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Fast (F6 or faster) ED Refractor...choices?


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I've been waiting for an Equinox 80 to turn up for sale which will look nice on my rig but also give me a wider view and had great reviews (I love my EQ120).

The plan is to guide with it while my F6-F7.5 120 images (F6 with reducer). Then if I need wider frames I can swap their roles.

But while looking around I'm seeing many choices in the F6 and faster range.

New the EQ80 is a lot but second and between £300-£350 which is my budget.

But I see things like the WO Megrez 72 APO which is a decent price new let alone 2nd hand.

I'd rather have 80+ aperture but to be honest FOV is more important.

What have you guys got in the fast refractor field and what experience do have on various offerings?

Black would be nice but I realise most are white. :)

I appreciate any comments :p

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Oh, and what's the major differences between WO's Megrez and Zenithstar offerings? :)

The colour (as far as I can make out)

Trouble is, faster than f6 you are, I'm told, pushing it for a doublet.

I've got a Megrez 88 (f5.6) which I find fine visually but I'm not sure how it'll be when I manage to get to somewhere dark enough to try imaging with my DSLR (I took a single 90 second shot at ISO800 in my West Midlands back garden through it just to see how bad the lp was and it came out a sort of magnolia colour)

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Hmmm, interesting.

I see so many quality images with the EQ80 and other fast wide scopes that look stunning. Most are in the doublet range. Gets a bit pricy when a triplet is thrown into the choices :p

I guess it depends what you expect - For a first dabble at imaging I'm going to give the Megrez a go. I'm sure I'll be pushed to see anything wrong with the results (as far as the scope goes - I'm sure there'll be plenty wrong with my technique) but someone with a £3k Tak would probably have a different opinion.

The same person who said I'd struggle imaging below f6 with a doublet also said I'm better off with a good doublet over a cheap triplet below £1k. :)

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I don't think the doublet-triplet thing is much of an issue on a budget because with a triplet you probably don't get as good a lens as with a doublet and the theoretical advantage disappears into the production detail. Making fast optics is always going to be dearer and a flattener will always be necessary on any lens without a rear element, though at what chip size does vary a lot.

I've a WO ZS66 with dedicated flattener. It's not bad at all but I consider these scopes a bit over-rated. The focuser is prone to droop and can't hold much. But still it is pretty decent.

What about the IKI 70 on this page? You'd need to ask Ian about a flattener.

Refractors from Ian King Imaging

Have you thought of a camera lens like the wonderful Canon EF200L? About 70mm aperture depending on f stop and screamingly fast. I bought a used one from a dealer for five hundred. I'm sure you could do better but as I'm not in the UK I just paid up. I think it's good and it would obviously be great on your Cannon. This is with a CCD;

http://ollypenrice.smugmug.com/Photography/Widefield-images-including/SIMEIS-147-HArgb/1182345194_8j8Pv-X3.jpg

Olly

PS I've crossed with Haitch there! Sorry. I don't think you can say that a doublet will or won't beat a triplet in the cheaper scopes. Meade 127 or ED120? Both great. The devil is in the detail.

I do have a three thousand pound (plus!) Tak and I consistently say that the advantage is, in fact, very small. It exists but it is small and wildly disproportionate with regard to cost. I also say this about our TEC140 which replaced the Meade 127. The Meade was very good and that's that.

Edited by ollypenrice
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TBH, f6 is pushing it for a doublet, although less so for a triplet. One of the best 80mm triplets is the 480mm focal length LOMO lens (there's a few scopes around with these lens cells in) and that's about as good as it gets. I think the only real way is to get a relatively quick scope like the equinox and use a reducer.

If you want faster than that, then we're looking at exotics like Takahashi Mewlons, SCT's with a Fastar/Hyperstar lens and the Intes Micro Astrographs.

Tony..

Edited by Whippy
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Sy borrow my WO 90. You know what it is you have looked through it! If you like it then you can buy one (not mine:D). It has a moonlite focuser on it so holding your camera would not be a problem. We could do a meet at Derwent some time to try it out.

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Massive thanks guys...some very good advice.

The issue with camera lenses, for my needs, is I need a scope that can guide when the other is imaging. But it's a very good idea and I maybe shouldn't have sold my ST80 guide scope and gone down that route :headbang:

That IKI 70 is very well priced with a flattener! Something to look into. A few searched posts have pointed back to those scopes. Hmmm :headbang:

Micheal...a very kind offer! Can I also borrow the C11...indefinitely? :p:D

Is the WO 90 F6.2 or F6.9? The problem is...if I love it I won't be able to afford one! :p It seems to have a similar FOV as my current 120.

Maybe I'm looking at it wrong but I'm looking for a wider field over the 120 which rocks on a lot of stuff I've been doing. Am I right in looking at the faster scopes or is there others which offer wider? Currently my EQ120, even with reducer, doesn't look like it will fully fit M31 whereas the EQ80 will. Maybe the EQ80 has always been the right choice (with the reducer). :)

Thanks so much for all the input guys.

Edited by astroimpulse
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Aperture 90mm

Focal Ratio F/6.2

Focal Length 558mm

Objective Type Doublet FPL-53 Air Spaced

Fully Multi-Coated, STM coatings

Resolving Power 1.35"

Limiting Magnitude 11.5

Lens Shade Retractable

Linear Focuser 360° Rotating Camera-angle Adjuster

1:10 Dual Speed Fine Focus

1.25" Adapter Included

1.25" Adapter Brass Compression Rings

Tube Diameter 90mm

Total Length 435 mm Fully Retracted, 520 mm Fully Extended.

Total Weight 7.3 lbs. (3.35kg)

Case Soft case

Case Dimensions

(WxHxD) 21"(W) x 8 "(H) x 6 "(D

I do not have a field flattener or focal reducer and as I said mine comes with a moonlite focuser.

If it is not suitable we could also try the WO66 I happen to own

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I would suggest taking a look at the Telescope Service TS Super Apo 80/480mm F/6 - Triplet FPL-53

http://www.teleskop-express.de/shop/product_info.php/info/p3881_TS-Super-Apo-80-480mm-F-6---Triplet-FPL-53---colour-free.html

Has to be one of the biggest bargains out there at only £590.00. Performance wise it compares with scopes costing twice as much. There are a few SGL members with this scope now (including me :)) and I think all of them have been very impressed. I compare mine to a TMB I used to have and another SGL member who owns a couple of Tak refractors describes the views as "Takahashi-esque" ,high praise indeed. :p

John

Edited by johninderby
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Yeh... seen that one and it does look excellent value for money. Hearing it's good from a user is encouraging.

Do you need the flattener?

There was another one that slips my mind but it was a 4 element scope. But searches brought me back here and one of the members was having a nightmare with it.

The TS looks cracking. Can't see them coming up second hand often though.

Michael: It would be great to try and hook up at the reservoir sometime regardless of scope testing :)

Edited by astroimpulse
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thanks Olly - I'm no expert (I did say I was told these things)... plus you've made me feel a bit better about my lowly Megrez! :)

It comes to something when we call a Megrez 'lowly' - but we don't, you do!!! Ironically, I'm sure. Excellent instrument. I remember my first view through one brought along by a guest.

Olly

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It comes to something when we call a Megrez 'lowly' - but we don't, you do!!! Ironically, I'm sure. Excellent instrument. I remember my first view through one brought along by a guest.

Olly

Well, I think I bought wisely with a limited budget but I haven't managed to use it for what I really bought it for which is taking snaps of the night sky with my old Canon 10D due to the LP issues 15 miles north of Birmingham.

Hopefully I'll be able to squeeze it in the car when I'm off to the Limousin for 3 weeks in the school hols where I'll have skies a little more comparable to yours to test it on. Then I'll maybe have a more informed opinion but I'm not getting my hopes up with it being that fast.

I'm really more of a visual (dob) guy but I haven't managed to figure out fitting the 14" (solid tube) in the car as well as the wife, 2 kids and a border collie. I would take the dob out to France and leave it but that would leave over 40 weeks of the year without it and I couldn't bear that.

Edit.. oops there I go again hijacking threads... sorry!

Edited by haitch
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NO...you're not hijacking :) It's all the same discussion :p Kinda like being in a bar...if you start a convo you don't expect only you to be allowed to contribute.

Hijack away fella :p Best way discover extra bits to your own questions.

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NO...you're not hijacking :) It's all the same discussion :p Kinda like being in a bar...if you start a convo you don't expect only you to be allowed to contribute.

Hijack away fella :p Best way discover extra bits to your own questions.

its your round then. Mines an ethos

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NO...you're not hijacking :) It's all the same discussion :p Kinda like being in a bar...if you start a convo you don't expect only you to be allowed to contribute.

Hijack away fella :p Best way discover extra bits to your own questions.

Well then, a couple of pints in, [reaches in pocket for photo] is there any chance I'll ever be able to image with skies like these? (yes I know I just plonked it on the gravel with a conifer between me and Polaris)

(the 10D doesn't take clip filters so it would have to be 2" but will it cope with thst much LP?)

90ish seconds at ISO800...

post-14514-133877608714_thumb.jpg

Edited by haitch
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Just checking the recommended TS 80/480mm and it may be over budget but it's value for money.

The problem is you need a flattener and then the adapter and it goes through the roof to about £830 squid before postage. Kills that off.

The Ian King 70mm looks very good for the price and includes a flattener for around the £330 mark.

But that TS has spun my head. At least the flattener can be used on other scopes.

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I have the APM counterpart of the TS 80mm F=480 (same scope, but without the TS branding). I bought it with the flattener (which helps a bit even visually with a 40mm Paragon), mainly because you got it EUR 50 cheaper. Even without the flattener, it is a very pleasing scope visually. Very sharp, high contrast images. Light in weight so good travel scope.

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I'd be using it for AP so I guess the flattener is important. Checking the TS site it seems if the flattener is bought with a scope the adapter is included free.

But 50 Euros is still a saving. Do you have a link for it?

I'm so going down the wrong path here! :D

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I'd be using it for AP so I guess the flattener is important. Checking the TS site it seems if the flattener is bought with a scope the adapter is included free.

But 50 Euros is still a saving. Do you have a link for it?

I'm so going down the wrong path here! :D

It is listed here:

TS Super Apo 80/480mm F/6 - Triplet FPL-53 - colour free

but I got the combo through APM, through this link (it was cheaper back then):

Teleskop online Shop , TMB, APO , Dobson , Professionelle Teleskope, Kuppeln , Teleskopabdeckungen , Teleskope , Ferngläser , Teleskope online kaufen , APM Telescopes - Verkauf Beratung Herstellung APM Triplet FPL-53 APO 80/480 - Photoversion mit 2"

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