[lytrytyr]

Actually there is not much difference between Greg and Ken Rockwell, only where the dividing line in the last 5% actually sits.

Has Greg asked us to support his growing family?

[Lowell Goudge]

Has Greg asked us to support his growing family?

no but although ken asks I ignore, so considering that I pay neither I consider them the same

[wildman]

I have often taken issue with Ken on other topics but on this I think he is pretty much spot on.


A few of his points where I think he pretty much nails it:
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"People would make far better pictures if they spent time learning how to make great photos with what they already own instead of worrying about their tools.

Even the cheapest SLR and compact cameras lenses are sharper than expensive lenses used to be, and all are sharper than most digital camera's ability to resolve fine details.

We need to worry about how a lens works as part of a much larger system of live tracking autofocus, aperture and exposure control, distance information fed to the metering system, vibration reduction, zooming, and more.

Only idiots find something's limits, and let themselves get stuck there complaining about it. It's every artist's duty to find his tools' limitations so he can work around them.

Most gear has always been much better than people's abilities to use it. [AMEN!]

In reality, everything moves, and nothing is flat. If nothing is flat, then only one point is in perfect focus while the rest isn't.

Not only do long lenses have paper-thin depths of field, but their biggest barrier to sharpness is our atmosphere!

Know your gear's limitations, and work within them. This is the basis of everything people do.

sharpness of any image is limited mostly by the format.

Your creative input to a photo makes far more of an imprint on the image than any small, and often invisible, difference in sharpness from one lens to another."
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In my opinion most folks on this forum, including myself, are kidding themselves when they think that the ultimate final esthetic quality of their images is being substantially limited by the quality of the glass they are using:…..

...A couple years ago I bought my Niece a cheap little 500mm FL, 70mm two element achromatic objective (that works out to about f/7 and 15x mag. ) astro scope from Walmart. They had a big pile of them all shrink- wrapped and all it said was made in Viet Nam. 50 bucks new.

I'm fimiliar with working with astro scopes so it was no big deal for me to adapt it to the old DL. A few backyard shots off of my deck.

Judge for youself. Note: these are really nothing more than over sized thumbnails really so don't be too critical of these little JPGS.

[Lowell Goudge]

wildman

I disagree strongly with one of your points

You said "Only idiots find something's limits, and let themselves get stuck there complaining about it. It's every artist's duty to find his tools' limitations so he can work around them"

I would reword this to be the following

Only idiots find something's limits, and let themselves get stuck there complaining about it. It's every artist's duty to find his tools' limitations so he can exploit them

this is a very small distinction, but a necessary one. a technician works within the limits of his tools, and artist exploits the limits.

[wildman]

I disagree strongly with one of your points

These points were made by Ken not me. I should have put them in quotes - my bad.

So far as the semantics is concerned you will get no argument from me.

[northcoastgreg]

but also in his rebuttal actually reinforces some of the underlying point, that almost every lens out there is sufficiently sharp, by stating that all kit lenses and superzooms have sufficient resolution for 95% of photography. If this is the case, does that mean that all the fancy primes expensive tele's etc... are filling the 5%?

No, it does not mean that. The fact that most kit lens and super zooms have sufficient resolution over some of their focal range does not mean that "fancy" lenses are needed only by 5% of the photographs; for that ignores my chief difference with Rockwell, which involves optical qualities other than mere sharpness, such as the speed of the lens, color rendition, etc. If you're shooting style involves taking candid portraits, you're going to need something faster than a kit lens. If you want to shoot wildlife, you may need something longer (and sharper: resolution can be important at longer focal lengths, as that is where the cheaper glass tends to fall short). When I finally was able to move up from cheap glass to higher end glass, I expected to find improved sharpness, but that didn't turn out to be the most obvious or noticeable difference. Yes, the more expensive lenses are sharper, but that's often only noticeable at pixel peeping resolutions. The most noticeable difference between cheap glass and expensive glass is the quality of the rendering, particularly the color rendition. Images from more expensive lenses just look better, irrespective of resolution.

[Lowell Goudge]

No, it does not mean that. The fact that most kit lens and super zooms have sufficient resolution over some of their focal range does not mean that "fancy" lenses are needed only by 5% of the photographs; for that ignores my chief difference with Rockwell, which involves optical qualities other than mere sharpness, such as the speed of the lens, color rendition, etc. If you're shooting style involves taking candid portraits, you're going to need something faster than a kit lens. If you want to shoot wildlife, you may need something longer (and sharper: resolution can be important at longer focal lengths, as that is where the cheaper glass tends to fall short). When I finally was able to move up from cheap glass to higher end glass, I expected to find improved sharpness, but that didn't turn out to be the most obvious or noticeable difference. Yes, the more expensive lenses are sharper, but that's often only noticeable at pixel peeping resolutions. The most noticeable difference between cheap glass and expensive glass is the quality of the rendering, particularly the color rendition. Images from more expensive lenses just look better, irrespective of resolution.

but by the same token, just because you spend more does not gaurantee color, and bokeh. that is one of the unfortunate truths about lenses and design. i don't think any one designer today starts out by saying i want great bokeh, at the end it is what it is, not the other way round.

I don't necessairly disagree with you here, it is just I am not sure that the qualities are directly related to the $$$ of the lens, aside from the obvious one that for lenses tending toward tele, price ~ focal length * speed and for lenses that are going wide price ~ 1/Focal length * speed. Every lens has a color cast that is a function of the glass used, and coatings used, bokeh is really random, in terms of quality. other things like lateral CA and distortion are also a mixed bag as a function of each lens design and trade offs made.

One thing I will agree with is really cheap zooms are..... really cheap zooms. but many kit lenses are made in ranges where optical design is still simple, and expensive components and elements are not required, and can be quite good, until you hit the design limits

[jaytee]

The point about our atmosphere is a valid one, here in Tucson we rarely have better than 10 mile visibility. That can be frustrating no matter how sharp of a lens I choose!

[lytrytyr]

I have often taken issue with Ken on other topics but on this I think he is pretty much spot on.

A few of his points where I think he pretty much nails it:
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"People would make far better pictures if . . . instead of worrying about their tools.

We need to worry about how a lens works

It's every artist's duty to find his tools' limitations so he can work around them.

This all seems too contradictory.

[tromboads]

And yet collectively the point is being missed.

Stop stressing about kit and think about the dam relationships you are trying to express in the photos you take!

[slip]

And yet collectively the point is being missed.

Stop stressing about kit and think about the dam relationships you are trying to express in the photos you take!

well said!
I think the point that is being made is that you need to find out the limitations of your lens then work around it. tons of practice with a kit lens is better then no practice with a * lens. know your equipment in and out, that is where the big improvements come!


thanks

randy

[wildman]

Just for the hell of it...

Tamron 18-200mm cheapo (220 bucks new) super zoom hand held full frame...

[slip]

to test this theory... If someone with a lot of primes/zooms take a photo of the same subject at the same focal length (lets say 50mm) and post them and let's see if you can tell the difference between the photos (don't forget to put in a couple of el cheapo's)
take out the exif.... would be very interesting to compare


thanks

randy

[bdery]

Pretty sure my lens is limited by depth of field as with most any optic,sensor has nothing to do with depth of field no more than film does

Yes, the sensor influences DOF. Your lens has a fixed resolution, that you can or cannot really exploit depending on your sensor (if your sensor can provide more resolution than your lens, you will see the resolution limit. If the sensor has less resolution than what your lens can provide, your picture will be limited by the resolution of the sensor).

Before we go any further, it is important to define the circle of confusion. It goes like this : take a dimensionless point. The image of the point formed by any lens will be a small circle, not a point. But that circle can be small enough that it will be perceived as a point nonetheless.That's when the sensor comes into play. If the circle is equal or small than a pixel on your sensor, it will be recorded as a point. If it's larger, it will be recorded as a circle. The largest circle that will be seen as a point is called the circle of confusion.

Still here?

Now, if the image of a point looks like a point, you will perceive the image as sharp. If it looks like a circle, you will perceive the image as... less sharp. Now, asyou move away from the point of sharpest focus, the image of your point will look more and more like a fuzzy circle. But as long as that circle is smaller than the circle of confusion, for all practical matters the image will still look sharp, because the circle will still look like a point.

That's the point.

So DOF is linked to the lens properties, of course, but also to the sensor.

I hope it helps.

[altopiet]

(if your sensor can provide more resolution than your lens, you will see the resolution limit. If the sensor has less resolution than what your lens can provide, your picture will be limited by the resolution of the sensor)

I find this thread very interesting. Do I understand what you say correctly, that the lens resolution will differ between 12mp K-x and 16mp k-5 sensors, which will influence image sharpness taken with the same lens on both cameras? If that is so, is there any simple way to find out at what mp a certain lens will reach optimal sharpness, for instance my 1961 Tak 105/2.8, FA 28-80mm, DA 55-300mm etc, or can one say that all 35mm film era lenses were designed for optimum use on 35mm film and should give the same results on a certain DSLR with similar mp sensor, and what would that mp's be, 12,16,24? If there was a simple way for me to know that, it would prevent me from wasting money, on especially old lenses, knowing that a certain lens can not be used to it's optimal capacity on my 12mp camera.