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Looking for a decent wide-field, grab-and-go scope

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#1 lxeth

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Posted 22 July 2021 - 06:18 AM

Looking for advice on a refractor to use primarily as a wide-field scope (not really interested in a reflector or a mak). I do a lot of double star observing (have a Vixen A80Mf f11 and an old Vixen 60mm f15 for this), but I want to look at some larger clusters, like Melotte 20 or the Hyades, and asterisms such as Kemble's Cascade or the Coathanger.

 

I'd also like to use this new scope as a grab and go (my scopes are stored on the second floor of our house, so I want something that is a little easier to carry down stairs and around corners; the 80mm f11 and 60mm f15 aren't too bad, but their length makes them a little difficult to maneuver), and so I'd like to be able to use the scope on planets and the Moon as well (a little CA wouldn't bother me, and I realize I probably won't be able to see details on the planets).

 

I do all my observing from the front driveway and small back yard with lots of light pollution from the neighbors and some nearby street lights. Not ideal by any means, but I have managed to spot M57 and M27 when the seeing was good, so not horrible either.

 

I'm thinking of three options (I'm planning to use a Porta mount):

 

1) Svbony SV503 70mm ED f6 (I'd really love to get the AT70ED, but can't get it shipped to Japan)
2) Svbony SV48 90mm f5.5 achromat
3) Skywatcher 102mm f5 achromat

 

Open to other options as well, but as you can tell from my choices, my budget is around 300 - 400 US. I may want to upgrade to a 2-inch diagonal someday, but I already have a lot of 1.25" and .965 eyepieces, so I'm planning on using a 1.25 diagonal with the scope. And, I've thought about the Svbony 503 80mm ED f7, but its a little above my budget and I'm not sure the extra aperture and smaller field of view would be worth it for what I want to observe.

 

Thanks in advance for taking the time to read this post and any advice you can give!


Edited by lxeth, 22 July 2021 - 06:19 AM.


#2 Ben the Ignorant

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Posted 22 July 2021 - 06:44 AM

Even the 80mm f/5 achromat has too much aberration for real high resolution on doubles and planets, so the 90mm and 102mm are out, aberrations are exponential with aperture at the same focal ratio. Not sure about the 90mm Svbony but the others have plastic cells in which the lenses float and they are NEVER collimated right unless you add centering screws and adjust the cell-to-tube mating. I've done these jobs on an 80mm f/7.5 and it's a little nightmare, not even worth the lengthy effort.

 

Later I got an 80mm f/7 ED semi-apo where NOTHING had to be adjusted, everything is made and assembled right with tight tolerances and excellent long-term collimation. Plus, as was obvious in a comparo on Lyra's double-double, the semi-apo is brighter, sharper, more neutral in color and easier to focus right with the double speed machinery.

 

You'll be painting yourself into a corner sticking to achromats, so do as you suspect you should do, save for a longer time and get yourself some truly sharp and bright optics with an accurate focuser. And if that's not possible, the 70mm semi-apo is a good second choice, in many trials and comparos I found the 70mm diameter is the threshold at which things become interesting in stargazing.


Edited by Ben the Ignorant, 22 July 2021 - 06:46 AM.

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#3 Binofrac

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Posted 22 July 2021 - 07:14 AM

This is not an exhaustive test but I've been very impressed with the capability of the Skywatcher short achromats when I've looked through them at astronomy gatherings. I was most pleasantly surprised by the Startravel 120. My scope is a 102mm f11 refractor and I've toyed with the idea many times of pairing it with a Startravel 102 for more grab and go opportunities. It would fill the gap between my scope and binoculars. The only reason I haven't is that another scope would be superfluous given my lack of time for observing.

 

Yes there is colour which of course won't show much for widefield use. The aperture can be stopped down easily to lessen it for planetary views but the colour never bothered me enough to do this.


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#4 Jon Isaacs

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Posted 22 July 2021 - 07:56 AM

I'm thinking of three options (I'm planning to use a Porta mount):

 

1) Svbony SV503 70mm ED f6 (I'd really love to get the AT70ED, but can't get it shipped to Japan)
2) Svbony SV48 90mm f5.5 achromat
3) Skywatcher 102mm f5 achromat

 

And, I've thought about the Svbony 503 80mm ED f7, but its a little above my budget and I'm not sure the extra aperture and smaller field of view would be worth it for what I want to observe.

 

 

This is the way I see it:

 

The Svbony 503 80mm F/7 ED would do it all.  It would be a better planetary/double star scope than the 80mm F/11 and it would still provide a generously wide field of view.  

 

Otherwise, the 102mm F/5 would be the best for deep sky/wide field and the 70mm ED would be the nicest scope.  I have an 80mm F/7 FPL-53 Doublet and it would be my choice. 2.8 degrees with 1.25 inch eyepieces, 4.75 degrees max with 2 inch eyepieces.

 

Jon


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#5 db2005

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Posted 22 July 2021 - 07:59 AM

The larger targets you mention are pretty good objects for binoculars. An 8x42 or 10x50 should serve you well, and are easy to carry around. For moon, planets and double stars you would be hard pressed to find a better price/performance ratio than the Vixen A80mf you already own.


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#6 markb

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Posted 22 July 2021 - 09:21 AM

Get the 102.

 

Color will be the issue, but a 4 inch f5 is still worth the compromises. I sold everything under 4 inch and use 5 or 6 inch achromats. I was happy enough but more satisfied after trying a Baader 495LP super sharp cut violet blocker. Obviously, my color issues exceed your choices.

 

EDIT in-home transport of the f5s was far far easier than the 76mm f15 and 4 in f8 tubes. Wall banging resolved. And I was always terrified I'd shatter my glass storm door on the last leg of the stuggle, um, journey.

 

On the 1.25 v2 inch ep, I have found I only use 2 inch barrel eps on the 30mm 80 or 70 degree eps, or the 100 degree 20. I usually bring just a Vixen 1.25 diagonal, so don't feel you're missing anything on the 2".

 

I have a wonderful 80 degree 20mm UO Widescan that has a barrel limited field at 1.25 and usually its plenty of field. Otherwise I skip right to the above eyepieces if I need a maximum, RFT field. Its rare for me to use a 20-30 mm 1.25 but if I do, one of the great 26mm/28mm plossls do the trick. I assume a similar 20mm/80 is out there.

 

A Baader 495LP makes a massive difference in using a fast achromat, I have classic Jaeger f5 achromats. On those big fast achros the resolution loss due to the short wavelength spread/defocus really hits you. The super sharp cut on the 495LP is great and provides a reasonable compromise overall. I do wish someone would redo the Chromacorr with the glasses out today though.

 

Wratten filters cut too much useful spectrum, and Baader Semi APOS and Fringe Killers are nice but not nearly good enough for a fat f5. The 495LP is a huge bargain, too, as bandpass filters go. Don't be tempted by lesser filters like Wratten numbers.

 

Consider selling the Porta and switching to a more capable Alt Az. If you aRe still shopping, broaden the search. The load capacity on the Porta is limited, and it will overload the bearing surfaces with the one sided load. How do I know? My big Jaegers, likely due to the glass mass, were bound up and sticky to move on my Porta II. I loved the Alt Az set up so I moved to a T head version, the AYO Swiss copy Williams EzTouch, and Sergio Bonilla.

 

If Vixen had just put an off side thread for a CW or CW shaft I would still have it. I there are a few beefier small Alt Az mounts out there, check some CN posts. Anything with a T head or CW provision would help. As always more mass means more mount and tripod. The short tubes really help on vibration damping issues, too.


Edited by markb, 22 July 2021 - 09:48 AM.

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#7 Mark Lovik

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Posted 22 July 2021 - 09:39 AM

I have an AT72EDii on a voyager 2 mount for grab and go.  I can get out the door and setup for viewing in 5 minutes.

  • Nice moon, Jupiter, and Saturn views (maybe to 110x)
  • I use 2" a diagonal and wide field eyepieces - 4+ degrees at 17x.  You can push to 5 degrees and lower power if you support larger exit pupils.
  • Balance on the mount can be a problem - the scope has a short dovetail out of the box and tends to be "back heavy"
  • The mount has manual slow motion controls to easily frame and center views

Any 70-80mm ED doublet refractor would be similar - including the Svbony.  There are some variations in color correction on F/6 ED doublets this size, but should be mostly controlled for visual use.

 

There are a number of similar mounts to the Voyager 2 that have a modest price.  In my experience these easily handle 70-80 mm scopes when tuned (simple process).  Others have mentioned successfully modifying these mounts to handle the vibrations common for 100mm scopes.  If you really want capability for larger refractors as grab and go, or want automated controls: then you are going to a different mount tier.

 

For wide field views - drop any idea of the Mak

  • I have borrowed a 130mm Mak from our club to examine it's optics.  It's maximum field of view is maybe 0.7 degrees.
  • Good for planetary -- horrible for wide field views.  Like looking thru a straw. 
  • Now you need a good finder, because locating objects becomes difficult -- really start needing a goto mount if you want to find your objects quickly.
  • For the wide field refractor -- low powers are almost good enough to be the finder. 
  • Smaller Mak (compared to the 130mm) would not be much better than the wide field refractor (assuming it's an ED refractor) for planetary views.

 

Different alternatives to consider

 

  • The new Celestron 100mm push to telescope, optics are not great, but the ergonomics are good as a grab and go telescope with push to capabilities.  I have looked thru an 80mm ED doublet swapped on the Celestron mount, and the original OTA packed off in a closet. Nice combination of mount and scope, where the mount load is reduced to a smaller scope, and the optics drastically improved with better ED optics.
  • Instead of the push to capabilities, I am starting to use a Dob trick for observing.  Search cloudy nights and you will find a number of threads on this topic.  Mount an small digital angle gage on the front of the scope (many have magnetic mounts with a grove for a tube.).  Get the vertical angle right (electronic atlas for phone or tablet) - then just sweep right or left to find the object.  Works well for a wide field scope, and avoids neck 'bendy' problems when looking at object at higher elevations in the sky.

Edited by Mark Lovik, 22 July 2021 - 10:14 AM.

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#8 sportsmed

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Posted 22 July 2021 - 09:42 AM

I have a Astro-Tech AT80ED and that would be a good option for you. SvBony and other companies have basically the same scope, but a 80mm f/7 ED scope would work well, good optics, fairly light, 560mm focal length, but can also do great on planets. I had mine up to 215x the other night on Jupiter and Saturn.


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#9 jeffreym

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Posted 22 July 2021 - 09:44 AM

So, here is the ED80, f/7 from our sponsor, Astronomics $400):

https://www.astronom...ractor-ota.html

 

Have fun,

Jeff


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#10 vtornado

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Posted 22 July 2021 - 09:46 AM

This seems like this is a "specialized" scope for wide field observing.

I would choose, the skywatcher 100 f/5 so you are not sinking too much cash into a special purpose scope.

The clusters you mentioned are viewed with low power so CA will not be a big deal.

The skywatcher has a 2 inch focuser.

 

To truly take advantage of wide field you will want to go 2 inch eyepieces. 

A good 2 inch eyepiece and diagonal will run you $300.00.

 

The venerable ST80 and its ilk are also good wide field scopes.   You will have to upgrade the focuser some day

if you want to use 2 inch accessories.  That will be as much as the scope.  It will be easier on your mount than

the 100 f/5

 

I have the ST80 with a two inch and it does what it is supposed to do sweep and look at big clusters.

If a 100 f/5 were to come up cheap here I would upgrade to get a bit more light grasp.


Edited by vtornado, 22 July 2021 - 09:48 AM.

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#11 Jon Isaacs

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Posted 22 July 2021 - 10:47 AM

Consider selling the Porta and switching to a more capable Alt Az. If you aRe still shopping, broaden the search. The load capacity on the Porta is limited, and it will overload the bearing surfaces with the one sided load.

 

 

This thread is about a small, grab and go, wide field refractor. The largest scope under consideration is a 102 mm F/5 Achromat. The Portamount handles 80 mm EDs and the similar weight 102 mm F/5 achros without a problem.. I go 300x on doubles with my Portamount.

 

The thing the Portamount has over the T-Head mounts is the ergonomics. The scope s behind the mount so you're not tangling with the tripod legs and the controls are perfectly placed.

 

 I have wooden legs on my Portamount and frequently use it with my NP-101, 12 pounds and 29 inches long. It's not ideal but it's workable as long as there's not too much wind.. I also have a T head mount which is more solid but ergonomically inferior..

 

Bottom line: The Portamount is a great mount for the scopes being considered here.

 

Jon


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#12 Stevencbradley

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Posted 22 July 2021 - 12:05 PM

I don't have specific scope advice, but I suggest spending some time on Youtube to help with your search. Many outstanding amateurs post there, as well as many experienced astrophotographers. The reason I'm suggesting YT is that most of the posters there also post photos of what they see, and video of the scopes, showing you their relative size (Ed Ting is my favorite). I've bought enough scopes in my life to know that the advice you *read* is not always the advice you should take, because you cannot get a measure of relative size or quality. For example, there are a couple of scopes I truly regret selling. My Stellarevue 80mm (achro, offered as a "semi-ED," I think) is the one I most regret selling. Second is my C9.25. The 80mm was a decent widefield scope, had some good optics. The 9.25 SCT was small enough to haul out of my garage, but big enough to see some great sights. The 80mm was long gone by that time, but I truly missed it. What I'm saying is that if I had been able to watch some of those scopes in action on YouTube, I might not have spent so much time & money acquiring items I ultimately sold. At the time, I had quite a bit of cash, so making all those trades was not an issue. I am much more limited now (retired), so I'm pretty careful, both buying & selling. 

I hope you get what you want , first time.


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#13 bobhen

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Posted 22 July 2021 - 12:34 PM

I have owned a 102mm F5 for 16 years. I have also owned an 80mm F5. The 102mm F5 does a better job on deep sky objects and still delivers a very wide view. The scope is also very portable.

 

For the moon and planets get a yellow filter or one of the CA reduction filters.

 

Here is what you can expect as far as the moon and planets are concerned…
You will easily see the rings of Saturn, some moons of Saturn and the Cassini Division.  Jupiter will show bands and some details. The moon will show lots of detail. Now, these views will be bested by other scopes that are more conducive to lunar and planetary but it’s not like you will just see mush with the 102 F5.

 

Stop the scope down to 70mm for daytime use and it is a very sharp spotting scope.

 

Bob


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#14 jcj380

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Posted 22 July 2021 - 12:52 PM

I like my ST80 for portability - it's light and short.   I did upgrade the focuser when Lunt had Crayfords on sale.  I use an AT25mm for a finder EP - I took off the RDF. 

 

There's some peace of mind in knowing it can be easily and cheaply replaced if something happens to it.  It also seems there's a reasonable used market for them.

 

OTOH, I am thinking of upgrading to an 80ED or maybe a 90-92mm APO for more of a "forever" scope.  We'll see...


Edited by jcj380, 22 July 2021 - 12:57 PM.

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#15 Ben the Ignorant

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Posted 22 July 2021 - 02:04 PM

You are looking for a decent refractor, some hard data to guide your choice here. My attempt at owning an affordable 80mm f/7.5 got me a scope with a plastic cell that let a large play between the lenses and itself. Never centered until I added centering screws around a lens and shims around the other, interesting job but boring job, and too tedious for the supposed saving of choosing an achro over a semi-apo.

 

After solving the centering problem in the lenses a tilt problem showed up, so, opening the thing again, checking the spacers, a gross difference in thickness had me making extra spacers. The stock spacers are glued, not at an exact 120° from each other to begin with, and the glue made very inconsistent thickness.

 

lens spacer a.jpg

 

Tiny strips of masking tape adjusted the gap.

 

 

 

lens spacer b.jpg

 

For extra stability I made a 6x60°, not essential on a basic scope but good practice in case a serious scope needs the same job one day. To gauge the consistency I slipped the little piece of folded paper between the lenses, and feeling the friction let me know, with a surprising fineness for such a simple method, how many strips of tape were required for evenness. The change in the gap didn't cause spherical aberration.



#16 Ben the Ignorant

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Posted 22 July 2021 - 02:22 PM

But...

 

star test achro.jpg

 

star test achro 2.jpg

 

...as you see in the star test, some miscollimation remained because the cell itself was tilted relative to the tube. I could never get the centering screws to do a perfect adjustment because the flexible plastic cell twisted, and the tilt conspired with it to make unpredictable and unstable collimation. Shimming the space between the cell and tube mitigated the problem but didn't solve it.

 

 

 

More than that, as the hairy green ring testifies, the doublet has a serious turned-down or raised edge, so contrast can never be great. The Ronchi pic makes it more obvious.

 

ronchi achro.png

 

These are the problems with an 80mm f/7.5 cheap achro in a plastic cell, with f/5 beams and/or larger diameters they would be worse. Trying to solve them costs more in time, effort and boredom than going for a more expensive semi-apo that's made right. The 80mm ED f/7 semi-apo I got had none of these mechanical and optical issues, on the contrary it's great in all its features. So a cheap fast achro will underperform and not be worth its entire price, but an "expensive" ED scope IS worth its higher price. Quality is a saving.


Edited by Ben the Ignorant, 22 July 2021 - 03:37 PM.

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#17 awong101

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Posted 22 July 2021 - 02:25 PM

How about the William Optics Spacecat/Redcat 51?

 

I highly recommend it for its unbeatable portability and impressive quality, check out my video of it here:

 

https://youtu.be/RhBM4AcN0Bs



#18 NYJohn S

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Posted 22 July 2021 - 03:00 PM

Looking for advice on a refractor to use primarily as a wide-field scope (not really interested in a reflector or a mak). I do a lot of double star observing (have a Vixen A80Mf f11 and an old Vixen 60mm f15 for this), but I want to look at some larger clusters, like Melotte 20 or the Hyades, and asterisms such as Kemble's Cascade or the Coathanger.

 

I'm thinking of three options (I'm planning to use a Porta mount):

 

1) Svbony SV503 70mm ED f6 (I'd really love to get the AT70ED, but can't get it shipped to Japan)
2) Svbony SV48 90mm f5.5 achromat
3) Skywatcher 102mm f5 achromat

 

Open to other options as well, but as you can tell from my choices, my budget is around 300 - 400 US. I may want to upgrade to a 2-inch diagonal someday, but I already have a lot of 1.25" and .965 eyepieces, so I'm planning on using a 1.25 diagonal with the scope. And, I've thought about the Svbony 503 80mm ED f7, but its a little above my budget and I'm not sure the extra aperture and smaller field of view would be worth it for what I want to observe.

 

Thanks in advance for taking the time to read this post and any advice you can give!

Just wanted to mention none of the listed scopes will fit Mel 20 & Mel 25 with a 1-1/4" eyepiece. With a 2" diagonal and 2" eyepiece the 70mm f6 will fit them most comfortably. It's tight with the others.


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#19 aeajr

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Posted 22 July 2021 - 03:35 PM

Field of view is driven by magnification and the AFOV of the eyepiece. Using .965 and 1.25" eyepieces is what is holding you back.

My AT 102ED F7 is my grab and go. 2" focuser and diagonal plus a 38 mm 70 degree AFOV 2" eyepiece gives me about a 3.6 degree FOV. A 20 mm 82 degree gives me a 2 degree FOV. The ability to hit 200x for the Moon, planets, and doubles makes this an all purpose scope.

A similar achromat would be less expensive and lighter but the same would be true. Just more CA.

The point is, if you want a wide FOV go with a 2" focuser and one or two 2" eyepieces. Then go to your other eyepieces for higher mag.

You mentioned a driveway. Keep your scope in the garage and transport becomes very easy.

Edited by aeajr, 22 July 2021 - 03:48 PM.

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#20 LDW47

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Posted 22 July 2021 - 07:22 PM

Get the 102.

 

Color will be the issue, but a 4 inch f5 is still worth the compromises. I sold everything under 4 inch and use 5 or 6 inch achromats. I was happy enough but more satisfied after trying a Baader 495LP super sharp cut violet blocker. Obviously, my color issues exceed your choices.

 

EDIT in-home transport of the f5s was far far easier than the 76mm f15 and 4 in f8 tubes. Wall banging resolved. And I was always terrified I'd shatter my glass storm door on the last leg of the stuggle, um, journey.

 

On the 1.25 v2 inch ep, I have found I only use 2 inch barrel eps on the 30mm 80 or 70 degree eps, or the 100 degree 20. I usually bring just a Vixen 1.25 diagonal, so don't feel you're missing anything on the 2".

 

I have a wonderful 80 degree 20mm UO Widescan that has a barrel limited field at 1.25 and usually its plenty of field. Otherwise I skip right to the above eyepieces if I need a maximum, RFT field. Its rare for me to use a 20-30 mm 1.25 but if I do, one of the great 26mm/28mm plossls do the trick. I assume a similar 20mm/80 is out there.

 

A Baader 495LP makes a massive difference in using a fast achromat, I have classic Jaeger f5 achromats. On those big fast achros the resolution loss due to the short wavelength spread/defocus really hits you. The super sharp cut on the 495LP is great and provides a reasonable compromise overall. I do wish someone would redo the Chromacorr with the glasses out today though.

 

Wratten filters cut too much useful spectrum, and Baader Semi APOS and Fringe Killers are nice but not nearly good enough for a fat f5. The 495LP is a huge bargain, too, as bandpass filters go. Don't be tempted by lesser filters like Wratten numbers.

 

Consider selling the Porta and switching to a more capable Alt Az. If you aRe still shopping, broaden the search. The load capacity on the Porta is limited, and it will overload the bearing surfaces with the one sided load. How do I know? My big Jaegers, likely due to the glass mass, were bound up and sticky to move on my Porta II. I loved the Alt Az set up so I moved to a T head version, the AYO Swiss copy Williams EzTouch, and Sergio Bonilla.

 

If Vixen had just put an off side thread for a CW or CW shaft I would still have it. I there are a few beefier small Alt Az mounts out there, check some CN posts. Anything with a T head or CW provision would help. As always more mass means more mount and tripod. The short tubes really help on vibration damping issues, too.

Whats more capable in an AZ than a Porta or am I missing something


Edited by LDW47, 22 July 2021 - 07:25 PM.


#21 LDW47

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Posted 22 July 2021 - 07:24 PM

Field of view is driven by magnification and the AFOV of the eyepiece. Using .965 and 1.25" eyepieces is what is holding you back.

My AT 102ED F7 is my grab and go. 2" focuser and diagonal plus a 38 mm 70 degree AFOV 2" eyepiece gives me about a 3.6 degree FOV. A 20 mm 82 degree gives me a 2 degree FOV. The ability to hit 200x for the Moon, planets, and doubles makes this an all purpose scope.

A similar achromat would be less expensive and lighter but the same would be true. Just more CA.

The point is, if you want a wide FOV go with a 2" focuser and one or two 2" eyepieces. Then go to your other eyepieces for higher mag.

You mentioned a driveway. Keep your scope in the garage and transport becomes very easy.

How much CA do you get viewing doubles and clusters and asterisms which I thought was the OP's main objective



#22 LDW47

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Posted 22 July 2021 - 07:31 PM

But...

 

attachicon.gifstar test achro.jpg

 

attachicon.gifstar test achro 2.jpg

 

...as you see in the star test, some miscollimation remained because the cell itself was tilted relative to the tube. I could never get the centering screws to do a perfect adjustment because the flexible plastic cell twisted, and the tilt conspired with it to make unpredictable and unstable collimation. Shimming the space between the cell and tube mitigated the problem but didn't solve it.

 

 

 

More than that, as the hairy green ring testifies, the doublet has a serious turned-down or raised edge, so contrast can never be great. The Ronchi pic makes it more obvious.

 

attachicon.gifronchi achro.png

 

These are the problems with an 80mm f/7.5 cheap achro in a plastic cell, with f/5 beams and/or larger diameters they would be worse. Trying to solve them costs more in time, effort and boredom than going for a more expensive semi-apo that's made right. The 80mm ED f/7 semi-apo I got had none of these mechanical and optical issues, on the contrary it's great in all its features. So a cheap fast achro will underperform and not be worth its entire price, but an "expensive" ED scope IS worth its higher price. Quality is a saving.

A lot of fellow astronomers love those cheap achros that aren't cheap performers, thats what counts not the $ sign  All the numbers and diagrams are meaningless when you are gazing sky ward on a dark, clear nite



#23 Ben the Ignorant

Ben the Ignorant

    Mariner 2

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Posted 23 July 2021 - 01:44 AM

Yes, many fellow stargazers have those cheap fast achros but they should know exactly what they are getting into before buying them. I bought an 80 f/7.5 for a me and another for a friend's birthday, his family uses it in their holiday home, they are only casual stargazers so top-end apo quality is not essential. Their achro needed a set of centering screws, though, factory alignment was far from good enough. They got the scope with the more acceptable mechanism and optics and I kept the other for me to improve more.

 

Among other problems the tube was not cut square:

 

achro tube.jpg

 

 

 

And the resulting diffraction pattern, at 140x if my memory is correct, was clearly decentered:

 

decentered achro.jpg

 

My apo 80mm doublet, 80mm triplet and 115mm triplet have no manufacturing or assembly problems, none. So as a basic scope all I can recommend from experience is an ED doublet.


Edited by Ben the Ignorant, 23 July 2021 - 01:51 AM.


#24 aeajr

aeajr

    Hubble

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Posted 23 July 2021 - 03:16 AM

How much CA do you get viewing doubles and clusters and asterisms which I thought was the OP's main objective

I don't see any CA in the AT102ED. Others might pick up a trace amount but I don't see it.

Great for wide field. I can go 3.6 degrees FOV with my 38/70 eyepiece.

Very clean split of the double double at 160x. Beautifully sharp.

Edited by aeajr, 23 July 2021 - 03:20 AM.


#25 Jon Isaacs

Jon Isaacs

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Posted 23 July 2021 - 06:37 AM

I don't see any CA in the AT102ED. Others might pick up a trace amount but I don't see it.

Great for wide field. I can go 3.6 degrees FOV with my 38/70 eyepiece.

Very clean split of the double double at 160x. Beautifully sharp.

 

If you point the AT-102ED at Venus and take a look about 200x, I think you will see some chromatic aberration, I know I do and my eyes are not very sensitive in the blue.  But in general, there is very little CA visible.  

 

Jon


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