Fitting a telrad on SW 250px flextube Dob

[AlexB67]

Hello,

Can anyone confirm if they fitted a telrad to the 10 inch skywatcher flextube Dobsonian ?  The top part of the OTA that slides out is just around 18cm long between the white rims that extrude out from the ATO. Info on the net suggests the base plate is just under this length, so does it fit or is it just a little too long ?  I'd definitely get a Rigel if I cannot fit it to the top part of the OTA, but I get the feeling it will just fit, it almost looks too good to be true, but it is almost as if they made it so that this accessory would fit perfectly in the gap that is there , but I rather know in advance before I pick it up and buy. 

My second question, with the finder scope as well as telrad, any balance issues on this scope ? since it is fairly heavy item. I don't have any heavy eyepieces at this time but could see it may be an issue if I added much more, but I suppose can be modded to cure that. 

Many thanks.

Edited October 20, 2013 by AlexB67

[knobby]

I've seen a telrad on a mates 250 flex... So it must fit? Unless he had to... Tweak maybe

[knobby]

Found a pic

[AlexB67]

Thank you, looks like provided it is fitted with the base plate ( not clear from that ) it does indeed fit in the gap, I imagine it would be fitted that way, and I see nothing overhanging the rim at the top, so that looks  promising

[NGC 1502]

If the Telrad base is listed as being a certain length, then you could return it if not to advertised spec........

But from what you have said, should fit ok.   (or tweak it, as knobby says, lots of DIY 'tweaks')   A Dob lends itself to people who cannot resist modding their scope.

The Telrad base fits with long sticky pads.   You can do a temp fit with duct tape to decide the best position.

Lots of cures for balance probs with extra finders or heavy eyepieces. One I've used is magnets on the tube, easy to fit / adjust, or remove as necessary.

Regards, Ed.

[AlexB67]

If the Telrad base is listed as being a certain length, then you could return it if not to advertised spec........

But from what you have said, should fit ok.   (or tweak it, as knobby says, lots of DIY 'tweaks')   A Dob lends itself to people who cannot resist modding their scope.

The Telrad base fits with long sticky pads.   You can do a temp fit with duct tape to decide the best position.

Lots of cures for balance probs with extra finders or heavy eyepieces. One I've used is magnets on the tube, easy to fit / adjust, or remove as necessary.

Regards, Ed.

Thanks Edd,  I am almost convinced 99% it will not be an issue now. I'd be picking this one up one second hand however so once bought that's it, it will need replacement tape. I suspect this would probably work perfectly though

http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_203489_langId_-1_categoryId_255228

[JamesF]

It's a really awkward fit with the standard baseplate alone.  It will fit, but perhaps not in the most convenient place.  The problem is that the back of the telrad body fouls the lower ring of the upper cage where it widens to take the truss, and it isn't possible to move it "just a bit" further round because then the baseplate fouls one of the spider nuts (make your own joke up there; I was spoilt for choice).

With a 2" or 4" extension the telrad body is lifted out of the way of the ring and there's no problem at all.

if you'd like a photo, let me know and I'll drag mine out so you can see how it fits.

James

[AlexB67]

It's a really awkward fit with the standard baseplate alone.  It will fit, but perhaps not in the most convenient place.  The problem is that the back of the telrad body fouls the lower ring of the upper cage where it widens to take the truss, and it isn't possible to move it "just a bit" further round because then the baseplate fouls one of the spider nuts (make your own joke up there; I was spoilt for choice).

With a 2" or 4" extension the telrad body is lifted out of the way of the ring and there's no problem at all.

if you'd like a photo, let me know and I'll drag mine out so you can see how it fits.

James

If you would that would be fabulous James. I think I understand from what you are saying, I suppose I can buy the riser bridge from FLO, does that make it much heavier still ? I'll buy you a cookie for the photo 

Edited October 20, 2013 by AlexB67

[AlexB67]

Coming to think of it, the Rigel is beginning to score some extra points though as a much less fuss alternative.  This hobby can be an awkward fickle so and so sometimes

Edited October 20, 2013 by AlexB67

[JamesF]

Here's the photo of mine:

Without the riser the telrad can't go where the optical finder is because it fouls the cage ring on the other side of the truss.  It won't fit where I have it for exactly the same reason.  Adding the 2" riser lifts the body clear of the cage ring and it would fit either side of the truss pole fitting, but I like to have the optical finder too so that's why I have the arrangement I do.

I'm afraid I can't comment on the balance however.  As you can see from that photo mine isn't exactly standard, mostly because I obtained it in a number of different pieces from different sources, and I fitted it to my own base:

And I've messed up the balance even more since I reassembled it by adding a Moonlite focuser.  The telrad is very light however, so if you have reasonable balance already I don't think it will be affected too much.  And in honesty, if it did make the top a little heavy it's such an incredibly useful thing to have that I'd just add a counterweight to the bottom end rather than not have one.

The position I have my telrad in does mean I have to "lean over" the OTA slightly to use it, but I've really not found that to be a problem at all.

James

Edited October 20, 2013 by JamesF

[AlexB67]

Thank you so much James.  So without the added riser the only way the telrad could fit if it was quite a bit more over to the right, it would clear the rim and be raised enough without one ?, but not sure I'd like that anyway for comfort, so to me looks the riser is pretty much a must and something else I'd have to get, Stock on these things always seem tight but hope I can find somewhere  that have them .  I'd want to keep the finder scope in any case also.  Nice job you did with the scope btw. 

I think the poem in my sig still has some mileage in it

[JamesF]

Thank you so much James.  So without the added riser the only way the telrad could fit if it was quite a bit more over to the right, it would clear the rim and be raised enough without one ?, but not sure I'd like that anyway for comfort, so to me looks the riser is pretty much a must and something else I'd have to get,

The problem is that "a bit more over to the right" is the end of one of the spider arms, and the base would then foul the nut retaining that, so it has to go "a fair bit more over to the right".

James

Edited October 20, 2013 by JamesF

[AlexB67]

Yes agreed, thank you for everything.  I think the Rigel wins possibly in spite of the much touted telrad, I can live with the 2 degree limitation I think in combination with the finder scope. Besides, it will be a cheaper more compact solution with the flash on off rings included by default  already, and a much smaller footprint makes it attractive in this case.

[JamesF]

You're very welcome

James

[AlexB67]

I read numerous reviews, and while the telrad comes out better I admit in most cases by a tad, there is not much between them I feel. In any case, It is not as if getting a rigel cannot be superseded at a later stage by a telrad, if I found it not to be  to my liking at some stage. 

I substituted the laser dot finder from the Heritage onto the 10 inch with a bit of tape, even held in my hand at one point wedged against the finder scope onto the OTA, and that already improved my ability to locate targets quickly by miles. I am  quietly confident the rigel will do fine. 

Now awaiting for the thread to spiral in a telrad versus rigel debate :0)  

Edited October 20, 2013 by AlexB67

[NGC 1502]

I read numerous reviews, and while the telrad comes out better I admit in most cases by a tad, there is not much between them I feel. In any case, It is not as if getting a rigel cannot be superseded at a later stage by a telrad, if I found it not to be  to my liking at some stage. 

I substituted the laser dot finder from the Heritage onto the 10 inch with a bit of tape, even held in my hand at one point wedged against the finder scope onto the OTA, and that already improved my ability to locate targets quickly by miles. I am  quietly confident the rigel will do fine. 

Now awaiting for the thread to spiral in a telrad versus rigel debate :0)  

Looking at the pics that James posted (such helpful chaps on SGL ) I'd completely overlooked the size of the rim at the lower edge of the upper tube.

If it were me, I'd fit a Rigel, solves a lot of problems, much smaller, and lighter as well.

Regards, Ed.

[AlexB67]

Looking at the pics that James posted (such helpful chaps on SGL ) I'd completely overlooked the size of the rim at the lower edge of the upper tube.

If it were me, I'd fit a Rigel, solves a lot of problems, much smaller, and lighter as well.

Regards, Ed.

I agree Ed, this is the conclusion I've come to. In the end weighing up the pros and cons I think the rigel is for me. The advice was great. I'd almost committed to a telrad, but just as I ended up buying 10 inch Flex Dob instead of a 12 inch solid tube that I almost could have ended up buying, the last minute decisions force you to think that little bit harder to ensure that I know whether it the right thing for me. I feared the rims would be an issue, and hence I started asking the questions on the forum. 

The pics James provided nailed that home how careful you have to be picking something like that, obviously it is doable, but all the same.  Hopefully it will be good advice for anyone else fixing a telrad to the 10 inch flextube DOb, because interestingly I could not find a thread asking about this particular issue, which is rare on SGL that something hasn't already been posted about a particular topic, or for that matter elsewhere on the net.

You can never be careful enough, buying and decision making is an enjoyable part of the hobby, going through the process before eventually deciding with great help from SGL. 

To turn it all on its head for the price and size I was briefly enamoured by the Baader Skysurfer III dot finder, John seems to rate it highly too, and seeing I seem to get on with a dot finder on my small scope so well, but anyway, the Rigel it is and will be ordered tomorrow.

James has given me another great idea. I swear my nearly empty plastic buckets of spare paint may well fit that size as spare dust covers, I would almost have thrown them away as I was clearing my room today, they may well just fit

Edited October 20, 2013 by AlexB67

[JamesF]

I think it's a good decision to go with the Rigel in this instance.  If I'd known then what I only found out the hard way after buying the telrad then I might have bought the Rigel myself

Fortunately I picked up the 2" extension second hand, shortly afterwards.

James

[AlexB67]

I think it's a good decision to go with the Rigel in this instance.  If I'd known then what I only found out the hard way after buying the telrad then I might have bought the Rigel myself

Fortunately I picked up the 2" extension second hand, shortly afterwards.

James

I also found looking around for that part in stock, they do charge quite high prices for little extras like that, as often seems to be the case with the little extras, like dew shields etc. 

All in all considering the rigel already comes with some extras like variable on/off pulse, it is pretty good deal I feel, even if it is made a little less solid.  If you want the on/off facility plus the riser base the whole telrad package is quite a bit more. The size, which is very much hammered home in your pics, the additional weight too, since a rigel weighs pretty much nothing without the battery pack, all those factors combined made me swing in the direction of the rigel in the end. No doubt  the larger 4 degree window is a nice thing to have, but not a must I feel in combination with a finder scope.

[knobby]

Off topic... But does the cloud dodger sticker work James? :-)

[JamesF]

Off topic... But does the cloud dodger sticker work James? :-)

Only in the sense that it has been dodging clouds for the last two months by staying indoors

James

[knobby]

:-)

[Moonshane]

I use telrads but only use them for initial placement of the scope, then switching to the 9x50 RACI. tis works fine for me and thus any sort of RDF would do, including the Rigel. I like the robust nature of the telrad base which I found a little less so on the Rigel I had previously. if it were my scope, I'd find a way to fit it and use the telrad and riser as this makes for less back bending too. either would be OK though.

[AlexB67]

if it were my scope, I'd find a way to fit it and use the telrad and riser as this makes for less back bending too. either would be OK though.

I knew it, there would be at least one person saying     The rigel from the dimensions I see sticks up by itself a bit already.  Some of the reviews say without the riser it is a bit more of a comfortable height  above the OTA, but obviously with the telrad you have the option for a 2 or 4 inch riser.  I agree though, from having read around the telrad is that little bit more solid and is a slightly better solution. Without having tried either admittedly .. BUT .. the rigel I feel is good enough overall for me and has some other pros that appeal to me   

In the end, In the scheme of things it is a relatively cheap addon either way, perhaps I'll learn the hard way and find I'll want the telrad later, but no biggie if I want one, then I'll buy one at some stage.  I suspect I'll get on with either.

[JamesF]

It's not like you won't be able to sell the Rigel fairly easily if you decide you've made the wrong decision...

James