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Should I get a 2" diagonal?

RobertI

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RobertI

RobertI

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Hi folks, I recently acquired a megrez 72 to complement my C8 for visual observing. I need to buy a diagonal for it and, as the megrez can take 1.25 or 2" eyepieces, was wondering if it is worth investing in a 2" diagonal.

I have a couple of Baader Hyperion eyepieces which can fit a 1.25 or 2" diagonal but not sure if there are any benefits such as wider field of view. I read the eyepiece guide on SGL and it appears that 2" diagonal/eyepiece would not give much benefit on a long focal length C8 but what about on the megrez 72? Is it worth the extra money?

Any help appreciated.

Rob

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John

John

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It would give you the option of using 2" eyepieces which can show a wider field of view than the 1.25" ones. The Hyperions though are 1.25" eyepieces even when you use them in 2" mode. You can remove the 1.25" barrel and you do get an approx 22mm 2" eyepiece of sorts but it's not a very good quality one. 

With the Megrez 72 you could get a 2" eyepiece that would show a 4 degree or more view of the sky. Great for really large objects such as M31. 

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Joves

Joves

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If I were buying a new diagonal (which I've just done, btw... Except this is the third 2" diagonal I've now bought, which should tell you something) I would absolutely get a 2"... No questions asked. You can fit the adaptor (supplied with many 2" diagonals) to also use your 1.25" EP's. The same can't be done with a 1.25" diagonal to use a 2" EP.

Honestly, moving to 2" EP's combined with the wide field capability of a short focal length refractor (mine is the Televue 76) like your Megrez is the best thing I've done in recent times to further my enjoyment of visual astronomy!

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NGC 1502

NGC 1502

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Hi Rob from a fellow Essex member.

Definitely +1 for getting a 2" diagonal.  As said, that would give you access to very low power and wide field.  It's something no other type of scope can do. You can do that with bins of course, but your Megrez 72 on a mount will do it far better, a rock steady view, and comfortable at a high elevation.

In September, I took my 70mm Pronto to Kelling Heath in north Norfolk. I was pleasantly surprised by what it could do.  Does well at home too, shows large objects like Kemble's Cascade, Pleiades, Beehive, Coathanger, etc etc, using 18x and 3.8 degree field - lovely  :laugh:

Regards, Ed.

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M4lcs67

M4lcs67

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John. I am glad you mentioned about the Hyperions and the fact that you realistically still need to keep the 1.25 barrel attached, even while using it in 2" form. I had wondered that myself. You have answered my question. Would that still apply to my 36mm Aspheric?

Thanks 

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John

John

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John. I am glad you mentioned about the Hyperions and the fact that you realistically still need to keep the 1.25 barrel attached, even while using it in 2" form. I had wondered that myself. You have answered my question. Would that still apply to my 36mm Aspheric?

Thanks 

As far as I know there are no lens elements in the 1.25" barrel of the Aspheric eyepieces. They are actually 2" eyepieces so using the 1.25" barrel cuts down the size of the field of view they give to the maximum that a 1.25" barrel can accommodate. If you used the 36mm in 2" mode it would show it's full 72 degree field of view.

Be careful if you insert one of the smaller Hyperions into a 2" diagonal, in 2" mode, with the 1.25" barrel attached as it could strike the mirror of the diagonal. Much better to use them in 1.25" mode really, even in a 2" diagonal. This applies to the normal Hyperions, not the Aspheric. 

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RobertI

RobertI

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Thanks for all your replies folks, really appreciated. Sounds like a no brainer and I shall be looking to get one one of these.

John - thanks for clearing up the issue of Hyperions - I was wondering about this too.

Looks like I'll need some 2" eyepiences too (so much for tightening my pursestrings!).

Next question of course - which is a good 2" diagonal to get, ideally under £100?

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Chris

Chris

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Hi Robert, hope you are enjoying the Meg72 :) +1 for a 2" and +1 for the Opticron which Earl has provided the link for. Its a cracking diagaonal for the money, used mine for the first time the other night and its top notch! The only down side is that they charge a tenner for shipping but it still works out to 69 pounds delivered to your door which is second hand money! 

I'm trying to remember if it was Earl who put me onto these diagonals? Bad memory kicking in :D

Chris

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M4lcs67

M4lcs67

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Mine is the Williams Optics http://www.firstlightoptics.com/diagonals/william-optics-2-dielectric-diagonal-with-sct-adaptor.html. Fantastic/classy looking diagonal. And I love the fact that it comes supplied with the 1.25 adapter as well. Everything about it oozes quality. Maybe a squeak more expensive than you wanted, but well worth the extra £20.

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Chris

Chris

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Mine is the Williams Optics http://www.firstlightoptics.com/diagonals/william-optics-2-dielectric-diagonal-with-sct-adaptor.html. Fantastic/classy looking diagonal. And I love the fact that it comes supplied with the 1.25 adapter as well. Everything about it oozes quality. Maybe a squeak more expensive than you wanted, but well worth the extra £20.

I think they all come with the 1.25" adaptor, the Opticron does for the half the price and is also dielectric with brass compression rings all round. I do like the carbon fibre side plates on the WO but is it worth another 50 pounds? I've paid 80-85 quid for a second hand Meade 5000 2" diagonal in the past so it amazes me that you can get  the Opticron for a lot less than this brand new. The build quality is right up there with the Meade 5000 in my opinion!

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John

John

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I think they all come with the 1.25" adaptor, the Opticron does for the half the price and is also dielectric with brass compression rings all round. I do like the carbon fibre side plates on the WO but is it worth another 50 pounds? I've paid 80-85 quid for a second hand Meade 5000 2" diagonal in the past so it amazes me that you can get  the Opticron for a lot less than this brand new. The build quality is right up there with the Meade 5000 in my opinion!

There is a fair chance that the Opticron diagonal is the same item as the William Optics just under different branding as I suspect is the Meade 5000. With one or two exceptions much astro stuff comes from a few factories in the far east and is sold under a number of brands here. The trick is to see through the branding and source the item you want at the best price  :smiley:

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Chris

Chris

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Very wise words John, I'm well onboard with this way of thinking :) I've not long bought a 5 position filter wheel for 45 pounds brand new from a fleabay shop, it looks identical to the ones that retail at 80 pounds, and I mean identical. I think a classic example is the BST EP's where identical EP's retail at double the price of the ones at Skies_Unlimited!

Chris

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RobertI

RobertI

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Thanks for the replies folks. The Opticron and Revelation look good and I'll probably go with Opticron based on cost.

The best example of branding premiums I have seen is the Canon TC-80N3 remote timer control which costs £110 on amazon, but the Yongnuo TC-80N3a (which is identical) is available for just........£9.99!!

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F15Rules

F15Rules

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Hi Rob,

I've got the Opticron Dielectric as advertised on Telescope Outlet (I got mine used but mint on Ebay). As John says, it is very similar to the William optics to look at apart from the cosmetic "trimmings". Oh, and I might modestly add that I put Starfox onto the Telescope Outlet deal.. :p

At £69 posted it's hard to beat and I defy anyone to seem a noticeable difference in diagonals costing twice or three times the price (I used to own an Everbrite 2", fine diagonal but no better optically). I've also used Revelation, Meade 5000 etc and would say the same about them. 

As far as the pros and cons of 2" diagonals vs 1.25" go, I'd offer the following:

Pros:

Better for holding big heavy eyepieces more securely.

More versatile, as you can use both 2" and 1.25" eps

Some people believe that if you use 1.25" eps with a 2" diagonal, you are using the centre of the bigger mirror, and so maximising the potential of that mirror by using the smoothest, most reflective portion of the mirror..I can't honestly say I've seen a significant difference myself, but maybe with very top end eps you would at the margin.

Balancing a refractor or Mak/SCT might be positively impacted using the bigger diagonal...for front heavy fracs this can help move the balance point a little further back so the scope is a bit higher off the ground when pointing high in the sky.

Cons:

More expensive than the smaller 1.25" eps

If you need more in focus, I have found that a 1.25" PRISM diagonal can be better in this regard, especially for binoviewing?

Not much else!

Good luck Rob, whichever one you invest in.. :laugh:

Dave

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