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Celestron Astromaster 70az

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#1 MaCheFai

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Posted 26 January 2021 - 01:52 PM

I've owned this telescope for a number of years and just recently started to clean it up and brush some of the dust off. It's in great condition, and as I've been recently reading up on telescopes, I realize i'm very limited by the type and the aperture it possesses. And I know many people recommend saving up and buy a better one, but I'm wanting to just make a few tweaks for now for $100. 

So I was planning on purchasing a Paradigm 12mm eye piece($60) and using it with my 2x Barlow. That would get me to 150x, and the max useful magnification for the scope is listed at 165x. Figured this would be way better than the 10mm that came with it. The eye relief and FOV is horrendous. 

I was also looking to swap out the diagonal with one of these: https://www.amazon.c.../dp/B08QRY4V97/

Does anyone have any experience with it? For $43 and 99% reflectivity, I figured it couldn't hurt. Is there a better option for the price based a long focal length refractor like this? 



#2 sevenofnine

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Posted 26 January 2021 - 02:01 PM

Unless the diagonal that came with the scope looks very cheap and plasticy I wouldn't bother. It's just a flat mirror in there and that's very easy to manufacture. Better eyepieces do help though. Something in the 30mm range is good. There are lots of objects that are bigger than you'd think. Good luck on your choices waytogo.gif


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#3 AtlantaAstro

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Posted 26 January 2021 - 02:46 PM

I would try out the diagonal you mentioned. More than likely the one you have currently is a aluminum mirror and I believe the SVBONY one is a dielectric that has more reflectivity. Might not see much of a difference on a small scope like that. The eyepiece you have described would probably do pretty well also. However, when you Barlow that 12mm, any image you may see might be darker than you’d like. I’m pretty new to this still but I wouldn’t count out getting a larger focal length eyepiece for those DSOs. They’re pretty cool in a larger EP. as you are aware you are quite limited based on aperture and focal length but I have a 90mm, 910FL, f/10 Orion refractor that sees some cool stuff with larger eyepiece like my 25mm and my 32mm. I have changed out my diagonal, focuser, and eyepieces and am pretty happy with my setup. I’ve pushed it about as far as it will go.

 

bottom line: keep it simple. Clean everything up well, try the 12mm with the new diagonal and compare. If worst comes to worst and you don’t see a difference or don’t like them you can always sell the newer pieces on here. Things go pretty quickly in these classifieds. Try it out and sell if you don’t like!


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#4 barbarosa

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Posted 26 January 2021 - 03:00 PM

The maximum useable magnification spec is not a a very useful number. Seeing conditions, mount and tripod shaking are generally against it. What happens is that the image scale is larger but the image is blurred.

 

The Astromaster 70  is a f/13 design. The field of view is small. A 2x Barlow makes it effectively an f/26 scope and it will be difficult to point by hand and difficult to track by hand.

 

Jupiter compared at f/13 and f/26 with a 13mm/ 60APOV EP and 2x Barlow  The actual fields of view are 0.87° and  0.54°

 

astronomy_tools_fov (17).png


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#5 clearwaterdave

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Posted 26 January 2021 - 03:11 PM

Hello.,I would try out the new ep before I bought another diagonal.,unless the one you have is damaged in some way.,An if I was going to go so far as to replace it I wouldn't want the cheapest one I could find.,.This is why they call it UP GRADING. You are replacing it with something better. I know you're thinking why put a xx$ diagonal on a x$ scope.,Well.,.you'll get better performance and you have now increased the overall value of your scope.,good luck.

   Here is my tweeked out 70mm.,lol.,

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#6 barbarosa

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Posted 26 January 2021 - 06:25 PM

To upgrade, to accessorize or to leave things as they are are very subjective decisions. I know a fellow who put a Moonlight focuser or a scope. Now he has a $400 focuser or a $400 scope. He is happy with the result, he  laughs at the ROI and cost/benefit ratio and is not worried about resale.

 

In this case the question might be whether it will be possible to see an improvement with a new diagonal, see it that is without using averted imagination  and is worth the $43 risk. The next question might be what is the risk?

 

The SvBony brand is not junk and no claims are made about 1/10 wave flatness or durability. It is covered by the Amazon return policy.

 

My bet is that the SvBONY diagonal is better optically and mechanically than the oem diagonal. How much of that putative optical difference is perceived is debatable, by my bet is that the OP will discover that it is better and keep it, because that is what we do.wink.gif


Edited by barbarosa, 26 January 2021 - 06:36 PM.

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#7 clearwaterdave

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Posted 26 January 2021 - 07:45 PM

Barbarosa is correct.,it's a personal decision.,My 1980's Meade's diagonal looks a little beat up but it works just as well to me as newer ones I've tried on it.,I bought an inexpensive Meade diagonal because I wanted the lightest I could find.,it was $22.,I think and it works fine.,my birdie scope is happy.,

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#8 Jim Haley

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Posted 26 January 2021 - 08:42 PM

With just $100 to upgrade, I think I would save that much more and get the Astronomy without Borders telescope, a 5" reflector for just $200.  Heck, you probably will have to wait for it so long that have time to save up the second $100.

 

On the other hand, do you have 7x50 binoculars?  That is what I would spend my upgrade funds on.


Edited by Jim Haley, 26 January 2021 - 08:42 PM.


#9 MaCheFai

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Posted 26 January 2021 - 09:32 PM

Unless the diagonal that came with the scope looks very cheap and plasticy I wouldn't bother. It's just a flat mirror in there and that's very easy to manufacture. Better eyepieces do help though. Something in the 30mm range is good. There are lots of objects that are bigger than you'd think. Good luck on your choices waytogo.gif

Yeah, the reason I even began considering it is because the plastic threads are barely hanging on with very minimal use. 



#10 AtlantaAstro

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Posted 26 January 2021 - 09:44 PM

Yeah, the reason I even began considering it is because the plastic threads are barely hanging on with very minimal use. 

If that’s the case, Get the diagonal. You won’t be disappointed


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#11 MaCheFai

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Posted 26 January 2021 - 09:44 PM

The maximum useable magnification spec is not a a very useful number. Seeing conditions, mount and tripod shaking are generally against it. What happens is that the image scale is larger but the image is blurred.

 

The Astromaster 70  is a f/13 design. The field of view is small. A 2x Barlow makes it effectively an f/26 scope and it will be difficult to point by hand and difficult to track by hand.

 

Jupiter compared at f/13 and f/26 with a 13mm/ 60APOV EP and 2x Barlow  The actual fields of view are 0.87° and  0.54°

 

attachicon.gifastronomy_tools_fov (17).png

So are you suggesting that it makes more sense to go with the paradigm 8mm and no Barlow? Since my focal length is 900, that would put me at 112.5x with a 60* FOV and 13mm eye relief.



#12 MaCheFai

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Posted 26 January 2021 - 09:51 PM

Hello.,I would try out the new ep before I bought another diagonal.,unless the one you have is damaged in some way.,An if I was going to go so far as to replace it I wouldn't want the cheapest one I could find.,.This is why they call it UP GRADING. You are replacing it with something better. I know you're thinking why put a xx$ diagonal on a x$ scope.,Well.,.you'll get better performance and you have now increased the overall value of your scope.,good luck.

   Here is my tweeked out 70mm.,lol.,

Ha! So it looks like you went down a similar path!

I wasn’t looking for a cruddy diagonal, but rather an inexpensive upgrade. The one I listed is a dialectric and looks to have 99% reflectivity and is aluminum, so fairly light too. The one that’s on there is an all plastic with a prism an bad threads. From what I read online, it’s pretty terrible.



#13 AtlantaAstro

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Posted 26 January 2021 - 09:52 PM

So are you suggesting that it makes more sense to go with the paradigm 8mm and no Barlow? Since my focal length is 900, that would put me at 112.5x with a 60* FOV and 13mm eye relief.

While two magnifications (12mm and then a barlowed 6mm) would be nice, if you plan on Max magnification most of the time it may be better to get a 7-8mm eyepiece with a wider field of view might be what you’re after. Skip the added weight of the Barlow.
 

If you get a 15mm, wide field eyepiece, you can Barlow that into a decent two step magnification duo. Your scope would do well with a 15mm and a 7-8mm (barlowed). 60x/120x magnification is a great start. Max magnification is only attainable under perfect skies which simply just don’t exist ha. Just my Two cents as a n00b


Edited by Atlanta AstroView 90mm, 26 January 2021 - 09:57 PM.

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#14 FlyingV74

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Posted 26 January 2021 - 10:00 PM

I have an old Jason 60mm x 700mm refractor. I found that using the 10mm eyepiece (70x) was about all that this little scope could handle. While your 70mm has a little more light grabbing capability, it isn’t all that much. If it were me.......I have 7-21 Svbony zoom that I enjoy with my new 8” dob. However, at low power the view is not all that wide. But if you enjoy looking at planets and tightly grouped things, then the narrower view is not a big deal. If you want a wider view at lower power, then the Astrotech Paradigm would likely be a good starting place (.....I do not have any and have not viewed through any of these eyepieces). And if you go for a low power eyepiece, you could certainly use a Barlow to get more power. But keep in mind that when you double the power, you get less brightness and less resolution (i.e. it will become blurrier).
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#15 MaCheFai

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Posted 26 January 2021 - 10:03 PM

To upgrade, to accessorize or to leave things as they are are very subjective decisions. I know a fellow who put a Moonlight focuser or a scope. Now he has a $400 focuser or a $400 scope. He is happy with the result, he  laughs at the ROI and cost/benefit ratio and is not worried about resale.

 

In this case the question might be whether it will be possible to see an improvement with a new diagonal, see it that is without using averted imagination  and is worth the $43 risk. The next question might be what is the risk?

 

The SvBony brand is not junk and no claims are made about 1/10 wave flatness or durability. It is covered by the Amazon return policy.

 

My bet is that the SvBONY diagonal is better optically and mechanically than the oem diagonal. How much of that putative optical difference is perceived is debatable, by my bet is that the OP will discover that it is better and keep it, because that is what we do.wink.gif

So I think I will, but do you know if I’ll encounter any issues with adding it to my particular scope? From what I read some had issues with new diagonals causing them to have to add a spacer. I believe this one uses an amici roof prism. So I’m worried moving to a mirror might cause unforeseen issues. 



#16 harbinjer

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Posted 26 January 2021 - 11:28 PM

As long as you're not near either end of the focusers travel, you'll likely be ok. I think the diagonal is a good upgrade if the other one is barely staying on. 

 

You might consider the goldine(or redline) 15mm eyepiece. SVBONY sells them too. They will work well at f13. 

 

Also consider posting a want add in the classifieds for a 25-26mm plossl eyepiece if you don't have one. Many people have some they don't need, and might help you out for cheap. 



#17 barbarosa

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Posted 27 January 2021 - 12:18 AM

The SvBONY diagonal you linked is not a prism diagonal which is good in your case. The product description calls it a flat mirror. Without a diagonal the image from a refractor is upside down. The mirror inverts and reverses it.

 

If it was an Amici prism diagonal it would be almost certainly the wrong choice for a refractor, and it would among other things shorten the optical path length and possibly require you to extend the draw tube. Some of these prisms have a small ID and cause vignetting. 

 

My most used EPs were about 20mm and 12mm. I had a 6mm and an 8mm that saw little use. I still have a very high quality 4mm that I should sell. You could say it is new in box condition.  Seeing always dominated. I often buy used gear and so have three Barlows. One of them a 2" has been on my f/7 refractor for several months, but i seldom used it on the main scope, an SCT at f/20 needs very good air.

 

The field of view terminology is confusing. The telescope has a fixed maximum field of view. Eyepieces are often spec'd for AFoV (Apparent Field of View). When I look through a 60 degree eyepiece I do not see 60 degrees of the sky.

 

Use this calculator to determine the actual field of view for any scope and eyepiece combination.

 

Enjoy the new diagonal what ever kind you buy.



#18 SDAngler

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Posted 27 January 2021 - 12:21 AM

I'm a newbie myself, so take this advice for what it's worth....I also have an Astromaster 70 AZ and picked up a Celestron 8-24 zoom EP.  There are a few versions of these zoom eyepieces and perhaps you can find one for <$100 on the classified section.  It works great and beats swapping out eyepieces and is like buying a bunch of eyepieces.  I've seen craters on the moon and have pointed it at a few stars.  Hope this helps....


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#19 Star Geezer

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Posted 27 January 2021 - 01:42 AM

I have been observing the night sky for a few years, I have been getting very good results with my AstroMaster 70Az, I use the supplied amici prism diagonal with the Celestron 8-24mm zoom eyepiece and the Orion Shorty 2x Barlow. Once the mount gets worn in, it’s not so bad either. I have observed Jovian transits and now have no problem manually tracking.


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#20 sg6

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Posted 27 January 2021 - 03:53 AM

Not sure the barlow will actually be useful, you will not get 150x out of the scope. 100x maybe but I doubt any more in realistic terms.

 

It is very much a case that they print impressive numbers on the side otherwise you would buy the competitors that did put them on the side, even though neither would actually manage and if both scopes were identical.

 

The other aspect is that as magnification goes up your view goes down. Much observing you will want a 1 or 2 degree view and that - even on a Paradigm - is 30x to 60x. If you do not have around 2.5 degrees the Pleiades M45 is well poor, even a bit pathetic. A few bright stars is not as good as the whole bright cluster.

 

I think people fail to fully understand "magnification". Magnification makes an object bigger up to an extent, then what you see is less of the same object.

 

Unsure of the eyepieces you have but do not select based on a number for the magnification alone.



#21 Star Geezer

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Posted 27 January 2021 - 09:54 AM

The Barlow was not specifically purchased for the AstroMaster 70Az and just used to push the zoom eyepiece a little further. The AstroMaster 70Az is not the scope for taking in a full view of the Pleiades, neither is an 8” f/6 Dobsonian. That is not what the scope is designed for, it is designed more for observing the Alcyon Star System within the Pleiades. Detail is a function of aperture, as long as you are getting good light from an object sometimes making that object appear larger in the eyepiece can bring that detail to light.


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#22 MaCheFai

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Posted 28 January 2021 - 09:56 AM

Okay, so I pulled the trigger on the Svbony diagonal(dielectric w/ 99% reflectivity, 4.4oz) and a 9mm Sbvony eye piece(68* FOV, 17mm relief, FMC, 5 elements/3 groups), links below. Got them both for $75 all in, which was less than I'd hoped for. Now I just need to wait like 6 weeks!  haha I'll report back once i've had a chance to tinker w/ them, for those that may be interested in similar upgrades for this celestron 70az or similar. 

https://www.aliexpre....5f887fb2FW1TpF

and 

https://www.aliexpre....584d2b74dKmOJh


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#23 AtlantaAstro

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Posted 28 January 2021 - 09:59 AM

I don’t think you’ll be disappointed. That’s a heck of a price for a diagonal and an EP


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#24 MaCheFai

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Posted 17 February 2021 - 11:27 AM

Parts arrived in 21 days, much of which was here stateside by usps. Of course, a snowstorm is bearing down. So it's not likely i'll be able to try these out for a bit. Will report back once I'm able to though.

 

Initial quality looks pretty darn good! Seems well constructed and solid, but not too heavy. I like the brass compression ring on the diagonal a lot and the eyepiece looks promising as well. Excited to give them a try!

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#25 clearwaterdave

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Posted 17 February 2021 - 08:29 PM

Good for you.,I was going to suggest the Vite 23+10mm eyepieces.,They sell them on e-bay for about 10$ each.,They have 62°fov and give up a fine view.,and they are very light weight.,keep us posted on how these work for you.,


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