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05-03-2009, 05:06 PM   #16
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QuoteOriginally posted by Squier Quote
Yup - nicely explained.

Now then - do you know of a free decent lens correction software ?

PT lens is good, but you get 10 shots at correction, then its kaput, or go buy it.
At $25 to license PTLens, I think that it is about as near to free as you are going to get for a useful CS4 plug-in.

Steve

05-03-2009, 05:21 PM   #17
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I've just found there's lens correction inside CS4 - so no need to purchase PT lens
05-03-2009, 06:31 PM   #18
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i use the hugin/panotools suite for lens corrections (the problem is it kind of lacks a database -- i proposed before that we help make one for pentax lenses -- this means you will need to play a bit and find the right settings for each lens you want to use it with, or find somebody who got the settings right ofr the same lens)
05-04-2009, 12:18 PM   #19
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QuoteOriginally posted by nanok Quote
not quite: by fisheye we mean fisheye (spherical projection, instead of linear, as mentioned above). it so happens that it is virtually impossible to get 180 - even "just" diagonal - fov with a linear projection (mostly due to physics, or one might say even due to geometry). this is why the concept of fisheye is often associated with 180. both the zenitar and the peleng (the 8mm you mentioned, i guess) are designed for a normal 35mm film frame. this means they are cropped on the aps-c sensors, so the peleng will not look like a "circular fisheye" anymore on the aps-c, and the zenitar will no longer be a 180 diagonal (so called full frame fisheye, because it fills the entire frame), the zenitar on aps-c becomes "merely" a very wide prime lens, with a (easily correctable, because it is not really distorsion, but honest spherical projection) fishyness to it, very compact, very well built (especially for the price), and pretty damn sharp i think, too. this is what i use it for (ultrawide on the cheap), sometimes i need to "correct" the sphericity, sometimes it works well for the shot and i leave it alone, other times it is impossible to notice it unless you've been there. to be very honest, the choice between linear and fisheye is choosing between two distorted renderings (linear is only perceived as more natural by most, but it is strictly not, and sometimes it is even perceived as very wrong), the moral of the story being, i guess: when you go ultrawide, you have to somehow project a noticeably spherical reality on a plane rendering, so no matter what you do, it will not be "right" (for a very known and easy to relate to example, think of map projections, any plane map of the earth in any projection you wish to choose will be distorted and wrong in one way or another, that's because the earth is "round", and the map is flat, and there's nothing you can do about it really)

hope this helps shed some light
Muchas gracias for all this! I already knew much of the physics/optics, and agree about the usage - I was just looking for labels. I checked a photo encyclopedia - no entry for fisheye! So I defaulted to the Wikipedia article on Fisheye lens and find that... the original is called circular fisheye, and the other is called full-frame fisheye. How mundane! (The last should really be called fill-frame, so as not to be confused with full-frame film/sensor formats. Dang, I hate this ambiguous terminology.)

Apparently the Peleng 8/2.8 *does* inscribe a complete circle in full-frame 135 format. The Vemar 12/5.6 also projects a circular image on FF-135, but only if the circular lens hood is left in place - it's cheating, gives less than 180 degrees. (I just verified this on my ZX-M.) The Wiki article (to which I've appended mentions of the Vemar 12/5.6 and Pentax DA 10-17) doesn't go into the math, but I compute that 5mm or 6mm is required for circular fisheye on an APS-C sensor. Well, now that I have the ZX-M, I can shoot REAL WIDE with Zenitar, and circular with the Vemar. And I'll still be quite happy with the Zenitar and the DA 10-17 on my K20D. And I can shoot circular on both with the Kenko adapter mounted on appropriate lenses, just not so sharp. Options abound!

For fill-frame de-fishing, I rely on PaintShopPro9, either the Fisheye Correction or Barrel Correction tools. These are the PtTools, licensed and incorporated. Sorry, I just never got into that new-fangled PhotoShop stuff -- old PSP enticed me when it was use-forever shareware, and I've stayed loyal (and the keystrokes are wired into my nervous system).

05-04-2009, 01:17 PM   #20
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QuoteOriginally posted by RioRico Quote
Muchas gracias for all this! I already knew much of the physics/optics, and agree about the usage - I was just looking for labels. I checked a photo encyclopedia - no entry for fisheye! So I defaulted to the Wikipedia article on Fisheye lens and find that... the original is called circular fisheye, and the other is called full-frame fisheye. How mundane! (The last should really be called fill-frame, so as not to be confused with full-frame film/sensor formats. Dang, I hate this ambiguous terminology.)
you are welcome, i guessed you know a thing or two, it was just to set things straight for whomever else might be reading.

the terminology is wrong i agree: calling 35mm film "full frame" makes no sense. it's just 35mm, what the hell.. and if a sensor happens to be the same size, okay, we already have a term for that size. there's nothing fuller about it than a compact digital (fingernail sized) sensor.

QuoteQuote:
Apparently the Peleng 8/2.8 *does* inscribe a complete circle in full-frame 135 format. The Vemar 12/5.6 also projects a circular image on FF-135, but only if the circular lens hood is left in place - it's cheating, gives less than 180 degrees. (I just verified this on my ZX-M.) The Wiki article (to which I've appended mentions of the Vemar 12/5.6 and Pentax DA 10-17) doesn't go into the math, but I compute that 5mm or 6mm is required for circular fisheye on an APS-C sensor. Well, now that I have the ZX-M, I can shoot REAL WIDE with Zenitar, and circular with the Vemar. And I'll still be quite happy with the Zenitar and the DA 10-17 on my K20D. And I can shoot circular on both with the Kenko adapter mounted on appropriate lenses, just not so sharp. Options abound!

For fill-frame de-fishing, I rely on PaintShopPro9, either the Fisheye Correction or Barrel Correction tools. These are the PtTools, licensed and incorporated. Sorry, I just never got into that new-fangled PhotoShop stuff -- old PSP enticed me when it was use-forever shareware, and I've stayed loyal (and the keystrokes are wired into my nervous system).
there is no "use-forever shareware". the only thing which guarantees "forever" in any way is opensource (by design, and also in practice). this is why i prefer to stay away from any non-open software, even if it is "free as in beer" (money is not the only factor), life is just too short
05-04-2009, 04:44 PM   #21
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QuoteOriginally posted by nanok Quote
the terminology is wrong i agree: calling 35mm film "full frame" makes no sense. it's just 35mm, what the hell.. and if a sensor happens to be the same size, okay, we already have a term for that size. there's nothing fuller about it than a compact digital (fingernail sized) sensor.
It's 'full' in relation to 135 still cams. But in 35mm cine, 'full' is HALF that; 135-FF is double-frame; 135-HF is 35-cine on it's side. I won't even try to keep track of all 35-cine formats, which have near-infinite variations for soundtracks, anamorphic lenses, whatever. Certain Wikipedia pages go into excruciating detail. Yow!

We can refer to any format by its technical description, but that gets rather tedious in informal discussions (and 4chan/p/ flamewars). So we can continue referring to HF (for APS-C) and FF, lost in our own little world, ignored by MF (645, 6x6, 6x7, 6x9) photogs. And woe befall any who try discussing PNS chips (1/2.7", 1/1.8", etc) whose labeling derives from usable areas of old vidicon tubes.

QuoteQuote:
there is no "use-forever shareware". the only thing which guarantees "forever" in any way is opensource (by design, and also in practice). this is why i prefer to stay away from any non-open software, even if it is "free as in beer" (money is not the only factor), life is just too short
Very early PSP was no-nag no-cost no-expiration shareware; evolved versions cost money. But it got me hooked. (Hey kid, have a snort of *THIS* stuff - for you, no charge, heh heh.)

Last edited by RioRico; 05-05-2009 at 02:32 AM.
05-04-2009, 04:55 PM   #22
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I have the 8mm Peleng, haven't really used it yet, but I was led to believe that there's free de-fishing software out there, in case you wanted to get a super-wide effect as opposed to fisheye.

Of course, I'm on a Mac, and I think that was for PC, but I can't remember.

I paid $190 for mine, mint, like 6 months ago--but now I see they're going for $300. What I HAVE learned about this lens is that you want to be at around F8 for it to be at its sharpest, and it's basically impossible for your shots NOT to be in focus.
05-05-2009, 01:44 AM   #23
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check out hugin, being opensource, it is available on mac also. defishing the peleng might degrade quality quite a bit, as the peleng is quite seriously fishy

05-05-2009, 02:59 AM   #24
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QuoteOriginally posted by nanok Quote
check out hugin, being opensource, it is available on mac also. defishing the peleng might degrade quality quite a bit, as the peleng is quite seriously fishy
Thanks!

I'm actually afraid to use this lens, and wish I had a digital to play with it first before film.
05-05-2009, 05:31 AM   #25
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Fisheye Technique etc

QuoteOriginally posted by Ira Quote
I have the 8mm Peleng... I paid $190 for mine, mint, like 6 months ago--but now I see they're going for $300.
About 6-8 months ago I was seriously considering the Zenitar and the Peleng from a dealer offering both for around US$175 each (M42 I think) but he never replied to inquiries. I found the Zenitar (PK) on eBay for that amount, and am happy. But I just can't justify US$300 or so for what would be a rarely-used toy. Even with dollars rising and rubles falling, the price hasn't dropped. Bother. And I've seen mention of the Sigma 4.5mm lens, which DOES project a full 180-degree circle on an APS-C sensor. Way out of my price range, however. Maybe I'll just glue a cheap peephole lens into a bodycap.

QuoteOriginally posted by nanok Quote
...defishing the peleng might degrade quality quite a bit, as the peleng is quite seriously fishy
Defishing s-t-r-e-t-c-h-e-s those pixels greatly. The only way to get any quality is to shrink the image similarly, like 60-70%. Turn the K20D into a 6mpx fisheye cam. (Here's an article on defishing Pelang imagery: Peleng Writeup ) It would probably be better NOT to defish, just compose pictures with the circular projection in mind. Above water, that pretty much means following this BRIEF GUIDE TO FISHEYE TECHNIQUE:
Look for 1) very close subjects; 2) level horizons with no off-center verticals; 3) centered intersections of 3 or more vertices; 4) views in and of round structures; 5) straight-up (all-sky) or straight-down (aerial) views without bothersome verticals; 6) views intended to be stitched into panoramas (you'll likely want the camera perfectly level, and rotate around the nodal point); and/or 7) stuff where you just don't care about the margins, distortion, softness, etc. With circular fisheyes you'll want spot or center metering, so the dark corners don't throw of the image exposure. Be careful of getting the sun, bright lights, or other glare-producing artifacts in the picture. Watch for your shadow, feet, tripod, trash, and other likely unwanted details. Use a small aperture for great DOF, and make sure the lens is clean or every speck of dust will show.
NOTE: Researching this by googling FISHEYE TECHNIQUE, I find amazingly little online info that's applicable to SLR photography. (Most references are about visualizing and navigating information spaces.) The above paragraph is just about the most comprehensive guide to fisheye photography extant. Pathetic, ain't it?
05-05-2009, 06:50 AM   #26
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defishing stretches pixels (interpolates) as much as needed (and/or requested by you, there are many ways to defish a fisheye ), in the case of the peleng you can expect quite a bit of quality loss, in the case of the zenitar on aps-c, using nona (part of hugin/panotools), i see nearly no discernable quality drop (in any case, nothing to worry about), so i am quite happy with my choice. for instance, the excellent 12-24/4 pentax is most certainly a better rectilinear ultrawide, and more flexible being a zoom, but at a lower price, compact size, good old honest manual focus build, complete with a dof scale, i'm not complaining, especially that in some cases the zenitars fishyness actually looks a lot more natural than the rectilinear projection. the zenitar is probably half the size of the 12-24, and you can probably hammer rocks with it, it's exactly what i need for my landscape shooting. now, if it would also be weather sealed (at least at the mount), and would be an A instead of an M, it would be a killer (as i said before, i believe that's a great niche pentax can fill there, i wrote a longer post about this, with some more detailed ideas some time ago, so i will not go into it again).

edit: shortly: in a day where almost everybody shoots digital or does digital post processing at least (after scanning), imho rectilinear ultrawides are wastefull and obsoleted, with a bit of firmware intelligence in the dslr, and some nice bundled software customized accordingly (like the oss hugin), fisheyes are the future, at least for digital photography (i know, a monstrous can of worms i am handing the key to right now)

Last edited by nanok; 05-05-2009 at 06:55 AM.
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