Larger aperture vs tracking

[stevejack]

Hi All,
Thought I would guage some opinions on this...

I have a 10" dob and am considering adding argo navis and an EQ platform or EQ6 perhaps. However, I am wondering whether instead I should grab a larger GSO 16" dob..?

Reason being - I can't see myself getting into astrophotography for quite a few years - and I at the moment I mostly view DSOs at medium to low powers.. the larger aperture of the 16" would be great for this and tracking isn't such an issue at these mags correct?

Currently I am using a laptop and analog setting circles + a digital inclinometer to find objects which is PRETTY good but obviously not great.

Would I be better off going for the larger aperture given my viewing preferences, or spending that money on argo navis + an EQ platform/EQ6 which would allow higher mags + more eypiece time to view the (dimmer) objects?

Of course I would like to buy both, but this beggar can't be too choosy :lol:

any opinions on the advantages/shortcomings of each? Its a question of how much I am willing to spend on this hobby, rather than how long I am willing to wait/save so it's one or the other.

[Paddy]

Hi Steve,

As a dedicated star hopper, I'd go for the bigger scope. I noticed no more difficulty observing with 16" vs my old 12", both without tracking, and the difference in detail visible in the 16" has been well worth the upgrade. The more so if you're going up from a 10".

[Bassnut]

Tracking isnt a such an issue with 16" :scared:.

umm, thats all wrong :D, a 16" scope is way heavier than 10', and probably has a longer FL, imaging/guideing hell, the EQ6 wont take that :lol:.

Stick with viewing with a 16" dob, WAY less money :P

[Gargoyle_Steve]

Whatever you do regards aperture, the Argo Navis is pretty much THE best accessory you can add to your scope. I too have done the "check laptop / move scope" thing, and it's cheap if you already have the laptop, and there ARE great reasons to have a laptop as well (ie running Starry Night Pro, etc) but the Argo Navis is the most direct, easiest to use, etc.


Steve

[stevejack]

Sorry mate - I was referring to the magnifications I am/will be using (low power) when observing which makes tracking less important than if I was using higher mags (on planets for example).

I just worry that for visual use only, spending another ~$2k on a 10" scope still only leaves me with a 10" scope :P
When I bought the 10" it was all that I could fit in my vehicle but things have changed now and I can transport a larger dob without issue.

If I get the Argo Navis on my 10", I'll need to purchase completely new encoders/mounting hardware if I upgrade to a larger scope correct? Is only the handset transferable?

Thanks for the advice guys, it's great to get your opinions on this :thumbsup:

[Ian Robinson]

Why would you need entirely new encoders for the Argo Navis, has the chap who manufactures them told you this ?

I'd think that so long as he knows the encoders , he could set your Argo Navis up to use the existing ones , so you would just have to reinstall on the big scope's axes.

[gary]

Hi Steve,

Gary Kopff from Wildcard Innovations here. Merry Christmas.

The good news is when migrating from the 10" to a larger aperture scope you
can typically retain the encoders and then only need change the encoder
mount hardware.

As an extreme, here is a link to a picture of a 48" scope, "Bararella", belonging
to a customer in Limpia Crossing Texas, which has an Argo Navis fitted.
http://www.wildcard-innovations.com.au/images/lowrie1.jpg
If you look closely, you can see the unit mounted on the altitude trunnion.

With an Argo Navis installed onto a Dob on its own, this provides a
'PUSHTO' system to allow you to locate and identify objects.
In other words, it helps you find more stuff.

Argo Navis also fully supports Dobs mounted on equatorial tables as well.
Or you can place a Newtonian on a mount such an an EQ6 and Argo Navis
supports that as well.

The majority of Dob owners don't own or use equatorial tables. They simply
nudge the scopes. As it turns out, as a rule of thumb, the better quality
premium commercial Dobs tend to have better 'feel' to them when you
move them compared to the generic commercial Dobs built at low cost in Asia.
'Buttery smooth' is a good way to describe the motions of a well built Dob.
If you have ever been lucky enough to get behind the wheel of a premium
performance car and compare its handling with a low cost commodity car,
you will know what I mean.

However, despite the fact they often feel great to push around manually, what
has become increasingly popular on premium large aperture Dobs
are motorized slew and track systems.

For Dobs in the 16"+ aperture class, the most popular tracking solution
these days is the ServoCAT slew and track system. The scope operates
in Alt/Az mode and there are a pair of servo motors fitted to each axis of
the mount. The ServoCAT is a 'black box" servo controller and the Argo Navis
interfaces to it and performs all the object offset and tracking rate
calculations on its behalf.

Again the big 48" scope in Texas uses a ServoCAT and they are incredibly
popular options on scopes from companies such as Obsession and SDM
as well as on home-built Dobs.

For highly portable Dobs with large apertures, the new Ultra Compact designs
will fit in the back of nearly ever car. See
http://www.obsessiontelescopes.com/telescopes/18_UC/index.html
http://www.obsessiontelescopes.com/telescopes/15_UC/index.html

These premium scopes are possibly more than you budgeted but might give
you some idea of the path ahead should the bug really bite.

The lower cost generics out of Asia, such as the LightBridge 16 and GSO 16
certainly provide enormous amount of bang for your buck and aperture rules.
However, they will never feel as nice to use as the premium Dobs when you
push them around and they require a lot of room in the car.

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au

[bmitchell82]

well having looked at club meeting nights at the difference between a whole bucket load of telescopes i can tell you one thing the difference between a 6" dob --> 8" dob is big. same with a 8 --> 10" but the difference between the 10 --> 16 floored me. Taranchula neb is like picking a spotlight out of a dark field. and faint faint fuzzies aka Ghost of Jupiter shows detail. Eta carina has colour ect ect even orion was starting to change a bit in colour not its normal blue hue.

If your not planning on photography then let the aperature virus run loose get the biggest baddest piece of machinery you can swallow!

I guess the only thing holding amature astronomers from going bigger than say 10/12" for photography is mount costings! when you look at 10k+ for a mount, and 5k+ for a piece of reasonable kit, its not cheap. but in also saying that CCD's/DSLR's are so sensitive you don't need aperature as much.

thats my 2 bobs worth and logic for you to chew on.:thumbsup:

[gary]

Hi Brendan,

Differences in color perception between individuals is interesting.

The topic of whether one can perceive color or not when observing M42 is
an old popular one.

For example, when I look at M42 with 8" of aperture, the first thing I think
of is that it is quite colorful, with lots of red/magneta and green watercolors.
This certainly is not any special skill and I guess I am just lucky.
Having assisted queues of the general public on occasion to look at M42
through telescopes, I have sometimes quizzed them as to what they saw
with respect perceiving color. Though I have never conducted a rigorous
study, I would say that the ability to discern at least the magneta/red and green
in M42 through 8" is the rule rather than the exception, based on the people I
have informally quizzed. Though one might speculate that a ten year old might
have better a stronger sense of color perception than, say, a sixty-five year
old, I also sense that age is not a big a detriment as it is with so many other
abilities. For example, sometimes when I quiz someone in their fifties or sixties
who has never looked at M42 in a telescope before and ask them whether
they see any color, the reaction can be a politer variant of "of course I see
it is in color. It is obvious, isn't it? Why are you asking me?" :) Yet on other
occasions I have people even in their twenties and thirties tell me that it is
all just black and white, even when other younger and older family members
have no trouble perceiving it.

Some observers say they can see color in M42 naked eye.

Color perception is a complex and sometimes surprising and counterintuitive thing
and it is interesting to read some of the older papers on the subject by Edwin Land
of Polaroid fame.

With regards aperture, you are absolutely correct. Aperture rules. Hope
you get the chance to look through something even larger soon. 25" scopes
are available for views at events such as the IceInSpace Astrocamp and
South Pacific Star Party.

By the time you get up to 36" I can tell you you could barely be bothered
wanting to use digital imaging as it looks possibly even more spectacular
with your own eye ball in real time. :thumbsup:

Happy New Year!

Best Regards

Gary

[bmitchell82]

Yes i could only imagin something like a meter wide mirror. Perth obs in biction has some good gear, though im especially fond of the old 1900's one they have there. im not sure what size the mirror is but it isn't small and i can remember omega cent as bright as a normal star and clearly seperated stars.

I guess the reason why i am running with photography for now is that i cant see those faint fuzzies without having to have a mirror that size. Dont get me wrong im all for looking at them in real time, theres nothing that beats your own photographic rendering of a image in your head!

One day i will more than likely get a massive dob, but i just don't have the carrying capacity with a little coupe and its not that easy to lug a big mirror around by yourself.

So last night when the minister of war and finance approved the purchase of the eq6 i was stoked because all i need now is a guide scope and camera to run in it and a cannon 350d,400d,450d and im away! Plus she can look in and see what im doing. :D

[stevejack]

Hi Gary thanks for post - you've certainly cleared it up for me.
It's great to know that I won't be wasting money on my 10" scope by buying the Argo for it now, if I eventually plan to upgrade to a 16" scope (or bigger?!?) down the line.

Cheers :)

[gary]

Thanks Steve,

You will certainly find it provides lasting value in this regard.

All the best for 2009, the International Year of Astronomy!

Best Regards

Gary Kopff
Wildcard Innovations Pty Ltd

[bojan]

Instead of Argo Navis, (too expensive!) have a look at Mel Bartels website
http://www.bbastrodesigns.com/BBAstroDesigns.html#Computer_Operat ed_Telescopes.

His stepper software is free (source available too), and for the same functionality as AN, you need just an old laptop and couple of encoders you can build yourself from old mechanical mouse (serial type).
I have it for years now (the whole system) and it works great.