Seeking advice on either OTA or dobinson

[joss]

hi all, im new here so i dont know if this has been answered before but here i go.

i have an EQ5 celestron mount with an 8"reflector and am looking to go for either a 12" or 14" reflector. i would preferably like an OTA i use with my EQ5 mount.

my question is will my mount and its current counterweights support the weight of said OTA or will i need to upgrade.

my back up option is a dobinson but i prefer the EQ mount so i can have high magnification and be able to easily follow my target.

can anybody help me out? thankyou

[Stu]

7 hours ago, joss said:

hi all, im new here so i dont know if this has been answered before but here i go.

i have an EQ5 celestron mount with an 8"reflector and am looking to go for either a 12" or 14" reflector. i would preferably like an OTA i use with my EQ5 mount.

my question is will my mount and its current counterweights support the weight of said OTA or will i need to upgrade.

my back up option is a dobinson but i prefer the EQ mount so i can have high magnification and be able to easily follow my target.

can anybody help me out? thankyou

Hi Joss,

Welcome to the forum and Happy New Year!

I think many would say the EQ5 is at its limits with an 8” reflector on it. The load capacity for visual is quoted at 9kg, and a 200PDS at 8.8kg without accessories. An 8” newt is also quite large, so is prone to catch the wind which adds to the challenge for the mount.

Can I assume you are using this for visual?

A 12” or 14” OTA is a much bigger and heavier proposition. The Skywatcher 300PDS is listed at 25kg, whilst the aluminium Orion Optics VX14 is 20kg, plus accessories, so either would be way beyond the capacity of your EQ5.

Personally, if I were doing visual then I would opt for a Dobsonian in this size. They are cheaper, easier to handle and generally more stable because the tube is supported on both sides. You can also buy something called an Equatorial Platform which you sit the dob on and this provides around 45 minutes of tracking time before needing a quick reset (takes a few seconds). This really helps with high power observing. I’ve added a picture of my 8” f8 scope on an EQ Platform, but they will take big dobs quite easily.

If wanting to do imaging then I would reconsider completely before doing anything as there are likely better/easier ways of achieving your goals, most likely using a refractor. The book Making Every Photon Count by Steve Richards is a great place to start.

If really wanting to use a large OTA on a mount, then I think the minimum needed would be something like an AZEQ6, possibly on an updated tripod like the Berlebach Planet. Used for visual in AltAz mode with a lightweight aluminium OTA like the Orion Optics VX12 or VX14 it would likely be OK.

@Captain Magenta likes a challenge and successfully uses a 12” Newtonian on an AZEQ6 so hopefully he can add some comments based on practical experience; I’ve used big refractors on this type of mount but not a Newt, although I did put a 12” f6 newt on an AYODigi II Alt Az mount briefly, and it wasn’t that easy or stable to use!

Hope that helps a little.

[Mr Spock]

I used to have an older model EQ5 (not the one I have now) on which my OMC-140 was quite happy. I then purchased a Skywatcher 250mm Newtonian OTA thinking I could stick it on the EQ5. It wobbled like a jelly. I quickly purchased an EQ6 which was better, though I wouldn't put anything bigger on it. 

If you want to follow at high magnifications then you need tracking. The Skywatcher Flextube Goto scopes are a good choice. My 250mm tracks really well and it's two components (base and tube) are easy for me to lift (I have a bad back). I see no reason why a fit person shouldn't easily move a 300 or 350.

The other option is a standard Dob on an EQ platform.

Putting a 300 or 350 on an EQ mount would need a heavy mount. You would need to be prepared for a lot of lifting unless you plan a permanent observatory.

[Captain Scarlet]

6 hours ago, Stu said:

@Captain Magenta likes a challenge and successfully uses a 12” Newtonian on an AZEQ6 so hopefully he can add some comments based on practical experience; I’ve used big refractors on this type of mount but not a Newt, although I did put a 12” f6 newt on an AYODigi II Alt Az mount briefly, and it wasn’t that easy or stable to use!

Yes indeed I had a SW 300p steel-tube newt on my AZ-EQ6 for a while, and it was (is) fine, even in some reasonably windy conditions. I only ever use it in Alt-Az mode. That newt came in at 27kg including its rings, eyepiece, finders etc. I've replaced it now with a carbon-tube 300mm-mirror newt which has saved me around 6kg. I should add also that the AZ-EQ6 sits on a Berlebach Planet tripod, and has an upgraded ADM main saddle. The biggest faff about it is actually the set-up, involving multiple trips carrying sometimes awkward loads to wherever I want to observe. It takes me around 25 minutes, though I plan to get a wheelbarrow at some stage which will shorten the time condiderably.

Magnus

 

Edited January 1, 2022 by Captain Magenta
added pic

[joss]

thank you all for your replies and a happy new year to you all.

reading through your replies has been very helpful and as as a result im throwing out the OTA plan and now looking at either a 12" reflector with a mount included or 

a 14" Dobinson with GOTO. I should of mentioned in my original question that i am primarily interested in visual observation but i am also open to looking into a bit of photography further down the line. I didn't know you could an Equatorial set up for a dobinson so that's now an option also. ill keep my 8" reflector as a secondary/backup scope as its pretty easy to move around. I cant set up a permanent observatory so i have to load my scope into my van and travel away from my village to minimize light pollution.

Any thoughts or advice on my 2 front runners the 12" skywatcher and the 14" skywatcher dobinson?

thankyou

[John]

Dobsonian is the design of the mount. The OTA that is mounted on it is, 99% of the time, a newtonian.

Any newtonian larger than 10 inches in aperture needs a pretty massive equatorial mount to be a useful instrument. 

For visual observing, I would stick to either a 12 or 14 inch newtonian on a dobsonian mount.

 

 

 

 

[joss]

good evening all

i went with the 14inch on the dobsonian mount in the end and despite seeing multiple pictures of them i was still surprised by its size, especially when it arrived on a pallet 🤣  i started to wonder what on earth i was getting into. couple of things that kinda concerned me was the mirror seems fairly exposed, there is no cover at the bottom of the tube and it seemed to attach with just 3 screws with springs over them. There were no instructions on how to put it all together so i watched everything up through trial and error. the other kinda problem i cant seem to solve is the longitude and latitude  co-ordinates on the goto, for example my longitude is -4 02' 56.40"W

but the goto wont let me put in a minus and the first set of digits is 3 and second is 2 example (000,00)

Am i being really dumb and missing something? if so how to i un dumb myself? 

thankyou

[Cornelius Varley]

3 minutes ago, joss said:

the other kinda problem i cant seem to solve is the longitude and latitude  co-ordinates on the goto, for example my longitude is -4 02' 56.40"W

but the goto wont let me put in a minus and the first set of digits is 3 and second is 2 example (000,00)

The longitude coordinates (first set of numbers to be entered) will be between 000 00 E/W and 180 00 E/W in degrees and minutes. The minutes component cannot be greater than 59. Latitude will be between 00 00 N/S and 90 00 N/S. E/W N/S are entered by using the scroll buttons on the handset. In your example the longitude would be 004 03 W.

Use Latitude and Longitude Finder on Map Get Coordinates (latlong.net) or Synscaninit or the Synscan app to find your coordinates.

[Mikeshuerto]

Hi Joss

Sorry, I know this post is 9 months old, but I'd thought I'd throw in my 10 cents.  In fact, I found your post when researching the topic.I  have owned a  SW 14" GOTO Dob for 2 years, and I have also pondered putting the OTA on an EQ8 for 'hoped-for' improved imaging performance.  So far I have not pushed the button. As someone mentioned above, for visual, the Dobson mount is great as is.  The primary reason for not trying an EQ mount  for imaging is that I already get great images with the Dobson mount.  I find that using a good astrocam, appropriate filters, short exposures and good processing software I can produce images that come close to fairly serious images generated on EQ mounts. The second reason is the cost of the mount, and the probable need to build an observatory to shelter it.    Here's a link to my astrobin page with images taken with the Dob.   Dont mean to show-off, but just want to demonstrate that with appropriate accesories a Dob can be a great imaging scope!  https://www.astrobin.com/users/MikeHuerto/