Mirror Lens  

In the panorama field, hardware is also part of the success. You can discuss here about it: camera, computer, pano head, anything
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GuzZzt
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Mirror Lens

by GuzZzt » Sat Sep 05, 2009 8:08 am

Has anyone tried to use a mirror lens for giga pixel panoramas? As I see it is the negative side not a big problem and the positive side are very good.
Negative
[uli]Donut shaped bokeh, but for panoramas is everything in focus so this should not be a problem.[/uli]
[uli]No auto focus, auto focus is normally turned off any way.[/uli]
[uli]No Image stabilization, is not needed anyway because we use a tripod[/uli]
[uli]Can't set the aperture. Can be an issue but the ~F11 value is not too bad. [/uli]

Positive
[uli]Light weight, very good because the normally used Merlin/Orion or gigapan cannot handle too much weight. (And it makes it easier to carry in your backpack too.)[/uli]
[uli]Compact size, this makes it more stable on a tripod.[/uli]
[uli]Cheap, everyone likes cheap, right :)[/uli]
[uli]Not a lot of lens segments gives almost no CA.[/uli]

The only problem I see is sharpness but I'm not sure how big this problem is. Has anyone tested and can say anything about the sharpness compared to normal tele lenses?

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by Castillonis » Fri Oct 16, 2009 10:11 pm

I recently purchased a 500mm f8 multi coated Russian made catadiotropic ( mirror, similar to Dobsion telescope ) lens after researching the mirror lenses on the internet. I have only used the lens one time under non optimal conditions when I was trying to compare a Canon 400mm f2.8L lens with no teleconverter, 1.4x tele, and 2.0x tele. I did notice that the lens had significant vignetting on a partial frame sensor, though I was shooting a panorama at sunset. Look at the examples at the two flickr groups. I would probably stay away from the cheap Opteka/Pheonix/other name lenses. Just spend slightly more to get a Tamron, or Nikon lens and an adaptor for your camera mount. I was hoping to use this in conditions where my subject is very far away. It might be a better choice when it is windy as well. Read Bob Atkins article below and in the end you will need to do your own tests as well to find out what works better for you.

Bob Atkins Review of Mirror lenses ( read this first, covers older lenses )
http://www.bobatkins.com/photography/tutorials/mirror.html

Flickr Mirror lens group ( many photographs to examine with lens brand and model noted )
http://www.flickr.com/groups/mirror_reflex/

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GuzZzt
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by GuzZzt » Wed Oct 21, 2009 7:30 pm

Thanks for the help, you are right that vignetting would be a big negative point. I know it was too good to be true :(

I will read more about Nikon or Tamron.

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by hankkarl » Wed Oct 21, 2009 8:27 pm

Vignetting isn't a big issue. I use a lens that has a lot of vignetting, and APP handles things ok. The lens has a FOV of 111x88 degrees, and I use 8 positions for a circular pano (360x111 degrees). So I get close to 50% overlap. APP handles it ok.

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by Castillonis » Thu Oct 22, 2009 12:08 am

The autopano documentation discusses vignetting in the Color and Brightness section, but I do not know if the software corrects specifically for vignetting.

If you use the Adobe Bridge to open you photographs for a panorama in Adobe RAW, you are able to make a correction for vignetting in the lens correction tab. That is the sixth tab over from the basic tab. You can press the select all button in the upper left hand side followed by the synchronize button just below it. You then can convert all of the synchronized camera RAW images to 16 bit tiffs or jpegs by clicking on the save images button in the lower left hand corner.

You can also make changes to individual images using the Adobe Photoshop Lens Correction filter. Though it would be better to do this using Bridge and Adobe RAW to automate the conversion for an entire panorama and apply these settings in a homogenous / consistent manner.
Filter -> Distort -> Lens Correction

According to Bob Atkins the MTF for detail will be 1/2 of that for an equivalent focal length refractive lens due to the small mirror at the entry blocking light.

Google Language tools

La documentation autopano discute du vignettage dans les
Couleur et la luminosité de l'article, mais je ne sais pas si le
logiciel corrige spécifiquement pour vignettage.

Si vous utilisez l'Adobe Bridge pour ouvrir des photos pour vous
un panorama dans Adobe RAW, vous êtes en mesure de faire une
correction de vignetage dans l'onglet de correction d'objectif.
C'est l'onglet sixième au cours de l'onglet de base. Vous pouvez
appuyez sur le bouton Tout sélectionner en haut à  gauche
côté suivi par le bouton de synchronisation juste en dessous.
Vous pouvez ensuite convertir la totalité du RAW synchronisée caméra
images à  16 bits ou TIFFs jpegs en cliquant sur le sauver
images de bouton dans le coin inférieur gauche.

Vous pouvez également apporter des modifications aux images individuelles à  l'aide
Adobe Photoshop filtre Lens Correction. Bien qu'il
serait préférable de le faire en utilisant Adobe Bridge et RAW
pour automatiser la conversion pour un panorama complet et
appliquer ces paramètres dans un ensemble homogène / uniforme
manière.
Filtre -> Déformation -> Lens Correction

Selon Bob Atkins la MTF du détail vous aideront être 1 / 2
de cela pour une longueur focale équivalente lentille réfractive
en raison du petit miroir à  l'entrée de blocage lumière.
Last edited by Castillonis on Thu Oct 22, 2009 12:09 am, edited 1 time in total.

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sakira
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by sakira » Sat Oct 24, 2009 12:31 pm

Hey GuzZzt.
Myself Sakira I read your post which contain about the positive and negative it is too wonderful
like you, so I'm happy because of I found something which is the best in my real life
I request to you if you have more thought about positive please post as soon as early.
Thanks.
where there is a will, there is a way.

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Apapane
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by Apapane » Sat Oct 24, 2009 6:14 pm

hankkarl wrote:Vignetting isn't a big issue. I use a lens that has a lot of vignetting, and APP handles things ok. The lens has a FOV of 111x88 degrees, and I use 8 positions for a circular pano (360x111 degrees). So I get close to 50% overlap. APP handles it ok.

Hank, I doubt you could take an 8 frame 360 with a mirror lens, try 800. :^\
I do agree, though, that APP and APG correct for vignetting very well.

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by DrSlony » Sat Oct 24, 2009 7:30 pm

Strange, I have an old Russian mirror lens here, 500mm on a full-frame, and I read it has no visible vignetting. I thought that was true for all mirror lenses. I can't connect it to my camera yet, don't have the right adapter, but I read from several sources. Perhaps it does vignette on a full-frame, but not on APS-C.

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by Apapane » Sat Oct 24, 2009 8:38 pm

I have a Celestron C-90 scope with Olympus adapters - will try it out.

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by GuzZzt » Sun Oct 25, 2009 11:33 am

I searched for mirror lens on gigapan.org and wound a few. Most of them looks good but for example this looks quite bad
http://gigapan.org/gigapans/3645/

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by Greg Nuspel » Sun Oct 25, 2009 2:50 pm

GuzZzt wrote:I searched for mirror lens on gigapan.org and wound a few. Most of them looks good but for example this looks quite bad
http://gigapan.org/gigapans/3645/

Almost looks like it was shot through a wire fence.
--Greg Nuspel

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by odyssey » Thu Oct 29, 2009 7:14 pm

Hey, that is my Gigapan. I took it with a Samyang 500mm lens. I did not do any vignette correction and stitched it with the Gigapan stitcher. I should go back and see what Autopano does with it. It was nice using such a light lens (on a beta Gigapan device at that). Its hard to focus and has shallow depth of field.
Nikon D200, Merlin/Orion with Nokia 800 & Papywizard
Two Panasonic FZ50's mounted in Stereo 3D on some interesting Gigapan stuff
[url=http://www.3dpan.org]www.3dpan.org Three Dimensional Panoramas![/url]
[url=http://www.odysseyexpeditions.com]www.odysseyexpeditions.com Tropical Marine Biology Voyages[/url]

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by GuzZzt » Thu Oct 29, 2009 9:06 pm

odyssey, it would be a very interesting comparison to see if autopano could fix the vignetting. Can you say something more about the focusing and DOF. Could you not use the focus indicator in the view finder to find focus or is it not good enough? And wasn't everything on infinity when you do a panorama like the one you did with the mountains far away?

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by odyssey » Wed Nov 04, 2009 3:14 am

OK, I applied a vignette correction in Photoshop to all images (using Bridge). Then restitched it with the Gigpan stitcher. I could not get Autopano Giga to align this at all so don't know what it would have been capable of.

Here is the new version http://gigapan.org/gigapans/35875/

When I mean its hard to focus, I guess I mean it's not super sharp. The focus indicator worked. I did not change focus during the exposure.

I think this one does look a lot better, but it still sucks.

This one was shot on a really sunny day with the Panasonic FZ-50 digicam (which is a great digicam as far as digicams go) and its miles and miles a better shot, even if there is some pixel noise upon zooming in 300% that is not visible on the Nikon D200 shot.

http://www.gigapan.org/gigapans/10823/ Aspen Highalnds shot with FZ-50

So, I have not used the mirror lens for panorama purposes since that day...

Any links on something that is good with a mirror lens?

Jason
Nikon D200, Merlin/Orion with Nokia 800 & Papywizard
Two Panasonic FZ50's mounted in Stereo 3D on some interesting Gigapan stuff
[url=http://www.3dpan.org]www.3dpan.org Three Dimensional Panoramas![/url]
[url=http://www.odysseyexpeditions.com]www.odysseyexpeditions.com Tropical Marine Biology Voyages[/url]


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