colorflow Posted June 3, 2007 Share #1 Posted June 3, 2007 Advertisement (gone after registration) Just noticed this yesterday. All the houses are leaning to the right in the second cropped photo. Went back there today to see if they are really leaning. They are not. Has anyone seen this? I am sure the lens does not do this with closer subjects. Pretty sure it was f5.6 ISO 160. Alan:confused: Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/25759-strange-distortion-using-the-cron-28/?do=findComment&comment=271527'>More sharing options...
Advertisement Posted June 3, 2007 Posted June 3, 2007 Hi colorflow, Take a look here Strange "distortion" using the Cron 28. I'm sure you'll find what you were looking for!
AlanG Posted June 3, 2007 Share #2 Posted June 3, 2007 It looks like you were aiming up and tilted counter clockwise (anti-clockwise) a little. This makes the right side straight and the left side leaning. That's all. Link to post Share on other sites More sharing options...
colorflow Posted June 3, 2007 Author Share #3 Posted June 3, 2007 It looks like you were aiming up and tilted counter clockwise (anti-clockwise) a little. This makes the right side straight and the left side leaning. That's all. Well, I may be tilted a little but don't believe I was aiming up since I was basically aiming straight across. In any case it would be very slight and should not be noticeable. Maybe again something I never noticed in film since couldn't blow up and scrutinize so easily? Thanks, Alan Link to post Share on other sites More sharing options...
colorflow Posted June 3, 2007 Author Share #4 Posted June 3, 2007 Also please note both sides of every house are leaning to the right, while the rooflines appear to be quite horizontal. So it does not seem to be due to tilt/shift. Alan Link to post Share on other sites More sharing options...
AlanG Posted June 3, 2007 Share #5 Posted June 3, 2007 Well, I may be tilted a little but don't believe I was aiming up since I was basically aiming straight across. In any case it would be very slight and should not be noticeable. Maybe again something I never noticed in film since couldn't blow up and scrutinize so easily? Thanks, Alan There is no way to know if any of those roof lines are exactly parallel to the camera sensor and thus should be recorded perfectly straight across the frame when the camera is level. And there is no reliable way with an M8 for you to know if you are aiming straight at the subject without angling up slightly. (Unless you use a level or are really good at spotting the converging lines in relation to the bright frame.) This result is pretty common if you are not using a tripod and a camera level. I've probably done it hundreds of times shooting handheld. And that's with an SLR that has a grid screen. (Rushing and not paying attention, knowing I can fix in post.) I think in this case the dock pilings actually are crooked so that might have thrown you off. Here is a corrected version that I pulled from the top left corner and left uncropped. If your lens is doing this, it is a kind of distortion I have never seen before. I guess anything is possible - but I'm not smart enough to see how a lens of this quality could be made with this kind of very unusual distortion. Use a tripod and level before thinking about it any more and see if that solves the "problem." Perhaps keep in mind that I photograph houses and other architecture for a living. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/25759-strange-distortion-using-the-cron-28/?do=findComment&comment=271552'>More sharing options...
rwfreund Posted June 3, 2007 Share #6 Posted June 3, 2007 Looks like Rockport. If it is, it usually leans a bit to the left. Link to post Share on other sites More sharing options...
luigi bertolotti Posted June 3, 2007 Share #7 Posted June 3, 2007 Advertisement (gone after registration) Before considering to send the lens to Solms, try to make a geometrically correct test with some proper target and tripod+level : BTW, has the pic been taken from soil or from some wooden pier or boat? This can often cause distortive effects on alignment... Link to post Share on other sites More sharing options...
colorflow Posted June 3, 2007 Author Share #8 Posted June 3, 2007 Thanks everyone for your replies. Yes it is Rockport, MA. and building do generally lean but not all in unison like that. Alan G. - I am just surprised that a very small angling could cause such apparent tilt/shift effect on such distant objects. Thought it would take more angling to produce such results, and generally on closer buildings. Yet the closer building on the right show no such effect? Thanks for your post work Luigi - Yes it was taken on land. I am not considering sending the lens to Solms. It is my fovorite and takes razor sharp pics. Only curious about this. Alan Link to post Share on other sites More sharing options...
twom4 Posted June 3, 2007 Share #9 Posted June 3, 2007 It's simply a case of one beer too many. :D Link to post Share on other sites More sharing options...
Jack_Flesher Posted June 3, 2007 Share #10 Posted June 3, 2007 Your image is not skewed, it is simply angled about 1/2 degree CW (I pulled it into CS to confirm this). Rotate it and you're done. You need to take Guy's workshop in the fall -- we'll be teaching some intermediate Photoshop techniques for M8 users Link to post Share on other sites More sharing options...
Jack_Flesher Posted June 3, 2007 Share #11 Posted June 3, 2007 Your image is not skewed, it is simply angled about .5 degress CCW (I pulled it into CS to confirm this). Rotate it and you're done. You need to take Guy's workshop in the fall -- we'll be teaching some intermediate Photoshop techniques for M8 users. (Of course after an evening with Guy, all your images the next day will be skewed!) Cheers, Jack Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted June 3, 2007 Share #12 Posted June 3, 2007 get you straightened out in no time. LOL Link to post Share on other sites More sharing options...
sean_reid Posted June 3, 2007 Share #13 Posted June 3, 2007 Looks like Rockport.If it is, it usually leans a bit to the left. Clever, that was pretty good. Cheers, Link to post Share on other sites More sharing options...
colorflow Posted June 3, 2007 Author Share #14 Posted June 3, 2007 Your image is not skewed, it is simply angled about .5 degress CCW (I pulled it into CS to confirm this). Rotate it and you're done. You need to take Guy's workshop in the fall -- we'll be teaching some intermediate Photoshop techniques for M8 users. (Of course after an evening with Guy, all your images the next day will be skewed!) Cheers, Jack Thanks Jack. Would you mind posting the rotated image? Still looks skewed after I rotate it. When and where will Guys workshop be? Thanks, Alan Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted June 3, 2007 Share #15 Posted June 3, 2007 Jack and I are planning Yosemite in late October, 3 day workshop . Keep you all posted on this. Even planned the famous steak dinner in it. LOL Link to post Share on other sites More sharing options...
lct Posted June 3, 2007 Share #16 Posted June 3, 2007 Typical 28mm behavior IMHO. Easy to adjust with the 'Perspective' tool of PS Elements here. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/25759-strange-distortion-using-the-cron-28/?do=findComment&comment=271965'>More sharing options...
Jack_Flesher Posted June 3, 2007 Share #17 Posted June 3, 2007 Here it is rotated 1/2 degree CCW and cropped back to 3:2: Howeverbut, you did have the camera pointed up at a slight angle... Personally, I do not find the resultant "keystoning" offensive or detrimental to this image, but since others mentioned it, here is with a slight perspective correction, again re-cropped back to 3:2. Note that keystoning is a perspective adjustment and *not* a skew adjustment: However, as a final version, the colors don't look quite right to me even on my laptop monitor. So here I made a slight color correction and applied some of our film-emulation processing techniques. Looks better to my eye, at least on my laptop, but respect others opinions will vary : I only spent about 5 minutes total on this and am not what I would consider "done" with it. If I have time, I may try and spiff it further tomorrow. Cheers Jack Link to post Share on other sites More sharing options...
colorflow Posted June 3, 2007 Author Share #18 Posted June 3, 2007 Looks much better Jack. My posting was just a straight LR jpg conversion using basic defaults. I don't find it offensive either, but just curious that keystoning is noticeable here - at this distance and with short buildings. I would have thought that even a tall building would look straight at this distance??? I understand why there is keystoning in general, but would appreciate a short tutorial on the effects of building height, distance, focal length, etc. Alan Link to post Share on other sites More sharing options...
Jack_Flesher Posted June 3, 2007 Share #19 Posted June 3, 2007 A short tutorial then... Keystoning, the convergence or divergence of verticals, is fact of life with ANY lens on ALL formats. The only way you can eliminate it is to have the camera perfectly level, or more accurately, have the SENSOR plane (film or digital) perfectly perpendicular to the ground. Any deviation from perpendicular induces the keystoning. However, the effects are far more pronounced with shorter lenses... So while 2 degrees of upward tilt induce readily noticeable convergence with say a 24mm lens, the same 2 degrees with a 600 will be barely measurable -- it is for sure there, just difficult to quantify. Moreover, the effect becomes more apparent in lenses that are more rectilinear. Most wideangle lenses have moderate amounts of barrel distortion. With this, the bases of any verticals (base being below the center-line of the frame) actually angle in from the barrel distortion. The convergence induced by an upward camera angle then bends them out back toward parallel, so you get away with more upward tilt; the barrel distortion camouflages the effect to a degree. (Yes the tops will have more convergence, but the larger central and lower half areas look more parallel and our brains accept that...) This is a typical issue for folks getting started with large-format photography and view cameras. Since LF lenses are generally very well corrected against distortions, the lines are straighter and the resulting effect is more apparent than they are used to seeing. (It's also easier to see it before you take the picture when you are looking at the actual image projected on the large viewing glass of a view camera.) All that said, I suspect the 28 APSH Cron M is also very well corrected for distortion, and hence the phenomena is simply more apparent than with other 28's... And a big PS: The rectilinear nature of the lens also makes non-level horizons much easier to spot for the same reasons -- so more care needs to be taken to keep the horizon level when when using the best wide glass Cheers, Jack Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted June 3, 2007 Share #20 Posted June 3, 2007 Well said Jack as always . If the spirit moves you can buy a hot shoe spirit level and if something is very critical to you than they work very well. Most folks will worry about left and right but the trick is watch the front and back . Obviously like this it was tilted up slightly . Now if he kept it perfectly level on all four corners lets say than most likely he would have to much foreground. This is were a shift lens becomes very handy , so if that is the case than just shift up until the desired effect. Link to post Share on other sites More sharing options...
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