Discussion in 'Photography Beginners' Forum' started by slat, Oct 19, 2017.
When shooting astrophotography shots should you use a hood or not? Would it make any difference?
A hood is good lens protection. Should have it on just for that reason alone.
I would recommend using one. The main benefit of using a hood is to prevent lens flare, which wide angle lenses tend to be more prone to. I would assume for astrophotography you are making an effort to get away from light pollution and strong light sources, but it will still help block any incidental light that could affect your exposure.
Hood is good. Not only does it reduce stray light hitting the lens from beyond the frame to reduce fog but it helps protect the lens. Always use one.
For astrophotography... the one unique problem you might occasionally face is dew. As the temperature drops, you'll find dew will start forming on metal and glass surfaces even before it starts forming on other surfaces. Having the hood will help it resist forming dew as quickly (it would still eventually dew up... it'll just take a bit longer if you leave the hood on.)
If you find you are having problems with dew, then a dew heater is your friend.... it's a strap that wraps around the end of the lens and runs on 12v power. Typically it's connected to a dew-controller ... which just pulses the power on & off and an adjustment dial that lets you set what percentage of time the strap is "on" vs. "off" (the more it's "on" the hotter it will get). The idea is to warm the optics just enough to fend of the dew (raise the temperature by just a few degrees) -- no more than that. If it becomes too warm, the air hitting the glass will create thermal currents and it will distort your optics.
Another alternative that some people will use is to use a hair dryer on the glass (between shots... not during an exposure). You can get 12v hair dryers (they're kind of wimpy... but they do well enough to deal with the dew problem.)
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