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Old 09-03-2013, 01:35 AM
dp297 (Dimitris)
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Megapixels and Printing sizes

OK, most DSLRs are about 8-12MP so that means according to various sources on the web that you could probably get a quite decent print at about 20X30cm.

Now the question is.....suppose you are doing narrowband imaging so only a portion of the pixels are utilized....how does that affect the quality of the print in the cases

1. SHO imaging
2. Ha imaging
3. HA + RGB imaging
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Old 09-03-2013, 05:13 AM
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absolut (Rob)
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You'll need to check with your image software, printing resolutions are expressed as dpi at the print size. Images from digital cameras usually default to 75 or 150dpi at a rather immense physical size. Scaling the image to half the size will double it's resolution.

With that covered, here is a image resolution guide for printing:

Large format inkjet posters = 150dpi for A2 or larger lowering the dpi is ok as the posters get larger because you are generally standing further from the finished product when viewing, eg 60-75dpi is good for A0.

Smaller format laser/inkjet = You can get away with as low as 150dpi if you don't have 20/20 vision or plan on looking at it very closely. I would recommend for a quality result using 300dpi images.

For commercial offset printing = 200-300dpi.

I hope this helps!

Rob
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Old 09-03-2013, 09:04 AM
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rogerco (Roger)
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Quote:
Originally Posted by dp297 View Post
Now the question is.....suppose you are doing narrowband imaging so only a portion of the pixels are utilized....how does that affect the quality of the print in
It's my understanding that all the pixels wil still be used, it's just that they will receive less photons, the print size will not be effected, just what image there is to print.
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Old 09-03-2013, 02:02 PM
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MrB (Simon)
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Note also that the print resolution required depends on how close you will be viewing it.
The company I work for had a trade stand at the recent AOG Conference (Australasian Oil & Gas), we wanted to exhibit one of our products but it's size was a serious headache. The next plan was to photograph it and have a life size print made.
Due to it's size, I stitched two 18mpix photo's together vertically in MicrosoftICE to make a ~26 megapixel image, this was then printed as a 2.4 by 2.4metre foamboard poster and placed on the back wall of our trade stand.
At 2.4m the print scale was approx two pixels per mm, or around 50dpi. The visitors would walk past the stand no closer than ~3 metres to the poster and by all reports I got, the poster looked amazing. I was too busy to attend and see it for myself unfortunately
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