Advice about telescope

[Alan64]

On 19/07/2018 at 18:21, LukeSkywatcher said:

Bresser ar 102 xs...................

The OP is interested in "...observing the moon, planets, double and variable stars, and the brighter deep sky objects, as my  back garden has quite a bit of light pollution."

It turns out the "ED" aspect of the Bresser suggested above is not so "ED" after all...

https://www.flickr.com/photos/109613429@N08/sets/72157679939576743/with/34160193491/

...and therefore not suitable for the observing agenda.

Instead...

https://www.firstlightoptics.com/evostar/skywatcher-evostar-90-eq2.html

...or... https://www.firstlightoptics.com/evostar/skywatcher-evostar-90-eq3-2.html

...and at or near the stated budget.

[happy-kat]

Don't they do the evostar 90 on an altaz mount? 

[devdusty]

Thanks Alan 64 for your recommendation about the Skywatcher Evostar90 .

My daughter bought this telescope for me 5 years ago, as a combined 65 th birthday and Xmas present. I chose it based on advice in astronomy books and magazines.

However I found it to be long and bulky for me to use easily. Also I could never align the finder scope with the  main telescope properly.

The equatorial mount was also very difficult for me to use. I could never seen to point the telescope in the direction I wanted to.

This is why I am reluctant to buy a reflector because of the culmination issues.

Chris P

[LukeSkywatcher]

"It turns out the "ED" aspect of the Bresser suggested above is not so "ED" after all..."

You are correct. It not true ED glass.

[happy-kat]

As you already own a telescope but a unsuitable mount have you considered using the telescope on a new alt az mount like an Az4. Would changing the mount address enough of the issues.

The Az5, another mount, has slow motion controls as well.

Az mounts move left right up down so go where you point them.

The finder scope could be swapped for something that works better for you.

The evostar 90 being an f10 focal length will show minimal to no chromatic aberration. A shorter refractor will be most likely f5 and this will show chromatic aberration on the Moon and bright planets and bright stars. Some people are more bothered by this than others.

Perhaps it is worth looking out for an alternative mount for your telescope. You may need a dove bar to help with mounting but we can help you know what you might need there.

If you buy second hand you'll have budget left for a new eyepiece.

Whatever you choose it sounds like you want to steer away from an Eq mount.

[FrenchyArnaud]

I am pretty sure a 130 or 150 pds, second hand, would fall way below budget and could be set on a basic alt-az tripod giving a decent set up for the budget. That is, if you are not against second hand. 

[Charic]

On 18/07/2018 at 22:29, devdusty said:

I went into my local Jessops store today,and they had a Ce!estron.   OK!

PS telescope for sale at a reduced price of 160 pounds. PS Huh?    Price!  sounds GOOD!

The staff did not seem to know much about it, BAD but they called up the information on their computer. Apparently it is a 127 mms reflector with a focal length of 1000 mm. However the telescope length was only about 600 mm.?  SAY THANKYOU VERY MUCH AND GOODBYE!

Is this worth buying or is there a problem with it.? NO!, The only problem is that you know little about it

Thanks for any advice.

Chris P

Welcome to the SGL.
Heed the advice already given from the previous replies, however, I actually owned the same  Telescope and I would not recommend your purchase.

Yes indeed, it sounds like the Celestron 127EQ Powerseeker (PS). I bought mine for the equivalent of about £40 and apart from the learning experience, and the quick decision made  to purchase the scope I presently own,  it was a waste of £40?

The scope is simple enough, but not powerful enough and the final image wasn't great either through the supplied eyepieces. I fully stripped the scope (a great learning curve as to how these telescopes work) put it all back together, even applied a decal/donut to the primary mirror in order to collimate to the best I could manage ( although this scope is factory collimated, and shouldn't  require any further modification ). In-fact you can just collimate with the naked, its that simple. Just gotta make everything look central.

What lets this scope down is the flimsy EQ stand, and the CONSTANT faffing and adjusting to keep the eyepiece in the right position? Its been far simpler for me using a Dobsonian ever since and my 8" 200P just fits the bill.

Now you also mention your 70, I know a lot of folk at 70 that are fitter than you think, but do consider the size and weight of any intended purchase you might consider. My scope is getting little use to be honest during the Summer nights where I live because its just too bright during the nights, but binoculars fare very well and are actually something else to consider for studying the night sky. Their great for expansive views, but cant provide the details that a scope would offer.

Lastly, did I mention, avoid THAT particular scope, the 127 Powerseeker. 

[Alan64]

On 24/07/2018 at 17:21, devdusty said:

Thanks Alan 64 for your recommendation about the Skywatcher Evostar90 .

My daughter bought this telescope for me 5 years ago, as a combined 65 th birthday and Xmas present. I chose it based on advice in astronomy books and magazines.

However I found it to be long and bulky for me to use easily. Also I could never align the finder scope with the  main telescope properly.

The equatorial mount was also very difficult for me to use. I could never seen to point the telescope in the direction I wanted to.

This is why I am reluctant to buy a reflector because of the culmination issues.

Chris P

That EQ-2 equatorial can be easily transformed into an alt-azimuth.  Also, a red-dot finder just might be easier for you to adjust, and without having to fiddle with all of those screws.  A red-dot uses two wheels to adjust the position; much easier...

...altitude(up and down), and azimuth(left to right), and just like the type of mount you're needing.  I'm thinking that the 90mm of aperture isn't quite cutting the mustard.  However that achromat that you have is ideal for your observing agenda.  What to do in that event?   

The master knew of the ideal focal-ratio long before anyone else, and with his 33mm f/5 Newtonian.  Newton was nigh an Andromedan, if not in toto...

That's what a Newtonian looks like on the inside.  The light from an object enters the front of the tube and strikes the big mirror at the bottom.  The big mirror then sends the light back up to the front to the little mirror.  Then the little mirror sends the light, the image of the object, to the eyepiece.  The path of light is rather simple, as you can see; an "L" shape. 

This is an example of collimation instructions for a Newtonian... 

https://garyseronik.com/a-beginners-guide-to-collimation/

The Jessops 127mm "Bird-Jones" reflector is similar to a Newtonian, but it has a lens embedded into the focusser...

  

That lens has to be removed in order to collimate that type of telescope; a rather nasty business, that.  In addition, the quality of the optics, the two mirrors and the lens, aren't quite up to snuff.  That would've been the worst telescope you could've ever purchased, but I understand that you were drawn to it for its greater aperture and its short tube.  This, rather, is what you were really after...

https://www.firstlightoptics.com/optical-tube-assemblies/celestron-c6-xlt-optical-tube-assembly.html

That's a Schmidt-Cassegrain...

It uses a lens too, there at the front, along with two mirrors.  It has to be collimated on occasion, but not as frequently as a Newtonian, and its collimation procedure is the easiest of all the mirrored designs of telescopes. 

Maksutov-Cassegrains...

...in larger apertures can be costly as well, however this 127mm is reasonable...

https://www.firstlightoptics.com/maksutov/skywatcher-skymax-127-ota.html

A Maksutov is the closest one can get, of the mirrored designs, to a refractor, in little to no maintenance and the quality of the views.  A Maksutov usually doesn't require collimation, but when it does its procedure is in between that of a Newtonian and a Schmidt, in difficulty.

That 127mm Maksutov would be ideal for what you're wanting to accomplish, in so far as the objects you wish to observe.  But that's just the OTA; no mount.  It even comes with a red-dot finder.  A Maksutov has a lens too, but it's thicker than that of a Schmidt, which requires adjustment to the outdoor temperatures before the images are steady enough to view.  Many owners place theirs outside for about an hour or so before they begin to observe.  Some even store theirs outdoors within a case or enclosure of sorts, to protect them from the elements, and to be ready to observe with without having to wait.  Schmidts have to adjust too, but not for as long.  Refractors and Newtonians, however, are usually ready to observe with in 15 minutes or less after they're taken outside.

You could place the Maksutov onto the EQ-2 of your refractor kit, but mounting it might require a little work.  You could then use the mount in an alt-azimuth mode.

The refractor...no fuss, no muss...

But in the larger apertures, 130mm and up, the instruments can be behemoths, and requiring large mounts; not to mention the cost.

Would this refractor kit be of interest...

https://www.firstlightoptics.com/omni-xlt-series/celestron-omni-xlt-102-az.html

The "rainbows" around the brighter objects would be there, but there would be a fighting chance to diminish them with a yellow filter...

https://www.teleskop-express.de/shop/product_info.php/info/p112_TS-Optics-Optics-1-25--Colour-Filter---Light-Yellow--8.html

https://www.teleskop-express.de/shop/product_info.php/info/p109_TS-Optics-Optics-1-25--Colour-Filter---Yellow--12.html

...or with this... https://www.firstlightoptics.com/achromat-semi-apo-filters/baader-fringe-killer-filter.html

But to see the planets up close, and to split double-stars, you would need 2x and 3x barlows to combine with your eyepieces, and to reach the higher powers necessary for that.  The same is true with a kit like this...

https://www.firstlightoptics.com/reflectors/sky-watcher-explorer-130ps-az-pronto.html  

Yes, that's a Newtonian, but you wouldn't need any filters to reduce the false-colour, as a Newtonian is 100% false-colour free. 

In the end, a Newtonian is not that difficult to collimate.  They generally arrive very close to being perfect, but they do require tweaking a little, oft upon arrival, and thereafter on occasion.  It's not like you'd have to take it all apart and put it back together, and as I have done...

However, refractors are best for splitting double-stars.