Forum:
Q & A
Thread:
circle of confusion & ppi &dpi, ?????
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Re: circle of confusion & ppi &dpi, ?????
Posted: 29 Mar 2009 at 13:01 GMT
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First of all I would like to thank everyone for trying to find an answer to my unclear question, you are right in saying that the question itself is confusing because I guess I am having problems expressing myself correctly.
Secondly I hope I did not offend anybody, it was not my intention to offend or question anybodies knowledge.
In the above link that you so kindly provided it states that at 5 lines per mm is when an average human eye can no longer distinguish lines at a distance of 25 cm, only graduations. This is the same for ponts, 0.02mm.
25 cm would be lets say the average viewing distance of somene picking up & looking at a print up to 8x10"
So the conclusion I come to with this theory is that the formula to calculate the resolution viewing an 8x10 print at 25 cm would be:
5 (5 lines,pixels or points/mm) x 25,4 (convert to inches) = 127 pixels per inch.
So my question is why is it recomended a 300 pixels per inch?
What information am I missing or what is it I dont understand?
Thank you all for your patience, I need an answer to this to be able to sleep at night 
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Forum:
Q & A
Thread:
circle of confusion & ppi &dpi, ?????
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Forum:
Q & A
Thread:
circle of confusion & ppi &dpi, ?????
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Re: circle of confusion & ppi &dpi, ?????
Posted: 27 Mar 2009 at 13:54 GMT
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actualy I suppose if you were printing at even higher DPI´s (if the printer permits.)you would be achiving a higher colour range but not a higher resolution, which would be determined by the PPI.
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Forum:
Q & A
Thread:
circle of confusion & ppi &dpi, ?????
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Re: circle of confusion & ppi &dpi, ?????
Posted: 27 Mar 2009 at 13:13 GMT
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Hi Ion,
The circle of confusion, or blurr point is cosidered to be the point at which the human eye can no longer distingush points, instead we see graduations of tone or colour. It is estimated that the average human viewing a print at about a distance of 25-30 cm that this point would measure about.20 or .25mm, there is a lot of info abut this subject on the web, wikipedia e.g.
Looking for an answer I also found that in print it is considered that 4 lines per mm is up to what the human eye can percieve which makes perfect sense with the .25mm coc.
I dont think you read the question thorughly though, dpi & ppi are not the same.
Dpi is used in printing (Dots per inch.),if there are only 4 or 8 colour inks in your printer then you require a larger amount of dots to represent a 1 colour pixel which can be more than one of 16 million different colours.
So the question is why 300 PPI?(pixels per inch) resolution .That would be 300/25,4 = 11.8 lines per mm.
I dont know if I made myself any clearer? 
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Forum:
Q & A
Thread:
circle of confusion & ppi &dpi, ?????
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circle of confusion & ppi &dpi, ?????
Posted: 27 Mar 2009 at 11:11 GMT
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hi, this thread might seem out of place but I have been investigating this for some while now & I cannot get it to make sense, maybe someone out there can help me fix this puzzle.
If a coc is considered to be about .20 or .025 mm & in print it is also considered that 4 lines per mm is the adecuate resolution so that the human eye cannot distinguish a point but a graduation, then why is the recomended printing resolution 300 ppi?
Should it not be 4(l/mm)x 25.4(convert to inches)= 101.6 ppi.???
I would understand if it was 300 dpi because a printer needs various dots to represent a colur pixel considering that there are only 4 to 8 inks to represent +16 million colours.
But why 300 ppi???? 
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Forum:
Panoguide website feedback
Thread:
Just a simple Thank You
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Re: Just a simple Thank You
Posted: 26 Mar 2009 at 6:11 GMT
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I second the motion, thanks to you all.
...& it is great that someone posted a positive criticism as well, we need some more positivity in the world today
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Forum:
Panoguide website feedback
Thread:
Open link in new window.
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Re: Open link in new window.
Posted: 26 Mar 2009 at 6:07 GMT
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I was just about to open a post on the same subject, its common web design practice to open such windows in a new/blank window, you do not want to loose web clients.It is annoying to close the panoviewer & realize that the post is no longer there & as one can see there are a lot of unhappy panners.
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Forum:
Tips & Tricks
Thread:
My 3$ panohead
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Re: My 3$ panohead
Posted: 26 Mar 2009 at 5:55 GMT
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Great Work HMS Beagle, I have been working on my own the last cople of days, tommorow I will do some testing & hopefully by next week I will have time to write a post about it.
I had a  hell of a time finding hardware parts,screws etc here on the Costa del Sol, thats why it took me so long but as I say I will write a more detailed post next week.
Its great to see people manufacturing their own heads because in the industry of photography they seem to want to chage us tenfold for everything, the only reasonable one seems to be Gregs Panosaurous which he appears to be progressing with very well.
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Forum:
Q & A
Thread:
Which lens to use for car interior panos?
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Re: Which lens to use for car interior panos?
Posted: 26 Mar 2009 at 5:33 GMT
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Hello you all, I´m a newbie to pano photography.
I like all your shots, especialy stalwarts, I think maybe you were a bit closer to the front of the car?
I just bought a Tokina 11-16 for Interiors but I see the sigma 8mm seems to be the icon in pano photography, I hope I chose well.
*** Just a note to the Webmaster/Administrator, would be much better if links opened in a new/"blank" window, general web practice, its a bit annoying when you close the panoviewer & you realize your in Googleland instead of back in the Forum .
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Forum:
Tips & Tricks
Thread:
Nodal Samurai, home-made pano-head bracket.
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Re: Nodal Samurai, home-made pano-head bracket.
Posted: 17 Mar 2009 at 11:33 GMT
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 Thanks for the grammatical correction.....
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Forum:
Tips & Tricks
Thread:
Nodal Samurai, home-made pano-head bracket.
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Re: Nodal Samurai, home-made pano-head bracket.
Posted: 17 Mar 2009 at 11:31 GMT
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I have just used the technique to find the NPP idicated in the above link & it works fine.
1. you will need to create a slider that slides the camera back & forth over the center axis of the lens.
2. level the tripod & camera so that when you pan it remains level.
3. position the camera where you will have a near vertical line, about a foot or two away, & a distant vertical line , a building for example.
4. the aim is that when you pan left or right that the distance bettween these two lines remains consistent, if the foreground moves left(relative to the building.) when you pan left then you must slide the camera foreward & viceversa.
It takes a bit of playing around but it works.
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Forum:
Tips & Tricks
Thread:
Nodal Samurai, home-made pano-head bracket.
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Re: Nodal Samurai, home-made pano-head bracket.
Posted: 17 Mar 2009 at 9:41 GMT
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Thanks Pete for sharing your knowledge in aid that the rest of us can benifit from it.
I am new to panos, stitching & Hdri, I am now learning these techniques in hopes to apply it commercialy to interiors & architecture.
I do find it a real piss take what these companies are charging for a bit of plastic, metal, nuts & bolts, they are asking for almost the same amount as my 11-16mm Tokina just cost me, NO_WAY.
So in the process of building my own I came across your project. The only thing I must say is that you appear to be considering the entrance lens the "nodal point" or "entrance pupil",when it appears to be somewhere in the center of the lens close to the aperture ring. there is a good article here in reference to that subject: www.vrphotography.com/data/pages/techtutorials/te...
Although I must say that having seen your panos you dont seem to have any problems with misalignment.
I think that anyone considering making their own should read this article though, I will try to keep you all posted when I finish my "Buddah Mk I", , just to keep in context.
Greetings you all!
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