When you're shooting an open star cluster, I think classic diffraction spikes like you get
with a newtonian reflector telescope look really really good the diffraction spikes effect is
strongest on bright stars and so it helps bring those stars in the cluster out from the rest
of the scene and the reason you get the classic sort of x style or plus style diffraction spikes
is due to the design of a newtonian reflector where light enters the front of the telescope
hits the primary mirror in the bottom before bouncing back off the secondary mirror and then
off to your camera on the side and the diffraction spikes come from this thing holding the secondary
mirror in place called a spider and the actual metal pieces here are often called the spider
veins a camera lens or a refractor telescope focuses light differently and it's a straight
through design sometimes you'll see diffraction spikes with a camera lens if you stop down the
aperture internally because the internal iris which controls the aperture isn't perfectly round
but these diffraction spikes are usually a little bit crazier and less predictable
and to me they're not quite as aesthetically pleasing
i know some people love them though but anyways i decided recently that i wanted to start testing
cheap ways to add diffraction spikes to lenses and i wanted to do this physically not with software
i know there are paid software plugins that can achieve a really nice look these days but i'm just
interested in how to achieve it in camera as we'd say i do all my initial astrophotography testing
uh from my light polluted home near boston massachusetts right here where i'm filming and
uh then only once i figured out something you know to my satisfaction do i really use a new technique
or a new piece of gear at a dark site because typically if i'm driving i don't want to waste
too much time with testing when i'm at a dark site so anyways last night it was clear and i had a few
tests in mind to do right here in the backyard the first test is i've been working um to get this old
soviet uh telephoto lens that i bought off ebay for 100 bucks to focus properly it's called the
tare 3s photo sniper and i saw some photos taken with it online i thought it was worth a gamble
when it arrived i quickly found it wouldn't focus to infinity with any uh camera i adapted to it
and the iris which is again the blades to control the aperture we're permanently stuck at f 22.
luckily this lens is very easy to take apart and repair and so i've been working on it and i
thought i had it working and so then last night i confirmed it was working so it's really a pretty
nice value at 300 millimeters f 4.5 but if you do buy one expect to put a bit of work into it
i might do another video about all that in the future so last night i i finished testing the
lens i realized my reconstruction of it had worked that went by pretty quickly so i thought i'd try
another test and so i taped some yellow thread to the front of the lens in the same x pattern that
you get with a spider on a newtonian and my goal here was to see if i could mimic the diffraction
spikes that spider veins usually give you except with a wide open lens i think i probably should
have tested it on a really bright star but instead i was really hankering to photograph
this thing called the coat hanger cluster or also known as Brocchi's cluster which is just
right off the beak of Cygnus and here's the result and i think that this worked reasonably
well it's a subtle effect but i think it looks pretty natural and i think the spikes would have
come out a little bit better with all the light pollution i googled around to see what others have
used to make spikes like this on refractive optics and i see many people recommending
fishing line or guitar strings um so i have some other things to test but i thought for a first try
thread worked pretty well and you can't beat the price i think i estimated if you know this much
thread and a little tape maybe four cents for this experiment um well that's it for this five
minute friday this week next week i'm going to be leaving for my annual trip to visit my family and
be hanging out in Minnesota and Wisconsin so i'll have a video about how i pack for airline
travel as an astrophotographer till then this has been Nico Carver nebulaphotos.com clear skies