HELPL!! Crosshairs only visible

[MadgieEm]

Please could I get anyones help or advice as to why I can only see the crosshairs in my telescope!

I have never come across this before, but as I was trying to focus on the moon, and then Jupiter, all I could see was the crosshairs. I use a Explorer 150P (EQ3 2) 6" Newtonian Reflector Telescope. I had the 2x Barlow lens in and the Super 25 wide angle long eye relief lens in that. . . Where have I gone wrong? This has never happened before.

Should I have used the super 10mm lens instead of the Super 25 wide angle long eye relief lens.

Please help as I would love to get my scope up and running again ASAP!!

[garethmob]

a stupid question...... but i have to ask to work out whats going wrong.... so i dont mean to be rude, i know a few members on here have accidently done it

but you have removed the cap on the end of the scope.. or the hartman mask

i assome you refiring to the crosshairs by the spider holding the secondary

[Steve 1962]

Sounds as though you could be well off focus - run the focusser from stop to stop to see you can find the focus point (it will change from eyepiece to eyepeice)

[MadgieEm]

Haha thats ok. Yes I did remove it. I could see the light of the moon in the eye piece but the black circle and crosshairs were in the way.

[daz]

Can you focus WITHOUT the barlow lens?

[garethmob]

have you collimated the scope at all or banged it or anything? it does sound like either the secondary isnt in line with the end of the scope or the focus it really out

[MadgieEm]

No I tried the eye piece without the Barlow, and same thing

[MadgieEm]

Its not been knocked or banged....It stands in my dinning room until I take it outside. I cant see that the secondary has moved...its very sturdy

[garethmob]

um, do you have a low profile focuser or the normal standered?

[MadgieEm]

??? No quite sure...??

[John]

What you are seeing is what you see when a newtonian scope is not in focus. The tricky question is why you can't bring it to focus now (with or without the barlow) when you could (presumably) before.

Things that could cause this would include the main mirror having moved up or down the tube (by a couple of cm not just a few mm), by the focuser not moving the eyepiece to the right focus point any more (hence the question about the focuser) or by the secondary mirror having moved (hence the question about the scope being knocked).

I assume that you have been able to get good focus (with and without the barlow) on other occasions - or is that not the case ?.

[garethmob]

thanks john i knew what i meant but i do have trouble explaining it sometimes

[RikM]

You haven't got the focus lock thumb screw done up have you? It's the one under the centre of the focuser. If this is tight (it should be loose), the draw tube won't move even though you are turning the focus knobs.

[garethmob]

that did amuse me for a while with the OTA i bought of earl id never seen the locking screw before i actually thought it was broke. see if its done up!

[MadgieEm]

ok...focus lock thumb? What is that?

Well as far as I can remember I always use the barlow, so not sure if I have had it focused before without it. But I have been able to use my scope before and focus it really well, but maybe I was using the other 10mm eye piece.

[garethmob]

its a screw under the focuser thats quite large (thumb screw you wouldnt miss it) that locks the focuser in place once u have it in focus (for astro photo i assume)

[MadgieEm]

Its not screwed tightly. Even when the screw is tight the focuser still moves

[John]

ok...focus lock thumb? What is that?

Well as far as I can remember I always use the barlow, so not sure if I have had it focused before without it. But I have been able to use my scope before and focus it really well, but maybe I was using the other 10mm eye piece.

It would be more usual to observe without the barlow in place and only add it when more magnification is needed. If you use the barlow with the 10mm eyepiece you will have the equivalent of a 5mm eyepiece and 150x with your scope which is useful for the planets and the moon.

I've re-read this thread and to be honest I'm rather stumped as to what the problem is, especially if you have been able to focus the scope fine before and it has not been adjusted or knocked in any way since then

The best thing would be to let someone who knows a bit about scopes have a look at yours. If that's mot possible perhaps you could take some photos of the scope focuser, the barlow and the eyepieces, setup in the way you were tying to use them and post them on here - we may be able to diagnose something from that.

At the moment I feel we are "shooting in the dark" a bit

[MadgieEm]

Ok...what I will do is try it with the 10mm tonight to see if I come across the same issues. If I do, I will take it to someone to have a propper look at it.

Thanks all for your help

[John]

...If I do, I will take it to someone to have a propper look at it.

Thanks all for your help

By all means post some photos of your setup as well - it might help us pinpoint the issue