aardappel
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Posts posted by aardappel
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<p>Marc: this isn't blind promotion, I've been making these photo compositions for 15 years now, and me making that app was filling a gap. I am sure others would enjoy it. I'm unlikely to make any money on it regardless.</p>
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<p>I love making composite photo grids (as you can see on my profile: http://www.photo.net/photos/aardappel ), and since there wasn't a good app for that, I made one: http://strlen.com/gridpic<br>
Opinions? Features you'd like to see?</p>
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<p>Mark: appreciate it!</p>
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<p>Frank: this isn't normal. It didn't used to do it, and I have yet to hear from another Nex 5n owner that has this same problem.<br>
Amos: thanks for trying!</p>
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<p>Just tested, if I point it at a very bright scene when on, aperture rings on the lens go tiny, then turn it off, aperture stays tiny, then turn it back on, it immediately throws the aperture all the way open (even though it was looking at the bright scene all this time).<br>
That still doesn't say whether its a lens or body problem I guess?</p>
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<p>Amos: it's on auto-ISO (before and after the reset) which does 100-1600 I believe. Tried setting it to 100, no difference.<br>
Frank: you're probably thinking of a different issue. The camera is somehow thinking that the scene is super dark when it gets turned on, which isn't normal.<br>
Gus: yeah, don't have any other lenses, maybe I can find a friendly camera shop here locally that will allow me to try.</p>
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<p>Mark: what is "magnify mode"?</p>
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<p>I tried "reset defaults", no change.<br>
And yes, the 16mm is from Sony.</p>
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<p>My Nex 5n, when I turn it on, starts with exposure way up (i.e. screen all white), and then takes 2 or 3 seconds to adjust to normal. If I take a picture within that time, it will be over exposed. If I wait, the camera functions normally and takes great pictures.</p>
<p>This is irrespective of what the camera is pointed at when turned on (bright or dark scene). It happens even when the camera has been off for a long time, so it is not a overheating problem. Actually, the only time this effect does not occur is when you turn the camera immediately back on after turning it off.</p>
<p>I don't remember it doing this when I bought it, and it is rather annoying having to wait before being able to shoot.<br>
<br />This is with the 16mm f2.8 pancake if that matters (only lens I have for it, other than the fisheye attachment). Happens both in auto and in P modes.<br>
<br />Is the camera broken? Googling for this issue didn't turn up anything.</p>
<p> </p>
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<p>The tool that can blend between these possible perspectives has been released at: http://strlen.com/bulk-fisheye-remapper</p>
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<p>Oscar, thanks, I didn't know about that lens, a stereographic lens that is affordable, wow!<br>
Though, the projection that lens gives is clearly superior to a regular fisheye, it is still on the fishy side, and not very rectilinear. Like in my original post, I prefer a blend between stereographic and rectilinear.<br>
I am using a D90 with a sigma 8mm fisheye nowadays, and wrote some software for it to convert in bulk the photos it generates to semi-stereographic (it allows you define with a slider exactly how (non)fishy you want it).<br>
I may release this software at some point, but sofar have written it just for myself, so it is not very user friendly, and only works well for my this kinda lens on a 1.5 crop factor.<br>
Email me if you want to hear when/if I release that software, plus I can send you a link to my private photo blog that has tons of examples. I'll probably post on this thread too.</p>
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<p>Alan: for sure software is the solution. However, higher quality could be achieved with lenses, and post processing with hugin is a lot of work if you have many pictures. Besides, the hugin trick is an approximation.</p>
<p>Being a programmer, I'll probably end up implementing this myself to streamline the process :)</p>
<p>Be curious to see what you produce :)</p>
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<p>To show the difference, here's semi-stereographic applied to an example picture on this page:<br>
http://www.imagetrendsinc.com/products/specpage_hemi.asp#hemi_lens</p>
<p>Now, I have to admit, fisheye hemi is indeed better for people, still. But you can also see how semi-stereographic is the more neutral of the 3: look at the pillar and the ceiling right behind the guys head. In fisheye, both are very round. In fisheye hemi, one is very round, the other very straight. In semi-stereographic, they both are mildly round.<br>
And like I said, semi-stereographic can be improved beyond this, but that would require custom software.</p><div>
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<p>Alan,</p>
<p>I used Hugin to produce the the bottom 3 pictures from the top one. The middle 2 are converting fisheye to stereographic, where #2 is converting the angles 1:1 (using Hugin's recommended settings), and #3 is by faking that my fisheye lens has more angle than it really does (I input 10mm instead of 16mm).</p>
<p>Though this does not do exactly the right transformation, I intend to write my own software to be able to get the exact formula I want.</p>
<p>As for humans, yes, this reduces the "banana" effect, but unlike the hemi software it doesn't pull them straight entirely. The disadvantage of the hemi software however is that it can stretch things near the top or the bottom of the image quite a bit, but since faces are often near the middle, I guess you don't notice that much.</p>
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<p>Alan,<br>
What both those links do is what I'd call a panoramic projection, i.e. it keeps fisheye horizontally (equidistant in this case), but rectilinear vertically. This does indeed look more pleasant than either just fisheye or just rectilinear, because it makes use of the fact that horizontal you have more angle to deal with than vertical. It gets rid of the typical "banana shaped people" on the edges of fisheye.<br>
But in terms of minimizing distortion, it is still inferior to "semi-stereographic", because it makes for very straight lines vertically, but still very round ones horizontally (as can be seen on some example images on the first link). semi-stereographic gives you mild roundness in both directions.<br>
However, the idea from this to treat vertical different from horizontal is a good one, so if you did semi-stereographic with X = tan(phi/1.4), Y = tan(phi/1.2) you might improve it over the uniform angle case.</p>
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<p>So, if you want a wide FOV, we all know the drill: either you choose fisheye, and put up with excessive barrel distortion that is fun at first, and tiring after, or you get the widest rectilinear lens, and either put up with excessive shearing and stretching at the edges, or the fact that its not really that wide at all.<br>
But at least in theory we can do much better, and I wonder why lens makers seem to never have explored this. Check out this comparison I made:<br>
<img src="http://strlen.com/photos/projection_comparison.jpg" alt="" /><br>
The top and bottom one correspond to the way pretty much all photographic lenses you can buy work, the top being a typical full frame fisheye, and the bottom is its rectilinear version (which is actually wider than most any real rectilinear lens would give you, but good for comparison).<br>
Now, the fisheye is equisolid, which is actually the worst kind of fisheye projection from the perspective of deformation at the edges. Stereographic projection (shot #2) is superior visually to what most any photgraphic fisheye lens does.<br>
But can we do better? I think yes: notice how mathematically, rectilinear and stereographic are closely related, both taking the tan() of the scaled angle, at factors 1 and 2 respectively. For some reason, when people talk about projections, you only ever see these formulas with 1 and 2, but what happens if you use other values? That's right, you get a projection that is a blend between rectilinear and stereographic, giving a good compromise that minimizes the distortions of either approach.<br>
I dubbed this "semi-stereographic", as in the third picture. Notice how in this picture the barrel distortion has been reduced compared to the 1st and second picture, and how the extreme stretching of the 4th picture is also not present. I personally think this is the ideal wide angle perspective. Note that I chose factor 1.4, but you could choose 1.5, or 1.3 or whatever, if you prefer a different balance between the 2 kinds of distortion.<br>
So, any thoughts on why there aren't more lenses that try to reconcile the 2 kinds of distortion? It seems odd to me that only the 2 most extreme forms are available.<br>
Note: you can simulate "semi-stereographic" in hugin by lying about your lens, i.e. when I load in a fisheye photo, rather than specifying its fisheye and 16mm (as is my lens), I say it is 10mm instead, and on the stereographic re-projection I specify a wider angle than normal as well. This will give you a similar effect as the tan(phi/1.4) above.</p>
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<p>Well, I am going to drop the idea. It was more something of, if it is easy and works well, it be a cool thing to have. I think I'll stick to software based fisheye -> rectilinear instead :)</p>
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<p>He said: "you really have to put the CS lens inside G1 to do infintiy focus... C lens already is 2mm 'inside' G1.. so it won't do infinity focus for CS lenses.".<br>
So sounds like it not such a good idea.<br /> </p>
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<p>dan: its not fisheye, its rectilinear, which is why its such a special lens (135 degrees!).. I have not seen anything like it anywhere.<br>
I don't have a G1 yet, so buying it just on the hope that it can be made to fit is a bit much risk (650$ for the camera, 400$ for the lens, + adapters).</p>
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<p>franklin: that's a shame, but good to know. Any other kind of camera that this particular CS lens might fit on?</p>
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<p>dan: thanks :)<br>
I presume you mean this:<br>
Would I additionally need a CS to C adapter? (the lens is a CS mount, which is subtly different according to wikipedia), or would the lens fit straight on the C mount adapter?<br>
Any idea if I am to expect problems focussing, vignetting, or such?</p>
<p> </p>
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<p>So, I am crazy for extremely wide angle lenses. I already own a very nice fisheye lens, and wouldn't mind a wide rectilinear lens, except that the widest such lens (the sigma 12-24) requires a full frame camera, and I am not ready to spend that much. 10mm APS-C lenses are less wide and don't excite me that much.<br>
So I randomly found this lens:<br>
http://www.use-ip.co.uk/theia-sy125a-ultra-wide-megapixel-lens.html<br>
it's 135 degree FOV (!), which is significantly more than even the sigma's 122 degrees.<br>
The question is: is there any way to get this thing attached to ANY digital camera (or even digital video camera)?<br>
I know the quality is likely to be crap, but for such a crazy rectilinear FOV at an affordable price (400$) I'd be tempted to try it out.</p>
GridPic: make composite photo grids of any size (iOS)
in Phone & Mobile
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