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07-31-2009, 09:58 AM   #1
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Old Lens/New Lens

Hello All,
I am a newbie amateur with a K100D super and have enjoyed the portraits I have made with my Pentax A 50mm F2 lens and recently purchased a Sears 50mm f1.4 for $10 and have like the images it has made. My question is this. How much better would my images be if I purchased the newer Pentax autofocus 50 mm f1.4? If the old manual lenses produce images as good as the newer autofocus lenses then why purchase a new one when the old ones are so reasonable. I know there are some situations where an autofocus would help but I learned on the old manual K1000 so this is not a huge inconvenience for me especially for portraits where I have time to set up a shot. Thank you in advance for your answers.
Mike

07-31-2009, 11:08 AM   #2
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The differences are not very large. I don't know a lot about your Sears lens so I'm assuming some things, but here are three reasons why. First, fast 50mm lenses don't vary much in lens design, so I wouldn't expect a huge design advantage for a new lens. In fact, Pentax's design for the FA is 25 years old, and has only changed a little over 50 years. Second, the f1.4 lenses were usually upgrades, so they are meant to be better. Third, your camera is only using the center two-thirds of the lens, and most optical issues are worst at the extreme edges. Fourth, cost-cutting wasn't as extreme then as it is now. Lenses built in the early 70s used construction standards that make today's super-premium lenses look like crap, even if the 70s lenses were ordinary optically.

The biggest image improvement you'd see is due to lens coatings. They affect color, contrast and flare rejection. Pentax had a huge lead here in the early 70s, so even old Pentax lenses have excellent coatings. Other old lenses may not. You can take the same shot of a colorful scene with your Sears lens and the Pentax-A 50mm f2 at f8 or f11, where both lenses should have decent sharpness. If the Sears lens has decent coatings, the photos will look the same. You might see considerable differences, though.

One other area where the lenses might be different is the quality of the out-of-focus areas. This is extremely subjective.

For other lenses than 50mm primes, newer lenses are often optically better. Zooms are far better than they used to be before computer design. Wide-angle lenses below 24mm are probably better. Computers do a better job correcting for optical issues that were previously ignored or related to digital sensors. So save your money if you like your 50mm results, but spend it on something new if you need a zoom that starts at 16mm.
07-31-2009, 11:46 AM   #3
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Totally aside from any difference in lens age or the presence of AF is the simple fact that the various versions of the 50/2 are the weakest of the 50's Pentax made. The 50/1.7 and 50/1.4 lenses - again, regardless of AF or age - are just better lenses. So the FA50/1.4 might be an improvement over the A50/2, but the A50/1.7 or M50/1.7 or M50/1.4 would be, too, for less than half the price (A50/1.4 isn't usually enough cheaper than the Fa to be worth considering).
07-31-2009, 11:50 AM   #4
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All the things Dave said...

Edit... What Marc said too...

In regards to your Pentax-A 50/2...The 50/2 has a reputation for so-so performance. Moving to any Pentax 50/1.4, 50/1.7, or 55/1.8 will be an upgrade. While older lenses often have better build, the FA 50/1.4 is no slouch and would be a fine choice if you are need AF.

The Sears 50s were generally the same lens as the Rikenon (Ricoh) 50s of the same vintage. The K-mount Rikenons are good optics and I would expect that the Sears-branded version would be too. While I am not willing to say that your Sears lens is the equal of a Pentax 50, it may well be all that you need from a feature/performance point of view.

I have several lenses in the range of 50-58mm and my current favs (in order) are:
  • Pentax-K 55/1.8
  • Auto-Rikenon 50/1.7 (M42)
  • Helios 44M 58/2
  • XR-Rikenon 50/2

Steve

07-31-2009, 12:00 PM   #5
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there are I think lots of differences depending on the lens optically. We will leave MF vs AF out of the question for the moment.

older lenses have different optical coatings, some of these cause as much as 2.5% of the light entering the lens to be lost in the coatings, nearly lossless coatings began with Super Multi Coated lenses. the older coatings may also influence color differently than newer coatings. Additionally these older lenses are more subject to lens flair from bright lights in the field of view and may benefit more with a lens hood.

many older lenses are not aprochromatic, which means they exhibit a separation of colors for out of focus parts of the image, usually green on one side purple on the other. With B&W this was not an issue, it was just out of focus and part of the bokeh but some people don;'t like it.

Older lenses had significantly different optical formulas, not all of them carried over. Most older lenses move the entire lens group to focus, newer lenses have focusing internal to them, moving only 1 element or group. IF makes focusing loads easier for autofocus motors, but as a result the bokeh of lenses could be different due to the different focusing mechanism

Digital lenses have coatings on the rear element to stop reflections from the sensors, that reduce contrast, older lenses don't, therefore on a DSLR the older lenses may have a lower contrast image. This is not necessairly a bad thing, and can be corrected.

Overall even if sharpness is the same there are a lot of characteristics that will impact the image as a whole, and some people swear by the older lenses for the bokeh or out of focus image behavior.

One other thing to note, old lenses are all metal and glass, and weigh significantly more than new lenses using modern materials. The feel, as a result, is much different between an old lens and a new one when manually focusing.

True digital lenses are designed to have the light exit the lens differently, so they hit the sensor at closer to a right angle.
07-31-2009, 03:29 PM   #6
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Lowell gave a great overview of the differences between old and new lenses.

I'll only add that the "newer" 50/1.4 you are looking at is not a digital lens so the digital coatings comment doesn't apply in this case. It of course is still very valid information. On the other hand, even non-digital coatings were (supposedly) improved over time.

Another thing I feel I must comment on is that if you are picky about your photos, lens flare is not really correctable - no matter how much you turn up the contrast and sharpen the image. You can mitigate the damage a little but you can't remove it completely.


I have the DA 40/2.8 ltd, the FA 50/1.4, a Sears 55/1.4, a super-tak 1.4, and (I think) a super-smc 2.0. Of all of them, my favorite is the FA 50/1.4 (which I assume is what you are looking at). It has a beautiful color rendition and is quite sharp in the sweet spot. CAs exist but are OK.

I quite dislike my Sears 55/1.4 in comparison. Definitely soft.
08-01-2009, 01:44 PM   #7
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Thank you all for that great information. Mr. Fletcher the FA 50 1.4 is indeed the one I have been looking at/for so I appreciate that info. As soon as I learn to post some photos I will post some that I have taken with my sears lenses to get some critiques on what I can do better. I look forward to the FA 50. Again thanks all for the great info.
08-02-2009, 07:17 PM   #8
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QuoteOriginally posted by Just1MoreDave Quote
For other lenses than 50mm primes, newer lenses are often optically better. Zooms are far better than they used to be before computer design. Wide-angle lenses below 24mm are probably better. Computers do a better job correcting for optical issues that were previously ignored or related to digital sensors. So save your money if you like your 50mm results, but spend it on something new if you need a zoom that starts at 16mm.
So a manual Tokina 24-40 would not be worth getting unless it was really cheap?

08-03-2009, 09:55 AM   #9
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QuoteOriginally posted by tojax Quote
So a manual Tokina 24-40 would not be worth getting unless it was really cheap?
I don't think that's necessarily true. I don't know a thing about the Tokina 24-40 you mention, but the comments above shouldn't be taken to mean all older zooms are bad. Some older manual zooms, like the A 35-105 f/3.5 are very well regarded.

More likely than not, you're better off with zooms with a fixed maximum aperture (true for even newer zooms) with a zoom range in the normal to short-tele ranges. The narrower the zoom range, the better your chances probably are with the older ones, too. That's by no means a given, though. The truly good zooms from before computer aided design are few.
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