Retina Xenon Barrel Distortion

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mh2000

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I just got some photos from my Retina IIa and was surprised to see that the barrel distortion was very bad... hadn't shot photos that brought it out until now.

Anyone have a good routine for correcting for it in Photoshop? Settings in PS or Panorama Tools etc.?

thanks!
 
Havent seen such distortions in pics from my Retina II and IIa, both have the same Xenon lenses. Could it be that something's wrong with the lens in your camera?
 
Is this the model with the removable lens that unscrews, so you can install a wide angle? Perhaps one of the lens elements is positioned wrong? Just guessing. I have a Retina IIIC with 35mm Zenon lens and I've never noticed this kind of distortion.

~Joe
 
ok, maybe they are more optical illusions... here is one image that made me suspect barrel distortion:


Image1.jpg
 
As far as I can see, all the straight lines are ramrod-straight, so I don't think you've got barrel distortion (as I understand it, anyway). The only curves I can see are where the paper backing to the windows has sagged, and the shadows behind the glazing bars show this up. Were you looking at the negative, or a print/scan when you thought you saw it?

Adrian
 
I was looking at some prints and had a number that had shadows and other stuff and guess maybe that and the curl of prints tricked my eyes... sorry... and thanks... (guess I was freaking out over nothing).

:)
 
I added a grid to it, and although the image isn't perfectly horizontal, you can detect some barrel distortion. I don't know what the percentage should be, but it's not uncommon to see this. I would consider this to be minor but something of which to be mindful when you're out shooting.

I think the Tessar-type lenses are a bit better in this regard. I've seen this with a modern-day Planar and a 1950s Sonnar, and it's usually been at medium distances: say, 3 feet to about 20 feet.

grid.jpg
 
I can think of at least half a dozen lenses I own that exhibit this amount of barrel distortion and one of them is the much revered 35mm Nokton.

That's not really that bad and until you shoot something with straight line verticals near the edge of the frame you're often not aware of it!
 
I don't know much about other P/P software but I use ACDSee Pro and it has a specific function for correction of this. Surely other programms would have it!
 
the panotools plugin is somewhat becoming the standard for this kind of correction and allows for very precise correction. I don't use ACDSee, but I'd guess it is similar to the simple one in Photoshop... I guess if I get really bored I shoot some graph paper and determine the panotools coefficients myself... otherwise, 0.5 correction in Photoshop seems pretty close.

thanks!

Keith said:
I don't know much about other P/P software but I use ACDSee Pro and it has a specific function for correction of this. Surely other programms would have it!
Click to expand...
 
straighten the image first (approx .58 degrees).

Once that is done, and re-laying the grid on it, I see almost no barrel distortion at all (maybe a .5 correction if it's bothering you). What I thought was at first, soon becomes apparent that it is a trick of shadow since the paper behind the window is not pressed up evenly against the glass.

*shrug*
 
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Get a view camera with some symetrical lenses. So called "process lenses" have about as little distortion as possible. They're expensive and really slow. Distortion is not a prime consideration of fast lenses designed for small format cameras.
 
it's pretty hard to stuff a view camera into my back pocket! ;)

As I said, I never thought the Retina had a *problem*, but sometimes it's nice to completely correct these distortions... and with software it is really easy if you have the distortion completely characterized... which exists for many many lenses, so I would be surprised if it didn't already exist for this one somewhere... just can't find it.

I really love my Retina... in case it seems otherwise...

Al Kaplan said:
Get a view camera with some symetrical lenses. So called "process lenses" have about as little distortion as possible. They're expensive and really slow. Distortion is not a prime consideration of fast lenses designed for small format cameras.
Click to expand...
 
mh2000 said:
ok, maybe they are more optical illusions... here is one image that made me suspect barrel distortion:


Image1.jpg
Click to expand...

You might have some very slight perspective distortion (it is what you get if you are shooting from a low position), but holding a straightedge to my flatscreen monitor, the lines on the right are very straight. That is not barrel distortion.

Edit: You might Google "foreshortening effect."
 
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Did you level the camera with tripod, bubble level etc when you took the pic?

Hand held involves so many variables, a bit down, a bit out of plumb, a bit of another ... Were the walls straight up? Out of plumb by 0.2 degrees, maybe? But BARREL distortion? Oh, my!

Have a beer from a barrel and do not fault the lens, unless you tripoded and bubble leveled the shot and checked the construction as well!
 
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using a bubble level and tripod, while a good thing, will not correct barrel distortion.

Yes, this shot was handheld and I doubt anything was perfectly plumb.
 
Overall, the distortion is so small that it's not worth worrying about.

It's something to keep in mind if shooting a photo that has lots of these lines -- such as a window frame, for example.

Otherwise, I wouldn't give it too much thought.
 
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