Ricochet

11 hours ago, Mr Spock said:

I notice in the Tak the field curvature seen in the f5 Newt isn't there. I'm guessing therefore it's f related.

It is the different types of telescope having field curvature that is in opposite directions. The zoom will be subtracting from the curvature inherent in the Tak and adding to the curvature inherent in the Newt. In fact, if it is your 12" you are talking about then the field will be effectively flat so the curvature you see is the true curvature of the eyepiece.

1 hour ago, stormioV said:

Would this be to similar to what I already have?

I would think so. What is the edge of the field like with the 25mm Starguider at F10? Do you see astigmatism or is it sharp? I know the eyepiece performs well by the time you get to F12.

1 hour ago, stormioV said:

I'm still thinking uff 24mm or es68 24mm would be better option.

Yes, but at F10 eyepiece aberrations will be small so the biggest upgrade will be in terms of coatings/transmission/reflection control. If you add a faster telescope at a later stage the differences will be more apparent.

As above, these are so new that I don't know of any reviews so we need someone to be a guinea pig and find out. Having said that we can look at the specifications and make some guesses based on that. 

The 15.5/19/25 look like a scaled design so their performance is likely to be similar to each other. I would guess that the 5 elements/3 groups are all in the body of the eyepiece but given the high eye relief/focal length ratio perhaps the first element is a negative lens. The eye relief of the 25mm doesn't quite match for a scaled design though. Elsewhere it is listed as 4/3 so perhaps it is an even more basic design than the other two. Given these are billed as "Flat field" when the same manufacturer also has an "Ultra Flat Field" we can assume that there is a bit of field curvature in the eyepiece, but as these are made by UO I think it is likely that this curvature matches (and so minimises) the direction of curvature in a refractor. Field curvature and astigmatism are opposite sides of the same coin and the design appears too basic to correct both so I think we can assume that that astigmatism will be present at the edges.

The 10.5mm is an outlier in that it appears to just be the 10mm UFF rebranded to fill a gap in this line. This is a known good eyepiece and reviews can be found elsewhere. Whether the lower cost has been made possible by some cost cutting somewhere (coatings?) or the manufacturer are simply accepting lower margins remains to be seen.

The 3.5/5.5/7.5 look like a "modern" design with a standard set of lenses in the body and a negative group in the nose. Specifically it looks like these are based on the 15.5mm. See how the outer body design of the 15.5 and 7.5 is identical in size. As the number of elements and groups increase by 1 this is a simple negative lens so the 7.5mm is probably quite nicely corrected but maybe the 3.5mm is pushing the design a little bit too far so it might be a bit soft in comparison. Also note how the AFoV has been trimmed from 65° to 60°. Perhaps this is a marketing trick to make the 10.5mm eyepiece not stand out so much, but also consider that if we double the magnification moving from the 15.5 to the 7.5 then we also double the size of the aberrations at the edge, which is indicative that perhaps the edge performance is not so good and needed to be hidden.

If your only desire is for use in an F9 scope the 25mm might perform well enough, but if you also wish to use it in the F6 scope I would suggest spending the additional money on the 24mm UFF instead (or ES68, Panoptic).

I would rent both scopes, the C6 to be used visually whilst the Vespera is stacking subs as an EEA device. This way both scopes give instant gratification during the holiday compared to astrophotography where all you might be doing is gathering data to process once you get home (aside from the issues with the unsuitability of the scope and mount).  Additionally, I would rent the scopes this week as well as next so that you can get used to setting them up and check that they work correctly before you are on holiday. 
 

With regards to additional eyepieces something like an 8-24mm zoom will work well in an f10 scope and should be available at a reasonable price. This should give good lunar views as the moon will be dominating the skies during the holiday. You should also get/make a dew shield for the C6 as the exposed front corrector plates are prone to dewing. 

I don’t find tracking with a dob that difficult a task so I suspect that something with a push to system like the Starsense dobs will be fine instead of a full go to system. With regards to size the weight can be off putting long term so a dob without motors might get more use. Ed Ting estimates that once the initial excitement has worn off an 8” will get used twice as often as a 10”. 
 

I also suspect that this is something best not given as a surprise as your son may already have his own idea as to which direction he wants to go in terms of upgrading. 

1 hour ago, TiffsAndAstro said:

Omg Ty so much

Your focus knobs axis is 90 degrees to your dovetail, like how mine arrived in the case but I rotated the tube rings so they're not as in pic below. 

 

It's ok for me to do what I have, right?

Yes, you can have the dovetail in any position you like. Mine sits on the right because I use it visually on an alt az mount where the scope sits to the side of the alt axis. 

1 hour ago, TiffsAndAstro said:

By Jove I think I've found where it should be, but a second opinion would be welcome

 

 

Yes. This is mine. 

As the tube is rolled steel perhaps some magnets could be epoxied to the bottom of the Telrad base to help it stay put. However, from memory the Telrad base has a V-block profile to allow it to be used with a variety of different sized scopes. With a 12" dob the arc of the tube under the Telrad base will be relatively flat so perhaps the problem with the original/replacement sticky pads is that there is only a very slim area of contact along each edge of the base. In this case you could potentially make some sort of adaptor or fill some of the space under the base to create a larger contact patch for the sticky pads to stick to.

I use Vixen SLVs (9/6/4) with my Lunt 50. If you end up double stacking there is an off axis reflection you want to keep out of the field of view, so wide angle eyepieces can be a hinderance. In addition, there will be a sweet spot in the centre of the fov which shows more detail so you will always want to be observing on axis. 

I can also recommend the R-sky observing hoods that FLO have recently started selling. I bought a white one, the only concern is how a large white hood looks to anyone else, so the black might actually be preferable. 

You’ve not included what I consider to be a vital piece of information, the focal ratio of your telescope, so that we can consider the question in terms of exit pupil. In my opinion the most important (DSO) eyepiece in your set is the one that produces an exit pupil between 2mm and 2.5mm with your telescope. I believe that your telescope is f/8.6 so the eyepiece that I would spend the most money on, and plan the entire eyepiece set around lies in the range 17.2-21.5mm, so in this case yes, you do need to add an 18.2mm Delite to your collection. However, in my f/6 scope the 13mm would generate an exit pupil in the 2-2.5mm range and so the 18.2mm would only be a luxury eyepiece rather than a necessary one.

17 minutes ago, Mr Spock said:

I suppose for me the best mid range eyepiece is the Nirvana. I'm looking at the moon tonight with my 12" and the 7mm Nirvana for x217 and it's very sharp and contrasty. Plenty of detail on Jupiter too. Remarkable for £85 https://www.firstlightoptics.com/ovl-eyepieces/nirvana-es-uwa-82-ultrawide-eyepieces.html

Note: the 16mm is pants.

I think that is the range I’d be looking at too. I’d probably start with the 10mm for the 10”, 13mm the 8”.

I saw a 28mm pop up on eBay a couple of days ago for £150 which would be a great choice for (almost) maxing out the fov.

Black stalked 9x50 RACI

White stalked 9x50 RACI

Same finder, different  colour scheme. Pick the one that matches your telescope best if you're bothered about that or whichever is cheapest. The Astro Essentials version is available bundled with a foot if you need an additional foot for a multi-finder setup - assuming you can fit it to the telescope.

On the filter front, I consider the Baader Neodymium a good planetary filter but I cannot recollect a single DSO that has been improved by using the filter.

40 minutes ago, dweller25 said:

@Nikolai De Silva

I would suggest before you change the collimation screws that you do a star test first to see if it needs adjusting.

If it does here is what to do…..

Some points on this:

• A star test must be performed with an eyepiece with a focal length equal to or shorter than the focal ratio of the telescope
• The star must be precisely centred in the field of view and stay centred during collimation. A off centre star looks the same as a uncollimated scope. For an undriven scope this means using Polaris, which at only 8° Nikolai may not be able to see.
• I believe the above instructions apply to adjustments made to the primary mirror, which cannot be adjusted for the scope in question.
•  Based on experience, never attempt to adjust the secondary using a star test, it will not go well.

Given the above, I would suggest a quick star test is a good way to check if the collimation looks ok, but if it is shown to be out it is better to accept the collimation is out and to just enjoy the views the scope provides in its uncollimated state, and then attempt collimation of the secondary the next day during daylight.

9x50 RACI plus some sort of red dot / Rigel / Telrad is pretty much standard on any large scope. On your Mak you probably want to save weight if possible so the Rigel or the Explore Scientific mini Telrad would be good choices. I would probably still go for a 9x50 over a 6x30 as there is a fair difference between the light gathering capabilities of the two finders.

For your refractor it depends on what you've got and how wide a field you can get from an eyepiece. If you can get over 3° then you can probably get away without the RACI. 

As for light pollution filters, the Astronomik CLS used to be a good one, but with the increase in LED lighting it is hard to recommend any light pollution filter these days. 

This video is worth a watch. I guess it could be summarised as ‘you can see more with a 10”, but you will use an 8” more’. Personally, there have been quite a few occasions where l have been glad that I didn't have anything heavier than my 8" when putting it away at the end of the night.

I don't get the ‘non slip' comment. Are they not PTFE? The pads supporting the mirror whilst not preventing thermal expansion/contraction of the glass is the entire point.

As for a source it is the sort thing that you can often be found available cut to custom sizes on eBay.

58 minutes ago, Nikolai De Silva said:

Is this out of collimation?

It is impossible to tell. You need to place some light coloured card or paper behind the secondary mirror so that we can see where the edges of the mirror and focuser are in order to judge whether they are concentric. You also need to smooth down the foil on your collimation cap so that the entire surface looks bright. The dark dot formed by the eye hole should be inside the doughnut on the primary mirror but with such a large dark section in your cap the hole is not visible.

1 hour ago, Nikolai De Silva said:

And also how to adjust the the secondary mirror where no bolts are there?

The three outer bolts are recessed and need adjusting via a suitably sized hex/allen key.

It could also be a transient astigmatism present only while the primary or corrector is cooling, which is more prominent now the temperature has dropped than it was over the summer months. 

1 hour ago, Neutrinosoup said:

Is it usually as easy as this!

No, you would usually have to adjust both mirrors. However, what you have described makes sense. When you collimate with a laser any error made in the collimation of the secondary will result in double the error in the primary collimation. It sounds like your scope was collimated in the factory and during transport only the secondary moved, hence you saw that the secondary was out and the primary was further out. When you fixed the error in the secondary it also fixed the larger error in the primary because in reality that error didn't exist, it just appeared to due to the error in the secondary.

As a visual observer how much did you find yourself using it as an EEA device, sitting there watching the image appear on the screen, compared to using it as an imaging device where you would set it on a target and then leave it until some time later to check whether it had produced an acceptable image?

Jupiter is very susceptible to atmospheric seeing, which is the stability of the atmosphere, not the darkness of it. In fact many people report that their best planetary views occur when there is a light haze in the air as there is no wind to blow the water vapour away. Due to this requirement for stable air, observing from a dark site will not necessarily show better results than observing from home, other than avoiding any negative effects from the heat haze coming off roof tops. Given the recent weather I would not be too concerned about any potential lack of sharpness over the last couple of weeks and would simply continue to observe without worrying too much about the collimation of the telescope or any other tweaks that may improve its performance. 
 

One important section of atmosphere that is often overlooked is the air inside the telescope itself. When moving a telescope from a warmer location to a colder one there is a cooldown period where the components are cooling and this leads to air currents inside the telescope. For a 5” Newtonian this isn’t very long but within the first half an hour of observing I would consider this a possibility and see if the sharpness improves later in the session.

There is no 6mm Starguider, but there is a 5mm. The 5, 8 and 12mm Starguiders are well corrected even in fast scopes whilst the longest focal lengths are best used in slow telescopes. This means that in the specific case of the 5mm Starguider vs the 12mm Starguider + Barlow there will be very little difference between them. However, as a general rule if you are using a fast telescope and cheaper eyepieces then adding a Barlow can often improve the correction of the eyepiece. 

I would choose a 5 and 12 over a 12 and Barlow as the eyepieces will be more parfocal, but if you were buying three items then there would be a good argument to buy 8, 12 and a Barlow so that you effectively have 4, 6, 8, 12 instead of buying 5, 8, 12, assuming that 4/5/6mm focal lengths are suitable for the telescope you will be using them with. 

1 hour ago, Neutrinosoup said:

Considering 1 or 2 for a small travel case when I visit my parents, Delos are big…..and I only have the 24mm panoptic 

Option 1 = Get the Baader zoom….

Option 2 = Take my Panoptic 24, and buy Delite 11/13 and Delite 5/7

(For use with a 72mm apo, focal length 430)

I have a 72ED and use 24 Panoptic, 13 Delite and 3-6 Nagler zoom. The only change I might make is to swap the 13 Delite for a 13 Nagler T6, which is also a small eyepiece. 

Given you currently use Delos I think you would be disappointed with the correction level and reflections in the BHZ at f6.

11 hours ago, Lung said:

Thanks again all. It does sound like a Mak is the way to go. The 102 is fine budget-wise, while the 127 is a bit more of a stretch once you add in mount, tripod etc. Will the benefits of the 127 over the 102 be noticable to a total beginner like me, or are they the kind of thing you'd need experience or different eyepieces etc to appreciate or make use of? There seems little point spending the extra now if the larger scope only comes into its on by spending more on accessories, or by having used it for several years first, but conversely if it really improves things for a beginner then it becomes worth the extra money from the outset.

The benefits of the 127 lie in its larger aperture. The aperture of the 127 is approximately 25% larger than that of the 102 which translates into a 25% better resolution for planetary targets, 55% brighter stars and a 25% increase in optimum magnification on all objects. The previously posted field of view images don't really show this difference too well. When you look though the eyepiece the apparent field of view is the same, so the different circles appear to be the same width, with all the contents magnified that little bit more. Setting up the various scopes and eyepieces in the desktop version of Stellarium would show this more clearly. As a beginner you won't notice the difference simply because you don't have any point of reference but I think if you had the two telescopes side by side you would see the difference. If I were buying myself one of these telescopes as my only telescope I would go for the 127 but in my current position with a larger telescope I would also be happy with a 102 as a planetary grab and go option.

11 hours ago, Lung said:

With that in mind, is there a recommended 102 and/or 127 Mak to go for? I see there's the Skymax, the Messier and I think a Celestron, so do any of those stand out or is a case of finding the best deal on any of them? Or have I missed one from a different company i should be looking at?

The Skywatcher and Celestron models are made by Synta so they should be the same with some minor differences to the fixtures. Ed Ting has recently done a review of the Skymax 102 that you might want to watch. Note that any visual DSO views will be small grey smudges nothing like the colour images he manages to get by sticking a camera on the end for hours and doing lots of post processing. The Bresser Messier scopes tend to be a little bit better mechanically, but optically probably about the same as the Synta scopes. The one difference between the two manufacturers that is notable is that the Bresser scopes are f/15 whilst the Synta scopes are f/13 so for any given eyepiece there will be a slight increase in magnification with the Bresser and a slight increase in field of view with the Synta. It probably means that the Bresser is slightly better for planetary but the Synta is a bit more of an all round scope. Any of these scopes would be a good choice and you're probably best off choosing whichever one comes bundled with the mount that you want to get.

9 hours ago, Vinnyvent84 said:

Can someone give me some advice / insight? I have a Nexstar 6SE living in a Bortle 8 zone in NYC. Would upgrading from a ES 2x Focal Extender to a Televue Powermate 2.5x show a worthy difference for lunar and planetary visuals?

Looking at your other posts your eyepieces are a 32mm TV Plossl, a 8-24mm BHZ and a 7mm X-Cel LX. With your f/10 SCT the only eyepiece that you can really use the 2X extender with for planetary is the 32mm Plossl, to emulate a 16mm Plossl, which is too low a magnification. For planetary you will want to be using the 8-10mm part of the range of the BHZ and (maybe!) your 7mm X-Cel LX. Setting your BHZ to 12mm and using it with the extender is almost certainly going to degrade a planetary image in an SCT, but might be useful for splitting double stars.

So no, you won't see any increase in planetary performance by upgrading to the TV Powermate, because either extender should remain in its box during those observations.