2019-07-01_Australian_Sky_&_Telescope

http://www.skyandtelescope.com.au 69

with a cable this short, but others may
need some form of extension such as an
active USB 3.0 cable or the addition of a
powered USB hub.
There are two USB 2.0 ports on the
DSI-IV for connecting filter wheels,
focusers and guide cameras. But note
that although these ports are powered,
they still draw their power from the
USB 3.0 connection. I successfully
tested two small cameras on these
ports, but your experience may vary
depending on how much power your
auxiliary equipment requires.

Getting started
Following instructions in the DSI-
IV’s quick-start guide, it was a breeze
installing the camera’s supplied
operating software (called Meade
SkyCapture), ASCOM drivers (needed
for operating the camera with third-
party software) and a copy of the user’s
manual on my aging laptop with an Intel
i7 Core processor running Windows

7. At first blush, the manual I installed
   from the CD-ROM sent with the
   camera appeared to be the same as the
   one that opens from the Help menu in
   SkyCapture, but it was actually an older
   version that had not been updated for
   the DSI-IV — stick with the version that’s
   displayed by SkyCapture’s Help menu.
   Using my own adapters, I attached
   a conventional camera lens to the
   DSI-IV and began bench-testing the
   camera. The ASCOM driver worked
   fine, allowing me to connect the DSI-IV
   with the software I typically use,
   including MaxIm DL for long-exposure
   imaging, and FireCapture for recording
   astronomical video clips. But for the
   sake of the review I wanted to work
   with the supplied software.
   SkyCapture is a slick-looking program
   with a user interface that I found
   relatively easy to navigate. It works with
   a variety of Meade cameras, and it has a
   number of features for Meade’s one-shot
   colour cameras that I couldn’t test with
   the monochrome DSI-IV. Nevertheless,
   within minutes I was capturing video
   clips and snapping still images, although
   my ‘long’ exposures were limited to

onlya fewsecondsbecauseofthebright

workshopenvironment(moreaboutthis

later).Therearealwaysbumpsonthe

roadtolearninganynewsoftware,and

I certainlyencounteredmyshare,but

nothingstruckmeasbeingduemoreto

thesoftwarethanmyowninexperience

usingit.Muchofmytimewasspent

learningthevideocontrols.Once

comfortablewiththemit wastimeto

getoutside.

GoingfortheMoon

WiththeexceptionofMars,which

at thetimewaswaytoosmallformy

imagingsetups,allthemajorplanets

wereinthemorningsky,somyvideo

testswerealldoneshootingtheMoon.

MeadeclaimsTheDSI-IVis capable

ofvideoframeratesashighas 23 per

secondat fullresolution,butmostusers

willexperiencelowerrates,especially

whenrunningthecamerainthe

preferred12-bit,ratherthan8-bit,mode.

Theissueis notsomuchthecamera

asit is howfastyourcomputercan

transferandsaveimages.Thesolid-state

driveinmylaptopisn’tasfastasthe

latestmodels.Youcancertainlyspeed

upframeratesbyreducingtheareaof

theCMOSthat’sbeingrecorded(using

croppedframesorwhatSkyCapture

callsROIfor‘regionofinterest’).This

is especiallytruewhenimagingplanets

sincethere’slittleadvantagetorecording

theblankskythattypicallyappearsin

theframe.EvenwiththeMoonI reduced

thesizeoftherecordedframetoisolate

lunarfeaturesratherthanthelarge

sweepsoflunarlandscapeseeninfull-

framevideos.Usinga smallregionof

interest,I typicallycapturedbetween 40

and 50 framespersecond.

Frameratesaside,whatreallycaught

myattentionwiththeDSI-IVis the

enormousfilesgeneratedwitheven

shortvideos,oftenexceedingfour

gigabytesfora 30-secondclipmade

pLeft: The DSI-IV only needs its USB 3.0 (it’s backwards compatible for USB 2.0 as well)

connection to a computer to capture images. The 12-volt input is just for the thermoelectric cooling

system and is really needed only for long-exposure imaging. See the text for details about the two

USB 2.0 ports. Right: Eight small heating elements bonded to the perimeter of the CMOS chamber

window were 100% effective at keeping the window fog-free during all of the author’s testing.

tThe DSI-IV is an excellent performer when

shooting astronomical video clips, even if

the author’s results were less than stunning

because of his seeing conditions under the

jet stream. This view of Schröter’s Valley was

processed from 200 frames selected from a

1,600-frame, 30-second video clip captured

on February 16.