I Am Cursed Ack Fi My New Telescope hates me

[Saladsamurai]

Hmm. You're going to need pretty high power to do proper star-test collimation. If your focuser's range prevents you from bringing a 10 mm eyepiece to focus, then the focuser is not appropriate for your telescope. I strongly advise you to try to stock focuser.

- Warren

So not being able to bring this chimney into focus is not normal then?

Casey

 

[chroot]

1/4 mile shouldn't be too close to focus. You might be near the end of the travel of the focuser, but it should be possible to focus the telescope on an object 1/4 mile away. Again, please try the stock focuser and tell us what happens in the same situation.

- Warren

 

[russ_watters]

I guess I missed the part about changing-out the focuser. There are several things that can go wrong there and a good rule of thumb for any new device you buy (whether it be your car, your computer, etc.) is to get it working stock before trying to modify it.

 

[chemisttree]

"Collimation" means an alignment of the optical axis of the telescope. When a telescope is collimated, it is collimated at every position of the focuser (assuming the focuser is properly installed and is on-axis).

Collimation with a star is usually done near focus (just inside or just outside focus), using the symmetry of the Airy disc as a guide.

- Warren

Salad's referring to some image shift he noted on the Crayford. His previous post described a variability of the collimation when he changed the focuser position. Now that he has seen it again on the Synta focuser I'm thinking that the orientation of the focuser tube is the source of all his problems. It may be that the focuser is not 'normal' to the plane of incoming light and is actually cocked at an angle...

It could be that the OTA is out of round from being dropped on the Synta focuser during shipment. It is aiming at a point slightly different than the position of the secondary.

 

[Saladsamurai]

I guess I missed the part about changing-out the focuser. There are several things that can go wrong there and a good rule of thumb for any new device you buy (whether it be your car, your computer, etc.) is to get it working stock before trying to modify it.

AMEN to that!

Chroot, I replaced the stocky and got that blessed chimney into focus! One variable eliminated!

Now...they accidently sent me two Crayford upgrades. i am going to try the other one now and see what happens.

Casey

 

[chroot]

Even if the focuser was not normal the optical axis, it would still be able to reach focus -- or, at least, some small part of the image would be in focus. Futhermore, he claims he can reach tolerable focus with one eyepice but not with another.

- Warren

 

[chroot]

Now...they accidently sent me two Crayford upgrades. i am going to try the other one now and see what happens.

There's so much going on here that you didn't tell us from the beginning Saladsamurai... it would have been so much easier for us to help you had you given us all the information from the beginning...

Anyway, you need to measure the distance between the top of the eyepiece and the OTA when each eyepiece is in focus. Any focuser replacement that is appropriate for your telescope needs to be able to put the eyepieces into those same exact positions.

By the way, are you using 1.25" or 2" eyepieces? Is your Crayford focuser a 2" focuser? Are you using an adapter to put a 1.25" eyepiece in it? Are you using the adapter properly?

- Warren

 

[Saladsamurai]

There's so much going on here that you didn't tell us from the beginning Saladsamurai... it would have been so much easier for us to help you had you given us all the information from the beginning...

Anyway, you need to measure the distance between the top of the eyepiece and the OTA when each eyepiece is in focus. Any focuser replacement that is appropriate for your telescope needs to be able to put the eyepieces into those same exact positions.

By the way, are you using 1.25" or 2" eyepieces? Is your Crayford focuser a 2" focuser? Are you using an adapter to put a 1.25" eyepiece in it? Are you using the adapter properly?

- Warren

Chroot, see post #1, step 2.

Or is it the "two" focusers that you are referring to? Because by that I meant that whoever boxed up the scope obviously lost track and put an extra upgrade in the box holding all of the parts.

Also; 2"Crayford 1.25" eyepieces...using 2---->1.25 adapter

Casey

 

[chroot]

Are the two focusers the same? If not, how are they different?

- Warren

 

[Saladsamurai]

Are the two focusers the same? If not, how are they different?

- Warren

The two New ones (the Crayford upgrades) seem identical. I installed the other upgrade (this makes both that I have tried) and I get the same poor results.

Since the two Crayfords yield the same result I will assume they are
identical. Thus, for simplicity's sake I will refer to my focusers as the Crayford and the stock (we'll pretend I don't have an extra one).

Now the stock appears to be in working order. However, when I install the Cayford, I cannot get things into focus at HIGH power. The focuser does not seem to be high enough.

That is, at its max extension it is about to come into focus; i.e. If I could extend it more, I would be in good shape.

Would does this require of me? Shimming?

Thanks guys,
Casey

 

[chroot]

Have you measured the distances between the eyepieces and the OTA at focus? Is the focuser not capable of this amount of travel?

If I were you, I'd just not use that focuser. Perhaps you really did get the wrong one. Can you call Orion and ask? Can you post the model numbers of the scope and focuser?

- Warren

 

[Saladsamurai]

I got it. The distance was off. I found another adapter type thing in the other box with the extra focuser.

I placed both the stock and Crayford next to each other and fully extended their tubes. The stock sat a scoach higher then the Crayford. So I took some stuff apart and unscrewed some others and found the culprit.

I am waiting for dark to find out if the spider vanes are an issue, but I have new ones coming.

Thanks for all the help,
Casey

 

[chroot]

Okay... if the spider vanes aren't an issue in the daytime, they won't be an issue at night. Just make sure you put the scope into proper focus. You may wish to start by focusing on something "easy" like the Moon, rather than trying to focus on stars. A surprising number of new amateur astronomers have problems focusing on stars, mistaking reflections and other light -- even when completely out of focus -- for stars in the eyepiece.

Now that you roughly know the positions at which both eyepieces reach focus for a distant terrestrial object, you'll know where to begin trying to find focus at night.

- Warren

 

[Saladsamurai]

Okay... if the spider vanes aren't an issue in the daytime, they won't be an issue at night

- Warren

That's good news. I have the finder aligned. And I have used a telescope like this before (only much smaller). This focusing/spider issue was the only problem.

Thanks for all the help,
Casey

 

[Saladsamurai]

Awesome.

 

[chroot]

Awesome.

I take it the scope worked at night?

- Warren

 

[Saladsamurai]

I take it the scope worked at night?

- Warren

Indeed. Thanks again for the help. If you had not suggested comparing the focusers, I would not have noticed that something was missing.

It may be common knowledge to anyone who knows anything about optics, but it had not occurred to me to check the lengthds of the focal tubes fully extended.

Casey

 

[turbo]

Indeed. Thanks again for the help. If you had not suggested comparing the focusers, I would not have noticed that something was missing.

It may be common knowledge to anyone who knows anything about optics, but it had not occurred to me to check the lengthds of the focal tubes fully extended.

Casey

Aha! It appears that you may need a (cheap) extension tube to achieve adequate back-focus with that Crayford-style focuser. That will let you take advantage of the "regular" and "fine" focusing adjustments of the better unit. You may be able to clamp the set-screws on your eyepiece adaptor with the eyepiece withdrawn part-way to get the same effect, but it's nice to get the proper accessory and make stuff work like it's supposed to.

 

[Saladsamurai]

This thing definitely works pretty sweet now.

I would like to invest in some sort of filter to aid in looking for nebula and what have you. Something that will help with the light pollution. Any suggestions?

 

[chroot]

Well, light pollution filters and "nebula filters" are two different animals. The typical "nebula filter" is an Oxygen-III filter, but they're expensive and only work on certain nebulae. They also block light of all other frequencies; stars become dim spots. Unless you know exactly where to look, these filters can actually do more harm than good, since you won't be able to star-hop.

You might want to start with a wide-band light pollution filter and just see how you like it. Don't go for a narrow-band filter, because they'll cause you the same problems with star-hopping. Don't expect miracles, but for $50 or so they can be a good tool to have in your eyepiece box.

All that said, you will probably find that the two most useful accessories will be: 1) a Telrad finder and 2) a couple of nice, high quality, versatile eyepieces, e.g. a TeleVue Zoom.

- Warren

 

[Saladsamurai]

Well, light pollution filters and "nebula filters" are two different animals. The typical "nebula filter" is an Oxygen-III filter, but they're expensive and only work on certain nebulae. They also block light of all other frequencies; stars become dim spots. Unless you know exactly where to look, these filters can actually do more harm than good, since you won't be able to star-hop.

You might want to start with a wide-band light pollution filter and just see how you like it. Don't go for a narrow-band filter, because they'll cause you the same problems with star-hopping. Don't expect miracles, but for $50 or so they can be a good tool to have in your eyepiece box.

All that said, you will probably find that the two most useful accessories will be: 1) a Telrad finder and 2) a couple of nice, high quality, versatile eyepieces, e.g. a TeleVue Zoom.

- Warren

Thanks Chroot. What exactly do you use zoom lenses for? I would assume for planetary or lunar viewing...

My scope can accept 2" eyepieces, but as you know, they are hella expensive What are the benefits? A wider field?

And What are the benefits of those super low power ones like 32-60mm?
Are those for deep, deep space?

Thanks for the advice.
Casey

 

[chroot]

The zooms are nice because they cover a range of magnifications, are user-friendly, and relatively inexpensive. Honestly, the only zoom eyepiece I can recommend are those from TeleVue. There are many other zoom lenses on the market, but most suck.

You don't necessarily need 2" eyepieces. Depending upon your telescope and your viewing styles, they may not help you at all. Some eyepieces only come in 2" versions to prevent vignetting.

- Warren

 

[turbo]

Ditto on the TeleVues - they are good solid performers. I have a nice selection of Plossls, and find no reason to go for the exotic designs, since I have a well-corrected 6" f:8 APO and even the plain vanilla TeleVues work very well, though I have a 4.8mm Nagler for star-splitting on those REALLY steady nights. You might want to go to a few star parties and see how other peoples' EPs perform in your scope before you start dropping $$ on 'em.

One thing - a Barlow lens can double the number of usable focal lengths you can view with. Get a good one, and the view will not be significantly degraded, and you can get higher power views while retaining the longer eye relief of the low-power EPs. Whether a 2X, 2.5X, or 3X, choose carefully and then choose your EPs in such a way as to avoid duplication of powers. Obviously, a 2X Barlow isn't going to do you much good for improving your variety of magnifications if you've already got EPs of 8mm, 16mm, and 32mm. You can make a diagram on graph paper to show what the best EP focal lengths would be for Barlows of various multiplications. Plan before adding to the EP menagerie, and buy quality. You may or may not sell your scope in favor of another, but chances are, your EPs will stay with you. It's best to buy the basic EPs from a really good manufacturer if you can. They are set up to figure, finish, coat, and mount lenses in really exotic $$$ EPs, and even their basic vanilla models will benefit from the high-tech, high-quality attitude that drives the upper end of their product line.

 

[Saladsamurai]

I just have a 10mm and 25mm that the scope came with (they are Plossls) and I have a 2X Barlow by Meade that I bought for my last scope..oh and a 17.5mm (why?) by Meade that came in the package with the Barlow.

Casey

 

[chroot]

We're not saying you must run out and purchase new eyepieces; I'm simply saying that you might get more utility for your $ with a new eyepiece than with a light-pollution filter. Then again, the light pollution filter might do you wonders. If I were you, I'd try to attend a star party in your area -- most people are more than willing to let you try out different bits of kit with your telescope.

The two most important accessories are actually also the cheapest: a good-quality star atlas and a good-quality finder. I personally suggest using star-charting software to print maps for yourself. You can get free charting software like Carte du Ciel, or you can buy commercial programs like The Sky and Starry Night. You can have these programs print maps as deeply as you need (with as many stars as you need) to star-hop anywhere you want to go. You can also put Telrad rings or other features directly on the maps, so you can translate the view in your Telrad to the map very easily.

A basic Telrad finder is about about $15, and I'll be damned if it's not almost universally the most useful accessory for someone new to telescopes.

- Warren

 

[Saladsamurai]

What should I use tp view things like planetary nebulae (viz. what do you use) like M57, etc...

Casey

 

[russ_watters]

Dark skies and a low power eyepiece.

 

[turbo]

What should I use tp view things like planetary nebulae (viz. what do you use) like M57, etc...

Casey

Experience will tell you what works best. The problems with faint extend objects generally boil down to one thing - lack of contrast. If you have dark skies, that's a point in your favor. The pop in a low power EP (longest focal length you've got) and locate and view your target. Then go to your next higher power and compare your impression of the object with that of your first view. Is there more detail visible in the higher power? Is the reduction in contrast detrimental to the view in the higher power. After a while, you'll develop a feel for this. Be aware that if one of the EP's does not feature edge-blackened, multicoated lenses, it may give you views with poorer contrast than a more powerful EP with better optics.

 

[Saladsamurai]

Anyone belong to an Online Astronomy Forum that they like? One where my telescope questions may be more appropiate?

I have tons of them...and I don't the think the questions regarding the skies quite qualify as the kind of "Astronomy" that PF had intended.

Thanks,
Casey

 

[hage567]

Astronomy magazine has a forum on their website: www.astronomy.com if you want to take a look at it.