ES ED-102 Focus Distance; EP and Camera

Discuss your refractor type scopes here.
Post Reply
User avatar
Mars Ambassador
Articles: 0
Posts: 117
Joined: Sat May 25, 2019 11:36 pm
Location: Mont Vernon, NH

TSS Photo of the Day

ES ED-102 Focus Distance; EP and Camera


Post by a100171 »

With my recent outings using my Explore Scientific ED-102, I ran into a couple issues with focus distance.

Using a standard 2" EP (in this case, an ES 25mm 70-degree EP) and a quality William Optics 2" diagonal, focus could not be achieved through the EP without the use of a tube extender. I was also able to get focus if I lifted the EP up in the diagonal a little bit. I happened to have 2" extenders, so it was not that much of a problem visually, and the views with the combination were stellar (pun intended).

Determined to get some pics of the Great Nebula, I elected to try using the Celestron Nightscape 8300 camera. The software loaded fine, the camera operated fine, but it seemed that no combination of extenders I had would get this into focus. Fidgeting around at sub 20 degree weather, I got close, but not close enough. I wanted to just get it focused/framed and let a few dozen/hundred snaps go to disk.

I am also a bit concerned with flexure from the focuser and a bunch of extension tubes. This is the stock focuser in the 102. The 8300 is not a light thing. I was hoping not to need a new Moonlite focuser for her.

I do have one of the Astro Tech 0.8x focal reducers (not mounted) on the shelf, but never used it.
Will this spare me external tube differences?

This is the older (it is 2 or 3 years old) ED-102. It is a 714mm focal length scope.

I would be interested in some feedback here. I have never had problems with my SCTs, or even the SNs in the past. It just seems like they made the tube a little short.
Meade 6", 8", and 10" SN, Meade 10" f/6.3 Lx200, ES ES-102, Meade 90mm DS-2000, Celestron CPC-800 HD, Celestron 11" EdgeHD, AVX, CGEM, CGEM-DX, Twilight I mounts. Omegon 2.1x 41mm Binocs.
Hyperstar for EdgeHD, ZWO and Celestron Nightscape CCD. A fully-functional Meade 12" RCX-400. And now: a Vaonis Stellina!
User avatar
Local Group Ambassador
Articles: 5
Posts: 2914
Joined: Sat May 11, 2019 7:55 pm
Location: San Diego, CA USA

TSS Awards Badges

Re: ES ED-102 Focus Distance; EP and Camera


Post by Bigzmey »

It is quite common for ED/APO scopes to make tube shorter than needed for EPs. This is to accommodate cameras for AP. Typically you would need 2" extension tube to get EPs in focus and you remove the extension tube to achieve the focus with camera.
Scopes: Stellarvue: SV102 ED F7; Celestron: 9.25" EdgeHD F10, 8" SCT F10, 6" SCT F10, Omni XLT 150R Achro F5, Onyx 80ED F6.3; Meade: 80ST Achro F5.
Mounts: ES: Twilight I; Bresser: EXOS2; SW: SkyTee2, AzGTi; UA: MicroStar.
Binos: Orion: Little Giant II 15x70, WorldView 10x50, Nikon: Action EX 16x50 & 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68s; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV; Russell Optics: SuperPlossls.
Diagonals: Baader: BBHS silver mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: Positive lock prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S; Astronomik: UHC, Orion: UltraBlock, SkyGlow.
Observing: DSOs: 2106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 1635, S110: 77). Doubles: 1385, Comets: 18, Asteroids: 95
User avatar
Orion Spur Ambassador
Articles: 0
Posts: 874
Joined: Sat May 11, 2019 8:40 pm
Location: Santa Barbara, CA

TSS Photo of the Day

Re: ES ED-102 Focus Distance; EP and Camera


Post by SkyHiker »

I often lift the eyepiece up in the diagonal instead of having to insert an extender. Not a problem for visual, I think.

I had to tune my ED127CF focuser. If you take the focuser wheel off the focuser you may see some hidden setting screws. Check those and tighten them if needed. Higher up where the inner tube slides into the end of the focuser tube there may also be some setting screws, same story. To make those screws work better and add stability, add an extender so the upper part of the inner tube is always covered by setting screws. After I did all this my focuser worked much better, and I never had to re-adjust anything. Search CN for this (not my post but someone else's with pictures).

If you switch from visual to AP you generally need fewer extenders. You may want to remove the diagonal, that should help a bunch too. I hope your camera has an articulating screen.
... Henk. :D Telescopes: 6" Mak-Newt (Comet Hunter), ES ED127CF, ES ED80, Zhumell Z12, AT6RC, Venture RX-7, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with DIY OnStep, AVX, LXD55, Tiltall, Cameras: Fuji X-a1, Canon SX40, Xt, XSi, T6, ELPH 100HS, DIY: OnStep controller, Barndoor trackers for 10" Dob and camera, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK
Post Reply

Return to “Refractor type Telescopes”