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09-18-2008, 06:16 PM   #31
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QuoteOriginally posted by dave sz Quote
the way i feel about my k100, i can't see myself pending more on a lens than i did on a ow older body. if i can spend that much on a lens, i'd rather upgrade the body...
That is a pity, as the 6Mp sensor is really a brilliant sensor. As I stated in my post above, many of my *best* photos were shot on the *ist D which used the very same 6Mp sensor and I have photos from that sensor using the best Pentax lenses that have been printed to A3+ which is 485mm x 330mm or 19" x 13" and they are as sharp as a tack! I even have a panorama which was printed 1,885mm x 330mm and it is also sharp as a tack! Don't dismiss the capabilities of the 6Mp sensor with a top quality lens as it will definitely benefit from the lens upgrade and produce the goods!

09-18-2008, 07:47 PM   #32
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QuoteOriginally posted by Marc Sabatella Quote
You *do* shoot RAW and know how to work the noise reduction tools, right? If not, that's really step one. But unfortunately, noise is just part of life when shooting handheld in low light without flash.
that's a good point. I am trying to get the shooting down first before moving into post processing.
09-18-2008, 07:52 PM   #33
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QuoteOriginally posted by cpopham Quote
Presumably, you're talking about higher ISO, 800 - 3200? I think perhaps you might rethink this if you compared high ISO photos from both camera taken with identical exposures. If you take a look at, for example, Imaging Resource's Comparometer - compare the high ISO photos at 100%. If you really want, resize the K20 image down to 6mpixel. The noise is definitely different, perhaps more pleasing even, but I'm not sure it can really be described as lower noise.
I'm not sure what cameras you're looking at. The K100D is no longer shown in the Comparometer. Also, I don't know what setting they used in the K20D photos. I did my own test. I shot the same scene with my K100DS and K20D at ISO's up to 3200. The K20D is set for Weak noise reduction. The K100DS has no user-accessible NR setting. It was clear that the K20 is at least one stop better.

QuoteOriginally posted by cpopham Quote
On the other hand, if you're talking about low ISO the noise is barely going to factor into it at all.
This particular thread is about a guy who wants to photograph a baby indoors in low light, so ISO is definitely relevant.

QuoteOriginally posted by cpopham Quote
I disagree absolutely. Consider this - I can buy (here in New Zealand) a 50-135 for about 5/6ths the price of a K20 - if I bought a K20 and then used my 50-200 on it would that be better than my K100 with a 50-135?

And then there are the possibilities the faster aperture opens up...
But the OP doesn't have a 50-200mm, he has a 50mm 1.4. There's no question that a K20D with a 50mm lens is sharper than a K100DS with a 50-135. I don't see how anyone can argue otherwise. The 50mm is also two stops faster.

QuoteOriginally posted by cpopham Quote
Isn't a crop for magnification a linear reduction in both dimensions? 50 to 135mm is 2.7x . 14.6 divided by 2.7^2 is about 2 mpixel.
Maybe. Honestly I know how many pixels are left when you crop a 14.6 mp image from 50mm to 135mm. All I know is, I can crop over twice as much as I used to with the K100.
09-18-2008, 07:59 PM   #34
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QuoteOriginally posted by dave sz Quote
the way i feel about my k100, i can't see myself pending more on a lens than i did on a ow older body. if i can spend that much on a lens, i'd rather upgrade the body...
This is one of the the things I'm thinking as well. While I originally asked a number of questions (softness is due to technique, not camera nor lens), the first question was, should I spend this much on a lens for the entry level K100DS?

Having said that, what I don't want to do is spend a few hundred on a cheaper lens, only to regret it a year or so later.

09-18-2008, 08:04 PM   #35
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QuoteOriginally posted by Lance B Quote
The K100D Super has a fantastic 6Mp sensor and will suit the DA*50-135 perfectly. Do NOT think that the 6Mp sensor is not up to the task, as it is one of the best sensors out there, as implemented by Pentax. Some of my BEST photos have been taken with the *ist D which uses this very same sensor.
But the 50-135mm is not sharper than a 50mm 1.4, which is what he's using now.

QuoteOriginally posted by Lance B Quote
The other advantage of "stopping a lens down", ie going to a larger numbered aperture, you usually get better sharpness from a lens. The FA50 f1.4 gets better sharpness from about f2 to f2.8 onwards and is probably at it's best at about f8
The 50mm 1.4 reaches maximum center sharpness at f4, and maximum sharpness in the corners and edges at f5.6.
09-18-2008, 09:13 PM   #36
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QuoteOriginally posted by Lance B Quote
That is a pity, as the 6Mp sensor is really a brilliant sensor. As I stated in my post above, many of my *best* photos were shot on the *ist D which used the very same 6Mp sensor and I have photos from that sensor using the best Pentax lenses that have been printed to A3+ which is 485mm x 330mm or 19" x 13" and they are as sharp as a tack! I even have a panorama which was printed 1,885mm x 330mm and it is also sharp as a tack! Don't dismiss the capabilities of the 6Mp sensor with a top quality lens as it will definitely benefit from the lens upgrade and produce the goods!

Agreed, the 50-135 on my K100D Super is just superb. There is a jump in image quality K100D --> K20D, but in no way does this mean that the K100D doesn't produce killer images with the 50-135 - it does.

You lose a ton of cropability, some noise reduction advances, but really only minimal IQ id lost in most situations with the K100D vs. K20D with the DA* lenses.


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09-18-2008, 10:53 PM   #37
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QuoteOriginally posted by audiobomber Quote
I'm not sure what cameras you're looking at. The K100D is no longer shown in the Comparometer. Also, I don't know what setting they used in the K20D photos. I did my own test. I shot the same scene with my K100DS and K20D at ISO's up to 3200. The K20D is set for Weak noise reduction. The K100DS has no user-accessible NR setting. It was clear that the K20 is at least one stop better.
The K100 and K100 Super show up if you set it ""all cameras" rather than just "current cameras". Have a look at the high ISO "Still Life" shots. The unfortunate thing about the comparison is they used different lenses. If you want to see the settings, look at the EXIF data on the images. I still stand by my opinion that with a properly exposed photo the level of noise (but not necessarily the appearance) is similar.

There are a good many reasons to buy a K20, and truth be told, I would dearly love one. Excessive noise in my K100 photos is not one of those reasons.

QuoteOriginally posted by audiobomber Quote
Maybe. Honestly I know how many pixels are left when you crop a 14.6 mp image from 50mm to 135mm. All I know is, I can crop over twice as much as I used to with the K100.
But see, the problem is that the 50mm is not equivalent to the 50-135, seeing as how if you take a 6mpixel crop out of a 14.6mpixel image, you get about a 1.6x magnification - so about an 80mm lens. This is a very long way short of 135mm, but probably still more than enough for many portrait styles.

QuoteOriginally posted by audiobomber Quote
But the OP doesn't have a 50-200mm, he has a 50mm 1.4. There's no question that a K20D with a 50mm lens is sharper than a K100DS with a 50-135. I don't see how anyone can argue otherwise. The 50mm is also two stops faster.
Nobody is trying to claim that a K100 with a 50-135 is going to capture more information at 50mm than a K20 with an FA 50. What is being discussed is that the 50-135 is an excellent lens which can deliver excellent results on any Pentax DSLR.
Just as it can on a K20, and just as the FA 50 does 'even' on a K100.

What is, however being pointed out is that cropping from 50mm is not the same as having a 50-135mm lens, and there are some things you can do with a K100 and a 50-135 that you cannot do with a K20 and FA 50, such as take shots at the long end of that zoom range. In exactly the same way, the K20 / FA 50 combo allows you to take photos at f1.4, which you cannot of course do with the 50-135.

Both cameras have a purpose, and both lenses have a purpose. Sometimes these overlap, sometimes they don't. What everyone DOES seem to agree on is that all four pieces of equipment are excellent.
09-19-2008, 12:25 AM   #38
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QuoteOriginally posted by audiobomber Quote
But the 50-135mm is not sharper than a 50mm 1.4, which is what he's using now.
I don't get your point. I stated in my original post that the DA*50-135 would be great on his K100D Super, and that it is not the camera that will limit the useability of the DA*50-135. My point is that if the FA50 is good, then the DA*50-135 will be good as well as it does not out resolve the FA50 and therefore the camera is not the limiting factor. Although, having said that, at every aperture and every focal length, the DA*50-135 outresolves the FA50 at f1.4 and f2.

I was also pointing out that the reason he may not be getting such good results from his FA50 could be due to camera shake, poor focusing or DOF issues.

QuoteQuote:
The 50mm 1.4 reaches maximum center sharpness at f4, and maximum sharpness in the corners and edges at f5.6.
You are correct, I misread the table, but that is neither here nor there. The point of fact is that the FA50 is soft wide open and that he needs to stop down a few stops to get the best sharpness from this lens and this *could* be the reason for his "soft" shots *and/or* it could be due to camera shake(poor light levels) or a too narrow DOF.

09-19-2008, 07:07 AM   #39
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QuoteOriginally posted by Lance B Quote
Although, having said that, at every aperture and every focal length, the DA*50-135 outresolves the FA50 at f1.4 and f2.
Well that's kind of a misleading statement, since 1.4 and 2.0 aren't available on the 50-135mm.

QuoteOriginally posted by Lance B Quote
I was also pointing out that the reason he may not be getting such good results from his FA50 could be due to camera shake, poor focusing or DOF issues.
I agree. In fact several people brought up the DOF issure earlier in the thread, including me. I don't think this fellow needs a 50-135mm to make better baby portraits, yet a whole bunch of people in this thread have told him to get one.

QuoteOriginally posted by cpopham Quote
I still stand by my opinion that with a properly exposed photo the level of noise (but not necessarily the appearance) is similar.
Not a fair comparison. They used the K20D default setting, which is NR off.

QuoteOriginally posted by cpopham Quote
But see, the problem is that the 50mm is not equivalent to the 50-135, seeing as how if you take a 6mpixel crop out of a 14.6mpixel image, you get about a 1.6x magnification - so about an 80mm lens. This is a very long way short of 135mm, but probably still more than enough for many portrait styles.
Well then, he could zoom with his feet.

QuoteOriginally posted by cpopham Quote
Nobody is trying to claim that a K100 with a 50-135 is going to capture more information at 50mm than a K20 with an FA 50. What is being discussed is that the 50-135 is an excellent lens which can deliver excellent results on any Pentax DSLR.
Just as it can on a K20, and just as the FA 50 does 'even' on a K100.
But a 50mm on a K100DS captures as much information as a 50-135mm on a K100DS. The OP is using a 50mm and K100DS and is asking if a 50-135mm will give him better portraits. I don't believe it will. Personally I would not spend $800 on a lens for the K100DS. I tested several primes and a DA*16-50mm on my K100DS and on a K20D. I opted to upgrade the camera because a camera upgrade was a bigger payoff in resolution than a lens upgrade on the K100. Not to mention the handling.

You asked earlier if a K20D with 50-200mm would perform as well on a K20D as a 50-150mm on a K100DS. That's an interesting question. I'll try to find some time this weekend to do a similar test. I'll compare a K100DS/50mm 1.4 vs a K20DS/18-55mm at the same aperture and focal length. That should provide similar results. I'm betting the K20 with kit lens outresolves the prime and K100.

PS Just to step back a bit, I don't believe the OP needs a K20D or a 50-135mm to take better baby photos. All he needs for better portraiture is to improve his skills with the lens and camera he has now.

Last edited by audiobomber; 09-19-2008 at 07:14 AM.
09-19-2008, 07:58 AM   #40
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QuoteOriginally posted by audiobomber Quote
Well that's kind of a misleading statement, since 1.4 and 2.0 aren't available on the 50-135mm.



I agree. In fact several people brought up the DOF issure earlier in the thread, including me. I don't think this fellow needs a 50-135mm to make better baby portraits, yet a whole bunch of people in this thread have told him to get one.



Not a fair comparison. They used the K20D default setting, which is NR off.



Well then, he could zoom with his feet.



But a 50mm on a K100DS captures as much information as a 50-135mm on a K100DS. The OP is using a 50mm and K100DS and is asking if a 50-135mm will give him better portraits. I don't believe it will. Personally I would not spend $800 on a lens for the K100DS. I tested several primes and a DA*16-50mm on my K100DS and on a K20D. I opted to upgrade the camera because a camera upgrade was a bigger payoff in resolution than a lens upgrade on the K100. Not to mention the handling.

You asked earlier if a K20D with 50-200mm would perform as well on a K20D as a 50-150mm on a K100DS. That's an interesting question. I'll try to find some time this weekend to do a similar test. I'll compare a K100DS/50mm 1.4 vs a K20DS/18-55mm at the same aperture and focal length. That should provide similar results. I'm betting the K20 with kit lens outresolves the prime and K100.

PS Just to step back a bit, I don't believe the OP needs a K20D or a 50-135mm to take better baby photos. All he needs for better portraiture is to improve his skills with the lens and camera he has now.

This is an interesting discussion, good points on both sides.

The K100D + FA 50 1.4 is a great baby combo. (Trust me.)

However, once that baby starts getting out into the yard, or just moving around the house more, the 50-135 becomes invaluable. (trust me again.)

The Tamron 28-75 f/2.8 is another good baby chaser, but being able to zoom out to 135mm at f/2.8 with exceptional IQ is great for catching the candid moments, like, for example when baby whips across the yard to grab the cat.

Improving technique has more affect on image quality than upgrading anything.


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09-19-2008, 09:56 AM   #41
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QuoteOriginally posted by audiobomber Quote
here's my reasoning:

- The 50mm 1.4 and 50-135 have similar MTF scores
- The K20D has a lower noise CMOS sensor that the K100DS CCD sensor, so better IQ
- The K20D has 14.6mp, so can be cropped to an equivalent fov of 135mm and still have about 6mp. At any larger FOV it will have more pixels, therefore higher resolution
I agree on the surface this seems somewhat logical (assuming your stats are correct). I'd still prefer to see photographic evidence before accepting it as fact.

Mind you, I am *not* necessarily recommending the 50-135 for the OP. By all accounts, a great lens, one capable would take great pictures on the K100D or any other Pentax DSLR. The bigger issue really is what focal lengths and apertures the OP needs for his purposes, and what else might held improve his shots.
09-19-2008, 05:46 PM   #42
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QuoteOriginally posted by audiobomber Quote
PS Just to step back a bit, I don't believe the OP needs a K20D or a 50-135mm to take better baby photos. All he needs for better portraiture is to improve his skills with the lens and camera he has now.
I think this is one thing we both agree on, so let's leave it at that.
I'll also be very interested to see the results of your test.
09-19-2008, 06:34 PM   #43
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QuoteOriginally posted by laissezfaire Quote
the K100D Super?

1) is this too good a lens for my K100D Super?
To get back to the actual original question... the answer is with out a doubt "No". this is not too much lens for your camera. This lens will take beautiful pictures on any camera.
09-20-2008, 07:04 AM   #44
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QuoteOriginally posted by audiobomber Quote
Well that's kind of a misleading statement, since 1.4 and 2.0 aren't available on the 50-135mm.
How is it misleading? The point I am making is that the poster asked if the DA*50-135 would be too good for his sensor. I merely stated that if the FA50 is not too good for the sensor, then the DA*50-135 wouldn't be either as it is not as good optically as the FA50 *except*, and this is why I said the comment "however, having said that, at every aperture and every focal length, the DA*50-135 outresolves the FA50 at f1.4 and f2", that it does outresolve the FA50 at f1.4 and f2. I fail to see how this is misleading and you seem to be trying to pick my points to pieces to try to win points in your(flawed) reply comments to my post.



QuoteQuote:
I agree. In fact several people brought up the DOF issure earlier in the thread, including me. I don't think this fellow needs a 50-135mm to make better baby portraits, yet a whole bunch of people in this thread have told him to get one.
I merely responded to his question which was, "would a DA*50-135 be too good for his K100D sensor?" and I merely stated that it wouldn't be. What he does with this lens is his business and he can make his own judgements on that score.
09-20-2008, 01:44 PM   #45
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I'm not trying to pick a fight Lance. I'm just debating my point of view in a lens forum. I admire your photographic talent and your input on these boards.

I just posted a new thread as a result of some things that were said here. https://www.pentaxforums.com/forums/pentax-dslr-discussion/37485-k20d-vs-k100ds.html
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