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Equipment Discussions >> Reflectors

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Moonlight Sonata
member


Reged: 02/23/13

Eyepiece Turret/Revolver for a Dob
      #5697551 - 02/23/13 11:17 PM

Hi everyone, I've been lurking around on Cloudy Nights for awhile researching various types of equipment to make observing through my 10" dob (XT10i) better and finally decided to join to ask a question of my own. When I first started researching eyepieces I found the convenience of a zoom eyepiece appealing but ultimately decided to go the fixed focal length route for a few different reasons. While browsing around some accessories on the Agena site I stumbled upon a piece of gear that I thought could help make switching between different focal lengths more convenient while preserving the quality and FOV of the eyepieces I currently use.

Baader Q Turret

I had a hard time finding much info an anybody using an eyepiece turret for a dob. Does anybody have any experience with this piece of gear or something like it? I know it would require sufficient in-focus due to extending the placement of the eyepiece, but are there any other concerns that would cause anybody to caution against using this? My main concern is the depth of each individual eyepiece holder. They look rather shallow, and my most used eyepieces are an ES82 14mm and ES82 8.8mm which have fairly long barrels. I know there are much more expensive turrets out there, but those are out of my price range and also seem impractical considering they incorporate a mirror or prism. Thoughts?


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SeattleScott
Pooh-Bah


Reged: 10/14/11

Re: Eyepiece Turret/Revolver for a Dob new [Re: Moonlight Sonata]
      #5697687 - 02/24/13 01:42 AM

Weight can be a problem with Dobs. Now you are talking the weight of up to four eyepieces plus the turret, which is probably heavier than most eyepieces. In order to keep the weight from moving the scope, you would have to really crank up the friction, which is going to make the scope's movements stiff and make tracking difficult. Especially when viewing objects low in the sky, where eyepiece weight is most critical for Dobs. One might be able to fashion enough counterweight to offset this however.

I wouldn't worry too much about the shallow sleeves. Parfocal rings should solve any problems that might arise there, although if the barrel is tapered it might be hard to attach the parfocal ring in the right spot. But the weight, that is a problem. Also, how easy is it to rotate the turret? Dobs do not lock down like many other scopes, although an azimuth brake could help in this regard. As you switch to higher magnification and the field of view gets smaller, you might find that the act of rotating the turret nudges the scope enough to put the target out of view.


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Moonlight Sonata
member


Reged: 02/23/13

Re: Eyepiece Turret/Revolver for a Dob new [Re: SeattleScott]
      #5697800 - 02/24/13 05:30 AM

I've wondered some about the weight issue, but if it makes switching eyepieces quick and easy then getting a few magnetic counterweights is a small price to pay in my mind. I've been fairly conservative in avoiding eyepieces that are very bulky. With the 4 EPs I intend to use with the turret the total weight would come to 36oz, about the weight of a single low power wide field EP. I haven't found any specs for the weight of the turret itself, but it's made out of aluminum/plastic, so I'd think it wouldn't be very heavy.

You raise a good point I didn't think about. I have no idea how easy it is to rotate the turret. Presumably, it would be easy, but I don't know if it would be smooth enough to keep an object in the FOV while bumping up the magnification. It would be interesting to hear from somebody that's used this turret on a dob if simply rotating the turret ends up nudging the scope.


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Dick Jacobson
scholastic sledgehammer


Reged: 12/22/06

Loc: Plymouth, Minnesota, USA
Re: Eyepiece Turret/Revolver for a Dob new [Re: Moonlight Sonata]
      #5697981 - 02/24/13 10:11 AM

For a really radical solution, see my recent project that includes a seven-focuser rotating secondary cage (see Seven-focuser secondary cage). It was a lot of work to build but works very well. The object almost always stays in view when switching eyepieces. My standard set of eyepieces includes a binoviewer and a couple of 100-degree eyepieces.

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csrlice12
Postmaster
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Reged: 05/22/12

Loc: Denver, CO
Re: Eyepiece Turret/Revolver for a Dob new [Re: Dick Jacobson]
      #5698124 - 02/24/13 11:38 AM

Wonder how this would work with orthos?

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Moonlight Sonata
member


Reged: 02/23/13

Re: Eyepiece Turret/Revolver for a Dob new [Re: csrlice12]
      #5698439 - 02/24/13 03:14 PM

Funny, I came across that seven-focuser setup while searching for info. That thing is wild! It must have been a tricky idea to conceptualize and build. So I take it if rotating that whole secondary cage doesn't nudge the object out of the FOV that you think rotating the little turret wouldn't create an issue either?

csrlice12, the Q-Turret is actually designed for use with orthos that can be bought as a package with the turret. So, I think it would work well as long as the other considerations raised don't pose a problem.

One thing I'm curious about is how securely the eyepieces would be held in place if they only fit part way into each sleeve. It appears the Q-Turret uses a single set screw for each sleeve. I'm not sure how secure that is compared to two set screws or a brass compression ring. I guess with a dob though the angle of the focuser never reaches a position that the eyepieces would be hanging down facing the ground. So maybe that's not something to worry much about?


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André Heijkoop
member
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Reged: 05/02/10

Re: Eyepiece Turret/Revolver for a Dob new [Re: Moonlight Sonata]
      #5698474 - 02/24/13 03:44 PM Attachment (45 downloads)

Just bought a Q-turret.
The Q-turret is not heavy at all. It is made of some sort of sturdy plastic, probably Delrin or ABS.
Attached a picture of the turret on my 24" Dobson.
In the turret are 4 UO HD's. I think the weight is less as a 2" Nagler alone.


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johnnyha
Postmaster
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Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Eyepiece Turret/Revolver for a Dob new [Re: André Heijkoop]
      #5698486 - 02/24/13 03:55 PM

That's the thing - it works great with orthos. But you start loading it with heavier longer eyepieces like the ES 82's and worse, and next thing you know it becomes less and less elegant looking and more and more difficult to use.

But it looks like fun!


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Dick Jacobson
scholastic sledgehammer


Reged: 12/22/06

Loc: Plymouth, Minnesota, USA
Re: Eyepiece Turret/Revolver for a Dob new [Re: Moonlight Sonata]
      #5698722 - 02/24/13 06:06 PM

Quote:

Funny, I came across that seven-focuser setup while searching for info. That thing is wild! It must have been a tricky idea to conceptualize and build. So I take it if rotating that whole secondary cage doesn't nudge the object out of the FOV that you think rotating the little turret wouldn't create an issue either?



When I rotate the cage I hold on to the truss with one hand and this usually steadies the scope enough so the object stays in view even at high magnification. I would be surprised if you have any problem using the Q-Turret.


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Moonlight Sonata
member


Reged: 02/23/13

Re: Eyepiece Turret/Revolver for a Dob new [Re: André Heijkoop]
      #5698902 - 02/24/13 08:48 PM

Quote:

Just bought a Q-turret.
The Q-turret is not heavy at all. It is made of some sort of sturdy plastic, probably Delrin or ABS.
Attached a picture of the turret on my 24" Dobson.
In the turret are 4 UO HD's. I think the weight is less as a 2" Nagler alone.




Thanks for sharing the pic of your setup. Have you tried using it loaded up with wide field EPs that have longer barrels and weigh more than orthos? Does it work pretty well for you so far?


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André Heijkoop
member
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Reged: 05/02/10

Re: Eyepiece Turret/Revolver for a Dob new [Re: Moonlight Sonata]
      #5699278 - 02/25/13 03:47 AM

Quote:


Thanks for sharing the pic of your setup. Have you tried using it loaded up with wide field EPs that have longer barrels and weigh more than orthos? Does it work pretty well for you so far?



I bought it last Saturday especially for the UO HD orthos. I didn't have the chance to test the turret in the field as of yet.
I also have a Nagler 12T4 and a Pentax XW5, I don't think the turret is suitable for those big 1.25" eyepieces, I will let you know how it works as soon as possible.


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André Heijkoop
member
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Reged: 05/02/10

Re: Eyepiece Turret/Revolver for a Dob new [Re: André Heijkoop]
      #5699952 - 02/25/13 02:33 PM Attachment (38 downloads)

Here is a picture off the turret with the XW5 and 12T4.
It looks funny. I still think the turret is not suitable for big 1.25" eyepieces.


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Jeff Morgan
Postmaster
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Reged: 09/28/03

Loc: Prescott, AZ
Re: Eyepiece Turret/Revolver for a Dob new [Re: Moonlight Sonata]
      #5699999 - 02/25/13 03:01 PM

An interesting idea. There are some issues for a Newtonian, but none insurmountable:

1) Torque may be an issue for truss designs. Solid tubes would probably be ok;

2) The scope would probably need to be balanced for it in the design phase and then built accordingly. Easy enough for the ATM. The commercial scope owner will have to use a sizable counterweight, which means lots of extra dead weight; and

3) Only four eyepiece positions! Most people have more than this. I suppose when you reach the highest magnification (position 4) you could start swapping out of that position and still retain most of the advantage.


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csrlice12
Postmaster
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Reged: 05/22/12

Loc: Denver, CO
Re: Eyepiece Turret/Revolver for a Dob new [Re: Jeff Morgan]
      #5700167 - 02/25/13 04:21 PM

For the price, I'm gonna have to check this out....Wonder if it would work on my XLT refractor? Backfocus issues?

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johnnyha
Postmaster
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Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Eyepiece Turret/Revolver for a Dob new [Re: csrlice12]
      #5700231 - 02/25/13 04:53 PM

The turret will require enough infocus to account for the length of the barrels, looks like at least 1". I am definitely considering this, I had never thought it possible to use a turret in my dob.

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Scanning4Comets
Markus
*****

Reged: 12/26/04

Re: Eyepiece Turret/Revolver for a Dob new [Re: johnnyha]
      #5700242 - 02/25/13 05:00 PM

Looks great, until the dew or frost sets in, lol. Then you'll have frosted or dewed up eyepieces to look through.

If you have dew buster, then you're looking at heating 4 eyepieces with 4 straps. What a mess that would be! Some focus points on eyepieces will require gobs of in or out focus as well.

Don't think I'd be interested in this at all.

Cheers,


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Moonlight Sonata
member


Reged: 02/23/13

Re: Eyepiece Turret/Revolver for a Dob new [Re: André Heijkoop]
      #5700345 - 02/25/13 06:13 PM

Quote:

Here is a picture off the turret with the XW5 and 12T4.
It looks funny. I still think the turret is not suitable for big 1.25" eyepieces.




A picture is worth a thousand words. It's helpful to see it loaded up with some bigger EPs. It does look kind of funny, but I wouldn't be bothered so much by that if it functioned well. Seeing how big the EPs are in relation to the turret does make me wonder how securely they would be held by the single set screw, especially if the barrels were too long to fit all the way in.

André, I can see why you'd recommend against trying it with big eyepieces. It seems like perhaps the bigger the EPs get, the more unsuitable the turret becomes. I'm not sure how they stack up next to each other, but I'm fairly certain my ES82s are shorter and weigh less than the 12T4 and XW5. Maybe with some less bulky wide-fields it would fall into a gray area of being a worthwhile piece of gear. I'm really on the fence about just ordering one and trying it out. It would be great to hear your feedback once you're able to test it out in the field!


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Jeff Morgan
Postmaster
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Reged: 09/28/03

Loc: Prescott, AZ
Re: Eyepiece Turret/Revolver for a Dob new [Re: johnnyha]
      #5700735 - 02/25/13 10:53 PM

Quote:

The turret will require enough infocus to account for the length of the barrels, looks like at least 1". I am definitely considering this, I had never thought it possible to use a turret in my dob.




Oh yes. Didn't think about that one. If it uses prisms that could be quite a bit of in-focus, a big problem for a faster Newtonian. Then there is vignetting to consider.

All the sudden eyepiece swapping doesn't look so bad.


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johnnyha
Postmaster
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Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Eyepiece Turret/Revolver for a Dob new [Re: Jeff Morgan]
      #5700997 - 02/26/13 04:03 AM

There are no prisms involved that's why you have to account for the length of the barrels, this turret just swaps eyepieces out and to do so you need room for the barrels to rotate w/o hitting the focuser or diagonal. Most turrets have a prism or mirror diagonal built in and the eyepieces rotate inside the diagonal, like the TEC - but this is just a revolving turret that attaches to the outside of the existing diagonal or in this case, the dob focuser.

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csrlice12
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Reged: 05/22/12

Loc: Denver, CO
Re: Eyepiece Turret/Revolver for a Dob new [Re: johnnyha]
      #5701278 - 02/26/13 09:49 AM

Thinking this would really be nice on my XLT frac with the orthos in it for planetary viewing...........

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