Can`t reach focus

[loKy (Simone)]

Hello!

I only recently bought a new 8 inch dob from bintel,and its fine,i put it togheter no problem and it looks ok(never seen one before).
I have tried to familiarise with the collimation etc etc,but I have a problem,i cant focus any star,i turn the knob all the way but it wont focus the star because it wont go any further,what I am doing wrong?..

..and sorry for my written English as is not my mother language

[glend (Glen)]

Is the focuser tube moving? There is a screw on it that locks it to the knob shaft, if it is loose the focuser tube won't move. Or are you saying it moves but not far enough inward?

[loKy (Simone)]

Thank you Glend,yes the tube is moving and I soon figured out that I have to tight that screw in order to use the focuser.Yes the tube does not move far enough so that I can focus stars,very annoying,i am using the 26 mm wide angle eyepiece....surely I am doing something wrong,thx for the reply Glend

btw:the tube focuser moves 42 mm ,is that ok for this type of focuser?(Crayford focuser with 10:1 microfocus)

[barx1963 (Malcolm)]

Did you get more than 1 eyepiece? If so which one are you having issues with?
Usually best thing is to start with the lowest power one, and work your way from there.
The lowest power eyepiece is the longest focal length, so if you have a 25mm and and 10mm eyepiece, try the 25mm first.

Malcolm

[loKy (Simone)]

Thx Malcom,At the moment I have only used the 30mm(not 25mm) wide angle eyepiece.I insert this into the 2 inch adapter,tight it a bit,but as I said I cant get it to focus on stars,it look like I need another 10mm to go before finally I can see clearly those stars
Well , I will try again in a couples of nights,,frustrating though....lol

Yes the scope came with 30mm,15mm,and 9mm eyepice

[glend (Glen)]

Well since you bought the scope new from Bintel I would ring them and explain your problem. Bintel claim that they setup each scope before they ship it and check the collimation. If so then the scope should reach focus. Most likely issue maybe the placement of the primary or secondary mirrors in the optical path. If you need more infocus this seems to indicate that the primary mirror maybe too far back - so this is a setup issue for Bintel service. I have bought several GSO scopes over the last few years and the mirror was always in the right place. Check with Bintel and they will probably walk you through checking a few things. Shipping scopes long distances can disturb the collimation, even if the locking knobs are done up properly.

[Allan_L (Allan)]

It is supposed to work out of the box, without having to change mirrors or add extra hard ware.

Ring Bintel, they have great customer service, and will help you.

[barx1963 (Malcolm)]

Originally Posted by loKy

Thx Malcom,At the moment I have only used the 30mm(not 25mm) wide angle eyepiece.I insert this into the 2 inch adapter,tight it a bit,but as I said I cant get it to focus on stars,it look like I need another 10mm to go before finally I can see clearly those stars
Well , I will try again in a couples of nights,,frustrating though....lol

Yes the scope came with 30mm,15mm,and 9mm eyepice

When you say the 2" adapter, what does that mean? Can you supply a photo of the focuser with the EP in it? Also a pic of the eyepiece itself may also help.
GSO/Bintel scopes normally only have the focuser tube which is 2" and an adapter for 1.25" EPs, while Skywatcher have separate adapters for both types.
One other check. Can you actually see the stars in the view, just out of focus, or is there nothing visible at all?

Malcolm

[loKy (Simone)]

Thank you for your help!!

Malcolm,,sorry,yes it comes with the focuser tube which is 2" and an adapter for 1.25" I have zero knowledge of telescopes. Ok,i have collimated the scope with a laser collimator(fun)understandably it arrived out of collimation,anyway,today I have pointed the scope to a tree branch using this 15 mm plossl eyepiece the tree is about 400 mt away,i could focus those branches nicely.Then have tried the 9 mm plossl and again,i could focuse and see the ants crawling(lol).

Then finally I tried the 30 mm wide angle 2".......and I could not not focus the same branch,also I notice black lines into the eyepiece...what do you think guys?,sorry about my ingnorance about scopes but this dob is the very first scope in almost 53 years,,,ehehehee

[Steffen]

My GSO Dob is the same. All eyepieces work without problems except for the 30mm SuperView which requires an extension tube.

Cheers
Steffen.

[loKy (Simone)]

Originally Posted by Steffen

My GSO Dob is the same. All eyepieces work without problems except for the 30mm SuperView which requires an extension tube.

Cheers
Steffen.

......perfect!....I had only used the dob twice,both only using the 30mm,but,,,,why putting the 30mm in the package if I cant use it? I will buy the extension tube then.

thankyou steffen!!!

[PSALM19.1 (Shaun)]

Hi Simone and congratulations on buying your new Dob! I have the same telescope except that it came with a 26mm 2" eyepiece: I seriously doubt that you need an extension tube to use a 30mm eyepiece that was supplied with the scope. I would certainly phone Bintel; it sounds like something is going wrong when you are inserting the 2" eyepiece. Wait until you get a look at the moon and a few planets, I'm sure you will be more than pleased with your purchase!

[CJ (Chris)]

Hi Simone, I have the same problem with my 8" GSO when using the 30mm 2" EP. I just drop it all the way into the focuser, withdraw it 10mm or so and then clamp it. It works for me.

[colls (Michael)]

Hi Simone

I had a issue with my 10 inch BINTEL Dob too. The only eyepiece which would not focus was the panoptic 27mm all the others were fine. I had to pull out the 27mm eyepiece about 5mm out of the focuser and lock it into place, then it would focus. I found out my problem which was that the locking screw on the focuser closest to the tube needed to be loosened more. It made the focuser extend out and now it works fine for me.
I hope this helps you or anybody who may have the same problem.

Regards
Michael

[loKy (Simone)]

thanks Shaun and Chris I will try that,as I said I am in a bit on a learning curve,...let you know how I am going

[barx1963 (Malcolm)]

Simone
Sounds like the solution is just moving it out a bit. I had a similar prob with my 12" GSO when I bought my first Ethos eyepiece, a 10mm. One thing I did was tighten up the collimation bolts to move the primary mirror. Procedure is to tighten one bolt one turn in order and just keep repeating until one bolt is fully tightened. Then recollimate just using the other 2 and you primary is now position as far down the tube as possible. If you think about it you should only ever need to use 2 of the three bolts anyway to collimate so leaving 1 fixed will be fine.
If that still doesn't work, you can sit the eyepiece out a bit and once you have used it a while consider a parfocal ring or an extension tube.
If interested I may have an extension tube here I am not using that I can send you (if I can find it!!)

Malcolm

[barx1963 (Malcolm)]

Sorry i found what I thought was an extension tube and it is actually a 2" filter holder for dual barrel eyepieces, so will not help. Sorry!!

Malcolm

[loKy (Simone)]

Thank you Malcolm,cheers,,

Well,,... at this stage I cant wait for that light southwesterly change on the weekend,for a reason I`d` love to find the sculptor galaxy as my first galaxy ever......hahaahaa thank you guys

[loKy (Simone)]

Hello!!

I have been using the 8 inch dob for a few nights,and I an getting better with it.My first target ever was the sculptor galaxy which it took me good few min to centered on the eyepiece.With my dismayed I could not believe how light polluted my farm is,i thought leaving 6 km from the first little town was safe but,,,incredible,i can see this huge glow of light in the east,and even more light polluted from those horrible horrible flood light, from the near quarry ....very sad,i never took notice before but I imagine I have to put up with.
So over all I like the telescope,but I am already tired of the eyepieces that came with it for 2 reasons.First one is that I have a parabolic view ,second the eye relief is petty bad and I have to stay very uncomfortably close in order to view,clearly they must be really cheap.
Still cant focus with the 30 mm with out lifting it a bit from the focuser and I let bintel shop know about it but they never replied(maybe my Caucasian accent scared them lol).Anyhow I`d love to upgrade the eye pieces and those orion EDGE ON PLANETARY eyepieces seam pretty decent,do you think guys they are going to work with an 8 inch dob?

.........grazie e ciao!!!!!!!!

Loky....the wicked

[raymo]

This focus problem turns up on the forum over and over again. Why don't
people buy Newts that don't have this problem, such as Skywatcher, and
probably some other brands. I have used about 8 SWs from 6" to 12",
and the only EP that has not quite come to focus with any of them was my old Unitron 20mm Erfle. Even that one was not a problem, as I just
pulled the EP out about 8mm, which was the other side of focus, and then racked the focuser back in for accurate focus. I understand that newbie
buyers might not know to look out for this problem, but vendors should
be aware of it, and push the manufacturers to fix it. The same thing
applies to the Newts that won't come to prime focus.[not Skywatcher].
I have absolutely no connection with SW, have just had many years
of trouble free use from their Newts.
I'm not saying that all EPs known to man will come to focus in SW Newts,
just all the ones I have used, which includes 15 and 30mm 2" 80 degree
ones.
raymo