens easy, or at least easier than designing from new? I suspect it is, which would explain the DA 35 f2.4 and DA 40mm designs.

03-01-2013, 10:56 AM   #47
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QuoteOriginally posted by boriscleto Quote
There will be no Pentax FF until there are new lenses to support it...
Excellent point! (has Pentax/Ricoh mopped themselves into a corner? )
03-01-2013, 10:59 AM   #48
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QuoteOriginally posted by rhodopsin Quote
Excellent point! (has Pentax/Ricoh mopped themselves into a corner? )
It is a conundrum.

When considering what would stimulate the sale of new lenses, a new mount would stimulate the sale of new lenses (if they had them to sell), but at what cost to the existing user base (who would then be incentivized to consider every other option Nikon)?
03-01-2013, 06:35 PM   #49
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QuoteOriginally posted by chesebert Quote
That's just how I processed the photo, I don't see CA with the original:

I do.

03-01-2013, 07:00 PM   #50
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QuoteOriginally posted by Digitalis Quote
I do.
Me too but it is simple to remove in post and it would also improve edge sharpness to

I find that many 24-28 mm lenses from the mid 80's to mid 90's exhibit lateral ca. My sigma mini spwide II is the same. Rally noticible until you remove it in post with a program that rescaled the color layers for CA correction
03-01-2013, 07:08 PM   #51
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K24/3.5 was very evident so I sold it and bought a K24/2.8. Still there, but not so noticeable. My worst lens for lateral PF was a Tamron SP 70~210/3.5 19AH. Very sharp and beautiful color but prone to PF.

[EDIT]: In response to Lowell's observation below, I should clarify. The Tammy displayed purple fringes in high contreast situations such as tree branches agasinst a flat blue sky. The K24/3.5 at widest apertures showed unsharp edges which I attributed to chromatic aberration, i.e. some colors in the spectrum did not perfectly strike the film in the identical place due to wavelength differences.

If incorrect then I stand corrected.

Last edited by monochrome; 03-01-2013 at 07:44 PM.
03-01-2013, 07:15 PM   #52
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QuoteOriginally posted by Lowell Goudge Quote
Me too but it is simple to remove in post and it would also improve edge sharpness to
Quite right, but on the FA*24 the CA is the least of your problems, there is noticeable field curvature and astigmatism. The only redeeming qualities of this lens is that it has low distortion and very high contrast even at f/2 - but IMO that only makes the CA from the lens stand out even more.
03-01-2013, 07:20 PM   #53
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QuoteOriginally posted by monochrome Quote
K24/3.5 was very evident so I sold it and bought a K24/2.8. Still there, but not so noticeable. My worst lens for lateral PF was a Tamron SP 70~210/3.5 19AH. Very sharp and beautiful color but prone to PF.
PF is not CA. Please be careful here

03-01-2013, 07:23 PM   #54
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QuoteOriginally posted by monochrome Quote
K24/3.5 was very evident so I sold it and bought a K24/2.8. Still there, but not so noticeable. My worst lens for lateral PF was a Tamron SP 70~210/3.5 19AH. Very sharp and beautiful color but prone to PF.
PF is not CA. Please be careful here
Latera CA is usually purple with higher magnification and green with lower magnification silting is green fringe inside and purple fringe outside
03-01-2013, 08:30 PM   #55
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QuoteOriginally posted by Lowell Goudge Quote
PF is not CA. Please be careful here
QuoteOriginally posted by Lowell Goudge Quote
PF is not CA. Please be careful here
Latera CA is usually purple with higher magnification and green with lower magnification silting is green fringe inside and purple fringe outside
Whoa...Deja Vu.
03-01-2013, 08:38 PM   #56
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QuoteOriginally posted by Digitalis Quote
I do.
Ok. At the extreme edge, yes.
03-02-2013, 01:28 AM   #57
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I was actually looking at the boat in the lower middle portion of that frame - if you can spot CA in a small web sized image, it is going to be blindingly obvious in a 16X24" print. To draw a modern comparison with a digital specific lens consider the DA15mm f/4. Which has some pretty bad CA in the corners, and although it is possible to correct it with software there is only so much information that can be recovered. The atigmatism and field curvature from the DA15mm f/4 cannot really be covered up - the FA*24mm f/2 also suffers from a similar degree of field curvature and astigmatism as the DA15.
03-02-2013, 08:48 AM   #58
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Please, please give us a DFA* 200mm F4 Macro, based on the FA* Macro so scarse and so sought after!

Kjell
03-02-2013, 08:59 AM   #59
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QuoteOriginally posted by Digitalis Quote
I was actually looking at the boat in the lower middle portion of that frame - if you can spot CA in a small web sized image, it is going to be blindingly obvious in a 16X24" print. To draw a modern comparison with a digital specific lens consider the DA15mm f/4. Which has some pretty bad CA in the corners, and although it is possible to correct it with software there is only so much information that can be recovered. The atigmatism and field curvature from the DA15mm f/4 cannot really be covered up - the FA*24mm f/2 also suffers from a similar degree of field curvature and astigmatism as the DA15.
Your observation escapes me. I am not even sure we are looking at the same thing. CA are the purple/green fringes, right? If yes, then I do see some toward the left edge where the buildings are, but I can't seem to make out any where the boat is.
03-02-2013, 07:27 PM   #60
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QuoteOriginally posted by chesebert Quote
CA are the purple/green fringes,right?
CA can also be can also be seen as Red/Cyan,Yellow/Blue fringing it really depends on the lens. Longditudinal Chromiatic aberration (LOCA) is almost always Purple/Green and is most common with non-apochromatic lenses shorter than 100mm - and sometimes it appears in lenses much longer than that the DA*200mm f/2.8 springs to mind. LOCA often appears in the transition point of in focus areas, and out of focus areas.
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