Newbie trying to set up a 7Artisan 4mm fisheye

[Ben Streissguth]

Hi Everyone,

I'm using v13 beta 1 (but I don't think my issue is there).  I'm following Hugh Hou's YouTube video EASY Pro Virtual Tour Setup w/ APS-C Sensor! 7Artisans 225° Fisheye Lens Review & PTGui Tutorial where he uses the following values:

Focal length: 3.83mm

Theoretical: 4mm

Horizontal field of view: 222.69

Fisheye factor: -0.608334

I must be missing something here (theory wise).  I understand that the Focal length and field of view are tied to each other, but when I enter the focal length, the field of view is blank. But when I add the field of view, the focal length changes to 7.73mm.  If I process my images using the 7.73mm I get a huge lens flair in my 360 image.

So I guess have two questions.  :)  1- How was Hugh able to set both the focal length and field of view? He talks about providing a file, but I never could find it, and haven't really looked into creating my own. 2- If I can't manually enter both values, are the some better values to use for my lens?

Thank you so much for any help

-Ben

[Erik Krause]

Am 08.03.2024 um 16:37 schrieb Ben Streissguth:
> So I guess have two questions. 🙂 1- How was Hugh able to set both the

> focal length and field of view? He talks about providing a file, but I
> never could find it, and haven't really looked into creating my own. 2- If
> I can't manually enter both values, are the some better values to use for
> my lens?

I guess it's a typo. However, the 7Artisans 4mm is in the lens database.
When loading the images, you should get a dialog asking (among other
things) the focal length. If you enter 4, you can select the 7Artisans
from the droplist.

Moreover, PTGui will, if allowed, optimize better values (there is
always a tolerance), provided you shot your images precisely from the
no-parallax-point, which should be the case, if you used a well-adjusted
panoramic tripod head.

As for the theory: focal length and field of view are linked via the
sensor size and the projection type. Focal length and projection are a
fixed property of the lens, but the field of view can be changed by the
sensor size, if the sensor is smaller than the image circle.

--
Erik Krause
http://www.erik-krause.de

[PTGui Support]

Hi Ben,

Check the cropping circle (in the Crop tab) and see if it matches the
image circle of your fisheye lens.

If it's wrong, this might be due to the wrong sensor size being set in
the Lens Settings tab.

If you can find the problem, just save the project file and attach it here.

If you just used PTGui's defaults and PTGui got the metadata wrong,
could you make a set of images available?

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 08-03-2024 16:37, Ben Streissguth wrote:
> Hi Everyone,
>
> I'm using v13 beta 1 (but I don't think my issue is there).  I'm
> following Hugh Hou's YouTube video EASY Pro Virtual Tour Setup w/ APS-C
> Sensor! 7Artisans 225° Fisheye Lens Review & PTGui Tutorial

> <https://www.youtube.com/watch?v=zYS9nTlVcBg> where he uses the

> following values:
> Focal length: 3.83mm
> Theoretical: 4mm
> Horizontal field of view: 222.69
> Fisheye factor: -0.608334
>
> I must be missing something here (theory wise).  I understand that the
> Focal length and field of view are tied to each other, but when I enter
> the focal length, the field of view is blank. But when I add the field
> of view, the focal length changes to 7.73mm.  If I process my images
> using the 7.73mm I get a huge lens flair in my 360 image.
>
> So I guess have two questions.  :)  1- How was Hugh able to set both the
> focal length and field of view? He talks about providing a file, but I
> never could find it, and haven't really looked into creating my own. 2-
> If I can't manually enter both values, are the some better values to use
> for my lens?
>
> Thank you so much for any help
> -Ben
>

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[Ben Streissguth]

Thank you Erik and Joost!  I did manage to finally get something to work.

Erik - I totally agree with Erik that it must be some error in his video.  I'm not entirely sure I understand what you mean when you say my lens is in the lens database.  I thought (from the support/faq page on the website) that that database was a place to store you're own lens.  Is there a prepopulated database I should download and install?

Joost - I think the issue was with the cropping.  :)  I'm attaching a zip of the project incase you'd like to take a look.  I'm more than happy to make images available. 

[PTGui Support]

Hi Ben,

PTGui includes some presets for common fisheye lenses. The 7artisans is
in that list. After loading your images, PTGui asks for the focal length
and lens type. Enter 4mm and pick the 7 artisans from that list.

This is separate from the Lens Database (in the Tools menu). This one is
initially empty but you can use it to store your own presets. This is
hardly ever used though. For custom settings, templates are usually more
appropriate.

PTGui doesn't recognize the sensor size of the α6700. This will be added
in a future update. When asked, enter a crop factor (focal length
multiplier) of 1.6.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 09-03-2024 15:32, Ben Streissguth wrote:
> Thank you Erik and Joost!  I did manage to finally get something to work.
>
> Erik - I totally agree with Erik that it must be some error in his
> video.  I'm not entirely sure I understand what you mean when you say my
> lens is in the lens database.  I thought (from the support/faq page on
> the website) that that database was a place to store you're own lens.
> Is there a prepopulated database I should download and install?
>
> Joost - I think the issue was with the cropping.  :)  I'm attaching a
> zip of the project incase you'd like to take a look.  I'm more than
> happy to make images available

> <https://drive.google.com/file/d/1vjDwTdFVzFCnyDwOGXrhOwTna-H1rgjY/view?usp=sharing>.

> On Saturday, March 9, 2024 at 3:58:16 AM UTC-8 PTGui Support wrote:
>
> Hi Ben,
>
> Check the cropping circle (in the Crop tab) and see if it matches the
> image circle of your fisheye lens.
>
> If it's wrong, this might be due to the wrong sensor size being set in
> the Lens Settings tab.
>
> If you can find the problem, just save the project file and attach
> it here.
>
> If you just used PTGui's defaults and PTGui got the metadata wrong,
> could you make a set of images available?
>
> Kind regards,
>
> Joost Nieuwenhuijse

> www.ptgui.com <http://www.ptgui.com>

> https://groups.google.com/d/msgid/ptgui/180c2652-3073-4a64-b401-e8fea491c2d3n%40googlegroups.com <https://groups.google.com/d/msgid/ptgui/180c2652-3073-4a64-b401-e8fea491c2d3n%40googlegroups.com> <https://groups.google.com/d/msgid/ptgui/180c2652-3073-4a64-b401-e8fea491c2d3n%40googlegroups.com?utm_medium=email&utm_source=footer <https://groups.google.com/d/msgid/ptgui/180c2652-3073-4a64-b401-e8fea491c2d3n%40googlegroups.com?utm_medium=email&utm_source=footer>>.

>
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