Louis D

2 hours ago, mikeDnight said:

Am I missing something?  It seems to me that unless the internal diameter of the baffle tube is a full 2", there's little point in using 2" eyepieces. All the 127mm Mak's I've used have had a much narrower baffle tube. And supposing the baffle on a 127mm Mak was a full 2" internal diameter, it would eat up a significant amount of useable surface area on the primary; bearing in mind that the thickness of the baffle tube, and its retaining ring also intrude into the surface area. A 127mm Mak is a terrific scope, but its not a wide field instrument, and it seems to me at least, that trying to use it as such would have detrimental effects. Using a 2" back on a scope with a baffle tube less than 2" would surely cause vignetting? 

Did you miss my empirical photographic posting earlier in this thread demonstrating limited vignetting with just such a setup?  It works just fine except when bright stars pass the edge of the rear baffle tube/port and create an ever larger oval reflection in the field of view.  I also wouldn't recommend it for lunar or solar work, either.

In my experience, central obstructions can also make it more difficult to spot dim companions next to bright stars, as in the E and F components of the Trapezium, than in an equivalent or even smaller aperture unobstructed system.  The obstruction makes the bright stars bloat so much that you just can't make out the dim companion stars no matter how good the seeing conditions are.

1 hour ago, michael.h.f.wilkinson said:

I have also always felt the 22 was best, but many people suggest the 17 is superior. I don't see that

Agreed, the 17mm is definitely not the strongest of the three.  It has enough SAEP to make it difficult to see the entire view at once when the field stop comes into view.  It also has some field curvature and a bit of edge astigmatism; although I could live with those two if the exit pupil were a bit better behaved.  However, it's not as bad as the SAEP in the Meade MWA 26mm I recently reviewed.

5 hours ago, DirkSteele said:

Shorts and t-shirt observing is the best!

Unless you're dripping in sweat in high humidity and getting eaten alive by mosquitoes as is the case right now here in Texas.  I much prefer our winter observing with pants, a light jacket, no humidity, and no bugs.

4 hours ago, Relpet said:

Having started this thread I've been interested to see how it's developed, especially since I bought the Omegon from John!  I'm still awaiting delivery of a 2" visual back but as soon as that arrives I'll hope to make a comparison of lunar views using a 25mm ES 2" and a 27mm 1.25" Orbinar flat field.  Not a direct comparison but close enough, maybe.  As John has said in other posts, the Omegon is a true 127mm so vignetting should, I imagine, be even less noticeable using the 2" but I certainly hope my ancient eyes will get added benefit from a 2" option.  I asked the question originally because the Skywatcher 127 is available with a 2" option in Europe,  (and I believe Canada) at minimal extra cost, but not in UK.  FLO, at my request, were asking the importers why it was not on offer to UK buyers but I've had no response.  It's irrelevant now anyway since I'm delighted with the Omegon.

The factory 2" version of the Skywatcher 127 is quite literally the original 1.25" 127 with the optional Mak to SCT thread adapter and 2" visual back standard.  Thus, the rear port and baffle is exactly the same size as the original 1.25" version.  How do I know, because I've got both an older Orion 127 1.25" version and a newer Celestron 127 2" version, and they're identical at the rear ports.  Celestron is owned by Synta/Skywatcher, so they're the same scope.

I suppose @FLO could offer an upgrade package for the 1.25" version by adding the thread adapter and swapping the visual back for a 2" version until their importer sees fit to offer it in factory form in the UK.

12 minutes ago, michael.h.f.wilkinson said:

I might at some point replace my Nagler 12T4 with the ES 12mm 92 deg. The 12T4 is my least favourite Nagler. If the ES 12 works well, I might even replace the 17T4

That's the exact path I went down.  Both ES-92s are superior to their NT4 counterparts in every way except for sheer size and bulk.  Luckily, the 22mm NT4 is the best of line, so I can continue to live with it quite happily.

You could also try the 9mm Morpheus.  Try as I might, I can't find much to distinguish its performance from my 10mm Delos.  You'd also be giving up very little in apparent field of view.

4 hours ago, Dippy said:

Good evening Alan, I like reading the subject material of your reviews, but most of the time I find it difficult to understand or follow what you are writing. Would it be possible before posting just edit, add  punctuation and finally trim at least two thirds of the writing. I can understand probably English is not a first language for most of the people, but really it is difficult to understand this really useful review. 

Perhaps we could get Wikipedia writers to post a plot synopsis for @alan potts's reports/reviews like they do for movies and books for folks who want only the executive summary and not the experience?  Have you asked J. K. Rowling if she could post a condensed version of her novels as well?  I'm sure we'd all appreciate it since many of us don't have the spare time to read 600 page books, and having a third party write that synopsis just isn't the same as having the original writer do it.

@Dippy Please do not read my reports/reviews either as they tend to be very lengthy and in depth as well; and as a Texan, I don't take well to being told I'm long winded in my story telling.

I dug around Pentax Japan with the Wayback Machine archives and located this eyepiece PDF that seems to have vector diagrams of the lenses that can be increased in size at will.

5 minutes ago, markse68 said:

any idea where to get a higher res version of that first image Louis? I’ve seen it posted a few times but not found a higher res version- checked ricoh japan site too. 

Mark

No, and I just checked the brochure tucked in with my XW 7mm, and there's no lens diagrams included on it either. 😟

I know FeatherTouch makes dual speed focuser knobs for SCTs, but I don't recall there being one for any Maks.

And these:

Where the DS line indicates sagittal field curvature and the DM line indicates meridional field curvature.  The origin is on axis performance and the vertical axis indicates performance trending toward the edge at the top.  As the two lines diverge, it indicates increasing levels of astigmatism.  The 5mm should have almost none with field curvature canceling that of most telescopes.

I composited together the max field of view in a Synta 127 Mak with a 1.25" eyepiece and with a 2" eyepiece, both while using a 2" visual back and 2" diagonal.  While some may disagree with me, I think it's pretty clear that there's a lot more true field of view available in a 127 Mak with very little vignetting when using 2" eyepieces.  By sampling luminosity center and at 85% to the edge in the 40mm image, it appears there's 65% of the center brightness available there which isn't bad at all visually at night.

1 hour ago, bomberbaz said:

However it is a little bit clumsy and stiff trying to move it. At least the 12" version was that I had. Had some fantastic views in it but I tired of all the setting up (wires, batteries, collimation, shrouds etc) also it was quite heavy and so went for the solid tube pushto. Far easier to use in my own personal experience.

And if you ever want tracking, you can buy or build an equatorial platform for it.

3 hours ago, alan potts said:

I had both the Mk 1 and 2 for a while when the Mk2 came out, I only noticed a little difference when using Ethos eyepieces which I imagine were a pipe-dream when the Mk 1 was launched, I do feel the Mk 2 improves stability all round though and is generally the better paracorr but at near on 500 quid, it should be.

Alan

Apparently, the Mk2 really shines at sub-F/4 focal lengths where the Mk1 began to struggle.  What f-ratio was the scope you were comparing the two in?

I've been using 2" visual backs on my Synta 127 Maks and haven't noticed any vignetting, just weird oval reflections as bright stars pass the edge of the rear baffle tube/port.  The TFOV isn't a little wider, it's a lot wider with a 40mm Meade SWA than with a 24mm APM UFF.  1.7 degrees is noticeably wider than 1.0 degrees to me at least.  It's like a breath of fresh air to be able to see more of the context around objects.  I might be off on the actual degrees since using a 2" visual back and diagonal extends the focal length somewhat, but the 70% increase in TFOV remains regardless.

As far as fitting a Crayford focuser to a 127 Mak, I wouldn't bother.  Neither of my 127 Maks has any mirror slop or focus backlash, and fine focusing is quite easy with the supplied focuser knob.  The 2" visual backs barely fit back there, so I don't know how you'd get a Crayford focuser to fit.  That, and you be extending your focal length even further than by just using a 2" diagonal versus a 1.25" diagonal.

As for the difference between them, I'm not sure how easy the fully GOTO telescope is to use manually if you just want a quick grab and go to peek at the stars without doing an alignment, especially through gaps in the clouds when alignment stars might be difficult to find.

Does anyone have experience using these FlexTube GOTO scopes in fully manual mode?  How are the motions compared to a push-to?   I assume the motors can be declutched from the axes and the scope can be used as ordinary Dob.  Can it be used as a push to in this mode using just the encoders?

6 hours ago, johninderby said:

Simple. Skywatcher is a very good deal in the UK and cheaper than in the US. Orion is for the American market and not common in the UK. Both brands are part of Synta.

Synta does not own Orion USA, it is an independent astronomy dealer that sources gear from not only Synta, but many other vendors under their Orion house brand.

SkyWatcher is the Synta house brand in Europe and other parts of the world.  It only sells Synta made equipment.

4 hours ago, Stardaze said:

I’ve gone with the Telrad as the Rigel I ordered was poor in build.

Sorry to hear that.  I bought mine 20 years ago and haven't had the slightest bit of trouble or breakage with mine.  In fact, the original lithium button cell is still going strong.  Even catching it on the door frame several times as I brought the scope from outdoors, knocking it loose and having it clatter to the concrete didn't phase it one bit.  I always forget how much it sticks out from the tube, and that I need to remove it before carrying the tripod and scope indoors.  The fact that it attaches with a plastic locking tab saved the attachment point from being damaged each time.

On the flip side, my original Telrad died after AA batteries corroded inside it.  I replaced the holder and still couldn't get it to light up.  My two replacement Telrads' potentiometers go from off to full on in the last few degrees of motion making it difficult to regulate down the brightness.  As such, I've had a pretty bad run with my Telrads over the past 22 years.

2 hours ago, Sunnydays said:

 Thanks so much for the input. I have reads many reviews on the zooms and have found that for the most part they have received no less then 4 out of 5 stars, with ease of use, being able to not have to refocus as much and the clarity has been praised as being on par or at times better then single eye pieces? It seems as though as i have quickly learned that most items come down to user preference and not so much that a single eye piece is going to give anyone 50% better viewing then a zoom. From what i have been told that for most eye pieces from mid to expensive, one might achieve Maybe 5-8% better viewing in general? Don’t expect a drastic change just because something is really expensive? When using my 25mm piece that i got with my 6se i was thrilled at the FOV, so if the zoom that i am looking at goes from 40*-60* which is in line with what the 25mm (60*)gives me, i would be happy? If i want to look at nebulae then I could just get a 32mm? Am I off base with my thinking???

Since your telescope is an f/10 system, it will be fairly gentle on eyepieces and indeed, the differences between lower cost, mid range, and premium eyepieces will be somewhat more subtle than if it was an f/4 system, for instance.  In that case, the differences are not subtle at all once you get away from the central 30% of the FOV.  Budget eyepieces become a blur, mid range eyepieces lose sharpness, while premium eyepieces keep on putting out sharp images at small focal ratios as the edge is approached.  Just about any 7+ element zoom will provide very good views in your telescope.

2 hours ago, Sunnydays said:

Isn’t 18mm eye relief pretty good? That’s what the zoom i was looking at listed it as? (Apertura 9mm - 27mm Zoom Eyepiece - ZOOM927), The Baader is 12-15mm which is still really good right?

I have a version of the 7.2-21.5mm zoom from that same manufacturer, and though they claim 15mm of design eye relief, it only has 9mm to 11mm of measured usable eye relief, depending on the focal length.  It also claims to have a 40 to 60 degree AFOV, but I measured it as 33 to 49 degrees which is significantly less.  As such, it's a very claustrophobic and difficult to use eyepiece with eyeglasses.  That, and the zooming action is incredibly stiff.  It takes two hands to zoom mine.  I will grant it is very sharp across its limited field, but so would wider AFOV zoom eyepieces be if stopped down by 10 degrees at each end.

Granted, the 9-27mm version has a slightly larger eye lens that seems no less recessed than the 7.2-21.5mm version, so if it claims 18mm of design eye relief, it probably has 12mm to 14mm of usable eye relief by extension from above.  This would make it fairly comfortable to use without eyeglasses, but still nearly impossible to use with eyeglasses.

1 hour ago, bomberbaz said:

There are loads available, this one is a good option.

extension tube

or this

screw in ext tube

I would stick with the first style.  The second one is a misnamed spacer ring that is too large in diameter.

The extension tube goes in the focuser followed by the barlow and then the eyepiece.

I have had the older Pentax XL 5.2mm for 22 years and love it.  I know at least one user reports eye interfacing issues with the XW 5mm and replaced it with a used XL 5.2mm and has had no issues since.  I've had similar issues with the XW 7mm, but not the XW 3.5mm.  The Morpheus 9mm is a real keeper.  I've read that the Morpheus 4.5mm has some EOFB, but is otherwise very good.  There is no M43 thread on the XL line, so there is that.  There's also the TV Delos line if your budget stretches that far.  If you don't need to wear eyeglasses at the eyepiece, I'd check out the APM XWA 5 mm 110°.

The Telrad has a 4° outer ring that the Rigel lacks.  It also has less parallax issues than the Rigel.  It's also huge compared to the QF.  I have both and prefer the Telrad on Dobs and the QF on refractors and small Maks.

However, if you're not into star hopping, a simple RDF will do nicely to put the scope on target.

Yep, up around 200x, M13 should start to resolve into diamond dust on black velvet in a 6" to 8" scope.  I haven't tried it in a 5" or smaller scope, though.