Orpington Astronomical Society

Astronomy => Alerts! Questions? Discussions... => Topic started by: MarkS on Mar 07, 2014, 05:35:29

Title: iPhone vs Henry Draper's 50min exposure
Post by: MarkS on Mar 07, 2014, 05:35:29
Compare this 1 sec iPhone image of the Orion Nebula to the first ever image of it by Henry Draper in 1880 - a 50minute exposure:
http://io9.com/the-first-photo-of-the-orion-nebula-compared-to-one-tak-1535930753
Title: Re: iPhone vs Henry Draper's 50min exposure
Post by: Rocket Pooch on Mar 07, 2014, 07:35:17
Also cars are quicker now.
Title: Re: iPhone vs Henry Draper's 50min exposure
Post by: RobertM on Mar 07, 2014, 07:40:39
Have to admire the man doing a 50 min session guiding by hand, today there are words for people that do that sort of thing... Push Here Dummy
Title: Re: iPhone vs Henry Draper's 50min exposure
Post by: MarkS on Mar 07, 2014, 07:44:27
Quote from: Rocket Pooch
Also cars are quicker now.

3000x quicker?
Title: Re: iPhone vs Henry Draper's 50min exposure
Post by: JohnP on Mar 07, 2014, 08:15:19
Don't forget Mark we are also talking colour V's B&W... so we are talking 3,000 + 3,000 + 3,000 times quicker.. :-)
Title: Re: iPhone vs Henry Draper's 50min exposure
Post by: Mac on Mar 07, 2014, 10:57:36
have you noticed the new star as well?

Might be just me, but.
Right hand side midle of the iphone image, One bright star, come in about 1cm to the left another star.

1880 image No star, ooking at the relative bightnesses, this should be visible on the original photo if it was there.
Title: Re: iPhone vs Henry Draper's 50min exposure
Post by: MarkS on Mar 07, 2014, 14:40:45
There are a few stars missing in the old picture.  I wonder if it has anything to do with relative sensitivites at various wavelengths - film vs iPhone sensor - so the iPhone may picking up signal that the film was not sensitive to?
Title: Re: iPhone vs Henry Draper's 50min exposure
Post by: Rick on Mar 07, 2014, 15:11:58
Good point, Mark. I'd guess it's very likely the film was sensitive mainly to blue, and not very sensitive at red...
Title: Re: iPhone vs Henry Draper's 50min exposure
Post by: MarkS on Mar 07, 2014, 17:08:55
We might be able to confirm this by looking at the spectral classifications of the stars in the image.
Title: Re: iPhone vs Henry Draper's 50min exposure
Post by: mickw on Mar 07, 2014, 18:04:47
Henry Draper's image is over 130 years old, and was hand guided.

With film grain and hand guiding he was lucky to get stars so tight.  There are also 2 other low mag stars to the lower left that have also disappeared from the iPhone snap.

The low mag stars probably blended into the nebulosity with camera movement.