Anyone here using a Mark V with Newtonians?
Posted 29 December 2013 - 02:56 AM
I have a Mark V but it can't reach focus in my Newt even when I put the 1.7x corrector in the nosepiece. Is there a Newt-specific OCA for the Mark V?
Posted 29 December 2013 - 03:43 AM
Posted 29 December 2013 - 11:03 AM
It quality is excellent, and it works beautifully.
Coma is perfectly corrected and the view is all I could ask for.
As mentioned, the power is high, but I still use it with the Mak V and ES 24/68s and find that most targets will still fit into the field of my 12" f/4.9 dob.
But remember, I moved from a C14, and one of the main reasons I went with the 12" dob over the 14" dob was to enjoy the slighly wider true field and slighty lower powers I could get when binoviewing!!!
There is also this. I did not have quite enough in-travel using the factory focuser. I really loved the factory focsuer too, and I tried hard to find a way to save it, but in the end, had to move to a Moonlight.
With this configuration I am able to reach focus, and the end of the 1.7x GPC is just clear of the light path (barely).
This may be an issue with the Seibert for some scopes. Don't know.
And I don't know the magnification with the Seibert, but I personally used one Siebert device (1x GPC for refractors) and was not happy with the result. Perhaps the Newt GPC would be different, but I don't want to personally bother with it at this time.
Anyway, the Baader 1.7 GPC with coma correction works great, but my lowest power is 106x. This is better than I coudl get with the C14 and a Denk Supersystem though, so for me, I am getting wider bino fields than I was before.
I also have a pair of 35mm Ultmas if I just need low power (about 73x) but of course the true field is only slightly bigger than with the ES 2468s.
And again, if you don't have sufficent in-travel, you will need to change focusers, or pull a plate if you are using a Moonlight with shims. My Moonlight is sitting dirctly on the base.
It took a lot of time with a calculater to figure out what eyepeice tube would be optimal in the event that I ever decided to go with a Binotron (which had to have a lot of nose extension when using the factory focusey by the way, and the Moonlight will be better for that too.
Posted 29 December 2013 - 03:24 PM
I now have a Starstructure dob with a Moonlight focuser. Normally the problem is that I need an extension tube but with the Mark V I don't have enough intravel. I assume the Baader GPC would work fine but it doesn't come cheap ($279 + ship). I'm already planning for an equatorial platform so looks like using the BV with the SST has to wait. It's a pity: with the BV and tracking, my C11 was providing just as good views of Jupiter as a Zambuto+Ostahowski equipped Newt. There's something magical that happens with tracking and using both eyes.
I'm not after wide fields though (I have an apo for that reaches focus with the Mark V + 1.25x GPC) - it's mostly planetary obs so if I get extra magnification, that's ok especially since I like using longer fl eyepieces with more eye relief.
Also, taking the tilt plate off the Moonlight would be a deal breaker for me as it's the only way I can get the secondary centered in the focuser as the spider doesn't adjust laterally. So while I probably could get the Mark V to focus this way (it's very close), I'm going to go with the Baader GPC when funds permit.
Posted 30 December 2013 - 08:56 AM
Can you folks provide some info on this?
Don't want to highjack the thread, but I haven't seen much about newts and binoviewers.
Posted 30 December 2013 - 10:09 AM
For example, if the eyepiece in monovision is giving 100x, with the GPC it will give 170x.
The Newt GPC is not for use with a refractor.. For that you need the standard GPCs, and if you only intend to do planets, you would likely want to 1.7x GPC (assuming the scope will reach focus with it) becaues this will give you enough magnification for that use I would think.
You could also use a barlow, but a 2x barlwo will give much more than 2x when used with a Binoviewer. Maybe 2.4x to 2.6x depending on the barlow and binoviwer used (Shorty Barlow with long light path bino will be the most magnification, traditional barlow with short light paty will give the closest to 2x).
A caution. Not all Newtonians will reach focus with the Newt GPC.
The Newt GPC requires a 2" focuser that has about 38mm of in-travel.
In other words, if you use a 2" eyepiece and when the eyepiece is in focus, the amount of focuser tube exposed above the focuser housing needs to be about 38mm (it depends on the binoviewer used and the focal ratio of the scope, but 40mm is pretty safe).
If you do not have this much tube left, you will not be able to rack the focuser in enough to reach focus with the Newt GPC.
In most scopes, if you are short only a few millimeters, you can lift your mirror with the collimation screws (Just crank them all the way up, then move them down a few millimeters and re-collimate) and that may make up the difference.
In this case, if you really want to use binoviewers and can't reach focus even with the mirror all the way up, you would have to go to a low profile focuser.
And with this, you run the risk of the focuser tube intruding into the light path when the BV is in place, though a tiny amount of intrusion is not really going to do enough harm to be seen.
If you are serrious about doing it, you may want to start a different post asking on the measurments and such.
Posted 30 December 2013 - 10:16 AM
It looks like there is quite a bit more to this than just getting a set of binoviewers!. I have been thinking about saving up for a while to get an upgrade. It seems once you binoview you never go back!
I appreciate the explanation of the magnification. I would generally want to use this on the Moon and Planets but you never know once you get on the slippery slope. I will do a bit more research and put a post in when I have the money saved.
Also the binoviewer will cost more than the scope at that point and I'm not sure if its the way to go. Although I have been very pleased with my mirror from Orion and get some great planetary and lunar views.
I do appreciate your time and help.
Posted 30 December 2013 - 04:21 PM
Get a used pair of Celestron, WO, or Burgess binos and try it.
Even if you need a barlow, this will give you a low cost way to test the water (I call this the "Will it Float" test).
Look at Jupiter, the moon, or any number of Messier objects.
If you like what you see, then invest in the time to figure out what you need if you want to go more into Binoviewing.
And if it does not float your boat, sell it. You will get most (or perhaps all) of your money back, and you will know the answer to the big question of "What's it all about", and "Do I need to be there or not."
Posted 30 December 2013 - 09:13 PM
I will take your advice. It a good way to start and the WO binoviewer comes with the eyepieces. I appreciate your ideas.
Happy New Year
Posted 05 January 2014 - 12:21 AM
Baader 1.7X Newt Coma Corrector left, 2X Powermate w/ T-ring Adapter and Quick Changer right (attached to MkV). Both perform beautifully.
Posted 05 January 2014 - 09:51 PM
Posted 05 January 2014 - 10:59 PM
Posted 06 January 2014 - 02:43 PM