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09-15-2008, 11:21 PM   #46
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QuoteOriginally posted by regken Quote
1) Any reasonably sized P & S sensor (1/1.8" or larger) or any CCD or CMOS APS-C, or 4/3 sensor with the same lens will look identical when shot at base ISO, processed through RAW, and printed at 8 X 10.
Since this is the first I've heard this, and it flies in the face of my personal experience, I have to ask - do you have a source for this knowledge?

QuoteQuote:
2) I haven't seen any lenses that a 10MP APS-C sensor can out resolve. There are most likely a lot of lenses that a 24MP or larger FF sensor will out resolve. There might even be a few that a 14MP APS-C senor can out resolve but I haven't found them. I'd give you 50 to 1 odds a 16-18MP FF senor will not be able to out resove any Pentax film lens ever made.
It seems like you're approaching this backwards - I was saying that a lens is capable of out resolving a sensor, not the other way around. For example, my Sigma 70 macro seems to outresolve my 6MP K100D - but my M 28 does not. I see a finer level of detail, more subtle changes in tonality, a more 'real' gradient of shadow with some of my lenses on the K20D vs. K100D. With some other lenses, I see no noticeable difference.

With film, I imagine you'd get the same effect using super-fine grained pro film vs. some bargain film with a very good lens.


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09-16-2008, 05:01 AM   #47
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QuoteOriginally posted by jsherman999 Quote

It seems like you're approaching this backwards - I was saying that a lens is capable of out resolving a sensor, not the other way around. For example, my Sigma 70 macro seems to outresolve my 6MP K100D - but my M 28 does not. I see a finer level of detail, more subtle changes in tonality, a more 'real' gradient of shadow with some of my lenses on the K20D vs. K100D. With some other lenses, I see no noticeable difference.

With film, I imagine you'd get the same effect using super-fine grained pro film vs. some bargain film with a very good lens. .

This is getting way off track. Let me try and state my position differently.
The obsession many posters have with the latest greatest gear is not justified. When a new person comes on this forum and asks advice many people recommend the most expensive body and costliest lenses. Unless that person intends to turn pro next week or plans on printing 24 X 36 prints and larger it is bad advise and does a disservice to not only the OP but misleads any other readers.

A quality P & S camera has many disadvantages when compared to a DSLR but IQ is not one of them when your intent is to print no larger than 8 X 10 at base ISO and are not concerned with DOF. The oldest APS-C DSLR made by anybody that is at least 6MP is capable of producing prints up to at least 14 X 11 that are as good as the latest model including the K20D as long as you are shooting at ISO 400 or less. To call a K10D or for that matter a DL obsolete is ludicrous when in actuality they will serve most people with 100% of their needs.

Lens advise that is thrown around is even worse than body information. Why would anybody that doesn't need a sealed lens, quiet operation, or f2.8 buy a 16-50 when there are IQ equal alternates for $300-$400 less? Ego? Furthermore, when recommending a lens don't you have an obligation to mention the possible probelms it might have along with it's strengths?

The whole discussion about lenses out resolving sensors is academic at best when an APS-C sensor has less than 15MPs. Most, if not all lenses ever made will out resolve that size sensor.

The bottom line is we have an obligation to our fellow entusiasts to be open and honest with our recommendations, warts and all. If your obsevations come from pixel peeping at 300% say so. If your conclusions are based on prints made to a certain size, include that. In another post Ben said

We will introduce a camera that does NOT allow one to magnify the image on the screen greater than 25 percent unless you actually commit to printing an image on a minimum size of 8 x 10 inches. Or A4 format. Once you press print and the printer is activated, you may magnify ONLY to the output of the said print. So for those of you needing to see a 100 percent magnification of the K20D at 220 dpi, you will have to invest in a A1 or minimum a A2 printer...

Sorry to rant on like this.

Ken
09-16-2008, 06:22 AM   #48
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QuoteOriginally posted by IsaacEastgate:
I new it was a huge mistake bringing my opinion to a camera forum, even if pentax users seem to have a much greater appreciation of old lenses. But many of you seem to be on the verge of pixel-peepers.
This was the reason why I asked the question: photography is more about experience than how much kit your money will buy. I am more interested in hearing about people's experience than about how much kit they have.

QuoteQuote:
I just feel that the image is about overall composition and mood. What you feel when you look at it, not what you see when you zoom in too far. Barrel distortion hardly effects the end image does it? Neither does vignetting in most situations.
Maybe I should not admit this, but I don't see things like CA, or PF, or other distortions. If the image does not look right it gets binned, but if the image looks good to me - which by definition means that if there are optical imperfections they are unimportant - then the image is kept.

To keep on topic, there are lenses that I have never had a good image from - those are "bad" lenses as far as I am concerned. Part of it is my inexperience with the lens, and part is the lens. For example I have a Hoya 28/2.8 M42 lens that I bought 20 years ago. (Sures, there's no point in me using it because my kit lens covers that field of view anyway, and the Hoya is a cheap lens). But the Hoya lens adds a blue cast which makes landscapes appear flat, so I have yet to find a subject that I can use it for. (However, it has been a good lens for me to take apart and hone my lens disassembly and cleaning techniques!)

Richard
09-16-2008, 07:42 AM   #49
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lens comparison

When I got my A50 1.7 the images just looked "better" than my only other lens at the time - which was the 18-55 kit lens. So I did some (lame) testing - just for sharpness. Here is a side by side comparison of the two.

both at f8 50mm 100% crop.

On the left is the kit lens, on the right the MF A50. I'm not saying the kit lens is bad, but it certainly is soft in comparison.

Name:  KitVs50mmat8.0.jpg
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09-16-2008, 07:52 AM   #50
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Equivalently, the 16-45 at f/4.5, followed by the 43 limited, same exposure:



Like meszidik, I don't consider the zoom a bad lens: it makes photographs that make sense, with good color, contrast etc. For a zoom perhaps it's even near the top of the scale... but the 43 is a 'good' lens and you can see the better definition in this sample. Do you need the qualities of the 43? No, not really, in order to make excellent photos, but can you use the added defintion? Sure!

Last edited by Nesster; 09-18-2008 at 03:00 AM.
09-16-2008, 08:18 AM   #51
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QuoteOriginally posted by regken Quote
This is getting way off track. Let me try and state my position differently.
The obsession many posters have with the latest greatest gear is not justified. When a new person comes on this forum and asks advice many people recommend the most expensive body and costliest lenses. Unless that person intends to turn pro next week or plans on printing 24 X 36 prints and larger it is bad advise and does a disservice to not only the OP but misleads any other readers.

A quality P & S camera has many disadvantages when compared to a DSLR but IQ is not one of them when your intent is to print no larger than 8 X 10 at base ISO and are not concerned with DOF. The oldest APS-C DSLR made by anybody that is at least 6MP is capable of producing prints up to at least 14 X 11 that are as good as the latest model including the K20D as long as you are shooting at ISO 400 or less. To call a K10D or for that matter a DL obsolete is ludicrous when in actuality they will serve most people with 100% of their needs.

Lens advise that is thrown around is even worse than body information. Why would anybody that doesn't need a sealed lens, quiet operation, or f2.8 buy a 16-50 when there are IQ equal alternates for $300-$400 less? Ego? Furthermore, when recommending a lens don't you have an obligation to mention the possible probelms it might have along with it's strengths?

The whole discussion about lenses out resolving sensors is academic at best when an APS-C sensor has less than 15MPs. Most, if not all lenses ever made will out resolve that size sensor.

The bottom line is we have an obligation to our fellow entusiasts to be open and honest with our recommendations, warts and all. If your obsevations come from pixel peeping at 300% say so. If your conclusions are based on prints made to a certain size, include that. In another post Ben said

We will introduce a camera that does NOT allow one to magnify the image on the screen greater than 25 percent unless you actually commit to printing an image on a minimum size of 8 x 10 inches. Or A4 format. Once you press print and the printer is activated, you may magnify ONLY to the output of the said print. So for those of you needing to see a 100 percent magnification of the K20D at 220 dpi, you will have to invest in a A1 or minimum a A2 printer...

Sorry to rant on like this.

Ken

I think I see what you mean, although we disagree on your assertion that a 3 year old P&S sensor is equal to the K20D sensor at ISO < 400 up to 8x10. I think you're discounting sensor advancement too much, especially with the latest generation of CMOS sensors. I posted a link earlier that you should look at - if you accept that there are better lenses than others in regards to color fidelity, contrast, and resolution, then I think you'd have to accept that it's possible for a sensor to show these differences - especially new sensors that are being designed to do so. What was true yesterday is not necessarily true today.

Mike Johnston has placed the K20D's image quality 2nd in the current crop of bodies, ahead of some much more expensive cameras. He's also called the DA 35ltd one of the better lenses he's ever used. I can almost guarantee that if he'd been shooting that lens on a *istD, he wouldn't have come to that conclusion - the K20D's sensor showed him what the lens was capable of.

Also, on a side note - if all we talked about in this forum were things that we need, and not things that we want, this place would be a ghost town - you can only say so many things about the kit lens before the eyes start to glaze over and people trot off to drudgereport.



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09-16-2008, 09:34 AM   #52
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QuoteQuote:
Daniel Lee Taylor , Aug 03, 2007; 06:33 p.m.

Bob - I really don't see anything in your post that was a response or retort to mine. (If that was your intent. It seems like it was.) What a lens can resolve at the bottom of the MTF curve is not what people at home judging images in Photoshop are noticing with their eyes.

Looking through Canon's library you can find lens charts where the lens has less than 50% MTF at 30 lpmm, center. Sometimes much less. If you put a lens like that on a 30D and a 5D, you're not going to see much difference between the bodies in the final images. Put one of Canon's great telephotos on, and you will clearly see the difference between bodies in the final images.

So when somebody comes on the board and says "man, most lenses can't out resolve my 30D let alone my 5D", they are not talking about resolution in the same way you are when you say lenses can resolve 150 or 200 lpmm. They're not shooting black and white charts under studio lights trying to find the last fuzzy pair of lines that can still be said to be distinct. (If they were doing that, they would be shooting B&W film any way.) They're noticing the differences between lenses in the rendering of details in the 10-50 lpmm range.

And in that respect, yes, DSLRs can "out resolve" many lenses. Worded more accurately: images from the DSLR would show improvement using a lens with a higher MTF curve.

As you point out, final resolution and MTF is determined by the interaction of the lens and the sensor (or film). But if you can no longer improve the image with a better performing lens, you could say the lens "out resolves" the sensor. If you can no longer improve the image with a higher resolution sensor, then you could say the sensor "out resolves" the lens.

My guess is there are plenty of people with consumer zooms who have been through 2 or 3 generations of DSLRs by now, and have noticed that the images didn't really improve when using those zooms.

States it pretty well, although he was responding to a good post by Bob Atkins in which Bob asserts that, at center, most current (2007 at least) sensors will not be able to outresolve most lenses.

link.



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