57 replies to this topic

[Nicole Sharp]

So I am about 99% of the way toward getting an Explore Scientific FirstLight 500/114 Newtonian, and I just wanted to know if there might be any issues with this?

 

https://explorescien.../fl-n114500eq3/

 

I already have a 1000/114 Bird-Jones Newtonian, but the Bird-Jones design doesn't work well for high magnifications, and it is clamshelled onto a terrible mount that makes it very difficult to use (an altazimuth GOTO mount without a motor and no manual adjustment knobs).  I have been considering all sorts of setups and telescopes to replace it, but I think what is going to work out best for me is something cheap, lightweight, and easy to use for afocal astrophotography with a smartphone or a point-and-shoot camera.  Once I have more experience with afocal short-exposure imaging, then I can decide if I really want to get a DSLR and a tracking or GOTO mount to be able to do longer exposures.

 

Pretty much the biggest things going for this telescope are it's low cost and it's really wide field of view.  I checked every telescope from Altair, Astro-Tech, Celestron, Explore Scientific, GPO, High Point, Meade, Omegon, Orion, Stellarvue, TPO, Vixen, and Zhumell, and apparently this is the cheapest telescope in the world (?!) with a 2-inch focuser.  I could really care less about that (I only want to use 1.25" accessories), but I do need a telescope with a focuser lock to put up to 2 pounds of weight on the focuser with an afocal camera adapter and an afocal camera.  Even with a 1.25" eyepiece though, the true field of view could be almost as good as my 7X50 binoculars, which is pretty impressive, so it should make a nice rich-field telescope in addition to being pretty good for planetary observing and afocal planetary/Lunar/Solar imaging.

 

As long as the telescope can see Comet Wirtanen (assuming the telescope arrives soon enough), ISS and Mercury transits, Solar/Lunar eclipses, and all 8 planets, I will be happy.  I think a 60-mm refractor fits that bill.  My primary interest is in Solar-System observing, so not really too interested in hunting down DSOs, but being able to see M31, M33, and some globular clusters would be pretty cool too.  I think a 60-mm refractor fits that bill as well.

 

Especially for Solar/Lunar observing though (and Solar observing is one of my favorite activities), that big 51-mm focuser needs a big secondary mirror, which will reduce contrast.  Just looking at the photos between a 500/114 with a 32-mm focuser and a 500/114 with a 51-mm focuser, you can definitely see the difference in size between the secondary obstructions.  The 650/130 version would have a smaller relative obstruction size for improved contrast, as well as more clear aperture, and a slightly slower focal ratio for reduced coma.  But the 650/130 Explore Scientific actually costs more than the 762/152 astrographic imaging Newtonian from High Point Scientific.  So it doesn't seem smart to pay more money for less aperture (and the High Point would have enough backfocus for a DSLR, if I ever did want to remount to a GOTO for long exposures).  And there is the rabbit hole that there will always be a better telescope for more money, so my philosophy is usually to get the cheapest one that works for what I want.

 

So should I be concerned about the loss in contrast with the 51-mm focuser on the 114-mm Newtonian specifically for afocal planetary, Lunar, and Solar imaging?  Or should it be tolerable?  The Orion 500/114 with a 32-mm focuser has a 30-mm secondary mirror, and I would imagine my 1000/114 Bird-Jones probably has something similar (even a 127-mm Orion Maksutov-Cassegrain has a central obstruction of only 39 mm).  I get pretty sharp contrast in the 1000/114 at low magnifications, particularly for Solar and Lunar observing (which is pretty much all that telescope is good for).

 

My only other concern is the mount, and how difficult it is to polar-align without a polarscope (though I don't think that would matter in the daytime for Solar observing).  But I am buying more for the OTA than the mount, and it comes with a Vixen-style dovetail, so I can easily remount it.  But if I did have to buy a better EQ mount, then I might as well get the 6-inch High Point reflector maybe.  Also not sure if I would need an extra counterweight if I am putting two pounds of accessories on the OTA?  I read that extra ES Exos Nano counterweights are basically nonexistent.

 

I would also need a carry case.  One of the biggest advantages of the 114-mm aperture is that I am hoping I can use my 114-mm Solar filter and my Meade StarNavigator 114/130 carry case for the Explore Scientific 114, without needing to buy a new Solar filter or a new carry case.  Any idea whether I would need a new case for the GEM or if the case designed for the fork mount would work?  I have to be able to carry the telescope up and down stairs and to and from the car to drive to an observing site, so having a good carry case for the telescope is extremely important.

 

Or could I be better off with a refractor instead?

Edited by Nicole Sharp, 06 December 2018 - 09:51 PM.

[Augustus]

The scope comes with an undersized secondary and useless finder.

[Nicole Sharp]

A refractor without a central obstruction would not have any similar issues with contrast.  But in that price range, the largest aperture I could get in an achromatic refractor is maybe 90 mm, and even that would cost a lot more than the 114-mm Newtonian.  Directly comparing a 90-mm refractor and a 114-mm Newtonian with a large central obstruction, wouldn't the Newtonian show more detail, since the increased aperture would make up for the loss of contrast?  Or does it not work that way?  Even with a 51-mm secondary (and I doubt it is that large), that corresponds to a clear aperture diameter of 102 mm, so mathematically it should outperform a 90-mm refractor?

[Nicole Sharp]

The scope comes with an undersized secondary and useless finder.

I would like to replace the finder with a Synta-style finder shoe.  I already talked to Orion, and they said their finder shoe will work for the Explore Scientific 114-mm Newtonian.

[Nicole Sharp]

The scope comes with an undersized secondary and useless finder.

What do you mean by undersized?

[Nicole Sharp]

This would probably be my top choice for a refracting alternative (640/80 achromat):

 

https://explorescien...s/fl-ar80640tn/

 

But not sure if it might be more difficult to replace the finder in the refractor with the higher curvature.

 

Also, the 640-mm only comes with an AZ mount, so I would still need to get an EQ mount to use for afocal planetary imaging (have enough difficulty keeping track of things at 1000 mm).  Plus the Newtonian rings come with 1/4-20 threads to add a guiderail for additional accessories.  Doesn't look like the refractor has that.

 

And I would think that a 500/114 Newtonian would perform a lot better than a 640/80 refractor?

[Nicole Sharp]

Any idea how well this particular telescope holds collimation though?  That might be a good reason to get a refractor instead.

[Jond105]

The eq nano is a terrible mount. My dad started his trip into Astronomy with one of these back in February before sending it back. You're adding a lot of weight to one end for imaging and have to use the slo mo controls as well. What budget are you trying to stick around?

[Nicole Sharp]

The eq nano is a terrible mount. My dad started his trip into Astronomy with one of these back in February before sending it back. You're adding a lot of weight to one end for imaging and have to use the slo mo controls as well. What budget are you trying to stick around?

The basic idea is just get the cheapest possible telescope that will get me some nice afocal images of Sol, Luna, and the 8 planets.  That's about it.  If I can see at least one comet and at least one asteroid, that would be pretty cool too.  I want something cheap, lightweight, portable, and easy to use.  It's really just for learning with so I can get more experience without the frustration of my current mount before investing in something a lot nicer and more expensive, and deciding if I need or want a DSLR camera for longer exposures.  The mount is more important than the OTA at this point probably, so that I can actually find things and keep an eye on them.  The hardest thing to find is OTAs with focuser locks.  I also want a short focal length so it is easy to find things as a beginner (i.e. not a Cassegrain).  I'm not willing to pay more for a manual telescope though than I would for a Celestron Nexstar 90SLT, so that is about the limit for budget.  Otherwise I might as well get a GOTO mount.

Edited by Nicole Sharp, 06 December 2018 - 11:20 PM.

[Nicole Sharp]

The eq nano is a terrible mount. My dad started his trip into Astronomy with one of these back in February before sending it back. You're adding a lot of weight to one end for imaging and have to use the slo mo controls as well. What budget are you trying to stick around?

 

What about the altazimuth version?  It is bundled with both the 640/80 refractor and the 500/114 Newtonian.  But these things are cheap enough that the mounts are essentially free I think.

[Nicole Sharp]

The cheapest telescope I have been able to find with a focuser lock is the Celestron PowerSeeker 70EQ, but I think that would be worse than the Explore Scientific FirstLight 640/80?

[Nicole Sharp]

I can't put a lot of magnification on my Bird-Jones, so I don't even know if it is possible to do high-magnification planetary viewing with an altazimuth mount?  You would have to make constant adjustments in both altitude and azimuth, versus only adjustments in one direction with a good polar alignment.  Without a polarscope though, I'm guessing 30 arcminutes or so in polar error might be the best to hope for?  But a polarscope won't help in the daytime for Solar observing.  If I see Sol drifting from polar error though, presumably I can make corrections.

Edited by Nicole Sharp, 06 December 2018 - 11:30 PM.

[GoFish]

Have you considered the AWB reflector?

https://shop.astrono...ector-telescope

 

If this meets your needs, it seems like a lot more telescope for the money. 

 

[Nicole Sharp]

Have you considered the AWB reflector?

https://shop.astrono...ector-telescope

 

If this meets your needs, it seems like a lot more telescope for the money. 

That seems like a poor choice for Solar observation.  I also need something with a full-sized tripod.  Plus it costs more than Explore Scientific.

Edited by Nicole Sharp, 06 December 2018 - 11:35 PM.

[vtornado]

Hello Nicole,

 

I don't do a lot of photography, mainly the moon and sun.

On an ASP-C sensor 1000 mm fl makes a nice sized image.

I would find someone on this forum that has the first light 500/4.  Technically I would be nervous about this scope.

An F/4 mirror is hard to grind well.  It is going to have non negligible coma.  It will be hard on eyepiecs, with the

outer edge of any wide field eyepiece will have a lot of astigmatism.  Small fast newts will have a relatively large secondary,

and the spider vanes look kind of fat on this model.

 

Have you thought about a c5?

I just picked one up.  I have not taken any photos with it because it has been too blasted cloudy for the last month.

I paid $225 for the tube with dovetail, visual back and synta finder shoe.

It will mount on smaller mount, probably a celetron slt class mount.

[Nicole Sharp]

The eq nano is a terrible mount. My dad started his trip into Astronomy with one of these back in February before sending it back. You're adding a lot of weight to one end for imaging and have to use the slo mo controls as well. What budget are you trying to stick around?

 

If the mount is worse than the OTA, then what might be the cheapest mount that would be good for high-magnification planetary viewing with a 500/114?

[vtornado]

If the mount is worse than the OTA, then what might be the cheapest mount that would be good for high-magnification planetary viewing with a 500/114?

CG4 is the best mount for the money for a small scope.

They are expensive new, used you can pick one up for 125-150.

They can be motorized cheaply for tracking.

[Nicole Sharp]

Hello Nicole,

 

I don't do a lot of photography, mainly the moon and sun.

On an ASP-C sensor 1000 mm fl makes a nice sized image.

I would find someone on this forum that has the first light 500/4.  Technically I would be nervous about this scope.

An F/4 mirror is hard to grind well.  It is going to have non negligible coma.  It will be hard on eyepiecs, with the

outer edge of any wide field eyepiece will have a lot of astigmatism.  Small fast newts will have a relatively large secondary,

and the spider vanes look kind of fat on this model.

 

Have you thought about a c5?

I just picked one up.  I have not taken any photos with it because it has been too blasted cloudy for the last month.

I paid $225 for the tube with dovetail, visual back and synta finder shoe.

It will mount on smaller mount, probably a celetron slt class mount.

 

I actually just ordered a 5SE last week but ended up canceling the order.  Still want to try to take it slow and not rush into too many big purchases all at once.  I have been researching for almost two years now into astrophotography, so I know what to get if I decide I want to do anything really fancy.  But I don't want to spend a lot of money on a DSLR camera and a tracking mount until I get more experience with basic afocal imaging first.  The telescope I have now is not terrible as long as I just keep it at 40X.  It is the mount that is the problem.  I literally have to grab the entire OTA and jerk it up and down and left and right because it is stiff on the broken motor and has no adjustment knobs.  But the long focal length and slow focal ratio make it difficult to use too for anything other than bright naked-eye objects.  I actually like using my 7X50 binoculars better than the 1000/114 telescope, because I can see more in the wider field of view.  It would be cool to be able to do that with a telescope too.

 

You do make a very good point about the focal ratio.  The 600/130 is a little bit slower than the 500/114.  I was partly leaning toward the 500/114 specifically for its shorter focal length though.  Same reason I picked the 640/80 refractor, since it has the shortest focal length I could find in a refractor under US$250 with a focuser lock and a chromatic aberration index greater than 2.5.

Edited by Nicole Sharp, 06 December 2018 - 11:49 PM.

[vtornado]

If you want something really cheap, there are lots of 114mm f/8 scopes out there on craigs list.

I see one a week.  Typically for $50.00.  If you go this route, there are differences.  Find one with

1.25 inch focuser, and look for the beefiest mount you can find.

You may not be able to get a tracking motor for these, unless you are handy can can adopt a modern one.

 

The celestron logic drive is versatile, The the speed can be adjusted, and you dont need any gears,

it couples onto the RA slow motion shaft.  You may have to mock up a bracket.

[Jond105]

CG4 mount is the lowest mount I would ever consider

[Nicole Sharp]

CG4 is the best mount for the money for a small scope.

They are expensive new, used you can pick one up for 125-150.

They can be motorized cheaply for tracking.

The ES Exos Nano is rated to 15 pounds though:

 

https://explorescien...-exosnanot1-00/

 

Which is better than this for the same price:

 

https://www.telescop...c/34/p/9011.uts

 

But anything like a CG-4 is going to end up costing as much as a Nexstar SLT.

[Jond105]

Exos nano is well over rated for the weight to put on it though.

[Nicole Sharp]

CG4 mount is the lowest mount I would ever consider

What is the difference between a CG-4 and an Exos Nano, other than being able to use a polarscope and add a motor drive?

 

https://www.omegon.e...-mount/p,33346/

 

https://www.telescop...c/34/p/9822.uts

 

https://www.astrosho...-mount/p,25185/

 

https://www.celestro...ount-telescope/

Edited by Nicole Sharp, 07 December 2018 - 12:09 AM.

[Nicole Sharp]

Exos nano is well over rated for the weight to put on it though.

A 500/114 Newtonian though would weigh maybe 4-5 pounds, 8 pounds tops with a lot of junk on it.

[Jond105]

CG4 has a beefier mount head, more counterweights, better movement, beefier legs. Without you being able to put a motor onto the nano with every turn of a knob just trying to get a pic would cause a great deal of shakes and dampening with 8lb weight.

Edited by Jond105, 07 December 2018 - 12:10 AM.