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02-05-2016, 08:39 AM   #721
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Testing a New Sigma 8-16mm_Is it a Keeper

I recently purchased a "new" Sigma 8-16mm lens through Amazon and it is being sent from Japan and will arrive in early March. I would appreciate any suggestions from those who have the lens and those knowledgable about testing a lens for problems to share with me some ideas I should consider to determine if the lens is "new" and that it is functioning as it should under various shooting scenarios. In other words to determine if the lens is a keeper or should be returned.

Thank you in advance for your input!!

02-05-2016, 12:08 PM - 2 Likes   #722
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02-22-2016, 02:22 PM   #723
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Optimize Performance of Sigma 8-16

I have a K3 and a K10D and recently purchased a Sigma 8-16 and I expect it to be delivered in early March 2016. I am interested in receiving suggestions from current users on how to optimize the performance of the lens and to create imaginative effects through the myriad of capabilities afforded by the K3 or approaches you have found by experimentation or examples that you have seen or read concerning the lens. I have seen some examples on Google; however, I have always been amazed at the ideas that come out of this forum. If you have examples of photos that document your point that would be ideal. Thank you in advance for sharing your experiences with the Sigma 8-16.
02-22-2016, 04:15 PM - 1 Like   #724
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Probably one of the 1st things you should learn about is perspective, perspective distortion and the different ways that perspective distortion can present itself, for example keystone distortion. For a lens as wide as this understanding where to stand with how and where to point the lens is paramount in getting the best out of this lens.


DAZ

02-22-2016, 05:30 PM - 1 Like   #725
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Don't put people in the extreme edges or corners - less than flattering. There is a profile for the lens in Adobe Camera Raw (Creative Cloud/Photoshop) which works nicely to reduces some of the distortion that remains.

02-22-2016, 07:08 PM - 1 Like   #726
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Another hint: extreme WA lenses generally produce more "natural looking" images if kept close to level, not pointed up or down too much. If you use them for interiors, for example the inside of a cathedral. including a lot of floor is fine, and if you don't want it, crop it out later to produce a quasi-panorama.
02-22-2016, 10:07 PM   #727
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QuoteOriginally posted by DAZ Quote
Probably one of the 1st things you should learn about is perspective, perspective distortion and the different ways that perspective distortion can present itself, for example keystone distortion. For a lens as wide as this understanding where to stand with how and where to point the lens is paramount in getting the best out of this lens.


DAZ
DAZ, dazzle me with some specifics that address what you are referencing or picture examples that makes the point. I will check out the terminology and see if I can find some examples and description that fills in the blanks. Thank you for your suggestion.

---------- Post added 02-22-16 at 10:10 PM ----------

QuoteOriginally posted by Arjay Bee Quote
Don't put people in the extreme edges or corners - less than flattering. There is a profile for the lens in Adobe Camera Raw (Creative Cloud/Photoshop) which works nicely to reduces some of the distortion that remains.
Arjay, good point, it appears from other photos that I have seen with this lens that the main subject should be as central as possible in the photo. I will keep your suggestion in mind when doing my shooting.

---------- Post added 02-22-16 at 10:16 PM ----------

QuoteOriginally posted by WPRESTO Quote
Another hint: extreme WA lenses generally produce more "natural looking" images if kept close to level, not pointed up or down too much. If you use them for interiors, for example the inside of a cathedral. including a lot of floor is fine, and if you don't want it, crop it out later to produce a quasi-panorama.
WPRESTO, thank you for your suggestion, from the pictures that I have seen (panoramas and inside of buildings) the lens seems to be held rather level as you suggest. Because of the curviture of the lens one would reasonably expect increased distortion as the lens is more or less than level. As you suggest when distortion is encountered it can be corrected by cropping. Thanks for insight!!

02-23-2016, 06:02 PM   #728
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I wonder how it will be on FF

02-23-2016, 07:49 PM - 3 Likes   #729
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As you asked so nicely MRCDH I guess I can wade in and see what I can stir up. 1st up a little light reading for you to do that range from the technical to the more photogenic. The following should acquaint you with the subject.

https://en.wikipedia.org/wiki/Perspective_distortion_%28photography%29
A Guide to Perspective Distortion Review - Introduction | PentaxForums.com Reviews
Portrait Lenses, Beauty and Perspective - digital Artform
Perspective Control in Images - Focal Length or Distance? (a tutorial) -- General Photography Talk in photography-on-the.net forums

The most important thing to realize here is it’s all based on the perspective of where your camera is looking and the distances between the various objects in the field of view. When you understand perspective and perspective distortion you understand why a normal lens is called a normal lens and why some photographers prefer certain focal lengths for portrait photography. It really starts become simple and obvious when you understand it.

The reason it is so important with this particular lens is because as you get farther from normal (and this lens is just about as far from normal as you can get in the wide direction) the more apparent perspective distortion becomes. This lens is so wide that the simple rules of just don’t do “X” almost don’t apply. It is imperative that you always are totally aware of the distances to all your subjects and the angle your cameras is at and how these angles change these distances.

As I am limited to the photos I can post to this forum (as in I can’t post anymore photos) I am limited to showing you examples from my Flickr site. This should be more than enough photos to get your eyes blurry. All of these photos were taken at 8 mm and if I remember correctly I made no effort to correct Keystone distortion. If you hover your mouse over these photos you should see a double ended line up in the right corner. If you click on that the photos should size down and you should be able to see the other information that Flickr will give you.

https://www.flickr.com/photos/dazt/24149779562/in/datetaken/lightbox/
In this photo you can see there is a little bit of convergence with some of the objects near the edge of the frame. But as this room was actually around it is very difficult for me to determine where the straight lines were.

https://www.flickr.com/photos/dazt/24149775042/in/datetaken/lightbox/
Again another round room but easier to see the straight lines. This is over 110° wide.

https://www.flickr.com/photos/dazt/20838537531/in/datetaken/lightbox/
Here is readily apparent the convergent effect.

https://www.flickr.com/photos/dazt/16599768277/in/datetaken/lightbox/


Here even though there are people relatively close to the edge of the frame they look for the most part normal. The reason is the importance of distance. If the people are too close to the camera and at the edge of the frame different parts of them will be significantly different distances and will generate the distortions. The person furthest away is actually the tallest at over 6 feet the person closest is only about 5’ 6”. More on that later.


https://www.flickr.com/photos/dazt/14238693063/in/datetaken/lightbox/
Another example of the convergence of the distance.

https://www.flickr.com/photos/dazt/13673991663/in/datetaken/lightbox/
Here I can make my shadow look much longer than it really is.

https://www.flickr.com/photos/dazt/13673997384/in/datetaken/lightbox/
More people at the edge of the frame. There is some distortion to the person closest to the camera but almost none in the distance.

https://www.flickr.com/photos/dazt/13673873694/in/datetaken/lightbox/
Technically the ramp is keyhole distorted here. In this case the distortion helps to increase the apparent size of the airplane.


https://www.flickr.com/photos/dazt/13673943844/in/datetaken/lightbox/
Here the people are too close to the camera and it does generate some unpleasant distortions. This is mostly apparent in people since we are very conscience of what people are supposed to look like. In this case it was unavoidable as there is no place else for me to go in the relatively small cockpit of a C-17. Without a lens as wide as this I would not have been able to of captured the cockpit as a whole.

https://www.flickr.com/photos/dazt/9533615204/in/datetaken/lightbox/
This view looks relatively normal. This is deceiving as if you are actually standing here you would’ve naturally have turned your head slightly one direction to the other to looked on the 2 different paths. They are over 90° apart. As you can see though the trees all look like they’re standing relatively straight up.

https://www.flickr.com/photos/dazt/8254380334/in/datetaken/lightbox/
Here by going portrait orientation I was able to keep the buildings in view with a minimum of keyhole distortion.

https://www.flickr.com/photos/dazt/8254374426/in/datetaken/lightbox/
Here going back to horizontal orientation and keeping the camera close to horizontal (it still pointed up slightly) I was again able to keep the buildings relatively square and capture both edges of the fountain.

https://www.flickr.com/photos/dazt/8253293835/in/datetaken/lightbox/
By moving up to the 2nd floor and standing at the edge of the balcony I was able to keep everything square and capture the entire room.

https://www.flickr.com/photos/dazt/8254112398/in/datetaken/lightbox/
Even though everything is relatively square here (except that which was naturally damaged in the storm) both the clouds and the wave lines on the sand still generate convergent lines.

https://www.flickr.com/photos/dazt/7483619908/in/datetaken/lightbox/
Here the perspective distortion makes the plane look like a tunnel.

https://www.flickr.com/photos/dazt/5905926177/in/datetaken/lightbox/
By cropping out the top and the bottom of the photo gives you a more panoramic feel and essentially eliminates the perspective distortion.

https://www.flickr.com/photos/dazt/5569714413/in/datetaken/lightbox/
Here the perspective distortion makes the slight path loop look much greater than it really is.

https://www.flickr.com/photos/dazt/5570259904/in/datetaken/lightbox/
Here you don’t really see the perspective distortion unless you realize that the flowers are all planted in a perfect square.

https://www.flickr.com/photos/dazt/5167457490/in/datetaken/lightbox/
Here again I kept the camera perfectly perpendicular to all of the vertical structures. The perspective distortion is in the shadows and the sun light. One of these days I intend to make better use of this effect I just haven’t found a subject better than this yet.

All of the above should give you enough to chew on with this new lens for a while. Remember pick your perspective 1st, then choose your framing for what subject matter you wish to include, this then will dictate your field-of-view angle and that will let you pick the lens length to use.

DAZ
02-24-2016, 04:32 AM   #730
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WOW! DAZ: Were you up all night composing that post? It's like getting a free how-to-do manual from the shelves of Barnes & Noble.
02-24-2016, 04:37 AM   #731
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QuoteOriginally posted by Transit Quote
I wonder how it will be on FF
it is only really usable at 16mm, with some corner fall off without crop mode on.
02-24-2016, 04:53 AM   #732
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One curious possibility when using an APS-C-only lens on FF without engaging the crop mode: when doing PP you can crop out approximately the equivalent of a vertically-framed image (taken on APS-C) without rotating the camera body, although obviously @ K5 rather than K3 mp. You could also crop out a square image that would cover a bit more horizontally and vertically than what you could get on APS-C, although with greater corner vignetting and IQ decline. I'm sure these possibilities have been mentioned elsewhere, so please don't be too harsh on me for repeating an observation I did not read. How much "extra" coverage you'd obtain would depend on the f-stop used and your tolerance for corner/edge dimming and IQ decline.
02-24-2016, 05:05 AM   #733
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QuoteOriginally posted by WPRESTO Quote
How much "extra" coverage you'd obtain would depend on the f-stop used
large format photographers like me know that you can squeeze a bit of extra frame coverage out of a lens by stopping it down: I'd expect this to occur around f/11~f/16 which might allow you to use it as wide as 14mm.
02-24-2016, 05:16 AM   #734
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QuoteOriginally posted by Digitalis Quote
large format photographers like me know that you can squeeze a bit of extra frame coverage out of a lens by stopping it down: I'd expect this to occur around f/11~f/16 which might allow you to use it as wide as 14mm.
But, allowing you'd get a circular image if used @ 8mm on FF, if you shot @ f16, then in PP you might be able to crop out a pseudo-panorama that covered a bit more horizontally than you would have obtained had the lens been mounted on an APS-C camera, again depending on your tolerance for dimming and IQ degradation as you you approach the edge of the image circle. No doubt some (many?) Pentaxians who purchase a K1 and have an ultra-wide will experiment and post the result.
02-24-2016, 09:27 AM   #735
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QuoteOriginally posted by DAZ Quote
As you asked so nicely MRCDH I guess I can wade in and see what I can stir up. 1st up a little light reading for you to do that range from the technical to the more photogenic. The following should acquaint you with the subject.

https://en.wikipedia.org/wiki/Perspective_distortion_%28photography%29
A Guide to Perspective Distortion Review - Introduction | PentaxForums.com Reviews
Portrait Lenses, Beauty and Perspective - digital Artform
Perspective Control in Images - Focal Length or Distance? (a tutorial) -- General Photography Talk in photography-on-the.net forums

The most important thing to realize here is it’s all based on the perspective of where your camera is looking and the distances between the various objects in the field of view. When you understand perspective and perspective distortion you understand why a normal lens is called a normal lens and why some photographers prefer certain focal lengths for portrait photography. It really starts become simple and obvious when you understand it.

The reason it is so important with this particular lens is because as you get farther from normal (and this lens is just about as far from normal as you can get in the wide direction) the more apparent perspective distortion becomes. This lens is so wide that the simple rules of just don’t do “X” almost don’t apply. It is imperative that you always are totally aware of the distances to all your subjects and the angle your cameras is at and how these angles change these distances.

As I am limited to the photos I can post to this forum (as in I can’t post anymore photos) I am limited to showing you examples from my Flickr site. This should be more than enough photos to get your eyes blurry. All of these photos were taken at 8 mm and if I remember correctly I made no effort to correct Keystone distortion. If you hover your mouse over these photos you should see a double ended line up in the right corner. If you click on that the photos should size down and you should be able to see the other information that Flickr will give you.

https://www.flickr.com/photos/dazt/24149779562/in/datetaken/lightbox/
In this photo you can see there is a little bit of convergence with some of the objects near the edge of the frame. But as this room was actually around it is very difficult for me to determine where the straight lines were.

https://www.flickr.com/photos/dazt/24149775042/in/datetaken/lightbox/
Again another round room but easier to see the straight lines. This is over 110° wide.

https://www.flickr.com/photos/dazt/20838537531/in/datetaken/lightbox/
Here is readily apparent the convergent effect.

https://www.flickr.com/photos/dazt/16599768277/in/datetaken/lightbox/


Here even though there are people relatively close to the edge of the frame they look for the most part normal. The reason is the importance of distance. If the people are too close to the camera and at the edge of the frame different parts of them will be significantly different distances and will generate the distortions. The person furthest away is actually the tallest at over 6 feet the person closest is only about 5’ 6”. More on that later.


https://www.flickr.com/photos/dazt/14238693063/in/datetaken/lightbox/
Another example of the convergence of the distance.

https://www.flickr.com/photos/dazt/13673991663/in/datetaken/lightbox/
Here I can make my shadow look much longer than it really is.

https://www.flickr.com/photos/dazt/13673997384/in/datetaken/lightbox/
More people at the edge of the frame. There is some distortion to the person closest to the camera but almost none in the distance.

https://www.flickr.com/photos/dazt/13673873694/in/datetaken/lightbox/
Technically the ramp is keyhole distorted here. In this case the distortion helps to increase the apparent size of the airplane.


https://www.flickr.com/photos/dazt/13673943844/in/datetaken/lightbox/
Here the people are too close to the camera and it does generate some unpleasant distortions. This is mostly apparent in people since we are very conscience of what people are supposed to look like. In this case it was unavoidable as there is no place else for me to go in the relatively small cockpit of a C-17. Without a lens as wide as this I would not have been able to of captured the cockpit as a whole.

https://www.flickr.com/photos/dazt/9533615204/in/datetaken/lightbox/
This view looks relatively normal. This is deceiving as if you are actually standing here you would’ve naturally have turned your head slightly one direction to the other to looked on the 2 different paths. They are over 90° apart. As you can see though the trees all look like they’re standing relatively straight up.

https://www.flickr.com/photos/dazt/8254380334/in/datetaken/lightbox/
Here by going portrait orientation I was able to keep the buildings in view with a minimum of keyhole distortion.

https://www.flickr.com/photos/dazt/8254374426/in/datetaken/lightbox/
Here going back to horizontal orientation and keeping the camera close to horizontal (it still pointed up slightly) I was again able to keep the buildings relatively square and capture both edges of the fountain.

https://www.flickr.com/photos/dazt/8253293835/in/datetaken/lightbox/
By moving up to the 2nd floor and standing at the edge of the balcony I was able to keep everything square and capture the entire room.

https://www.flickr.com/photos/dazt/8254112398/in/datetaken/lightbox/
Even though everything is relatively square here (except that which was naturally damaged in the storm) both the clouds and the wave lines on the sand still generate convergent lines.

https://www.flickr.com/photos/dazt/7483619908/in/datetaken/lightbox/
Here the perspective distortion makes the plane look like a tunnel.

https://www.flickr.com/photos/dazt/5905926177/in/datetaken/lightbox/
By cropping out the top and the bottom of the photo gives you a more panoramic feel and essentially eliminates the perspective distortion.

https://www.flickr.com/photos/dazt/5569714413/in/datetaken/lightbox/
Here the perspective distortion makes the slight path loop look much greater than it really is.

https://www.flickr.com/photos/dazt/5570259904/in/datetaken/lightbox/
Here you don’t really see the perspective distortion unless you realize that the flowers are all planted in a perfect square.

https://www.flickr.com/photos/dazt/5167457490/in/datetaken/lightbox/
Here again I kept the camera perfectly perpendicular to all of the vertical structures. The perspective distortion is in the shadows and the sun light. One of these days I intend to make better use of this effect I just haven’t found a subject better than this yet.

All of the above should give you enough to chew on with this new lens for a while. Remember pick your perspective 1st, then choose your framing for what subject matter you wish to include, this then will dictate your field-of-view angle and that will let you pick the lens length to use.

DAZ
Daz, I am truly dazzled! I will highlight this posting and will reference it to everyone who might have a question on how to specifically address any additional questions I may pose on any forum in the future. By the time I am through reviewing this I will apply for my Phd in perspective, convergence, Keystone distortion, perspective distortion et al, and the overall handling of ultra-wide photography in general. Thank you for all the time you spent in assembling this information and I will take the appropriate time to study and digest it. As it has been said "Seek and ye shall find, knock and it will be opened unto you".
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