mental4astro
27-07-2009, 11:18 PM
Hi all.
I received my new Celestron FirstScope this morning at 8:30am! I had ordered it from York Optical not two weeks ago, with none in the country back then. The purpose of this little scope for me is to utilise it as a large finder to sit on the lower end of the soon to be rebuilt Odyssey II.
http://www.celestron.com/c3/images/files/product/21024_firstscopeteles_mid.gif
Many thanks Michael for your assistance in getting this puppy to me.
Its very novel design would appear to make it a smart little beginners scope. It comes as a very bare, minimally accessorised 76mm, f/4 scope on a stripped down 'Dobsonian' tabletop mount. No finder scope here, though two knurled nuts come threaded into the tube where the optional extra finder would sit. Tricky for the inexperienced to aim. Tube cap & focuser plug are included.
Two eyepieces come with the unit: 20mm Huygenian & 4mm Special Ramsden.
First light was tonight, with alpha centuri the first target to come to terms with the aiming of the scope with the H20mm. The image that greeted me was less than encouraging. The image was dimmer than the f/4 ratio would suggest, & the stars exhibited terrible distortion & chromatic aberration. Definately the wrong EP design choice for such a fast f/ratio.
The next target was Omega Centuri. The image again was disappointing, dim, highly distorted & the soft fuzz of the globular cluster resisted any form of resolution. At this point I grabbed the old Kellner EP that I modified by adding crosshairs that came with my Celestron C5 years ago. What a difference! Finally the little scope began to deliver the images I was expecting, even with a such a lowly EP. No distortion, no discernable chromatic aberration, & Omega began to hint at resolving!
A bright crisp image. The crosshairs were easily discernable, vindicating my decision to not get an illuminated EP as I suspected the fast f/ratio would give an image bright enough to show them neatly.
M7 was next. Its position right on zenith really showed the limited capacity for aiming this scope without a finder, whatever its size. It became a hit & miss affair, were the search relied more on my experience of handeling dobs rather than beginners luck. Not easy. However, M7 was a lovely bright crisp mass of white stars. Again viewed with the K25mm (sorry, but the H20mm aint going to see the dark of the night again).
Jupiter was the next target, with the SR4mm in the focuser. Very dissappointing again. Such a poor quality EP. Seeing conditions were poor, but the disk still refused to focus clearly, with a cloudy aspect surrounding the image. The Galilean moons also showed distortion, chromatic aberration & 'cloudiness'. I changed EP for a Vixen LV5mm. The disk did focus sharply, but the 'cloudiness' remained!
I will need to speak to Michael about this. Both the SR4mm & LV5mm EPs were clean, & no condensation to smear the image.
The single arm 'dob' mount actually moves very smoothly in both axis. The altitube bearing uses a nut to control friction. The azimuth bearing is pre-tensioned, light & smooth.
To sum up, the FirstScope is a nice little unit. It really needs the addition of some type of finder or the novice user could quickly loose interest. The standard EPs that come with it are poor quality. Decent EPs make the FirstScope a delight to use. Crisp, bright images. Everything I had expected for this fast little scope, with a delightfully easy & stable mount to use.
I received my new Celestron FirstScope this morning at 8:30am! I had ordered it from York Optical not two weeks ago, with none in the country back then. The purpose of this little scope for me is to utilise it as a large finder to sit on the lower end of the soon to be rebuilt Odyssey II.
http://www.celestron.com/c3/images/files/product/21024_firstscopeteles_mid.gif
Many thanks Michael for your assistance in getting this puppy to me.
Its very novel design would appear to make it a smart little beginners scope. It comes as a very bare, minimally accessorised 76mm, f/4 scope on a stripped down 'Dobsonian' tabletop mount. No finder scope here, though two knurled nuts come threaded into the tube where the optional extra finder would sit. Tricky for the inexperienced to aim. Tube cap & focuser plug are included.
Two eyepieces come with the unit: 20mm Huygenian & 4mm Special Ramsden.
First light was tonight, with alpha centuri the first target to come to terms with the aiming of the scope with the H20mm. The image that greeted me was less than encouraging. The image was dimmer than the f/4 ratio would suggest, & the stars exhibited terrible distortion & chromatic aberration. Definately the wrong EP design choice for such a fast f/ratio.
The next target was Omega Centuri. The image again was disappointing, dim, highly distorted & the soft fuzz of the globular cluster resisted any form of resolution. At this point I grabbed the old Kellner EP that I modified by adding crosshairs that came with my Celestron C5 years ago. What a difference! Finally the little scope began to deliver the images I was expecting, even with a such a lowly EP. No distortion, no discernable chromatic aberration, & Omega began to hint at resolving!
A bright crisp image. The crosshairs were easily discernable, vindicating my decision to not get an illuminated EP as I suspected the fast f/ratio would give an image bright enough to show them neatly.
M7 was next. Its position right on zenith really showed the limited capacity for aiming this scope without a finder, whatever its size. It became a hit & miss affair, were the search relied more on my experience of handeling dobs rather than beginners luck. Not easy. However, M7 was a lovely bright crisp mass of white stars. Again viewed with the K25mm (sorry, but the H20mm aint going to see the dark of the night again).
Jupiter was the next target, with the SR4mm in the focuser. Very dissappointing again. Such a poor quality EP. Seeing conditions were poor, but the disk still refused to focus clearly, with a cloudy aspect surrounding the image. The Galilean moons also showed distortion, chromatic aberration & 'cloudiness'. I changed EP for a Vixen LV5mm. The disk did focus sharply, but the 'cloudiness' remained!
I will need to speak to Michael about this. Both the SR4mm & LV5mm EPs were clean, & no condensation to smear the image.
The single arm 'dob' mount actually moves very smoothly in both axis. The altitube bearing uses a nut to control friction. The azimuth bearing is pre-tensioned, light & smooth.
To sum up, the FirstScope is a nice little unit. It really needs the addition of some type of finder or the novice user could quickly loose interest. The standard EPs that come with it are poor quality. Decent EPs make the FirstScope a delight to use. Crisp, bright images. Everything I had expected for this fast little scope, with a delightfully easy & stable mount to use.