Image versus non-image Newtonians

[ftclausen]

Hello All,

I'm looking at this 150mm Newtonian Skywatcher Black Diamond (https://www.ozscopes.com.au/skywatcher-black-diamond-150-750-dual-focus-f5-photo-reflector-ota.html) but there are other examples of Newtonian being image vs. non-image.

I want to do both visual observing and imaging with, potentially, this OTA. If I get the "photo" Newtonian does that mean visual is somehow compromised?

Extending my question if I may:

I am based in Sydney's inner-west so want to observe/image what will be primarily be planets, double stars, clusters, and perhaps some nebula if possible. Would a 150mm Newtonian reflector be OK for this situation? I am also considering something like the Celestron C6 XLT but these kinds of OTAs are a bit scarce at the moment.

The mount I am looking at is a Saxon HEQ5 that'll give me some future proofing for heavier OTAs in the future.

[raymo]

The main difference as far as you are concerned is that many Newts are aimed at visual use, and don't have enough back focus to allow a camera to come to focus. All SW Newts can be used for either AP or Visual. The 6" SW would do just fine.
raymo

[PaulSthcoast]

Hi Fred and welcome.

I would suggest to search for posts from Stratrek ( Martin).

He has taken many outstanding images with a humble
150mm Newtonian.

He also has many procedures for imaging set up, should
that be the path you venture down.

Lots to discover.

Paul.

[The_bluester]

To expand a bit on the difference. The "Imaging" Newtonians will typically have a slightly shorter tube (So the primary mirror is a little closer to the secondary, and the eyepiece) which might mean that to bring some eyepieces to focus you need an extension tube to move the EP further out, but many camera combinations you would not be able to rack the focuser far enough IN to get it in focus without the shorter tube. Imaging tubes may also have a bigger secondary mirror and sometimes bigger diameter and/or "better" focusers.

Plenty of people have taken tubes that could not be brought to focus with a camera attached and shortened the tube or moved the primary mirror cell up inside the tube to fix that problem but if you want a dual purpose scope it is easier to have an "Astrograph" tube and use an extension to get eyepeices to focus if required than to have to modify a less suitable scope.

[Startrek]

I use 3 different Bintel GSO newts for imaging
6” f5 newt
6” f6 newt
8” f5 newt

and all reach focus with my Canon 600D and new ZWOASI2600MC cooled OSC without any special adapters etc...

Ryan maybe be able to advise on his newts too

Cheers

[ftclausen]

Firstly, thanks all for the timely replies and friendly welcome. I'll quote inline:

Startrek wrote:
> I use 3 different Bintel GSO newts for imaging

How are these for visual observing?

As for The_bluester's reply: Thanks for the details! it would be ideal to not have to modify the OTA itself to get going with either visual or imaging. And I plan to buy a dedicated astro imaging camera but not yet dived in depth there. Are these (like the ones from ZWO) like "eyepieces" themselves? They don't "sit on" an existing eyepiece?

[Startrek]

For visual observing these newts are great , I also have my big kahuna the 12” f5 Goto newt dob which is unbelievable
However the quality of observing is dependent upon atmospheric conditions and the quality of your eye pieces amongst many other factors
I only use premium Televue eye pieces ( Delos , Panoptic, Ethos and Apollo 11 ) which provide excellent views in all my scopes
I forgot to mention , with my 6” and 8” newts I image both Deep Sky Objects ( DSO’s ) and planetary imaging
Cheers

[ftclausen]

Good info, thanks! With your and the others' help I'm looking to pull the trigger on a Bintel 6" F5 (https://www.bintel.com.au/product/bintel-6-inch-f5-ota/?v=322b26af01d5) combined with the Saxon HEQ5. Primary investment obviously being the mount because I want to use that for a while and have some room for growth.

I'm going to practice visually to start with and learn the set-up then start imaging once more familiar with it.

And I'll need a 12v power supply so was thinking of just looking at Jaycar or somewhere like that unless there is a compelling reason to use a Celestron one.

[Startrek]

Great choice !
Buy a Powertech 12V 7.5amp power adapter from Jaycar ( $45 ? ) for your mount (based on having house mains power ( extension lead ) available)
The mount needs a good solid power supply even though specs say 3amp is good enough, but buy the 7.5 amp. Comes with a cigarette socket so your mounts power cord can plug straight in
Cheers
I have procedures for the HEQ5 mount to set it up ready to observe or image as follows -
Find True South line
Align tripod to True South
Set up tripod
Fit mount head
Set Home Position on mount
Balance your telescope
Synscan polar alignment routine

If your interested let me know ....

[mura_gadi]

Hello,

A little more basic, the F ratio is the multiplying factor that is based on the size of the mirror by the length of the tube. The lower the F ratio the faster the scope is, lower number = faster the scope.

Visually faster scopes need to be corrected with additional hardware and require far more expensive eyepieces to handle the steeper light cone. Slower scopes tend to be longer therefore harder to balance, move around and generally need a larger mount/tripod than a faster scope with the same aperture.

Imagine the same size mirror with a longer tube, your field of view(FOV) reduces as the tube length increases. With a newt you will often see a 4 line spike associated with stars, at F9+ that effect diminishes to the point that you won't see them at all much like a refractor scope.

Generally slower scopes of the same aperture allow you to see more detail, in the bands of Jupiter, the rings around Saturn etc, but won't allow for really wide fields of view.

At F5/6 your closer to an all-rounder scope, the F6 will be slightly better optically, the F5 will have a wider FOV with the same EP and still be a good optical scope. Below F5 you start to have problems with optics from a visually point of view. Faster scope at F4.5 or less are great for digital image collection, but would really suck visually with cheap eyepieces for instance and no correction hardware like a parracorr.

Like most things in life one shoe doesn't fit all, I'd stay above F5, considering your location most DSO's are going to be a stretch unless you really know what your doing with your camera. Some DSO's like M42 are just big and bright and like planets show up well despite surrounding light pollution. Having said that, there are plenty of DSO's you could capture in a Bortle 6+ area. (Bortle is a reference to your light pollution levels)

You can overcome most problems with deep enough pockets though.


Steve
Ps. Get a copy of the "The Southern Sky", cheap as chips 2nd hand and plenty available, nice section at the back of the book with the best 25 DSO (deep space objects) at the back and plenty of good advice even if some of it is now very out dated(re: imaging with film!!!, omg I remember when you had to worry about your photo's being public as they shot out of the film processing unit... ).

[ftclausen]

Where I will use the mount I do not have house leads available - I live in a unit so walk to the common area without power. It sounds like with the Powertech one still needs a lead _while being used_? I will not be able to charge it during sessions - just afterwards.

If you have procedures for the HEQ5 available then anything is much appreciated! Thanks!

[mura_gadi]

Read a recent thread about power options

[ftclausen]

Thanks for the excellent write up especially the difference between F5/6 - those are my choices right now. And I'll definitely look for "The Southern Sky" book too.

After your write up I'm leaning F6 and with imaging (when I get to it) I'll be doing smaller brighter objects; both because of where I live and experience level.

Finally, while deeper pockets can overcome challenges, alas even deep pockets can't buy more time :)

[mura_gadi]

I'd lean towards a GSO scope for three reasons;
1) The entry level scope have a fine focuser sooner in GSO line up than SW line up,
2) GSO have "bob's nobs" which are toolless collimation screws - simply better at night full stop,
3) GSO uses BK7 glass which focuses on returning more light accepted by the eyeball, the other glass type just returns more light full stop which isn't necessarily better as it can interfere with your useable light waves - visually anyway.

For glass type refer to the military specs for mirror/lens design, they are very well documented for procurement proposes and explain the different glass types very well.


Steve

[Startrek]

Yes you need main power to plug the Powertech 12V 7.5 amp power supply , most of these power units are mains plug in unless you go to a stand-alone 12V battery but that’s another story

Attached are the procedures for the HEQ5
Cheers

[ftclausen]

I was just speaking to Bintel also to get their advice (and stock levels) on with regards to the 6" f6 vs f5 Bintel GSO newt. They said their 6" f5/6 newts are meant for visual and won't reach focus with, for example, a ZWO. I see your ZWOASI2600MC works without any special adapters which is great - I am wondering if an entry-level ZWO like ASI120MC-S would work as well. I've love to go with one of those newts but it'd be a pity if basic imaging was not possible out-of-the-box.

[ftclausen]

Thanks for much for these guides and clarifying the Powertech use.

[Startrek]

Sorry but who ever you spoke to at Bintel ( obviously not Don ) is totally wrong. They are probably reading off their website information on these scopes which mentions they are visual scopes and not really meant for DSO imaging, but I’ve imaged so many DSO’s with these scopes I’ve lost count , in fact I won Bintel image of the month in October 2019
My 6” f5 and 6” f6 newt reach focus with both DSLR and OSC ( APS-C sensors )
Here’s some images with my 6” f6 newt using both DSLR and cooled OSC camera captured from Sydney Bortle 8 horrible light polluted skies
Cheers

[Startrek]

Also the ZWOASI120MC is more suited for planetary imaging not DSO imaging
Just bear in mind with long exposure DSO imaging you will need to “Autoguide” which is another thing to learn with more expense.
If you want an entry level camera for DSO imaging with these newts then I would recommend the ASI1294MC and ASI071MC. I use the ASI2600MC which is their high end DSO cooled colour camera but is unbelievable in performance

[ftclausen]

Thanks for confirming your success with the Bintel 6" newts and the images look amazing - good work! I will, most likely, put in an order for the Bintel (GSO) 6" F6 + Saxon HEQ5 tomorrow.

I do want to do mainly planetary imaging but, for my initial foray into imaging, I'll have to do non-planet things since they're below the horizon for now (and looking at the ZWO cameras you mentioned). I was thinking of mainly trying with clusters, double stars, the moon, orion nebula. I appreciate that without autoguiding it'll limit DSO options but I look forward to just practicing and take satisfaction from small incremental improvements.

Finally, immediately after getting the mount and OTA, I'll be just doing visual while learning the set-up.

[Startrek]

Thanks Fred
One thing I failed to mention ( apologies) , the 6” f6 Bintel newt comes with a single speed focuser as standard. For imaging you will definitely need a dual speed focuser ( I had mine replaced from the start care of Don at Bintel )
If intend to image later this year , I would have Don order a dual speed focuser now and fit it later on ( I suspect they wouldn’t have a dual speed focuser in stock as it’s a special order for this size scope )
Martin

[ftclausen]

Ah, yes, I'll be sure to request one of those. I actually went there today and (I didn't have the sense to ask for a name) the person who helped mentioned the 6" F5/6 newts did have a dual speed focuser (or maybe one of them did). Anyway, I'll be sure to order that if not present already.

[ftclausen]

To close the loop: I am now the proud owner of

- SkyWatcher HEQ5 Pro Dual: Bintel recommended the SW mount due to parts availability in Australia. Functionally similar to the Saxon EQ5 one; certainly for my needs anyway.
- Bintel 6 Inch f/5 OTA newt: Initially I had requested the f/6 OTA but this was not in stock anymore so went with f/5. From reading/discussions I think it'll make minimal difference for visual viewing (as compared to f/6) and will have a wider field of view. In any case, a vast improvement over what I have now.

This is for my 40th birthday on the weekend so I'm resisting unboxing until then - reading manuals and the guides Martin so kindly sent in the meantime :)

I'm sure I will have some follow-up questions before too long.

[Startrek]

Enjoy your new rig !!
Happy to help
Now for some clear nights !!
Martin

[AdamJL]

+ happy birthday!

[sharpiel]

The cloud gods will not be happy about this at all :rofl:

[Muzfox]

Martin, you seem to be the man to talk to regarding the 6" F6 GSO Newt. I notice Andrews are now advertising it with the dual focuser which is sweet. Do you need a coma corrector with it? I'm currently DLSR imaging at around 400mm and think this scope would be ideal of me to punch in to 900mm on my HEQ5. Just trying to work out what acessories I would need to at least get going with it (currently thinking scope + collimator).

Thanks in advance!

Murray

[Startrek]

Hi Murray
Yes my 6” f6 still suffered from coma in the edges so I took advice from many APers and bought a Baader MCCP Mk3 coma corrector, fixed the issue on my 6” f6 and 8” f5
These work down to f3.9
They cost a bit but are light weight , quality optics and screw straight into your Nikon or Canon t ring adapter. You can even screw filters on the end of it
I use a ZWO Duoband filter in my Baader CC for my ZWO2600MC cooled OSC camera
Cheers
Martin

[Rerouter]

Did the baader help move the focus out? my 6" GSO really needs the focuser racked in right now for photos, and would love to move that back a little.

[Startrek]

Ryan
I had to move my primary mirror on my 6” f6 GSO Bintel newt closer to the focuser end by about 5 or 6mm using round cork spacers ( they are available from Bunnings ) on the primary mirror support
I removed the original Chinese spacers which were 2mm thick and used 2 Bunnings cork spacers which moved it out about 5mm or 6mm
This gave me plenty of in and out travel on the focuser for imaging

[raymo]

Just buy an SW Newt, and you won't have to mess about, they're all
suitable for visual or AP out of the box.
raymo

[Startrek]

Raymo
I own and have used both both Skywatcher and GSO newts over the past 4 years
Skywatcher OTA’s especially the focusers are inferior in manufactured quality ( not optics ) IMHO to GSO , poorly machined thin walled adapters and grub screws have crappy threads
It is worth the “mess about” on the 6” GSO which takes 15 minutes to do
By the way my GSO 8” f5 newt reaches focus out of the box
I’m considering a 10” f5 newt for my new Obs late this year and it will definitely be a GSO
Cheers
Martin