Issues focusing 150 1400 Reflector

[Handy]

I am trying to get into astronomy, and astrophotography, and as I am just starting out, I'm trying to keep it on a budget. With that in mind, I realize that buying secondhand equipment is not always ideal.

I recently purchased a Twin Star 150 1400 Reflector on an EQ mount. Aside from some other issues that I have already attempted to resolve, including getting my finder scope realigned, and ensuring the mount was properly assembled, I have run into another problem that I cannot seem to figure out.

While attempting to focus on the moon after I first acquired this scope, all I could see was a giant white blob. The trees in the foreground, however were extremely clear. I called it quits for the night to see what things looked like during the day. And, not to be let down, I could focus on objects between 30-40 yards, but after a distance of 50-75 everything started getting blurry again. Past that, nothing is in focus at all. I've been using a Plossl 25mm AF 40 eyepiece. 

 

I will be grateful for any help.

[dweller25]

I think you need to remove the extension unit in the focuser

Edited February 3, 2020 by dweller25

[Cornelius Varley]

Hello and welcome to SGL. I'm going to assume that  the focuser drawer tube moves all the way in and all the way out when you rotate the focuser wheel on the side of the focuser. I will also assume that you have no extra extension tubes in the focuser drawer tube that will stop the telescope achieving focus at infinity, the eyepiece needs to be closer to the telescope at infinity.  This type of telescope is known as a Jones-Bird reflector (it usually called several other names which the swear filter will block 😁) . The Jones-Bird uses a type of barlow within the focuser which increases the focal length of the telescope to 1400mm (you have probably already noticed that the telescope tube is a lot shorter than 1400mm). The second function is to correct for spherical aberrations inherent in the spherical primary mirror. If the corrector lens is missing you might not be able to reach focus at greater distances. You can check to see if the corrector lens is there by  rolling a piece of paper towel into a tube and gently pushing it down the focuser tube.

[Handy]

There is a secondary lens that I can see in the very end of the focuser tube. Also, the focuser tube does move smoothly throughout its range, from all the way in, to all the way out. There is an extension tube on the eye piece to accommodate the 1.25" lens. It is threaded onto another 1" Inner diameter piece which has a hole for a thumb screw to secure a lens. That is threaded directly onto the focusing tube which does not have a thumb screw hole, but is also a 1.25" I.D. I put the 25mm lens in that and had some good results so far. Unfortunately, I live in a fairly heavily wooded area, and can't get anything more than about a hundred yards off. I will see what happens later on but so far the results are promising. Thank you for the information! 

 

Any other insights will be greatly appreciated.

Also, based on all that, is there anywhere I can go to find better accessories, such as shorter extension tubes, or different lenses? I knew going into this adventure there would be additional costs, and I knew this telescope wasn't exactly the best, but it was cheap (I am now at least its third owner, and I have no idea how old it is.)  I've been looking at Amazon, and a few other sites for some replacement parts (I need to specifically replace one of the fine adjustment poles), but I don't really want to sink a bunch of money into a bunch of junk that will turn out to be useless for my needs, either in the short term, or in the future as my skills (hopefully) grow.

[Cornelius Varley]

13 minutes ago, Handy said:

There is an extension tube on the eye piece to accommodate the 1.25" lens

Does the focuser require the extension tube ? A few photos might help to identify the problem.

[Handy]

I just got a few shots, I'll start out with the focuser tube, and work up through the whole set up.

[Handy]

Focuser tube with 1" Inner diameter and threads, this is the first piece to have a place for a set screw for a lens. Hopefully I've got the hole in decent enough focus.

[Handy]

Extender/adapter for the 1.25" lens.

[Handy]

And while probably not entirely necessary, the whole set up.

[johngm]

you need to remove that extension tube on the focuser to reach infinity focus

John

[Cornelius Varley]

13 hours ago, Handy said:

Focuser tube with 1" Inner diameter and threads, this is the first piece to have a place for a set screw for a lens. Hopefully I've got the hole in decent enough focus.

The eyepiece should be located at this position, but the opening is only 1" diameter.

 

13 hours ago, Handy said:

Extender/adapter for the 1.25" lens.

With extension tube attached the telescope won't focus at infinity.

[Cosmic Geoff]

Seeing that long extension tube immediately rings an alarm bell. You need to eliminate it and get the eyepiece closer to the main telescope body. 

[Handy]

I have to thank you all again for all the information. I took off all the extensions and just let the eyepiece rest in the 1.25" hole on the focuser tube. I had since fairly good results last night. I got the moon, and Orion's... sword. In focus. But I was getting very noticeable coma and aberration. And at the moment attaching my dslr to this rig is just right out. I'm going to continue working on alignment of the spider with the hopes that it's not a true collimation issue with the primary mirror. 

[Cornelius Varley]

10 hours ago, Handy said:

But I was getting very noticeable coma and aberration

Probably common with this type of telescope.

[John]

17 minutes ago, Cornelius Varley said:

Probably common with this type of telescope.

Yes. Bird-Jones design I believe ?

 

[joe aguiar]

Just so you know wont get cristal clear images from that kinda scope at best it will be semi clear on highter powers.

I just tested that design in Nov so not long ago on Saturn which was not great this yr.

I didnt log the power but my guess was 150x since I was showing 3 people I didn't want it to go out fov too fast

They liked it cause was first time seeing Saturn ever but I was iffy on the view.

I posted on other posts few weeks later I tried my tak and SW evostar on Saturn which was even lower and those views where much better.

You might not have noticed since theres nothing to compare it to but maybe when u push the power u may then see it never snaps into 100% clear focuse.

Joejaguar 

[Handy]

So with all of this new information in mind, I'm definitely going to have to upgrade in the future. Are there ant recommendations on brand/ type of telescope? My end goal is to be able to take some photos with my DSLR through the telescope? Or should I start a new thread for that question? 

[RT65CB-SWL]

Hi @Handy and welcome to SGL. 

4 hours ago, Handy said:

So with all of this new information in mind, I'm definitely going to have to upgrade in the future. Are there ant recommendations on brand/ type of telescope? My end goal is to be able to take some photos with my DSLR through the telescope? Or should I start a new thread for that question? 

In answer to you third question: "My end goal is to be able to take some photos with my DSLR through the telescope? " - What do you want to take images/photos of? - If you can answer this question then we can advise in depth. Unfortunately no telescope does all in this hobby. 

[joe aguiar]

Ap or imaging is more about the mount and camera.

A small 70 to 80mm apo can be all u need and they r colour free which is what u need.

Depending on budget u can get away with a cg5/eq5 but most would say get the heq5 so its rock solid.

If your scope moves at all even couple mm it will be seen in photos.

Joejaguar 

[Handy]

Right now, for some wide field shots, star trails, and moon shots, I'm using an Orion EQ1 mount with my Canon eo6. Lenses I've had some success with have been my 75-300mm telephoto, and my fixed 500mm telephoto sometimes paired with a 2x extender. I would be interested in being able to get some deeper field objects though (star clusters, nebulae, hopefully planets as well). Hence why I'm looking to upgrade into telescopic range. 🙂