Bintel vs Skywatcher f5 6” newts

[RussellH]

So Bintel have Skywatcher 6” f5 newt listed as an Astrograph, but not the GSO version of the same scope.

Skywatcher https://www.bintel.com.au/product/skywatcher-black-diamond-150mm-f-5-ota/?v=6cc98ba2045f
Bintel https://www.bintel.com.au/product/bintel-6-inch-f5-ota/?v=6cc98ba2045f

So what are the differences that make one for AP and the other for visual? The description just talks about a small secondary mirror. Is that it.

Also, does anyone have an opinion on the Skywatcher for AP?

Thanks. Russell.

[Startrek]

Russell
Done my homework over a 6 month period on the Skywatcher 6” and 8” f5 scopes vs the Bintel GSO 6” and 8” f5 and f6 scopes for both visual and astrophotography

They both get the job done in their price category but I find the GSO focusers superior and the general build a bit better quality ( finish , hardware used , paintwork etc) Also the secondary and primary mirrors have better adjustment in the GSO

GSO use BK7 glass for their mirrors
Skywatcher use Pyrex which is a little more expensive
Personally I can’t see any difference

I have a Skywatcher 12” Goto Dob which is an excellent instrument for the money. Only reason why I bought a Skywatcher is that GSO don’t make a 12” Goto dob

I think from memory the Skywatcher 6” and 8” are slightly heavier than the GSO

I went GSO for my astrophotography rigs and Skywatcher for my big visual rig

Very happy with my decision

My 2 cents ....

Martin

[raymo]

All SW Newts have sufficient back focus for AP, some GSO Newts do and
some don't, so maybe the listed 6" f/5 doesn't.
raymo

[Startrek]

All the GSO 6” and 8” newts reach focus
When I bought mine I asked Don from Bintel to fit some 3mm cork spacers to bring the primary mirror into the OTA a bit
A 3mm packer or spacer gives you more travel on your focuser
It’s just a tweek I requested and it’s great especially for planetary and lunar focusing on live view with your Barlow’s or Powermates etc...

[RussellH]

Thanks guys.

This may be my lack of understanding, but I don’t know why they just don’t build them all with more back focus these days, and throw in an e tension tube to use if needed to keep the eyepieces at the correct distance. Is there an option to just fit low-profile focusers to increase back focus?

I think all astronomy retailers need to overhaul their shops. With Atrophotograohy being so accessible these days, i think every scope and affected accessory should state their backfocus distances. Also a side issue but every item should state their mounted weight, so the impact on loading up your mount can be calculated, since there are so many extras you can throw on these days.

[RussellH]

I as just looking at coma correctors if I wanted to try an f5 instead of f6, and may have found a solution to both several problems at once.

Bintel Coma Corrector
https://www.bintel.com.au/product/bintel-coma-corrector-2-inch/?v=6cc98ba2045f
GSO Coma Corrector
https://agenaastro.com/gso-2-coma-corrector.html

This coma corrector has a back focus requirement of 75 - 80mm. So shouldn’t this mean no matter whether you throw it on an AP classed, or visual classed scope, it’ll provide plenty of back focus distance? At least for Canon Camera’s, with a standard back plane at 55mm, there should be room to spare. From what I’ve found so far, without any extra attachments, it’ll need a 15 or 20mm spacer to reach back focus.

So what am I missing here? If a coma corrector is recommended anyway (maybe not for an f6, but it can’t hurt) what’s bad about doing this, and why wouldn’t it be a universal solution to the question of whether there’s enough back focus or not on a particular scope?

The two main concerns I can think of is possible vignetting down the long focus path (easily corrected in post editing) and the extra long tube length throwing off mount balance and being slightly less stable mechanically and possible visually.

There must be a big gotcha - what am I missing?

[Startrek]

You will need a coma corrector for both f5 and f6 newts
Remember you are looking at a $300 or $400 telescope ( budget low end ) not a $2000 or $3000 newt
I’ve tried the Bintel GSO coma corrector for AP and it doesn’t cut it , only for visual
The tried and tested coma corrector around the world for years is the Badder MCCP mk3
Fits straight into my Canon 600D then into the focuser not other adapters needed
Mines works perfectly to the edge of field in both scopes
There not cheap but a small investment for ongoing long term results, you get nice round clean stars
Once again I did my homework !!
A coma corrector won’t fix your back focus
Have the spacers fitted to the primary and your off and running
Cheers

[RussellH]

As you say, $300 telescope. Adding a $330 coma corrector just seems wrong :) But of course it’s transferrable to any upgrades I make, just kind of hard when starting as all the extras are turning out to be triple the price of the scope itself.

Is a 3mm spacer enough to cope if you starting adding extras such as an oag though? Or does. 3mm spacer give you more than 3mm back focus distance? I’m concerned somewhere down the track it’ll hit that back focus wall again.

I’m also still trying to see if I can fit an 8” onto the HEQ5. I know 10kg is the recommended max. I’ve got what I think are all of the extras and the f5 8” total at about 10.5kg at the moment.

If it wasn’t for all the recommendations against it, the f4 would come in at about 10kg. Apparently somewhere once there was even a carbon fibre version, which would have weighed even less, but it seems to be not available currently.

[Startrek]

The 8” f5 is to big and heavy for the HEQ5 particularly if you intend to do long exposure AP ( 3 to 10 minute subs ) If you are only going to do short exposures up to 1 minute then the 8” f5 should be OK. If you are buying a second hand HEQ5 then it will be more subject to periodic error so with more weight you just multiply the problem so guiding will struggle a bit , plus add poor seeing conditions and frustration looms
The 8” is more prone to wind than the smaller scope that’s why you would need the bigger mount EQ6-R
Don’t underestimate the 6” f6 it’s a great scope
I bought the 8” f5 to chase after galaxies amongst everything else down at my dark location
3 to 4mm spacers or packers will give you an extra 2 to 3 turns of your focuser , plenty
Here’s some of my images taken this year with the 6” F6 and HEQ5 mount

All the best !!

[RussellH]

I know Martin, if it wasn’t for needing it customised, I probably wouldn’t still be debating, given I’m now committed to a coma corrector wither way. The 6” f5 would be nicer if it wasn’t for the focal length drop. Going from 900mm to 750mm seems a lot on paper, although when I put it into the FoV calculator at Astronomy Tools, it doesn’t look that much different. Plus the 900mm barely covers the main Orion Nebula cloud whereas the 750 surrounds it nicely, so that is a bonus.

The depressing part of the FoV calculator is looking at the planets with these specs, they’re just tiny points of light, so I guess there’s no escaping a 2nd scope for Planetary imaging. I haven’t been game to look into the requirements for that, as I know the $$$ signs will scare me away, but I know the temptation will keep gnawing in the back of my mind.

*edit* a thought. How badly does a barlow affect imaging quality? Maybe a 2x barlow on the f5 would satisfy me on some of the smaller NSO’s for now?

[tileys]

A benefit you will get with the Skywatcher over the GSO - at least for the time being - is that the newish ASI autofocusser is apparently compatible with the Skywatcher focusser but not the GSO one...

[RussellH]

Oh really? Well that puts a fly in the ointment. While the autofocusser is on my list, it is a “if manual doesn’t work” thing down the track. I am uograding to a 10:1 focusser though, so not sure if that makes a difference. Can you point me to where you found out this information?

[Startrek]

I dont use the astronomy tool calculator because my 6” f6 can easily fit the Orion Nebula and lagoon nebula in FOV with room to spare
On paper it shouldn’t but in reality no issue at all
My DSLR crop sensor frames nearly all objects in the sky except for Eta Carinae ( about 75% ) and the running chicken ( about 50 %) but these are huge objects
Don’t always trust these calc tools with templates , to me they are only a guide

Cheers

[Startrek]

I use a Televue 4 x powermate and 5 x powermate to image planets
Get my focal ration up to around f25
The Canon 600D on 5 x zoom get you close to 1:1 pixel resolution
This combo works well but ultimately seeing conditions governs the quality of your planetary images

[RussellH]

Looking at the product details for the ASI focuser, it looks like the compatibility part is the mounting bracket. That shouldn’t be a big issue to overcome as I could probably design one that works on my 3D printer.

So the FoV tool is a bit out, fair enough, I’m still leaning towards the f5 at the moment, as I think I can get it with the 10:1 focuser for the same price as the f6 without.

As for the barlow, good to hear it can be done (not sure I can afford Powermate prices though). Even if not imaging, I need something to impress the wife to justify the money I’m spending, and there’s nothing like seeing the rings of Saturn to impress people.

[tileys]

Yes - I think it's just the mechanical linkage so a homeprinted bracket could put the focusser in the correct alignment with the GSO focusser I imagine - I have an f/4 with the 10:1 GSO focusser - I would be keen on getting the focusser as I'm not happy with my focus regime ;) - too much manual fiddling

[RussellH]

Yeah when I was investigating the F4 versions, it seems focussing is the only drawback people have issues with, but it’s a big issue. With the focuser and software to automate it, that would seem to nullify the f4 arguments, unless there’s more problems with them that I haven’t come across yet. Of course that assumes the software does a good job too.

Now if only they could get software and hardware to automate collimation of RC scopes, I’d be in nirvana with a wide newt and a long RC :)

[RussellH]

Bummer, the focuser listing was a mistake so no saving on the 6” f5 :(

[ausastronomer]

Hi Russell,

It isn't a problem with some telescope designs, but it is with newtonians. The more back focus you have, the larger the secondary mirror required to fully illuminate the required field size. For visual astronomy you want to minimise the size of the secondary mirror, as a larger secondary mirror causes slight degradation in image quality. For astrophotography the size of the secondary mirror does not matter.

Cheers,
John B

[RussellH]

Ahh right. That explains the descriptions talking about the secondary size. Thanks for the explanation.

I’m back looking at the 8” f5 again. I should be able to keep weight around 10.5kg if all the manufacturer specs are right. I know the concern is image stability with any movement, but my scope will basically be ina static position and I can possibly build a shelter. An 8” ends up same price as the 6” with an focuser upgrade.

[RussellH]

Having slept on it, I’m flip flopping again and am back to looking at the 6”. The focuser upgrade is the bother still.

How critical would focus be on a 750mm scope? Is the dualspeed focuser a must-have? They don’t produce one to fit the 6” model, so the manufacturers obviously don’t think so.

As an alternative, would a motor controlled focuser like the Orion Accufocus provide enough precision on a single speed focuser?

[Startrek]

Russell

Bintel’s ad for the Sky-Watcher 6” f5 newt is not Bintel’s writing its Skywatchers writing copied by Bintel
SkyWatcher name all their F4 and F5 newts as either Astrographs or suitable for astrophotography
I chose to buy the Bintel GSO 6” f6 newt instead of an f5 as it has a focal length of 900mm which gives you more flexibility with imaging DSO’s , Planets and Moon
I have irrefutable evidence that my 6” f6 newt can image anything in the night sky with good detail from my Canon 600D DSLR at either of my 2 locations both Sydney ( Bortle 8 sky ) and south coast NSW ( Bortle 3 sky ) I’m happy to send more images if more evidence is required or there is any doubt !!
As mentioned previously you must have a dual speed focuser to allow fine focus of your objects for AP. An electronic focuser is an overkill on this scope but you can go down that path if you choose
Bintel can fit a dual focuser to the 6” f6 newt as they fitted mine and it works incredibly well . Speak to Don Whiteman he has done everything for me on my 6” f6 newt ( unless things have changed but he is usually very accomodating )

Cheers

[raymo]

I have to disagree with you Martin, the SW $99 electric focuser I put on my
8" f/5 was the best accessory I had; no need to touch the scope and cause
vibration, and amazingly tiny adjustments possible with quick taps on the
focuser button, improved my focussing experience immensely.
raymo

[RussellH]

I don’t doubt anything you have said Martin, and I have already commented on your great images, but you had to get things customised to do it, and I wonder down the track if there’s issues, whether that will cause me grief as it’s not a spec machine? Plus my interactions with Bintel haven’t been great so far, even though I haven’t talked to Don, but what if he’s not there when I need help?

Regarding the focuser, I actually like to dabble with Arduino gear, and I found a couple of easy custom focuser mods this morning that look like fun projects. Parts to build one are about $25 - $35 and that allows interfacing to software which will autofocus for you. So while it’s not the easy route, it is heaps more enticing, especially for the price, so I’m not concerned about the 2 speed upgrade at this stage, and if the do-it-yourself fails, I can also get the 2 speed myself down the track. I realised my concerns about light leakage can probably be taken care of just with some foam packing material if needed.

[RussellH]

Oh, also I note in their description for the f6 it says no coma corrector is required, but I assume that’s just because they’re marketing it for visual astronomy, not photography. Even with the f6, the coma corrector is still essential? It’s a big chunk of cash :(

[raymo]

You don't have to customise anything with SW Newts, ready to go out of the box, except for the $99 electric focuser of course.
raymo

[RussellH]

I’m talking about the Bintel model.

[Startrek]

Dear All
My comments are purely from my own experiences and so far everything has worked ok for me
I’m not suggesting my journey is the only journey but it has worked for me and I just want to help others starting out just like I did
Through great advice from many IIS members ( Raymo included ) doing my own homework, getting out there and observing and imaging , trial and error etc...I’ve been fortunate to get off an running in astrophotography pretty quickly ( and not waste to much money ) with good results and enjoying every minute of it
Clear Skies
All the best !!

[RussellH]

Well Martin, you’ll be happy to know, I’ve just placed an order with Bintel for the 6” f6. Don was busy, but the other guy I talked to knew what I wanted, so they’re going to make the mods.

Given the random bits and pieces coming from elsewhere for the guide scope and the autofocusser, it’s going to be a while before I have my final setup, but now at least I can get some sleep without tossing and turning with indecision.

Well, about hardware anyway. Now I can start the software investigation and get confused by the millions of options....

Thanks for putting up with my flip-flopping in this thread everyone and special thanks to Martin for all his input and patience.

Russell.

[ausastronomer]

I haven't had much need to buy astronomy gear over the past 15 years, as my telescopes are all excellent for my needs, and I am more than happy with the 4 Pelican cases full of eyepieces I have had for a very long time. On the rare occasions I do need something, I always call Don at Bintel.

They may not always be the cheapest, but I am more than happy to pay the very small premium for the exceptional customer service. Don has been an astronomer himself for decades and knows what most people need, unlike many astronomy retailers who merely redistribute cardboard boxes and tell people what they think they want to hear.

Cheers,
John B

[Startrek]

Thanks Russell
I sure you will be happy once you get your head around the set up and running of your mount and telescope

One question I haven’t asked you , what location will you be imaging from ? Urban or country area ?

John
Yes Don is a wealth of knowledge , he’s done just about everything in Astronomy , decades and decades of experience both in Australia and overseas

Russell

I’m happy to let you know what I use in regard to software for Goto and tracking, guiding , stacking and processing but most important get other advice from guys a lot smarter than me

Happy to help where I can

Martin

[RussellH]

I’m in the foothills of the great dividing range, west of Brisbane. Pretty much dark out the back yard at least. The highway is in the distance to the north, so some traffic lights from there is all.

Software I’m going to start compiling a huge list of whats available in the hopes it may help others, assuming I don’t give up half way through :)

[Startrek]

Russell
Lucky you, nice dark skies !!

For both my 6” f6 and my 8” f5 newts I polar align using the Synscan polar alignment routine ( I have no view of the SCP at both my sites )

For Goto and tracking I use EQMOD , Stellarium scope and Stellarium my planetarium ( all free )

For DSO , Planetary and Moon capture I use Backyard EOS classic edition ( about $65.00 )

For Stacking I use deep sky Stacker ( Free )

For processing I use Startools ( about $ 80 I think )

All the above very user friendly for the beginner and intermediate

Cheers

[RussellH]

Great.

I’m hoping todo as much as possible via my iPad and Raspberry Pi, at least up to the image capture stage, processing will still require a PC probably. Not sure I can go completely computer-less, but I hope I can get pretty close.

I’m starting a spreadsheet tomorrow, so will hop over to the software forum as start collecting from there. I’ll add your stuff to the list.

Russell.

[ausastronomer]

What a lot of people don't realise is that Don is quite an accomplished telescope builder.

In the photograph attached the scope on the left is an 18"/F4.5 Obsession, 2nd to left is Gary Kopff (Wildcard / Argo Navis). In the middle is a 20"/F5 Don Whiteman / Mick McCulloch creation, with a superb Jerry Wilkinson Galaxy mirror, proudly known as "Hector". On the right hand side is a 25" / F5 Obsession and between the 25" Obsession and "Hector" is myself and my then 10 year old son Jake. Hector belongs to Andrew Murrell.

The photograph was taken in 2006. The 2 x Obsessions were pretty new. Hector was built in about 1992 and was 14 years old at the time of the photograph. During the first 14 years of its life, it was one of the most used telescopes on the planet, as can be seen by the varnish wearing off, which didn't affect it's performance. Hector has the distinction of being the instrument used by Andrew in discovering his planetary nebula (Murrell 1) in 2004.

As can be seen in the photograph Hector shares a lot of similarities of design with the classic Obsession style scopes, notwithstanding Don and Mick built it about 6 or 7 years prior to Dave Kreige releasing his book, "The Dobsonian Telescope".

[MatthewB]

Hi RussellH i have a Skywatcher Black Diamond 6in 750mm Newtonian on a HEQ5 PRO GOTO mount and i am extremely great Scope you can not go wrong Don was very helpful when i was shopping around and working out what i needed .

I hope this helps

[RussellH]

Thanks Matthew.

I’m still awaiting delivery, so haven’t had a chance to check the scope out yet, but I’m getting little surprises in the mail every day from the dozens of other bits and pieces I’ve ordered from eBay to complement the scope and my electronic interfaces to computerise eveything.

Russell.

[RussellH]

Well, after emailing them, I’ve just heard back from Bintel and they’re telling me they can’t make the mods I requested, so I’m back to square one and don’t have a telescope :( They said I’d have to call and talk to Don on monday to find out why he can’t make the mods. I’ve spent all my money on other accessories on the assumption this was the scope I was getting, so now I’m up the creek. Most of it’s not a drama, but if it comes down to eweight issues for the mount again, I’m in trouble.

So, any suggestions what I do now?

[RussellH]

Right, if anyone’s still reading this, I just want to finish with the fact I’m going for the Skywatcher 6” f5 and Don from Bintel has sorted my earlier miss-step with the f6 scope, so kudos to the customer service on that one.