What hap­pens when a modern DSLR cam­era is hooked up to a cen­tury-old tele­scope?

Sky at Night Magazine - - CONTENTS -

Dur­ing 2017 we jour­neyed to the Cal­i­for­nian hills to cap­ture the cos­mos through the 129-yearold Great Re­frac­tor at the Lick Ob­ser­va­tory, 120km south of San Fran­cisco. Our goal? To point this his­toric tele­scope to­wards some of our favourite tar­gets and cap­ture its an­tique ob­serv­ing power through the eyes of a modern DSLR cam­era.

A con­tact at the Uni­ver­sity of Cal­i­for­nia, Santa Cruz put us in touch with the Lick Ob­ser­va­tory staff, and once we ex­plained the na­ture of our pro­ject, they too were in­trigued at the prospect of us­ing this mighty tele­scope to cap­ture deep-sky im­ages with a con­tem­po­rary cam­era.

We quickly learned that the cost to op­er­ate the 19th cen­tury relic would be sig­nif­i­cant, so we launched an over­whelm­ingly suc­cess­ful Kick­starter pro­ject to fund this as­tro­nom­i­cal mad­ness. We were able to make four, three-hour trips to the ob­ser­va­tory dur­ing the year, and much plan­ning was re­quired to en­sure we could cap­ture qual­ity astro im­ages while al­low­ing for the steep learn­ing curve of get­ting to know our way around the his­toric in­stru­ment.

The Lick Ob­ser­va­tory was the brain­child of James Lick, born in Stump­stown (now Fred­er­icks­burg) Penn­syl­va­nia, on 25 Au­gust 1796. Af­ter mak­ing his for­tune in the hous­ing boom of San Fran­cisco, spurred on by the Cal­i­for­nia Gold Rush of the mid1800s, Lick de­cided to spend his money build­ing one of the largest tele­scopes of the era, in the world’s first moun­tain­top ob­ser­va­tory.

Clas­sic, el­e­gant crafts­man­ship

When nav­i­gat­ing the nar­row trail to reach the ob­ser­va­tory to­day, you get a feel for how tough its con­struc­tion must have been. The steep road up Mount Hamil­ton climbs into Cal­i­for­nia’s Di­ablo Range just east of San José, and although it’s only about 40km from the base of the moun­tain, it takes roughly an hour to tra­verse the windy moun­tain trail. How­ever, the route pro­vides some amaz­ing views of the Santa Clara Val­ley along the way.

The Great Lick Re­frac­tor is some­thing we were both al­ready fa­mil­iar with, hav­ing vis­ited the tele­scope in the past and taken a tour of the ob­ser­va­tory. We were mes­merised by its his­tory and the crafts­man­ship be­hind its con­struc­tion: par­tic­u­larly the fact that the in­stru­ment is 17m long with a whop­ping 1m aper­ture! Look­ing through

a reg­u­lar 2-inch eye­piece at the end of the Great Lick Re­frac­tor is a real treat, but we were ex­cited to have the op­por­tu­nity re­place that eye­piece with our Canon EOS 6D DSLR cam­era to see how well the two would com­bine to im­age the night sky.

The tele­scope tube is so long that, in or­der to view ob­jects near the hori­zon, the en­tire ob­ser­va­tory floor has to be hy­drauli­cally raised so you can ac­cess the eye­piece. Its an­tique con­trols, over­sized gauges and brass fin­ish­ing make you feel like you’re aboard one of Jules Verne’s ex­tra­or­di­nary craft. Adding to this il­lu­sion are the hand wheels on the main tele­scope fo­cus and the mount con­trols that were

built by the 19th cen­tury US man­u­fac­tur­ers Warner & Swasey Co, both of which re­sem­ble steer­ing wheels on old ves­sels. You can eas­ily drop a reg­u­lar eye­piece into the 11,400kg tele­scope, and while the 129-year-old lens has its im­per­fec­tions, its light­cap­tur­ing power can still leave ob­servers in awe.

Tricky track­ing

Imag­ing with the Great Lick Re­frac­tor us­ing a modern day DSLR cam­era proved to be a re­ward­ing feat. While the track­ing isn’t as good as many con­sumer tele­scopes avail­able to­day, this doesn’t re­ally mat­ter be­cause the power of the lens pro­vides

plenty of pho­tons, even with short ex­po­sures of 20 to 30 sec­onds. The lens does suf­fer from some chro­matic aber­ra­tions, which means that it bends the red and blue wave­lengths of the light spec­trum slightly out of sync, caus­ing them to look a bit blurry. But frankly, this is a triv­ial prob­lem in the grand scheme of things. Af­ter all, stand­ing in the grounds of this his­toric build­ing, ob­serv­ing an­cient light from dis­tant gal­ax­ies through a ti­tanic 129-year-old re­frac­tor and cap­tur­ing them on a dig­i­tal cam­era is enough to make any­one mar­vel at the prow­ess of hu­man en­deav­our, and the won­ders of the Uni­verse around us.

A draw­ing from 1889 – the year af­ter the Great Lick Re­frac­tor achieved first light – de­signed to em­pha­sise the mas­sive scale of the pro­ject The view from the Ob­ser­va­tory look­ing down from the Di­ablo Range to­wards San José

The Lick Ob­ser­va­tory was built atop Mount Hamil­ton in Cal­i­for­nia (at an al­ti­tude of 1,280m), and is ac­cessed by a very windy road

The Great Lick Re­frac­tor at the Lick Ob­ser­va­tory – an el­e­gant scope for a more civilised age

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