[clackers]

If you print a wide-angle shot large and then view it from a close-enough distance, these supposed distortions disappear. Viewing a wide-angle image from a far-off telephoto viewing geometry creates this problem.

Sure. We were talking about shooting with UWA lenses elsewhere, and with those we're often better off retreating to extend the shooting distance and cropping the final image to the composition we want.

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Last edited by clackers; 03-08-2018 at 07:52 PM.

[danielchtong]

Sure. We were talking about shooting with UWA lenses elsewhere, and with those we're often better off retreating to extend the shooting distance and cropping the final image to the composition we want.

Sometimes there is no way to extend the shooting distance. There are way in pp to lessen the UWA effect.

It came from a fisheye Zenitar 16mm with all the curves
.

.
.
After defishing pp is done getting rid of most wide angle distortion
.

[clackers]

After defishing pp is done getting rid of most wide angle distortion
.

Sure, Daniel, but note that whenever pixels are dragged closer together there are often cropping losses, and where they're pushed apart there's resolution loss, so these things do incur a cost.

Architectural photographers will pay lots of money for a tilt-shift lens to avoid many such problems.

[photoptimist]

Sometimes there is no way to extend the shooting distance. There are way in pp to lessen the UWA effect.

It came from a fisheye Zenitar 16mm with all the curves
.

.
.
After defishing pp is done getting rid of most wide angle distortion
.

Alas, the UWA effect really can't be fixed because of the mathematics of UWA lenses.

In a true rectilinear lens, all straight lines in the scene are straight lines in the image. But an unavoidable mathematical consequence of that is a stretching distortion of circular objects (faces, flowers, & wheels) at the edges and corners of the UWA frame. A rectilinear lens preserves all lines, but distorts any circles that aren't in the center of the image.

In a true fisheye or equi-angular lens, all angular heights and widths of objects are preserved so that every circular object looks as high as it is wide (undistorted). But an unavoidable mathematical consequence of that is a curvature distortion of all linear objects at the edges and corners of the UWA frame.. A equi-angular lens preserves all circles, but distorts any lines that don't pass through the center of the image.

Although one can try to find a happy mid-point by adding fishiness to a rectilinear lens image or only partially removing fishiness from a fisheye lens image, the result will actually have some of both types of distortion: both warped lines and warped faces/flowers/wheels.

[aslyfox]

Hey everyone I’m new to the forums. Iv been doing some research and I’d just like some other Pentax users input. I have a K-1 and mostly do indoor/outdoor portrait/model photography and sports photography. I was wondering what you guys would say is the “best” or at least most impressive lens for portraits (full body / half) ?

I have not read the entire thread so I apologize if this has been mentioned before

but has the OP considered the D FA * 70-200mm F2.8

" HD Pentax-D FA* 70-200mm F2.8 ED DC AW

Introduction

In order to cater to professional photographers, a manufacturer must meet several requirements. In addition to a full frame body, a 70-200mm F2.8 telephoto lens is very high on the list. It is thus not very surprising that Pentax released its own version of that lens just prior to the launch of the Pentax K-1 itself. , , ,

A 70-200mm lens serves many purposes, especially on full frame.

It can be used for portraits (both outside and in a studio),

sports, weddings, photojournalism, wildlife, concerts and shows. Such a lens also comes with high expectations. Photographers will expect a high level of optical performance, fast AF, and high reliability. . . . "

Read more at: HD Pentax-D FA* 70-200mm F2.8 ED DC AW Review - Introduction | PentaxForums.com Reviews

now you do have to deal with the weight, size and price but nothing is perfect

I was lucky enough to find an " experienced " " like new " one in the forum's market place

https://www.pentaxforums.com/forums/130-lens-sample-photo-archive/320138-hd-...-ed-dc-aw.html

https://www.pentaxforums.com/reviews/hd-pentax-d-fa-star-70-200mm-f28/sample-photos.html

[dadipentak]

The 77 is my go-to.

[danielchtong]

Alas, the UWA effect really can't be fixed because of the mathematics of UWA lenses.

In a true rectilinear lens, all straight lines in the scene are straight lines in the image. But an unavoidable mathematical consequence of that is a stretching distortion of circular objects (faces, flowers, & wheels) at the edges and corners of the UWA frame. A rectilinear lens preserves all lines, but distorts any circles that aren't in the center of the image.

In a true fisheye or equi-angular lens, all angular heights and widths of objects are preserved so that every circular object looks as high as it is wide (undistorted). But an unavoidable mathematical consequence of that is a curvature distortion of all linear objects at the edges and corners of the UWA frame.. A equi-angular lens preserves all circles, but distorts any lines that don't pass through the center of the image.

Although one can try to find a happy mid-point by adding fishiness to a rectilinear lens image or only partially removing fishiness from a fisheye lens image, the result will actually have some of both types of distortion: both warped lines and warped faces/flowers/wheels.

I agree. But what we are dealing with is purely perception . And if the distortion is of a nature that is ok from a photography or arts point of view, we the photographer takes that.
See my 2 images of March 13. I personally think (IMO) that the distortion and subsequent defished image is presentable or in simple terms ok.
I have deviated from the subject line on portrait though

[photoptimist]

I agree. But what we are dealing with is purely perception . And if the distortion is of a nature that is ok from a photography or arts point of view, we the photographer takes that.
See my 2 images of March 13. I personally think (IMO) that the distortion and subsequent defished image is presentable or in simple terms ok.
I have deviated from the subject line on portrait though

Excellent points! Yes, the artistic function of photography certainly does make good use of distortion. The circle distorting effects of rectilinear UWA and the line distorting effects of equi-angular/fisheye UWA can used to good effect.

And it all does tie back to portraiture because people are so highly sensitive to distortions of human faces and bodies. Distortions that are acceptable or even artistic in a shot such as your nice image of that tall sculpture in the stairwell become unacceptable if people are in the frame with squashed faces and fattened, warped bodies (a UWA lens can add a proverbial 50 pounds to the subject's weight). That's not to say one can't use rectilinear UWA or fisheye lenses for portraiture (your fun image of the baby proves that). But it does create special challenges in composition especially if the faces or bodies are not perfectly centered in the image.

[normhead]

Look for yourself:
Lens advice: 31mm limited vs. hd 35mm f2.8 macro limited - PentaxForums.com

Had it with three different copies of the 31. Even I'm not that unlucky. Effects like that are inherently part of wide-angle lenses especially as you head south of 35mm, but they can be corrected. The FA31 costing as much as it does without that correction on 60% of the frame makes it not worth its price.

Every lens has to be understood to be used properly. No lens does everything well.
What I conclude from this are number of points.

It's inaccurate to call those large group shots "portraits". A portrait is different than a group shot, and this thread was about portrait lenses.

Almost any lens can be criticized because it doesn't do what it wasn't designed to do. I wouldn't criticize a macro lens because it doesn't do fisheye images. How is your criticism any different?

If you believe the 31 isn't good for portraits because it doesn't do large group shots well, I struggle to see the relevance.

If you read down your previous post, all the errors you present in your interpretation were pointed out, but you seem reluctant to benefit from the responses.

The "weakness" you point out is actually caused by correction to prevent distortion. You don't explain how adding more correction would create less distortion.

Don't go on lens reputation. Go on actual images for what you plan to do. Don't assume that because a lens is a top rated lens it will be good for what you want it for. It will be good for what it's designed for. Nothing more.

There are no "this lens is good for everything" lenses.

It is simply an error to call your large group shots "portraits". They're "group shots". I mention this because it might confuse new and inexperienced readers.

Personally I would be asking myself "How is it that so many good photographers have a different opinion than mine?' For myself it is in answering those types of questions that I eventually figure those things out. If you don't work through that, it's awfully hard to learn anything.

[BrianR]

Alas, the UWA effect really can't be fixed because of the mathematics of UWA lenses.

This is a decent discussion of the effects you're talking about (as well as correction options, mandatory as it's a dxo article), I especially liked the clear comparison of the sporting equipment photo: Understanding volume deformation | www.dxo.com

It's always a good idea to figure out where not to put people in the frame of your ultra-wide or fisheye. Unless you want to use the distortion creatively of course

[Sandy Hancock]

For those still trying to educate MadMathMind, I think he has left the building; some people are not interested in facts which counter their preconceptions.

I would be interested in where @Mrgoodintention went with all this though

[clackers]

For those still trying to educate MadMathMind, I think he has left the building; some people are not interested in facts which counter their preconceptions.

I would be interested in where @Mrgoodintention went with all this though

He's actually done a little more than that and put his FA31 up for sale a while ago.

[SSGGeezer]

He's actually done a little more than that and put his FA31 up for sale a while ago.

Sold it in fact. I am glad I didn't have the funs to spend on another lens or it could have been me! But the focal range is already covered by multiple lenses in my collection already, but LBA cares not for what you already own!

[monochrome]

I am always shocked when I read abc Limited* is garbage. I am disinclined to read further.


* applies to almost any lens, not just Limiteds.

[UncleVanya]

I am always shocked when I read abc Limited* is garbage. I am disinclined to read further.


* applies to almost any lens, not just Limiteds.

My first reaction to poor results from a lens I am shooting is to look to my own technique and appropriateness of my use. Then focus fine tuning... Etc.