Is there something wrong with my new Mak?

[kiwigazer]

Hi all, newbie here. I have just bought a 90mm Mak and tried it for the first time last night on the Pleiades and the Orion Nebula.

I used the 25mm eyepiece that came with the scope and noticed that some of the stars near the edge of the field threw out rings that went across the centre of the field. I swapped to another 25mm eyepiece I have that I haven't had problems with but the same thing happen.

I changed the diagonal to another one but still the same problem with both eyepieces.

I am suspecting now there is a flaw in the optics of the scope itself.

Or is this something that you get with Maks?

Any help would be appreciated

[Dave In Vermont]

I wish you had a picture to back this. But on the face of your description it does sound like an optical problem. There certainly shouldn't be rings projecting to the center of your FOV.

I'd take it back to where it came from. What variety of Maksutov is this? Where did you purchase it from?

Very odd,

Dave

[RT65CB-SWL]

Hi kiwigazer and welcome to SGL. 

I am with Dave on this. Take it back.

1. If it is new then you should not encounter any issues with a reputable dealer and they should exchange it 'like for like'.
2. If it is secondhand take it back to the seller and get him/her to refund you and/or get it corrected or collimated... then run off with your refund. I would not feel comfortable if the seller of the s/h 'scope says they will keep your money whilst it is being corrected/collimated... and when it has been corrected I still would not feel comfortable... (unless of course the seller knows what he/she is doing).

[kiwigazer]

Thanks Dave and Philip

The scope is new and is actually an exchange for another scope I bought off this company. The first one which was a 70mm short refractor had excellent optics but I sent it back because the tripod was too light weight and was basically a camera tripod which I found too hard to track objects with.

I had no problems with the exchange, the woman at the company was very helpful and should be fine exchanging this one.

The scope is under the brand of "Saxon" which I gather is an Australian company and has a good reputation.

My other scopes are a f/5 Skywatcher 150mm Newtonian on a German equatorial and a f/11.8 Skywatcher 127mm Mak on a goto mount. I am seeking a portable, easy assembly scope that I transport around in my car etc.

Thanks again for the advice

[tooth_dr]

Hope you get sorted. Always frustrating but the best move in the long run is to exchange it. One of the big benefits of buying new (and from a reputable company like you have done) is the ability to have some cone-back if problems arise. 

[JOC]

What's the view like in the daytime?  I know nothing about these telescopes, but it might be an interesting comparison?

[RT65CB-SWL]

On 17/10/2017 at 09:10, JOC said:

What's the view like in the daytime?  I know nothing about these telescopes, but it might be an interesting comparison?

Ah! that's a good point. I never though of that one!  

When I had the mishap/accident of my ETX 105, I had the conceptual plan of a replacement backplate using the damaged ABS plastic rear section dimensions (+/- 4mm) to acheive the correct length/diameter etc., hence the somewhat unsightly/ugly protrusion. It was OK in the daytime on terrestrial targets and for a quick look at the Moon. Venus, Jupiter, Saturn and bright stars would show that the collimation was misaligned and flare/ghost on one limb. 

 <---the conceptual replacement backplate.

 

During early May of this year [2017], I had a re-think of how it should look and ended up with this... (see photos below).

 <--- with an ETX to SCT adaptor...   <--- after the 're-mod'.

I have yet to test it properly under a night sky [firstlight since the 're-mod' was mid-June 2017]. Targets were Jupiter, Saturn and stars in Virgo showed an improvement, i.e. being more pin-points and spherical donut shape when in/out focus... and using my 2x laser collimators the red dot appears closer to the centre of the collimator target too. 

[RT65CB-SWL]

I have just found this photo in my photo archive...

This is Jupiter before the 're-mod' and collimation...   ...of my ETX 105. 

[ronin]

Could be simply that in transit to you the scope got a knock, not even a heavy one, and the mirror jumped and is no longer orthogonal (straight for want of a simpler description). I assume that the focuser still makes a difference to the view as that is the other "common" thing, the focuser gets wound out too far and the threads disengage and that also allows the mirror to move.

Neither would be "serious", in a way as it is a case of remove mirror cell and reassemble with everything aligned right and attached, but each need it to be returned for rectification. A retailer will just put another in the post and at their own time look at the item from you.