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Downside to Dobsonians?

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#1 Neptune

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Posted 24 November 2020 - 09:50 AM

Always had SCT's and APO Refractors for the last 40 years. Thinking of going to a 14" dob. I'm getting older and lugging the 11" Edge in and out of the house is becoming less and less appealing.  Was thinking of a 14" short focus DOB (read compact at f3.5 or f4).  But, I have been spoiled by GOTO, so I would want that and a drive of some sort, I'm not a big fan of the nudge, bump or push.  So, what is the downside to DOB ownership?  I'm in GA now and we have lots of dew.

 

David



#2 TOMDEY

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Posted 24 November 2020 - 10:10 AM

Downsides:

 

>dew... possibly more than some others, unless addressed with heaters

>many/most of the cheap ones have crummy optics

>need to be aligned

>open config gets dirty easier

>if too fast, needs coma corrector and premium eyepieces

 

Note that all of the above can be easily addressed; most people go way too fast... F/3.5 is unnecessarily fast in that little size.    Tom


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#3 mic1970

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Posted 24 November 2020 - 10:11 AM

I don't know if these are downsides, and it sounds like you probably know some of these.

 

1.  Less magnification if you like planets, but your collecting more lights so pick your poison.

2.  Depending on what you get, traveling with it can be difficult for tub dobs.  At 14 inches you are probably going with trusts though.

3.  Some would say collimation, but I don't really see that as a downside.  It is just a set up step like polarizing a mount.  

4.  You can get go to dobs, so that isn't really a downside

 

For me that's really it.  


Edited by mic1970, 24 November 2020 - 10:12 AM.

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#4 siriusandthepup

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Posted 24 November 2020 - 10:12 AM

A Dob that size won't be much easier to lug around. Getting older means - no big Dobs.

 

Think 10 - 12" f/5 Dob max.

 

Then you need a drive system - I would suggest just getting encoders and a Sky Commander type computer for locating objects. A full on GOTO system adds thousands to the price tag and extra weight as well.

 

I'm there too buddy. No more 18" scopes for me either.

 

good luck!!


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#5 mic1970

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Posted 24 November 2020 - 10:14 AM

Agree on the weight comment below.

A Dob that size won't be much easier to lug around. Getting older means - no big Dobs.

 

Think 10 - 12" f/5 Dob max.

 

Then you need a drive system - I would suggest just getting encoders and a Sky Commander type computer for locating objects. A full on GOTO system adds thousands to the price tag and extra weight as well.

 

I'm there too buddy. No more 18" scopes for me either.

 

good luck!!



#6 Keith Rivich

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Posted 24 November 2020 - 10:31 AM

Always had SCT's and APO Refractors for the last 40 years. Thinking of going to a 14" dob. I'm getting older and lugging the 11" Edge in and out of the house is becoming less and less appealing.  Was thinking of a 14" short focus DOB (read compact at f3.5 or f4).  But, I have been spoiled by GOTO, so I would want that and a drive of some sort, I'm not a big fan of the nudge, bump or push.  So, what is the downside to DOB ownership?  I'm in GA now and we have lots of dew.

 

David

Not to many downsides to a dob/newt. That's kind of their point. Simplicity.

 

If you can fit it through your door you can leave it assembled and use a hand dolly to move it around. Collimation is less an issue if you can leave it assembled. 

A tracking platform will take care of your tracking without go to.

A Stellar Cat type drive would give you tracking and go to. 

Dew is pretty easily controlled.

 

A 14" scope is a nice upgrade to the 11". A 16" would be even better...not much different in mobility and weight as compared to a 14". 


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#7 jerobe

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Posted 24 November 2020 - 10:38 AM

The main reason I don't have a big dob is the ergonomics of viewing positions.  With a dob, I'm always kneeling, bending, crouching, hunching over and craning my neck.  After an hour or two, I'm finished. I do much better with smaller scopes on tall alt-az mounts.  I give up a few inches of aperture but enjoy the session much, much more.


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#8 mic1970

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Posted 24 November 2020 - 11:04 AM

LOL... I think Santa needs to bring you an astronomy chair.  

 

The main reason I don't have a big dob is the ergonomics of viewing positions.  With a dob, I'm always kneeling, bending, crouching, hunching over and craning my neck.  After an hour or two, I'm finished. I do much better with smaller scopes on tall alt-az mounts.  I give up a few inches of aperture but enjoy the session much, much more.


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#9 MitchAlsup

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Posted 24 November 2020 - 11:36 AM

most people go way too fast... F/3.5 is unnecessarily fast in that little size.    Tom

I am going to disagree--to an extent.

 

There are advantages to speed in that size:: take my 13" F/3

 

13newbase02.JPG

 

Notice that the primary is at hip height, above the dust and moisture of the ground.

Notice the assembly is so short one can hold the top and the altitude bearing at the same time, making precise altitude adjustments more precise.

 

The only downside is one needs very short FL EPs in order to operate at high power.


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#10 vdog

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Posted 24 November 2020 - 11:48 AM

I have a 16" dob.  It's big, bulky, and heavy.  I store it in an outdoor garage on wheels, with my observing area being the paved area right in front of the garage so that I can easily roll it in and out for use.  If I had to carry it anywhere to use it, I probably wouldn't.  I can't imagine a 14" will be much easier.  You'll need a plan for how to get it in and out of storage and to and from your observing area.

 

I get dew where I am, but not to an extent that a shroud doesn't easily remedy.  However, we don't see nearly the humidity levels you do, so you may likely need heaters.


Edited by vdog, 24 November 2020 - 12:49 PM.

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#11 *skyguy*

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Posted 24 November 2020 - 11:55 AM

The only downside to a big dob ... for me ... is observing at the zenith.


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#12 BradFran

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Posted 24 November 2020 - 11:56 AM

Big, heavy and need to cool down. Collimation is regularly needed. They are a pain to point at the zenith (Dobson's hole). Tracking, setting circles or even full go-to are possible, but add another layer to deal with. A ladder or step stool may be required depending on size and observer height. Your 14" f/4 should be fine without and should even allow seated observing. I have comfortably observed while seated on a cat's perch with a 16" f/4. Dobs are well worth it in the end though! waytogo.gif


Edited by BradFran, 24 November 2020 - 11:59 AM.


#13 Eddgie

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Posted 24 November 2020 - 11:57 AM

If you can store it at ground level where you can move it with a hand truck, wheel barrow handles, or a dolly of some sort, a 14" will be easier to use than the telescope you have.  

 

If you can't, then that is a different story.  The base on these mass produced units way in at a hefty 75# to 85# and I can tell you that the shape makes them awkward to pick up even though they have handles. The ground board forces you to lean quite far over because there is no way to lift with only your legs.  If you think you are prone to back issues do to age or other factors, this should be a serious consideration.  The OTA will also be heft and not super manageable.

 

If you go for a new super-fast premium reflector, at this point in the expenditure curve, you might want to start considering an image intensifier and a 10" Dob with Go2.  The 10" is far more manageable.

 

Dismiss the remark about crummy optics. I do not think that is the case at all, though the optical quality would be variable and you should have no reasonable expectation that they would be excellent, though my own 12" Go2 dob did have quite good optics.

 

Anyway, even with a cheap 10" dob and an image intensifier, you will see things that you would not be able to see in a 14" or even 16" dob. 

 

Commercial 14" though is going to be heavy.  If you don't have a roll-out storage location, it is a lot to manage


Edited by Eddgie, 24 November 2020 - 11:57 AM.

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#14 sl-he

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Posted 24 November 2020 - 12:47 PM

LOL... I think Santa needs to bring you an astronomy chair.  

Hahaha, fully agreed grin.gif


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#15 cuzimthedad

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Posted 24 November 2020 - 01:01 PM

This year I took ownership of a 15" F/4.5 Teeter knowing there were things I'd have to do to make it work for me that aren't necessarily telescope related. I'm 65 and since retiring, not as active as I was which means I have to exercise, stretch, and keep on top of my physical health. I've been a dob and refractor owner for 14 years and take for granted that each scope comes with it's own set of user definitions. My concern is the end game which is observing and enjoying my time doing so. Once you've accepted having to set up and cool down, learn the different details of drive systems (for my dob it's Nexus DSCs and ServoCat drive), and become familiar with it's operation, you can set forth and have a blast. I think it's important to define your own limitations and expectations. For me, the 15" works just peachy, but in 7 or 8 years, maybe not so. But for right now, in the moment, I'm very happy with my telescope and I don't really look at it's functionality as a downside at all. Think of it as driving a motorcycle or a Camaro. Both are fun to drive, both get you to a destination...or not...but both have different handling characteristics to learn. I don't know if any of this helps or if I just rambled on to much, but good luck with your search and have fun with the journey!


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#16 Jon Isaacs

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Posted 24 November 2020 - 01:16 PM

1.  Less magnification if you like planets, but your collecting more lights so pick your poison.

 

 

:scratchhead:

 

That is not how it works for me.  The ability of a telescope to magnify an object is primarily related to the aperture.  

 

Some thoughts:

 

- Dobs are quite good about dew...

 

- Eyepieces:  An F/3.5-F/4 Dob means you will want to be investing in a Paracorr 2 and some rather expensive eyepieces, if you don't have TeleVue or similar eyepieces already.  

 

- Ergonomics with Dobs is like any SCT or refractor, a good chair is the key to comfort and relaxation. 

 

- Dobs, even GOTO Dobs are well suited for people that like to tinker with things.  To a Dob owner, Collimation is an opportunity to assist the scope in providing the best possible views, it's something to be embraced and enjoyed.  To an SCT owner, collimation is generally something they'd prefer to avoid... 

 

Jon


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#17 Thomas_M44

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Posted 24 November 2020 - 02:23 PM

Lack of polar RA tracking was about the only functional downside I felt during my 12 years of owning/using an 8-inch f/7 Dobsonian. (BTW: most satisfying all-around telescope I've even owned, sold only due to illness-related near bankruptcy)

 

Having said that, my 8-inch f/7 Dob with good balance and nice smooth teflon bearing surfaces was *much* smoother and easier to manually guide during higher magnification viewing than the my little TV85 on it's quirky and un-smooth (expensive) HD-4 alt/az head.

 

Presently, I see there are clever DIY (and some offered complete online ) motor-driven tilting-platform RA tracking bases for Dobsonians which seem entirely adequate for 30+ minutes of adjustment-free visual viewing.  This seems quite a refreshing development.

 

Lets face it: John Dobson's clever innovations spawned nothing less than a revolution in affordable and transportable large-aperture amateur telescopes --a gift to us all flowerred.gif


Edited by Thomas_M44, 24 November 2020 - 02:25 PM.

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#18 gwlee

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Posted 24 November 2020 - 02:25 PM

I have owned about eight inexpensive, good quality 6” or 8” dobs over the years. All of them where a bit shakier than I would like, and the 6” scopes had poor focusers. Otherwise, no complaints. 


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#19 RobertMaples

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Posted 24 November 2020 - 03:23 PM

A Dob that size won't be much easier to lug around. Getting older means - no big Dobs.

 

Think 10 - 12" f/5 Dob max.

 

Then you need a drive system - I would suggest just getting encoders and a Sky Commander type computer for locating objects. A full on GOTO system adds thousands to the price tag and extra weight as well.

 

I'm there too buddy. No more 18" scopes for me either.

 

good luck!!

The Orion xx14g (14" with full goto) is only $600 more than the xx14i (14" with Intelliscope object locater) - $2900 vs.$2300.


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#20 TOMDEY

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Posted 24 November 2020 - 03:41 PM

I am going to disagree--to an extent.

 

There are advantages to speed in that size:: take my 13" F/3

 

attachicon.gif13newbase02.JPG

 

Notice that the primary is at hip height, above the dust and moisture of the ground.

Notice the assembly is so short one can hold the top and the altitude bearing at the same time, making precise altitude adjustments more precise.

 

The only downside is one needs very short FL EPs in order to operate at high power.

No coma corrector?!



#21 coopman

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Posted 24 November 2020 - 03:45 PM

Too much aperture can cause temporary blindness.


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#22 Neptune

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Posted 24 November 2020 - 03:51 PM

If you can store it at ground level where you can move it with a hand truck, wheel barrow handles, or a dolly of some sort, a 14" will be easier to use than the telescope you have.  

 

If you can't, then that is a different story.  The base on these mass produced units way in at a hefty 75# to 85# and I can tell you that the shape makes them awkward to pick up even though they have handles. The ground board forces you to lean quite far over because there is no way to lift with only your legs.  If you think you are prone to back issues do to age or other factors, this should be a serious consideration.  The OTA will also be heft and not super manageable.

 

If you go for a new super-fast premium reflector, at this point in the expenditure curve, you might want to start considering an image intensifier and a 10" Dob with Go2.  The 10" is far more manageable.

 

Dismiss the remark about crummy optics. I do not think that is the case at all, though the optical quality would be variable and you should have no reasonable expectation that they would be excellent, though my own 12" Go2 dob did have quite good optics.

 

Anyway, even with a cheap 10" dob and an image intensifier, you will see things that you would not be able to see in a 14" or even 16" dob. 

 

Commercial 14" though is going to be heavy.  If you don't have a roll-out storage location, it is a lot to manage

Eddgie, That's why I was going with a 14" f3.5, not one of the mass produced pieces.  There was a gentleman in CA that purchased a DobStuff brand DOB and it looked VERY manageable for that size. Not sure what the exact weight of the whole scope or components was though.  Very fast cool down with a sandwich type mirror as well.  Visual only.

 

I am going to disagree--to an extent.

 

There are advantages to speed in that size:: take my 13" F/3

 

attachicon.gif13newbase02.JPG

 

Notice that the primary is at hip height, above the dust and moisture of the ground.

Notice the assembly is so short one can hold the top and the altitude bearing at the same time, making precise altitude adjustments more precise.

 

The only downside is one needs very short FL EPs in order to operate at high power.

Now this looks almost grab n go.  I like the styling also.  Did you make it yourself?

 

I have a 16" dob.  It's big, bulky, and heavy.  I store it in an outdoor garage on wheels, with my observing area being the paved area right in front of the garage so that I can easily roll it in and out for use.  If I had to carry it anywhere to use it, I probably wouldn't.  I can't imagine a 14" will be much easier.  You'll need a plan for how to get it in and out of storage and to and from your observing area.

 

I get dew where I am, but not to an extent that a shroud doesn't easily remedy.  However, we don't see nearly the humidity levels you do, so you may likely need heaters.

vdog, That's why I was going with a 14" f3.5, not one of the mass produced 'boat anchors'.  There was a gentleman in CA that purchased a DobStuff brand DOB and it looked VERY manageable for that size and it had a sandwich mirror for extremely fast cool down with the advantage of lighter weight.


Edited by Neptune, 24 November 2020 - 07:32 PM.

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#23 brentknight

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Posted 24 November 2020 - 04:13 PM

Always had SCT's and APO Refractors for the last 40 years. Thinking of going to a 14" dob. I'm getting older and lugging the 11" Edge in and out of the house is becoming less and less appealing.  Was thinking of a 14" short focus DOB (read compact at f3.5 or f4).  But, I have been spoiled by GOTO, so I would want that and a drive of some sort, I'm not a big fan of the nudge, bump or push.  So, what is the downside to DOB ownership?  I'm in GA now and we have lots of dew.

 

David

David,

 

A premium Dobsonian has very few downsides.  High quality mirrors, smooth yet accurate motions, significant size and weight reduction.

 

Your absolutely right about the "boat anchor" Orion and SkyWatchers.  I've been there and the best thing I did was to get the base rebuilt by DobSTUFF.  But I don't think you need to go as fast as F/4 if your looking for a manageable size.  The F/4.6 in my old XX14g never gets high enough that I can't sit in my adjustable chair...

 

XX14g on DobSTUFF.jpg

 

If you can go without adding motors, you'll save yourself a lot of unnecessary hassles as these scopes are much easier to move manually than the mass produced ones.  Get a Nexus or something similar if you need the Push-2 (Star-hopping works just fine for me).


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#24 MitchAlsup

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Posted 24 November 2020 - 04:58 PM

No coma corrector?!

I do not consider needing a coma corrector a "disadvantage"

 

I consider it a part of the cost of a big Newtonian (as it helps scopes as slow as F/6 al the way to as fast as you dare.)


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#25 MitchAlsup

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Posted 24 November 2020 - 05:00 PM

Now this looks almost grab n go.  I like the styling also.  Did you make it yourself?

I made every piece except:: Primary, secondary, and focuser.

{Lockwood, Lockwood, Starlight Instruments}


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