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07-16-2011, 02:04 PM   #16
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QuoteOriginally posted by dgaies Quote
Have you used both the Canon 50/1.8 and Pentax F50/1.7? (or the FA50/1.4 which you linked to, which is a different lens BTW).

I'm guessing the answer is no.

As I said early, the 50/1.8 is a nice lens and a tremendous value, but it is not superior (other than in terms of cost) to the Pentax offerings in terms of IQ nor build quality.
I'm new so I don't know all the places for lens data, where can I find this information with pentax 50/1.7 vs canon 50/1.8. I assumed pentax 1.4 would be better than 1.7.

07-16-2011, 02:11 PM   #17
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QuoteOriginally posted by bob13bob Quote
well, when the new canon 50mm 1.8, is cheaper even when new, significantly sharper with less CA when both are at 1.8, and across most f-stops. not looking good for pentax options. If we want to bring in-body SR in to this; that's great but not really necessary for a fast 50mm. Also in-lense SR is vastly superior to in-body SR, so we can't get 100% apples to apples match

dpreview.com - Lens Review - Fullscreen
It's tough comparing different lenses across different bodies with different sensors. That said, going by the link you provided, the Canon does measure sharper @ 1.8. Once you stop down a little, the Pentax catches up in sharpness and is sharper on the edges. Although the Pentax does have more CA.

How did you come to the conclusion that in-lens SR (which the Canon 50/1.8 does not have) is "vastly superior" to in-body SR? I've used multiple cameras with sensor-based SR and optical-based SR, and find on shorter focal lengths they are equally good, @ 300mm in-lens SR is about 1 stop better, which I don't think is a "vast" difference.
07-16-2011, 02:12 PM   #18
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QuoteOriginally posted by VaSA Quote
If you're talking modern glass, than yes, Pentax has a huge disadvantage. But if you're like me and use mostly MF, then Pentax is the way to go.
why would go with mf only lens when i can get an mf/af lens for $80 used
canon 50 1.8 $80 used *sharper/significantly less CA most f-stops including 1.8
pentax 50 1.4 $300 used
pentax 50 1.4 mf-only $70 used (Pentax-M SMC 50mm/1.4 Lens)

I do not know how weigh Bokeh on canon vs pentax, when taken in context with sharp/CA. Are the old 1.4 mf better IQ than the newer 1.4?

Last edited by bob13bob; 07-16-2011 at 02:20 PM.
07-16-2011, 02:17 PM   #19
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QuoteOriginally posted by bob13bob Quote
I'm new so I don't know all the places for lens data, where can I find this information with pentax 50/1.7 vs canon 50/1.8. I assumed pentax 1.4 would be better than 1.7.
Well, the first thing to keep in mind is that comparing lens data ("by the numbers") is difficult between brands. I can't speak to the dpreview data specifically, but typically unless the same body wasn't used to test the two lenses you are trying to compare, then it is often difficult to compare the numbers in a meaningful way. Again, I don't know if the data you linked to is normalize in some way to account for that, but typically comparing numbers between brands is difficult to do by the numbers.

As to the comparison between the Pentax 50/1.7 vs 50/1.4, they're different and each has their own set of potential advantages. Most people agree that at large apertures the 1.7 is sharper than the 1.4 By about f/2.8 things even out. There are also slight differences in the rendering of the two lenses, and many people prefer the OOF/bokeh that the 1.4 offers. Obviously the 1.4 is also half a stop faster if you need it.

07-16-2011, 02:20 PM   #20
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QuoteOriginally posted by bob13bob Quote
why would go with mf only lens when i can get an mf/af lens for $80 used
canon 50 1.8 $80 used *significantly sharper/less CA most f-stops including 1.8
pentax 50 1.4 $300 used
pentax 50 1.4 mf-only $70 used (Pentax-M SMC 50mm/1.4 Lens)

I do not know how weigh Bokeh on canon vs pentax, when taken in context with sharp/CA. Are the old 1.4 mf better IQ than the newer 1.4?
You have an interesting way of interpreting data. The link you supplied does not support your statement.
07-16-2011, 02:22 PM   #21
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Hmm, I went to compare the Pentax DA 15mm with a Canon 15mm... oh wait, Canon doesn't have one!

Well, unless you count a fish-eye
07-16-2011, 02:26 PM   #22
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lens testing may not be perfect, but I personally value data and numbers over a lot of things. Once any one buys in to a system, we all bias ourselves a bit.

Anyone see any sides by sides, that may demonstrate lens better despite having less sharp/more CA.
07-16-2011, 02:34 PM   #23
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QuoteOriginally posted by bob13bob Quote
lens testing may not be perfect, but I personally value data and numbers over a lot of things. Once any one buys in to a system, we all bias ourselves a bit.

Anyone see any sides by sides, that may demonstrate lens better despite having less sharp/more CA.
I don't personally recall seeing a direct comparison between the two, probably in part because I don't really see what the point would be. Are you suggesting that your decision on which system to buy, Pentax or Canon, would hinge on the comparison between the 50/1.8 and 50/1.4 (or1.7)? I would suggest that whatever differences exist between the lenses are considerably smaller than the other factors one should consider when choosing a brand/system.

07-16-2011, 02:37 PM   #24
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QuoteOriginally posted by luftfluss Quote
You have an interesting way of interpreting data. The link you supplied does not support your statement.
you are correct. I adjusted my statement. Taking another look:
at f1.8 I would prefer canon
2.2 to 3.3 I would prefer pentax
3.5 onward prefer the canon.

no taking bokehs in to account, give the penax used price is almost 400% canons, data points to clear winner. What am I doing wrong here.
07-16-2011, 02:37 PM   #25
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QuoteOriginally posted by bob13bob Quote
lens testing may not be perfect, but I personally value data and numbers over a lot of things. Once any one buys in to a system, we all bias ourselves a bit.

Anyone see any sides by sides, that may demonstrate lens better despite having less sharp/more CA.
Numbers are great, research is even better. Did you research Canon/Nikon/Pentax etc. prior to buying into a system? Each system has it's own strengths and weaknesses.

Data and numbers work as a basis of comparison only when there is strict control of variables. In this case, Canon and Pentax have different size sensors. Also, there is sample variation when it comes to lenses. For example, one 50mm lens that measures , say, 2000 lph does not mean every 50mm lens will measure 2000 lph. Maybe some will measure 1900. Maybe some are slightly decentered so one side measures 2000 and the other side measures 1700.

You might like Welcome to Photozone!. They do lens tests and publish the measurements. They also note that you cannot compare lenses across different systems.

Oh, and according to Photozone, the Pentax FA 50/1.4 statistically wallops the Canon 50/1.8.
07-16-2011, 02:39 PM - 1 Like   #26
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QuoteOriginally posted by bob13bob Quote
you are correct. I adjusted my statement. Taking another look:
at f1.8 I would prefer canon
2.2 to 3.3 I would prefer pentax
3.5 onward prefer the canon.

no taking bokehs in to account, give the penax used price is almost 400% canons, data points to clear winner. What am I doing wrong here.
For one thing, not listening to the people who are trying to explain things and help you out.
07-16-2011, 02:44 PM   #27
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QuoteOriginally posted by bob13bob Quote
you are correct. I adjusted my statement. Taking another look:
at f1.8 I would prefer canon
2.2 to 3.3 I would prefer pentax
3.5 onward prefer the canon.

no taking bokehs in to account, give the penax used price is almost 400% canons, data points to clear winner. What am I doing wrong here.
Pretending for a moment that everything is equal, I would say, "prefer for what purpose"? For example, at f/4 the Canon has higher center sharpness, whereas the Pentax has higher edge sharpness. So if I had access to both lenses, maybe I would use the Canon to take a photo of my cat, while the Pentax for a landscape shot.

As far as prices go, yes, Pentax has a hole in their lens lineup for a new cheap 50. Comparing apples-to-apples, though, a Canon 50/1.4 is $400.

Bokeh is tough to quantify, because some people care very much about bokeh, some don't. It's subjective, because people find different kinds of bokeh pleasing.
07-16-2011, 02:53 PM   #28
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QuoteQuote:
Numbers are great, research is even better. Did you research Canon/Nikon/Pentax etc. prior to buying into a system? Each system has it's own strengths and weaknesses.
Research without data is not research.

QuoteQuote:
listening to the people who are trying to explain things and help you out.
listening does not equal believing.

Thanks for the photozone mention. I'll read up on it.
07-16-2011, 03:05 PM   #29
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QuoteOriginally posted by bob13bob Quote
Research without data is not research.
And data used without fully understanding what the data itself means, and how the data can be properly interpreted, is often misleading and can cause you to come to a premature and/or incorrect conclusion.
07-16-2011, 03:06 PM   #30
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QuoteOriginally posted by bob13bob Quote
Research without data is not research.

listening does not equal believing.

Thanks for the photozone mention. I'll read up on it.
Data != numbers.

You may want to switch to Canon, and I'm not saying this in a "you just don't 'get' Pentax way". Pentax is currently a niche player, and right now that niche includes old lenses, WR and Limiteds. To be a serious Pentax user is to acknowledge its shortcomings and work around them - in this case, no new cheap 50, but for a few bucks you can get a gorgeously metal M 50/1.7. The fact that you've soured on Pentax so quickly would indicate, barring an epiphany, that you won't ever be truly happy with them, forever casting your eyes upon a throng of shiny new Canon lenses.
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