12" Goto Dob, PD1 Package - What else do I need?

[Robert Anstruther]

Hi all

I took the plunge and have begun getting a setup together for AV.  I owned a Watec 120N and done quite a bit 2 years ago but since then I have had to sell my scopes to buy a house and have am just now getting back into it.

So so far I have;

12" Skywatcher Flex Tube Dobsonian GoTo

Phil Dyer Camera (full package)

UHC/LP/OIII and RGB Filters

I also do visual observing so was going to change the focuser to a 10:1 but I have read here and there if I use a reducer the in focus changes, so I am wondering what the effect of using a different fouser would do.  This thread shows a different camera but the same scope, however I'm unsure of the setup I would need with my 300p.  Does the 0.5x focal reducer attached directly to the camera?

http://stargazerslounge.com/topic/123173-samsung-video-dobson-xx12i/

The other question was with regards to a monitor - is a laptop sufficient or does other (I have seen people using old cctv monitor) viewing devices yield better results?

I have tried to contact Phil but the number on his site isn't working and I have not had an email back yet which is slightly worrying, however I understand this is probably more of a hobby than a business for him.

Hope someone can help.

Cheers

Rob

[Spacedout]

Hi Rob,

Welcome back to VA!  Others here will help on the focuser as I'm not too sure but regarding the monitor there are several things you can do.  Yes you can use your laptop you'll just need a frame grabber of sorts or like me you could just plug the video signal from the camera direct in to your TV if the TV is capable of course.  Also it is correct that an old CCTV CRT monitor will give a better image but the problem there is that they can be quite big and bulky.  My set up these days is slightly different but have a look at my gallery as all images were photos taken from my TV with no processing so it gives you an idea. 

Good luck

Karl

[DoctorD]

Hi Rob

The x0.5 reducer attaches to the 1.25" nosepiece on the camera and will move the focus point in towards the primary - you might have trouble achieving focus - if you do try without the reducer.

CCTV monitors, especially CRT ones give you greater control over the picture, however you can achieve good results with a lap top and a capture dongle with the added benefit of being able to record what you see. Try what you have before looking at anything else. Sharpcap is a flexible solution for video capture and allows you to adjust most setting on the camera and display.

If you plan on working remotely, a small monitor will help in setting up and alignment - Chris/Macavty spotted this one:

http://www.amazon.co.uk/gp/product/B0045IIZKU/ref=oh_details_o00_s01_i00?ie=UTF8&psc=1

Too small for real observing but great for alignment and pretty good resolution (I could not resist even though I have a 7" LCD monitor too!).

Hope this helps

Paul

[Robert Anstruther]

Hi Rob

The x0.5 reducer attaches to the 1.25" nosepiece on the camera and will move the focus point in towards the primary - you might have trouble achieving focus - if you do try without the reducer.

CCTV monitors, especially CRT ones give you greater control over the picture, however you can achieve good results with a lap top and a capture dongle with the added benefit of being able to record what you see. Try what you have before looking at anything else. Sharpcap is a flexible solution for video capture and allows you to adjust most setting on the camera and display.

If you plan on working remotely, a small monitor will help in setting up and alignment - Chris/Macavty spotted this one:

http://www.amazon.co.uk/gp/product/B0045IIZKU/ref=oh_details_o00_s01_i00?ie=UTF8&psc=1

Too small for real observing but great for alignment and pretty good resolution (I could not resist even though I have a 7" LCD monitor too!).

Hope this helps

Paul

Thanks alot Paul great info.

If I do have issues with focus do I need an extended c mount? Like the ones at the bottom of the page? http://www.modernastronomy.com/camerasAstroVideo.html

I think I'll use the PC to start because of its versatility, cheaper and easier for the time and also I can use if I goto dark sites.

[shirva]

If you struggle for focus can always move the scope on truss bars all though I dont think you need to...been wanting a 8" goto so keep us informed lol

[DoctorD]

Hi Rob

If you have problems focusing with the reducer, you will need to move the camera further in towards the secondary mirror.

You may be able to achieve this will a low profile 2"-1.24" adapter for your focuser or you may need to modify your scope (as Davy said, shorten the trusses).

I've no first hand experience of this so only echoing what I've read elsewhere (I've got a MAK, and SCT and a refractor).

Let us know how you get on.

Paul

[hemmi]

On my 10" truss dob, I had to shorten the  truss tubes by a full 3" to achieve focus with a .5x reducer.  If your dob is the truss type this is easy, but if its a solid tube you may have some difficulties.  A low profile focuser may help, if your close.  

[Robert Anstruther]

Super! Thanks! I spoke to Phil today so my camera will be on its way now.

I read somewhere about shortening the trusses, I just guess you need to ensure collimation is bang on after you do it.

My last conundrum is the optical train;

I'm going to get this focuser - http://www.firstlightoptics.com/skywatcher-focusers/skywatcher-dual-speed-low-profile-1252-inch-crayford-focuser.html

Now I want to use a focal reducer and also, possibly some of my filters.  However all my filters are 2".  If the nose-piece is 1.25" where are my filters and focal reducer going to go? (I haven't bought one yet so guidance on 1.25" or 2" would be great).  Should I place a 1.25" focal reducer on the nose-piece and my filters on focuser adapter?  Or should I try and mount the reducer (2" in this case) onto the filter and then both to the adapter?

I'm getting everything on the weekend or thereabouts but I want to flock the dob and so some minor mods to help the goto and seal the base unit prior to using it.

I'll start another thread once I have everything and do a 'Newbie Video Astronomy' thread and include all the conundrums I have met and asked questions about - followed of course by some pictures and videos! (May be a few weeks though!)

Clear skies

Rob

[hemmi]

Super! Thanks! I spoke to Phil today so my camera will be on its way now.

I read somewhere about shortening the trusses, I just guess you need to ensure collimation is bang on after you do it.

My last conundrum is the optical train;

I'm going to get this focuser - http://www.firstlightoptics.com/skywatcher-focusers/skywatcher-dual-speed-low-profile-1252-inch-crayford-focuser.html

Now I want to use a focal reducer and also, possibly some of my filters.  However all my filters are 2".  If the nose-piece is 1.25" where are my filters and focal reducer going to go? (I haven't bought one yet so guidance on 1.25" or 2" would be great).  Should I place a 1.25" focal reducer on the nose-piece and my filters on focuser adapter?  Or should I try and mount the reducer (2" in this case) onto the filter and then both to the adapter?

I'm getting everything on the weekend or thereabouts but I want to flock the dob and so some minor mods to help the goto and seal the base unit prior to using it.

I'll start another thread once I have everything and do a 'Newbie Video Astronomy' thread and include all the conundrums I have met and asked questions about - followed of course by some pictures and videos! (May be a few weeks though!)

Clear skies

Rob

I don't know of a way to install a 2" filter with this setup, maybe others may have a way.  As for the focuser, I have the same exact one.  Its a decent focuser with smooth movement, but it will sag with very heavy eyepieces or bino viewers when fully extended.  But I have had zero issues with this sagging from my mallincam.   Its no moonlight, but it is leaps and bounds from the cheap focusers most of these dobs ship with.  I think you would be happy with it.

Just be aware if you shorten the trusses, you will not be able to get regular eyepieces into focus anymore.  You may want to see if you can order spares! so you can switch them out when you want to do visual.

What dob do you have by the way?

[Robert Anstruther]

I don't know of a way to install a 2" filter with this setup, maybe others may have a way.  As for the focuser, I have the same exact one.  Its a decent focuser with smooth movement, but it will sag with very heavy eyepieces or bino viewers when fully extended.  But I have had zero issues with this sagging from my mallincam.   Its no moonlight, but it is leaps and bounds from the cheap focusers most of these dobs ship with.  I think you would be happy with it.

Just be aware if you shorten the trusses, you will not be able to get regular eyepieces into focus anymore.  You may want to see if you can order spares! so you can switch them out when you want to do visual.

What dob do you have by the way?

Thanks Hemmi

I am picking it up on Saturday - its a 12" Skywatcher GoTo Flex Tube.

I'm planning on placing some tubing on the trusses of equal length rather than cut the original ones then trying to lock them in place, I will see how it goes though!

Thanks for the info on the focuser, unfortunately budget only allows for it and I can't find another with a low profile as this, unless you have an idea of another?  Does

I'll have to think of a way or I need to buy more filters!

Thanks

Rob

[hemmi]

Thanks Hemmi

I am picking it up on Saturday - its a 12" Skywatcher GoTo Flex Tube.

I'm planning on placing some tubing on the trusses of equal length rather than cut the original ones then trying to lock them in place, I will see how it goes though!

Thanks for the info on the focuser, unfortunately budget only allows for it and I can't find another with a low profile as this, unless you have an idea of another?  Does

I'll have to think of a way or I need to buy more filters!

Thanks

Rob

Well in that case you can just adjust the tube length on the skywatcher tubes.  No cutting necessary, as it slides in and out

The focuser is fine, it should serve you well.  Just don't expect to hang heavy binoviewers from it while fully extended out.

[stev74]

Hi Rob,

As already said the Skywatcher isn't a truss dob it's a Flex Tube so there's no need to cut the tubes as they extend so all you need to do is don't extend them fully if you are using the x0.5 focal reducer - you should find if you extend the scope to about 1cm to 2cm below fully extended and tighten them there that should be enough. That's how it works with my 300P with the x0.5 focal reducer attached to my Mintron's 1.25 adapter, if you are buying a newer SW 300P you will find there are already extra locking points drilled into the flex tubes, see this thread for info.

If you want to attach 2" filters and don't want the expense of a filter wheel buy a 2" to 1.25"  adapter that's threaded for 2" filters like this one .

HTH

Steve

[Robert Anstruther]

Hi Rob,

As already said the Skywatcher isn't a truss dob it's a Flex Tube so there's no need to cut the tubes as they extend so all you need to do is don't extend them fully if you are using the x0.5 focal reducer - you should find if you extend the scope to about 1cm to 2cm below fully extended and tighten them there that should be enough. That's how it works with my 300P with the x0.5 focal reducer attached to my Mintron's 1.25 adapter, if you are buying a newer SW 300P you will find there are already extra locking points drilled into the flex tubes, see this thread for info.

If you want to attach 2" filters and don't want the expense of a filter wheel buy a 2" to 1.25"  adapter that's threaded for 2" filters like this one .

HTH

Steve

Great thanks Steve,  I understand about the lenght of the tubes as I don't have the scope yet I was unsure how to lock them into position other than the standard full height, I don't think mine will have the additional holes as its a few years old.  So if you use it 1-2cm before the full lock point are you just tightening screws against the tubes?

Thanks for the link, exactly what  I need!

Cheers for all the great help so far

Rob

[stev74]

Yeah you can just tighten the locking screws at any point on the tube, the locking points are there so when you are fully extended you have an easily repeatable point if you know what I mean which will add in collimation and achieving the same focus points but certainly not essential. It's a lot easier and cheaper to do it that way than having to buy a low profile focuser or seat the primary mirror higher up the OTA and for focusing eyepieces you can then just use a extension tube or an old barlow with the lens removed. 

[Robert Anstruther]

Yeah you can just tighten the locking screws at any point on the tube, the locking points are there so when you are fully extended you have an easily repeatable point if you know what I mean which will add in collimation and achieving the same focus points but certainly not essential. It's a lot easier and cheaper to do it that way than having to buy a low profile focuser or seat the primary mirror higher up the OTA and for focusing eyepieces you can then just use a extension tube or an old barlow with the lens removed. 

Thanks - I may still get a focuser but its great to know you still adjust.

I'll let you know how I get one.

Thanks again for your help everyone, can't wait to start observing and see some serious views!!