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08-31-2018, 07:14 AM   #1
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Need recommendation for the best Rectilinear FF Lens at 24mm or less

As an archaeologist, distortion is killer. Any recommendations for a prime or zoom that is 24 mm or wider that provides a good rectilinear image?

So many thanks

Chuck

08-31-2018, 07:18 AM   #2
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Apsc or full frame ?
08-31-2018, 07:26 AM   #3
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There's the Pentax 15-30, as a first obvious choice. Now for other options:

Did you look at the laowa 12mm? In absolute terms it's expensive, $950, but it's very wide and seems well corrected for distortion.

Other options I know of are a few from samyang, although people day decentering is an issue and the 14mm has visible moustache distortion, and irix 11 and 15mm, which were recently reviewed here on PF.
08-31-2018, 07:31 AM   #4
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Distorsion correction does not play you need the RAW for the publication and documentation? Even in camera correction profiles can be applied to original Pentax lenses if jpeg works for you.

08-31-2018, 07:34 AM   #5
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I am happy with my Rokinon 20mm f1.8 lens. Not sure how good your post processing skills, but it is also possible to use a longer focal length lens and stitch your images together. just a thought.
08-31-2018, 07:36 AM   #6
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The DFA 15-30 has a very pronaounced distorsion at the wide end. At 24mm may be good. The Irix 15 again not that good. The Lowa 12mm is very well corrected, better then the Irix 11, but much wider then your needs cropping to 24mm equvivalent it gives approx 9MP. (Which is more then enough I think, but more detail means more documentation for the future...)
08-31-2018, 08:04 AM   #7
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QuoteOriginally posted by gaweidert Quote
I am happy with my Rokinon 20mm f1.8 lens. Not sure how good your post processing skills, but it is also possible to use a longer focal length lens and stitch your images together. just a thought.
There are also various types of stitching.
  • Rotational Stitching - This is where you rotate around a single nodal point. Depending on how wide you go, say a full 360 degrees, you can get some interesting distortion in and of itself. Doing 180 degree (or less) very little distortion is introduced.
  • Linear Stitching - This is where you take a number of images moving along a straight line, say every foot and then stitch them together. If you have a scene that is deep, then you can get some perspective distortions.
  • Shift Lens - This is where you use a shift lens, and shift both to the left and right, and then stitch the resulting 3 images together (left, center and right) together. A 28mm shift lens provides a resulting stitched panoramic image that has essentially no distortion that has the same field of view of a 17mm lens.



Last edited by interested_observer; 08-31-2018 at 08:10 AM.
08-31-2018, 08:19 AM   #8
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He said he is an archaeologist, so making panoramas are not an option. Even the text is placed on the image to be surly not exchanged accidentally. (My wife is an archaeologist also.)
08-31-2018, 08:22 AM   #9
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QuoteOriginally posted by Ronald Oakes Quote
Apsc or full frame ?
Thread title says FF.
08-31-2018, 08:25 AM   #10
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Check lenstip.com. They do good reviews. Not many Pentax lenses, but Pentax 15-30 is similar to Tamron 15-30 in other mounts. Samyang/Rokinon also gets reviewed.
08-31-2018, 10:46 AM   #11
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ZEISS 21mm f/2.8 ZK Distagon T* Manual Focus Lens 1678-933 B&H

Might take a while to find the ZK version for K mount.
08-31-2018, 01:47 PM   #12
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I'm a big fan of my Sigma 24mm f/1.8 EX DG Aspherical Macro - have not noticed any fishyness to it at all! super sharp for me too!

---------- Post added 08-31-18 at 02:49 PM ----------

24mm Club - Any and All 24mm - PentaxForums.com

This might be a good resource for other 24mm glass
08-31-2018, 02:55 PM   #13
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Sigma 12-24, maybe?

https://www.pentaxforums.com/userreviews/sigma-12-24mm-f4-5-5-6-ex-dg-aspherical-hsm.html
08-31-2018, 04:09 PM   #14
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QuoteOriginally posted by cdurfor Quote
As an archaeologist, distortion is killer. Any recommendations for a prime or zoom that is 24 mm or wider that provides a good rectilinear image?
Maybe the Samyang 24mm f1.4 AS UMC. I don't own it but the distortion in the following review doesn't look that bad

Samyang 24 F1.4 vs Canon 24mm F1.4 II
08-31-2018, 04:58 PM - 1 Like   #15
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QuoteOriginally posted by 08amczb Quote
He said he is an archaeologist, so making panoramas are not an option. Even the text is placed on the image to be surly not exchanged accidentally. (My wife is an archaeologist also.)
Yes, he indicated that he is an archaeologist, however he is looking for a wide angle lens (24mm or wider) with as little distortion as possible. Physics/optics enters in to this. As with any wide angle lens, you are going to get some sort of distortion. Going to a lens with a longer focal length that is not wide angle and either stitching via a shift lens or employing a linear technique is a reasonably accepted approach to acquire a "wide angle" view without the inherent distortion. This provides a non-distorted view - with a wide field of view, without the native wide angle lens distortion.

Panorama is a photography term. Mosaic, image mosaicing, Photomosaics, photogrammetry, linear slit photography, multi-viewpoint and image exploitation are other terms that are somewhat interchangeable that utilizes the same or very similar approaches. They are also utilized and accepted across a wide range of various scientific endevours.
Very few scholars were accorded access to the dead sea scrolls. Individual images of the small fragments were made to document, provide better access, and to preserve the scrolls. When the images of the various fragments were arranged in a linear order, so that they could be interpreted within their original context - the interpretation of the scrolls made a giant leap in progress, in terms of increased quality and speed. And, yes - I am oversimplifying here....Stitching and/or mosaicing is able to be done with controls that will address various quality assurance concerns. In terms of quality of measurements, utilizing the same camera / sensor, concerns about the size, and orientation along with the type of pixels are negated.

You can stand back, in order to take a single image of say 40 feet of pictographs, or you can use a linear stitching technique, in order gain better resolution and definition, while maintaining size and contextual relationships across the entire subject matter, being imaged.

Stitching or mosaicing is already being used at a macro level in archaeology. Using LIDAR sensing technology, georeferencing and orthorectification - extraordinary large amounts of imaging information can be combined with in a GIS system to produce analysis and understanding not available previously.This same technology is available at the micro level, to the individual archaeologist digging in the pit, wishing to record some visual information - with a context or size larger than an single individual image.

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