A little disheartened

Smigatron (Ben) · #1 27-10-2011, 02:50 PM

Hey all,

A couple of months back was my first post here and I got my first telescope, an 8" Dob.

Having no experience using a telescope before, I decided to wing it and try to learn the ropes by trial and error. I tried to be realistic about my expectations. I didn't expect to be able to see amazing things like what you see in hubble images. I would have been satisfied even just seeing the moon and a few surface features.

I have managed to get out there on a few clear nights and try my luck. My first night I was happy just to swing the scope around and focus in on a few random stars. I had no expectations and was reasonably happy with how it went.

My second time, I went out a little more focused. I packed everything in the car and drove out to a really dark open space, and had Stellarium loaded onto my laptop with a Messier list in case I had any luck. The first thing I did was got my bearings. Figured out which way was north, south etc. It was fun figuring out what constellations were where, and trying to learn the sky. When I decided to get down to business, my first target was Jupiter. I was a little disappointed in what I saw, but not surprised.

http://www.flickr.com/photos/4811359...in/photostream

This is not my photo, but is similar to what I saw. It was just a white blob that was much worse quality than what appears in the photo. The surface appeared to be moving but I put that down to 'heat haze' as a guess. I tried to get a better image for an hour or so, adjusting my focus, changing my eyepiece between a 10mm and a 25mm (they came with the scope). I couldn't get any results, so I messed around for a while, zooming in on random stars, just messing around.

I was feeling a little lost after I packed up and went home and told myself maybe it was a bad night for it and I would get better at it. I decided to wait until a night where I could get a good view of the moon.

That night came a week or so later where the moon was in it's first quarter. I have heard that it is better to view the moon around this stage because the lack of light reflection makes it easier to make out features (craters etc). I set the scope up, a little excited, and had a look. With the viewfinder's small magnification, it looked pretty good. When I looked through the scope's eyepiece all I could see was a quarter moon shaped blob of light. No focusing could make it look any better. Different eyepieces didn't help. It was like looking into a torch. The light was bright, but not enough to make my eye uncomfortable. Surely an 8" Dob could give me a decent look at the moon? I got the ****s and packed up, feeling defeated.

A couple of weeks later, I was working night shift and noticed that it was an amazing night. Everything was so clear. I was excited to get home and get the scope out when I finished. Eventually I got home and decided to try Jupiter again. Nope, same old thing. Round blob of white with the 'heat haze'.

I am on the verge of giving up. I may be a total noob but I am convinced I am doing something wrong, or don't have the right eyepieces or equipment. I really don't know. I am posting here hoping someone will tell me I am doing something stupid, or give me a bit of a nudge in the right direction.

I have seen great pictures that people have taken with 8" Dob's before and I can't even get a look at anything that even resembles a planet or our own Moon.

h0ughy (David) · #2 27-10-2011, 03:04 PM

you have to remember that any of the images you see of Jupiter are taken with a Barlow lens (mostly 5x ones) and a video camera and then stacked and processed. if you have a higher mag eyepiece like say a 15mm, 10mm or even a 6mm you will see the planet a little larger and if your lucky make out the banding but don't even think your going to see Jupiter like the images you see. The seeing can kill most views of it through turbulent air to sky fogging etc. keep going at it but the best advice i can give you is seek out other like minded people to view with - track down a club or there may be some others on IIS who live near you. There is encouragement in numbers, and other gear to look at and through!

ballaratdragons (Ken) · #3 27-10-2011, 03:04 PM

Sounds like your scope is way out of collimation (alignment).
Quite easy to fix

supernova1965 (Warren) · #4 27-10-2011, 03:17 PM

Quote:

Originally Posted by ballaratdragons

Sounds like your scope is way out of collimation (alignment).
Quite easy to fix

I second this opinion I think Collimation is the problem you need to find a friendly local IIS member to help you out.

koputai (Jason) · #5 27-10-2011, 03:18 PM

It could be that your scope is not reaching focus. My 8 inch Dob (a GSO/Bintel) will not reach focus with most eyepieces.

What I've always had to do was either hang the eyepiece way out of the focuser tube, just enough for the focuser to hold it (very dangerous and not great alignment), or what I've done for quite a while now, permanently leave a 2 inch diameter, 35mm long extension in the focuser and fit the eyepieces in to this.

I've never understood why a telescope would be sold without the ability to reach focus, but that's how it is.

Ben, just try moving the eyepiece as far out of the focuser you can with the focuser still able to grip the eyepiece. Rack the focuser all the way out, get your bright blob in the middle, then gradually rack the focuser in. See if that helps.

Cheers,
Jason.

Paddy (Patrick) · #6 27-10-2011, 03:27 PM

It does indeed sound like collimation as most likely cause or as Jason says, not reaching focus. Where are you? It's highly likely that there will be someone near who could help out.

ballaratdragons (Ken) · #7 27-10-2011, 03:28 PM

Quote:

Originally Posted by koputai

It could be that your scope is not reaching focus. My 8 inch Dob (a GSO/Bintel) will not reach focus with most eyepieces.

Cheers,
Jason.

That is bad!

Either get someone to adjust your mirror location (closer or further) or take it back to Bintel and get them to do it.
Sometimes the Primary or secondary mirror has been adjusted too far up or down the tube. Really bad if its the secondary as it puts it out of alignment with the focuser too.

It all needs adjusting.

The only scopes that shouldn't reach focus with an Eyepiece are dedicated Astrographs.
ALL other scopes should focus.

Terry B · #8 27-10-2011, 03:38 PM

The moon is a good test. You should be able to see crisp craters that shimmer a bit.
As stated before, focus or collimation will be the problem.

AndyK (Andy) · #9 27-10-2011, 04:02 PM

Hey Ben, don't give up.

I also have an 8" DOB. It's a flex tube type which supposedly needs collimating just about every time they're used. The day I brought it home (I bought it second-hand) I simply took it out from the back seat of the car, put it together, extended the flex tube bits and waited for dark.
That evening I pointed it at the moon with a 25mm eyepiece and was rewarded with beautiful, crisp views. A few days later in really poor seeing and with Jupiter not very far abve the horizon I was easily able to make out the bands. This was all without any attempt at collimating.

I'm fairly convinced that in your case there's something not quite right with the telescope as others have indicated. I don't think it's anything you're doing. Tell us where you are and I'm sure there will be somebody who can help. Don't be disheartened ... you'll get there and believe me, it's well worth persevering.

Poita (Peter) · #10 27-10-2011, 04:25 PM

Get a friend over that knows scopes, or take it into bintel, it definitely has a problem. Even in bad seeing you will see Jupiters bands and the moon should be crisp and amazing with the 25mm even on a bad night. Definitely a problem, sounds like a focus issue. Take it in or give them a call, once sorted you will be amazed, trust me!

koputai (Jason) · #11 27-10-2011, 04:25 PM

Quote:

Originally Posted by ballaratdragons

It all needs adjusting.

Hi Ken,

You would think so, but I've attended to all that. I haven't measured it, but I suspect that my particular scope has a longer than specified focal length.

Anyhow, this isn't about me.

Cheers,
Jason.

Stu Ward · #12 27-10-2011, 06:38 PM

I would definately recommend you let us know where you are, I'm sure that someone nearby would help you out with your Collimation issue

If you live anywhere near me, I' be more than happy to come help you out

Stu

mental4astro (Alexander) · #13 27-10-2011, 06:43 PM

Give Jason's suggestion a go. I too have a couple of eyepieces that require them to be pulled out quite some way to focus. I also have one that leaves very little in-travel in the focuser. All with the same scope too.

Forgey (Paula) · #14 28-10-2011, 12:50 AM

Hi Ben, my first view of jupiter was like what you saw then someone at the local astronomical society mentioned to me the Collimation issue. I now get good views.
I would say yours definitely needs Collimation.

Smigatron (Ben) · #15 28-10-2011, 01:13 AM

Thanks a lot for the replies everyone

Seems like the common consensus is that my scope needs to be collimated. I have done about 5 whole minutes worth of research on it, and it seems that I either need a laser collimater or a film canister, and I don't have either. I live in Richmond, NSW, but I can travel anywhere within a couple of hours if someone is generous enough to help me out.

As for the suggestions saying that I shouldn't put my focuser in all the way, I will try that as well, as soon as I get a reasonably clear night. The weather here sucks at the moment and the sky is just clouds.

I'm lucky enough to be near the Bowen Mountain (Crago?) observatory and I know they do viewing nights there. The first chance I had to go there, it was raining so I assumed it would have been cancelled. Last week they had a session but I was in Tassie and I missed it.

Thanks again for the advice everyone. I'm a little more motivated now and not quite ready to throw the towel in yet.

big_dav_2001 (Davin) · #16 28-10-2011, 06:10 AM

Hey Ben,

I'm in Schofielfds and would be happy to get you around and help you out, and show you a couple of things (unfortunately my scope is too big for me to transport and come to you). Pm me if you're interested in catching up.

Davin

Barrykgerdes · #17 28-10-2011, 07:03 AM

Quote:

Originally Posted by Smigatron

Thanks a lot for the replies everyone

Seems like the common consensus is that my scope needs to be collimated. I have done about 5 whole minutes worth of research on it, and it seems that I either need a laser collimater or a film canister, and I don't have either. I live in Richmond, NSW, but I can travel anywhere within a couple of hours if someone is generous enough to help me out.

As for the suggestions saying that I shouldn't put my focuser in all the way, I will try that as well, as soon as I get a reasonably clear night. The weather here sucks at the moment and the sky is just clouds.

I'm lucky enough to be near the Bowen Mountain (Crago?) observatory and I know they do viewing nights there. The first chance I had to go there, it was raining so I assumed it would have been cancelled. Last week they had a session but I was in Tassie and I missed it.

Thanks again for the advice everyone. I'm a little more motivated now and not quite ready to throw the towel in yet.

If you know Bowen mountain try it again. The dates are published on the ASNSW web site. There would most certainly be someone there to help.

Barry

Poita (Peter) · #18 28-10-2011, 07:22 AM

You may just need an extension to put the eyepiece in. Try some distant terrestrial targets during the day if you can, a faraway tree perhaps and get focus. Don't be afraid to pull the eyepiece almost completely out to see if focus can be achieved.

Stu Ward · #19 28-10-2011, 12:24 PM

Quote:

Originally Posted by Poita

You may just need an extension to put the eyepiece in. Try some distant terrestrial targets during the day if you can, a faraway tree perhaps and get focus. Don't be afraid to pull the eyepiece almost completely out to see if focus can be achieved.

Whilst this may help to achieve focus, it should not be necessary.
The scope should be setup to allow all eyepieces to be dropped into their natural stop point and get good focus

Who manufactured the scope ?
Was it brand new ?

Stu

Poita (Peter) · #20 29-10-2011, 08:04 AM

Quote:

Originally Posted by Stu Ward

Whilst this may help to achieve focus, it should not be necessary.
The scope should be setup to allow all eyepieces to be dropped into their natural stop point and get good focus

Who manufactured the scope ?
Was it brand new ?

Stu

I agree that it shouldn't be necessary and if the scope is new, call the retailer and get it sorted out.

But trying it during the day could help troubleshoot where the problem is.