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1.25" or 2" accessories?

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#1 Sidewyz1

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Posted 03 August 2020 - 01:04 PM

Hey all, I'm excited to be here and I'd like to express my gratitude to all.

 

I've just purchased a Skywatcher 200P f/5.9 8" dob and am starting my research in accessories.  I think I need in order:

  • collimation tool
    • Cheshire or laser?
  • moon filter
    • adjustable or fixed?
  • solar filter
  • barlow
  • eyepieces

 

The scope has a 2" single speed focuser with a 1.25 reducer.  The only eyepieces I currently have are 1.25. 

$2-350 budget to start.  What should I get?   

 

PS already ordered Left Turn at Orion. 



#2 havasman

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Posted 03 August 2020 - 01:58 PM

I certainly agree with your placing collimation tools as #1 priority. But the moon filter, not s'much. I've had several and they all just degrade the image IMO. If you were anywhere around here, I could give you a couple. A healthy eye is capable of dealing with the brightness of even a full moon produced by much larger than 200mm apertures. Plan your lunar observing for session end or before a break and you'll maximize available image quality and never compromise any other observation or your time. Barlow? They're specialized tools not every kit needs. Just know why you're adding one if you do. If you go w/a solar filter I recommend you read the Baader Astrosolar film website and follow their very fine instructions for building a housing for their film to come away with top quality white light filter for $10 - 20. I did and it's good.

 

The single advantage 2" eyepieces bring is the potential for a wider field. The 2" barrel can hold a larger field stop than a 1.25" barrel. A 1.25" eyepiece kit can be a top quality set.



#3 macdonjh

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Posted 03 August 2020 - 03:04 PM

Sidewyz1,

 

Welcome to Cloudy Nights.

 

I certainly agree with your placing collimation tools as #1 priority. But the moon filter, not s'much. I've had several and they all just degrade the image IMO. If you were anywhere around here, I could give you a couple. A healthy eye is capable of dealing with the brightness of even a full moon produced by much larger than 200mm apertures. Plan your lunar observing for session end or before a break and you'll maximize available image quality and never compromise any other observation or your time. Barlow? They're specialized tools not every kit needs. Just know why you're adding one if you do. If you go w/a solar filter I recommend you read the Baader Astrosolar film website and follow their very fine instructions for building a housing for their film to come away with top quality white light filter for $10 - 20. I did and it's good.

 

The single advantage 2" eyepieces bring is the potential for a wider field. The 2" barrel can hold a larger field stop than a 1.25" barrel. A 1.25" eyepiece kit can be a top quality set.

+1

 

Collimation tools are almost necessary for Newtonian owners.  You can collimate without tools (at least some people can), but tools make it so much easier.  I prefer to use a laser with the Newtonians I have.  They make the initial alignment very fast and easy.  I then fine tune collimation by looking at a slightly defocused star image in an eye piece.  You probably got a "collimation cap" with your scope and you can use that to verify your secondary mirror is correctly centered relative to your focuser.  That is an adjustment a laser does not help with.

 

Moon filter: I've had both 13% and variable and don't use either anymore for the reasons havasman lists.

 

Barlow: if you're going to try one now is the time before you have a big eye piece collection.  The biggest advantage to a Barlow is being able to use the same eye piece(s) to produce different magnifications.  If eye relief is important to you, a Barlow can help there as well be enabling you to use long focal length eye pieces with large eye relief with the Barlow to get higher magnifications and maintain eye relief.  If you get a big collection of eye pieces first, you may find the Barlow going unused.

 

Solar filter: that is up to you.

 

Eye pieces: don't be too hasty buying a bunch of eye pieces.  Perhaps start with 32mm, 9mm and 6mm Plossls.  That will provide you with 36x, 150x and 200x magnification, probably good quality eye pieces and not too much expense.  Those three magnifications will allow you to figure out what you like to observe and how you like to see it, if eye relief is important to you (a 6mm Plossl will have very little eye relief), whether or not you want wide field eye pieces (they can be expensive).

 

You'll also want an observing chair.

 

Good luck.



#4 gnowellsct

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Posted 03 August 2020 - 03:37 PM

I would delay the solar filter for a year or two.  Not much going on in the sun in white light.

 

You need to understand that two inch eyepieces--there aren't many of them below 20mm.  And the ones that are below 20 mm are often 1.25" eyepieces with a skirt of steel that lets you put them into a two inch diagonal without an adapter.  

 

Two inch eyepieces are fantastic but in your scope you will likely find an 18 to 20mm to be your most used eyepiece.  So don't choose by whether it is two inch or not, choose by the Apparent Field of View.  (AFOV).  My tastes in glass run (a) expensive and (b) towards "moderately wide fields" -- in the neighborhood of 70 degrees.    If you want an 80 or 100 degree eyepiece I'm sure someone will help you out.  There are budget alternatives.  

 

In the premium categories the Nikon 17.5 mm and the Delos 17.3 mm (Televue) would be a very nice fit.  

 

You *do* need a 30 mm two inch eyepiece of 70 degrees or more in order to scan the sky and find stuff.  Your scope is nearly f/6, it might be OK to go for a 40mm ocular for maximum wide field, but the usual wisdom regarding exit pupil (try to stay at 5 or 6 mm or smaller) would argue against that.  A 40mm in your scope is about f/7 which is a bit wide (40/5.9)=6.8.  I would actually "go for it" but conventional wisdom would suggest you stick closer to a 30 mm (30/5.9=5.1 mm exit pupil).  

 

So I would suggest you prioritize something in 30mm (two inch format, 70 degrees AFOV or more), and something in the 17 to 20 mm range (70 degrees or more, two inch or 1.25", the two inchers will actually be 1.25 inch).  

 

The 24 Pan Optic and 27 Pan Optic are frequent choices among Dob users.  Reminder:  There is a used market, which is very good for oculars, and there are a number of mid-priced and low-priced imports from mainland China under various names, so check out what you feel comfortable spending.

 

Greg N



#5 Paul Sweeney

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Posted 03 August 2020 - 04:09 PM

For collimation I prefer the cheshire with the cross hairs. I you want a laser, be aware that the cheap ones need to be collimated themselves. I have a middle quality laser, and it also needs collimation very often. The cheshire is cheap and always works the same, but it is not as convenient to use.

For eyepieces with your budget, go with 1.25s. Try buying used so you can test various brands. I tried 2" eyepieces, but the quality of cheap wide angle eyepieces was poor and the outer half or third was not sharp, so why bother? If you want good 2" wide angle eyepieces, your budget will get you one, maybe two. I also use a 40 mm eyepiece to get the lowest magnification possible. I tried a 32mm, and preferred the 40.

Moon filters are like eyepieces - the cheapies tend to mess up what your expensive eyepieces are are trying to give you. Once you push up the power, you won't need one anyway.

Build your own solar filter. It is cheap and easy.

Barlow? Try one and see. I personally don't like them.

Before you spend your cash, see if there is a club in your area. You may be able to try out their equipment and save yourself some aggravation.


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