Help identify object in the sky (planet visible in daytime)

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drabina

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Well, I couldn't wait. You guys rock :)<br /><br />Here is the original as downloaded from my camera:<br />original image<br /><br />Image of the balloon:<br />balloon image<br /><br />Another image of the balloon:<br />balloon image<br /><br />My camera is Pentax isDL:<br />23.5 x 15.7 mm CCD sensor<br />6.31 million total pixels<br />6.1 million effective pixels<br />3008 x 2000 image size<br /><br />Lens is Sigma 70-300mm f/4-5.6 DL Macro Super<br />8.2 - 34.3 degrees picture angle<br /><br />I had the zoom all the way up at 300mm so with 1.5x factor for istDL sensor, the actual focal length was 450mm. Though EXIF reports 285mm (427.5mm converted) as the actual focal length used. This might be true because lenses usually do not have exact range that's printed on the barrel.<br /><br />Thanks.
 
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votefornimitz

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Yeah, it is most definitely not that balloon...<br />It could be a balloon, but it'd be of the much smaller variety....<br /><br />If any of you far more experienced people want to pm me or post here why my way of solving the mathematically proved horribly insufficient, please do, I'd to be able to do something akin to this in the future and end up with the right answer... <div class="Discussion_UserSignature"> <span style="color:#993366">In the event of a full scale nuclear war or NEO impact event, there are two categories of underground shelters available to the public, distinguished by depth underground: bunkers and graves...</span> </div>
 
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Mee_n_Mac

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<font color="yellow">If any of you far more experienced people want to pm me or post here why my way of solving the mathematically proved horribly insufficient, please do, I'd to be able to do something akin to this in the future and end up with the right answer...</font><br /><br />Without doing a rigorous dissection, I'd say you made the problem harder than it was. You went off to calculate areas and a more simple geometry was all that was needed. The thing to understand with optics and a focal plane is that angle (from boresite) gets translated into distance (on the focal plane) from center. Look at the Feild of View (FOV) portion wiki I linked to. The diagrams are worth at least 17,328 words of mine. Thus each pixel corresponds to a fraction of the whole FOV. <br /><br /> <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>
 
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votefornimitz

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Ah...<br />Thank you very much...<br />I know you pushed the link on me earlier, but lack of interest in photography had me thinking it was irrelevant...<br />I'll see what I can make of it now... <div class="Discussion_UserSignature"> <span style="color:#993366">In the event of a full scale nuclear war or NEO impact event, there are two categories of underground shelters available to the public, distinguished by depth underground: bunkers and graves...</span> </div>
 
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adrenalynn

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Thank you for following up so quickly, Drabina! If you haven't heard it yet - welcome to SDC!<br /><br />All the EXIF viewers I have access to, including EXIF-Pro (which is kinda the defacto), CS3, Fovea, MS, etc all report your focal length as 190.0mm, which gives a "35mm equivalent" of 285mm total. <br /><br />I suspect whatever you're using to read the focal length may be doing the 35mm equivalent for you? Otherwise, <br />the Pentax is reporting the Exif incorrectly. Not impossible, and I don't have Pentax' software to double-check.<br /><br />Looking at the measurements against the sensor size, that conversion to 285 from 190 actual might make more sense. I'll calibrate Fovea and see what it says against the 190mm actual (23.5x15.7mm)... <br /><br />[edit to add: Time to clean your sensor. <img src="/images/icons/wink.gif" /> You have a pretty good dust-spot there. I have one on my 20D that has been really "sticky"] <div class="Discussion_UserSignature"> <p>.</p><p><font size="3">bipartisan</font>  (<span style="color:blue" class="pointer"><span class="pron"><font face="Lucida Sans Unicode" size="2">bī-pär'tĭ-zən, -sən</font></span></span>) [Adj.]  Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.</p><p><strong><font color="#ff0000"><font color="#ff0000">IMPE</font><font color="#c0c0c0">ACH</font> <font color="#0000ff"><font color="#c0c0c0">O</font>BAMA</font>!</font></strong></p> </div>
 
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drabina

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I have plugged all the right numbers into the formula that my friend provided and the object size appears to be:<br /><br />At 285mm (425mm converted):<br />at 1 mile the size is 2.61ft<br />at 2 mile the size is 5.23ft<br /><br />At 190mm (285mm converted):<br />at 1 mile the size is 5.76ft<br />at 2 mile the size is 11.52<br /><br />I really can't tell what the actual distance to the object was, but it did appear to be very far from me. This was a clear day, no clouds, so the visibility was great. I would say that the way the object appeared, it wasn't a small party balloon. At the distance I thought the object was, a 1ft balloon would be a lot smaller or not visible at all.<br /><br />My friend also said that with weather balloons usually the measuring equipment is mounted hundreds of feet below so it might not be visible in the picture.
 
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drabina

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<blockquote><font class="small">In reply to:</font><hr /><p>All the EXIF viewers I have access to, including EXIF-Pro (which is kinda the defacto), CS3, Fovea, MS, etc all report your focal length as 190.0mm, which gives a "35mm equivalent" of 285mm total.<p><hr /></p></p></blockquote><br />That 190mm converted to 285mm sounds right matematically, but I wouldn't understand why having 300mm at my disposal, I wouldn't use it. The lens is not specifically designed for digital camera so the readings might be off. I just know myself and because photography is my hobby, I wouldn't use lower zoom setting to photograph something small like this. I have taken pretty decent photos of moon with this lens handheld so keeping it steady even at 300mm is not a problem for me. I guess this is another mystery :)
 
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adrenalynn

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I wanted to apologize if it sounded like I was being critical. My post might have read that way (when I re-read it it sorta did to my "virtual ear") - that wasn't my intent. I tend to be very stuck on the technical detail. It's a requirement in what I do, and is somewhat important here for analysis. So please pardon my drilling into any questionable detail at a fine level. <br /><br />[edit to add:] We can go at this another direction. If you shoot something of reasonably known size at infinite focus, we can work backward and look at the EXIF and figure-out if the focal length matches the EXIF given a known-sized obect. <div class="Discussion_UserSignature"> <p>.</p><p><font size="3">bipartisan</font>  (<span style="color:blue" class="pointer"><span class="pron"><font face="Lucida Sans Unicode" size="2">bī-pär'tĭ-zən, -sən</font></span></span>) [Adj.]  Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.</p><p><strong><font color="#ff0000"><font color="#ff0000">IMPE</font><font color="#c0c0c0">ACH</font> <font color="#0000ff"><font color="#c0c0c0">O</font>BAMA</font>!</font></strong></p> </div>
 
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drabina

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Adrenalynn: No worries, no offense taken. I am puzzled myself by the EXIF data. I have edited the post above to include numbers with the reported focal length as well as the one I think I was using. Now you got me thinking and I am reaching for my camera to take another picture at 300mm to see what the EXIF reports.
 
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drabina

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<blockquote><font class="small">In reply to:</font><hr /><p>We can go at this another direction. If you shoot something of reasonably known size at infinite focus, we can work backward and look at the EXIF and figure-out if the focal length matches the EXIF given a known-sized obect.<p><hr /></p></p></blockquote><br />I guess you were right, the test picture taken at 300mm shows as 450mm converted in EXIF. So the original picture of the object in the sky was actually taken at 190mm.<br /><br />I can't take a picture of something very far now because it is dark. The light switch plate was 26ft from the camera and it measures 2.75x4.5in. Hope this helps. <br /><br />Going to sleep now, it is after 11pm here in NJ and my kid will definitely wake me up at 7am or earlier tomorrow <img src="/images/icons/frown.gif" />
 
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adrenalynn

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I shoot a lot of photos, both for fun and commercially, and I can tell you that it wouldn't be the first time that I went to grab a "once in a lifetime" shot and did something "stupid". Like the time I couldn't figure out why I couldn't pull a focus on a stooping eagle... Turned out that I had managed to put the lens in macro. <img src="/images/icons/blush.gif" /> I missed a half dozen opportunities over ten minutes because I figured the camera/lens was malfunctioning... <img src="/images/icons/blush.gif" /> <img src="/images/icons/blush.gif" /> <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p>.</p><p><font size="3">bipartisan</font>  (<span style="color:blue" class="pointer"><span class="pron"><font face="Lucida Sans Unicode" size="2">bī-pär'tĭ-zən, -sən</font></span></span>) [Adj.]  Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.</p><p><strong><font color="#ff0000"><font color="#ff0000">IMPE</font><font color="#c0c0c0">ACH</font> <font color="#0000ff"><font color="#c0c0c0">O</font>BAMA</font>!</font></strong></p> </div>
 
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adrenalynn

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Nice! Thanks!<br /><br />That one calculates "close enough"* to correctly, and matches the EXIF. So I concur that we've correctly established that your focal length on the UFO was 190mm * 1.5 crop-factor, providing 285mm corrected 35mm equivalent.<br /><br />Thanks again for being so helpful!<br /><br />* we have to accept some error because focus changes actual focal-length. Your UFO was sharp focus, so it was at actual infinite, give or take. <div class="Discussion_UserSignature"> <p>.</p><p><font size="3">bipartisan</font>  (<span style="color:blue" class="pointer"><span class="pron"><font face="Lucida Sans Unicode" size="2">bī-pär'tĭ-zən, -sən</font></span></span>) [Adj.]  Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.</p><p><strong><font color="#ff0000"><font color="#ff0000">IMPE</font><font color="#c0c0c0">ACH</font> <font color="#0000ff"><font color="#c0c0c0">O</font>BAMA</font>!</font></strong></p> </div>
 
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siarad

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That date is rather old but currently Venus? is visible here in Wales, where no stars are visible even at night, into quite well after dawn.
 
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Mee_n_Mac

Guest
<font color="yellow">That date is rather old but currently Venus? is visible here in Wales, where no stars are visible even at night, into quite well after dawn.</font><br /><br />A good thought but I think we've ruled out planets. First someone checked and on the date in question and looking in the direction the pic was taken, there were no visible planets in that part of the sky. Second I checked on the angular sizes of Venus and Jupiter, the 2 brightest, and they seem to be too small to be the object captured.<br /><br />So the calculations above should give a range of sizes and distances that may aid in identifying the likely "culprit" while ruling out others suspects (like planets and nearby sightseeing balloons). <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>
 
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drabina

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I have done some research on the internet and weather balloons before launch are inflated to about 6ft in diameter. They reach altitudes of approx 25 miles. During the ascend they expand to about 24-32ft in diameter and after that they burst. So the size calculated from my friend's formula would match the size of a weather balloon if it was little more than 1 mile from me.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>At 190mm (285mm converted):<br />at 1 mile the size is 5.76ft<br />at 2 mile the size is 11.52<p><hr /></p></p></blockquote><br /><br />So if we ruled out planet, tourist balloon and party balloon, I guess the next step for me would be to check if there are any weather balloon launching stations near Niagara Falls. Back to searching the internet....
 
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