johnturley

Be interesting to hear how it compares with the TOA 150 that you used to have, whether performance is almost as good or as good.

John 

Observed Mars again at around 18.00 yesterday (27 November) when the Mare Erythraeum should have been on display, despite a reasonably steady image little detail was visible, and the South Polar Cap could just be discerned, indicating continuing dust storm activity, although according to the BAA website these are now weakening.

John 

I also got my first reasonable view of Mars for a week or two last night, observing between 21.00 and 22.00 I could just make out Solis Lacus, although it was not very district, indicating some possible dust storm activity.

I could also just make out the South Solar Cap, unlike in November 2005 when it appeared to disappear completely.

John 

2 hours ago, vlaiv said:

Would that still hold at F/7 and could we possibly add another criteria - light weight - what would be options then?

IMHO the 36 mm Baader Aspheric is not bad at all in my f7 Esprit, but not that great in my f5 Newtonian.

Is there any reason why it might perform better in an f7 triplet refractor than say in an f7 Newtonian.

John 

5 minutes ago, Don Pensack said:

If you are looking for an inexpensive wide field eyepiece good at f/5, you will buy a lot of different eyepieces to discover that such an eyepiece doesn't exist.

Cheap---well corrected in the outer field---wide field.  Pick any two.

A couple candidates for you: TeleVue 41mm Panoptic, Pentax XW 40mm for maximum field with good correction.

Thanks Don

The trouble with the above is that they are both big heavy eyepieces which I was trying to avoid due to balance issues with my scopes.

John 

16 hours ago, globular said:

 

You should perhaps target something around 4 to 5mm exit pupil = focal length of 20 to 25mm.  Maybe you can push it to 6mm pupil = 30mm fl as you have such a large aperture?

To give a similar TFOV to your Meade they would need to be hyper wide - which makes them heavy and expensive.

A better compromise is probably to give up a little TFOV to save weight and cost.

I wasn't looking for an eyepiece with a smaller exit pupil, I already have a 24 mm Explore Scientific 82 degree eyepiece, just eyepieces around 50mm and 35mm to provide a wider field and/or less aberrations than my existing Meade 56mm Plossl and Baader 36 mm Aspheric.

I thought at first that the 50 mm StellaLyra Superview eyepiece with a stated APFOV of 60 degrees might provide an improvement over the 56 mm Meade, and although the level of aberrations appeared acceptable, it turned out that the actual APFOV was only around 48 degrees or less, giving a resultant actual field of view that was significantly smaller than both the Meade 56mm Plossl and Baader 36 mm Aspheric. There does not appear to be much available around 50 mm that might be better than the Meade, the Masuyama 50 mm might be slightly better, but at £499 it is a high price to pay for something that at best would only be marginally better.

At around 35 mm, there are more options, the Masuyama 32 mm looks good on paper, but it appears that the 85 degree APFOV from a 5 element design will result in a lot of aberrations towards the edge of the field, especially in a f5 instrument. The 35 mm Aero according to some reports might be an improvement over the 36 mm Baader, and at a relatively modest price of £105, or the 30 mm APM Ultra Flat, although the actual field of view of the latter will be significantly smaller than the 36 mm Baader.

John 

3 minutes ago, John said:

I found the Aero ED 40 a really nice eyepiece even in my F/5.3 12 inch dob. Not perfect but surprisingly well corrected across the field of view for a relatively low cost super wide 2 inch.

I recently sold it though because I find that I just don't use that longer focal length under my skies. The 31mm Nagler and the 21mm Ethos work better for me with regards to background sky darkness and DSO contrast. Hugely more expensive though and much heavier eyepieces.

For the £60 or so that the Aero ED 40 cost me pre-owned it was a great performer though.

 

 

Thanks John

Is the quoted 68 degree APFOV of the Aero ED genuine, it looks very compact compared to the Panoptic especially in the 40 mm focal length.

I would probably however more likely go for the 35 mm as a replacement for the Baader Aspheric 36mm, may however wait until Rother Valley Optics showroom re-opens (hopefully sometime in the spring), so that I can look at one before deciding whether to purchase.

John 

8 minutes ago, John said:

https://www.cloudynights.com/topic/562496-masuyama-32mm-85-deg/

 

Thanks John

It looks like that it would have some shortcomings in an f5 Newtonian like the Baader Aspheric

26 minutes ago, globular said:

 

The maximum TFOV you can get with a 2" barrel is an eyepiece with a 47mm field stop - like the Masuyama UltraWideField 32mm which would give 1.51 degrees.  A lot more magnification but only slightly more sky than the Meade.  It weighs 450g so is quite light.  As I say, I can't speak for it optical quality.

 

The Masuyama UltraWideField 32mm looks promising on paper with a quoted APFOV of 85 degrees, and about half the price and weight of the 31 mm Nagler, but wonder what the edge performance of the 5 element modified Plossl design of the Masuyama would be compared to the latter. 

John 

My widest 2in eyepieces are currently a Meade 56 mm Plossl, and a Baader 36 mm Aspheric. The former with a 52 degree apparent field of view gives just a slightly larger actual field of view than the latter with a 72 degree APFOV, and my experience indicates that these quoted APFOV’s unlike those quoted by some manufacturers such as StellaLyra are more or less correct. I should add that the 56 mm Meade is one of the original 5 element smoothside, (made in Japan) Plossls, similar I understand to the Masuyama, and not a true Plossl. 

I have looked into bettering these, but there do not seem to be many alternatives available, especially as I wanted to avoid excessively big and heavy eyepieces as my 14 in Newtonian on which my Esprit 150 is piggybacked is quite balance sensitive, and you can’t lock the dec axis. The Meade 56 mm weighs 550g, and the 36 mm Aspheric is quite a lightweight for a 2in eyepiece at 400g.

Although it is really too low a power to use in a f5 Newtonian, the 56mm Meade Plossl gives a surprisingly good edge performance in this instrument.  On the other hand the 36 mm Aspheric whilst giving quite good edge performance with the f7 Esprit, it is not so good with the f5 Newtonian. The edge performance with the latter can be improved by using a Coma Corrector, but the problem is not so much that the edge of field displays a lot of coma, but that the centre and the edge focus at different points, i.e. if you focus on the edge, the centre is out of focus, and vice versa.

One problem however with the 56mm Meade is that you have to hold your eye a few centimetres away from the eyepiece when viewing, and with being an old eyepiece does not have a rubber eyecup. I did wonder how this eyepiece would compare with the current Tele Vue 55mm Plossl, but I did have the chance to compare it 30 years ago with the then Tele Vue product, and thought that the Meade was sharper, but this was comparing a 5 element to a 4 element design. The current Meade version does have a rubber eyecup, but is now only a 4 element (made in China) version, and suspect it would not perform as well. Incidentally the original Meade 5 element (made in Japan) Plossls were priced similar to the Tele Vue Plossls, but the current 4 element (made in China) versions are about half the price. The current 5 element 50 mm Masuyama would probably be better, but priced at £499 it is a high price to pay for something that might only be marginally better. When I first saw the 50 mm StellaLyra eyepieces with a quoted APFOV of 60 degrees advertised, I thought that this might be a suitable alternative, but it turned out that the actual APFOV was only around 48 degrees, and gave a significantly smaller actual field of view.

Looking for something superior to the 36 mm Aspheric, eyepieces such as 35 and 41 mm Panoptics, plus the 31 Nagler spring to mind, but they are all big, heavy, and very expensive eyepieces.

Would be interested to hear about other people’s views and experiences, and any other recommendations.

John

12 minutes ago, vlaiv said:

 

If 36mm Aspheric has larger FOV - and it does since field stop is 45mm - it might tick the right boxes - at least vs 50 mm / 42 mm SuperView. On the other hand, if I wasn't planning on upgrading F/10 scope - then sure, 42mm Superview would be cost effective wide field to use.

The 36 mm Aspheric will give a slightly wider actual field of view, I'm pretty sure that the quoted APFOV of 72 degrees is more or less correct, and this figure is also confirmed on Eyepiece Planner (beta) . Another nice thing about the Baader Aspheric is that when looking through it, the field stop is quite sharp and well defined against the night sky compared to the 50 mm StellaLyra (I haven't seen a 42 mm to compare it with), and you don't have to place your eye several centimetres away to see the full field, plus you can also get (if required) an extension ring for the Aspheric, although I don't think that you will need it. At £139 it is however  twice the price of the 42 mm StellaLyra, definitely don't bother with the 50 mm, which according to Eyepiece Planner (beta) has a slightly smaller actual field of view. 

John  

1 hour ago, vlaiv said:

Out of interest, how do you compare edge performance of the two in fast telescope (Aspheric vs SuperView)?

Hi Vlaiv

I would say that through my f7 Esprit, there wasn't a great deal of difference in edge performance between the 36 mm Aspheric and the 50 mm StellaLyra, but through my 14in f5 Newtonian, the edge performance of the StellaLyra was noticeably better, but you have to bear in mind that you are comparing a 72 degree APFOV to only about 48 degrees. 

Incidentally the view through the 36 mm Aspheric with my 14in Newtonian, can be improved by using a Coma Corrector, but the problem is not so much that the edge of field displays a lot of coma, but that the centre and the edge focus at different points, i.e. if you focus on the edge, the centre is out of focus, and vice versa.

Although it is really too low a power to use in a f5 Newtonian, the 56mm Meade Plossl gives a surprisingly good edge performance in this instrument, although it is one of the original 5 element, made in Japan Plossls, similar I understand to the Masuyama, and not a true Plossl. 

Was thinking of staring a separate thread on the best 2 in wide field eyepieces.

John 

Got the chance last night to try out the 50 mm StellaLyra SuperView eyepiece on the Pleiades last night, both through my 150 mm Esprit and my 14 in Newtonian, I was pleasantly surprised that there was only a slight falling off of image quality towards the edge of the field of view, even through my 14in Newtonian. 

However as anticipated the actual field of view was significantly smaller than through not only my Meade 56 mm Plossl, but also my 36 mm Baader Hyperion Aspheric. I would estimate the actual field was at least 10% smaller than through the 56 mm Plossl, and assuming the stated APFOV of 52 degrees for the latter is correct, this would make even the revised (by FLO) APFOV for the StellaLyra of 48 degrees to be a bit on the optimistic size, and I would estimate the actual figure to be between 45 and 47 degrees. According to the information given in Eyepiece Planner (beta) the field stop diameter is 41.88 mm (slightly smaller than for the 42 mm SuperView), when it could have been up to 46 or 47 mm, which would have given an APFOV of around 53 degrees (which the Masuyama 50 mm has), presumably the manufactures have reduced the field stop to reduce edge of field aberrations. 

Since I purchased this eyepiece based on the manufacturers stated APFOV of 60 degrees (which would have given a wider actual FOV than both my Meade 56 mm and Badder 36 mm), I will therefore, sorry FLO, be returning this eyepiece, its really annoying when the manufacturers quote a very inaccurate APFOV, and they must know when this is the case. 

John 

6 minutes ago, rofus said:

Hi John

 

do you know if the locking lever at the bottom does basically the same thing?

Partially engaging the locking lever will prevent the focuser from slipping, but if engaged too much then the fine focuser won't work, also was worried that trying to turn the focusing knobs while the locking lever is partially engaged could damage the mechanism.

John 

27 minutes ago, wornish said:

 

The very small socket headed bolt(screw) shown with red arrow on the photo was very loose.  I just tightened it a little with an allen key and everything now works great.

The bolt I think sets the friction pressure for the fine focusser.

This is for my Esprit 100 so not sure if its the same for the 120.

 

Hope this helps

 

 

Dave

Do you know what size Allen key fits this bolt, I have similar problems with the fine focuser on my Esprit 150

I've tightened very slightly the 2 bolts either side of the focuser as shown in the in the photograph below with a 2mm Allen key, to prevent the focuser from slipping, however if you tighten them too much then the fine focuser won't work. You also have to be careful not to slacken them off too much, otherwise I understand that there is a risk that the pressure pads can fall out, which are very difficult to replace.

John 

On 13/11/2020 at 11:23, vlaiv said:

 

https://eyepieceplanner.com/#/

which gives:

Red asterisk means that values are calculated and not measured - apparently, measured value here is field of view - probably by some sort of timing method (star drift for example). It says that 50mm has only 48° AFOV and 42mm has 58° AFOV. This makes 50mm one show less sky than 42mm.

50mm offers longer focal length and larger exit pupil. In slow scope that can sometimes be beneficial. In fast scope - you'll soon have larger exit pupil than is recommended and there is really no point in using 50mm vs 42mm as result will be virtually the same.

If you are after max true field of view - then you should really look for eyepieces with 46-47mm of field stop. There are few models that deliver that, but they are not cheap. Probably most affordable one is this:

 

 

Interesting chart, according to which the Stella Lyra 50mm eyepiece Super View Wide Field eyepiece has a smaller APFOV than standard 2 in barrel Plossls such as the Meade 56 mm, and the Teleview 55 mm (both of which have 46mm field stops), despite being described as 'Wide Field' , and as you say will show less sky than the 42 mm.  The only 2 in eyepieces which would give a marginally larger true field of view than the Possls would be the Masuyama 50 and 60 mm eyepieces, which are very expensive. I think that my Meade (5 element made in Japan) 56 mm Plossl is of similar design to the Masuyama eyepieces, and not a true Plossl. 

I am waiting for the next clear night to compare the Stella Lyra 50 mm with my Meade 56 mm Plossl.

John  

12 minutes ago, gilesco said:

Well it has arrived and looks all OK. Can't help but notice that the dew shield says Esprit 120 (which is what it is), but the focuser is labelled ED100, which should read D=120 F=840 f/7

 

 

Looks like they fitted a focuser intended for an Esprit 100, I think that they both have the same focuser, but I can understand that its a bit annoying.

John 

24 minutes ago, HollyHound said:

Oh, that's disappointing... I haven't had a chance to try mine yet (still back in it's box for now, as had others arrive), but if it is that much smaller then regrettably I might have to do the same. Will give it a quick go in the StellaMira on the next clear night and see. Would be interested in any feedback if you do get to try it too.

Yes, ideally I will compare it on the Pleiades and the Andromeda Nebula with my Meade 56mm Plossl, through my Esprit 150, Sunday appears to be the first chance of a clear night,

John  

On 13/11/2020 at 09:26, FLO said:

@vlaiv @John  As you know, these GSO manufactured eyepieces have been on the market for many years in one form or another. But they are new to FLO. We added them to our website only yesterday so if either of you notice any specifications that need correcting please let me know 🙂 

Steve 

Ordered the 50mm from FLO on Wednesday, and it arrived this morning.

It is a nicely constructed eyepiece and quite lightweight, but the stated apparent field of view appears to be MUCH smaller than the quoted value of 60 degrees, probably about only about 45 degrees, and similar to what you get with most 40mm Plossl eyepieces in 1.25 in barrel diameter. I will therefore probably be returning this eyepiece, but may try it out in one of my telescopes first to make sure. 

I was originally attracted to the 50mm Super View eyepiece, as on paper it would have provided an wider actual field of view than my Meade Series 4000 (original 5 element smoothside made in Japan) 56mm Super Plossl, which has a stated APFOV of 52 degrees.  However holding up the 2 eyepieces side by side, the APFOV of the 56mm Meade eyepiece is significantly wider, despite the longer focal length. 

Its very disappointing when the APFOV turns out to be much smaller than the quoted value, if it had turned about to be just slightly smaller, say around 55 degrees, I would probably have kept the eyepiece. I can remember  back in the 1970's buying a 47 mm RAS fitting (threaded 1.25 in) Charles Frank Ultra Wide Angle eyepiece, which had a stated apparent field of 57 degrees, but in reality it turned out to be less than 30 degrees! I did not realise at the time that it was not possible to produce a 47 mm eyepiece with a 57 degree APFOV in a 1.25 in fitting, I don't know why some manufacturers quote these over optimistic figures, as it inevitably leads to disappointment. 

John    

On 16/11/2020 at 08:49, maw lod qan said:

 

I can only hope to make it to '32 and hope for another storm!

 

Unfortunately according to Sky Map Pro, expected peak on 17 November 2032 virtually coincides with full moon.

John 

Was completely clouded out here too.

John 

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

I have the 5, 9, and 15 mm SLVs, and compared the AFOV simply by holding pairs up to both eyes, pointing at an evenly illuminated white wall, and checking whether the image circles matched. The 9 mm and 15 mm match, but the 5 mm compared to either shows that the 5 mm has a slightly smaller FOV. Not something you would really notice in everyday use, but the 5 mm definitely has the smaller FOV. Therefore, I find it most likely that it has a 45 degree AFOV rather than the 50 degree AFOV of the 9 and 15 mm

I have the 4 mm SLV and the AFOV is definitely smaller than the stated 50 degrees, significantly smaller than that of some 50 degree Plossls that I have, and would also estimate AFOV to be about 45 degrees. 

John 

48 minutes ago, Louis D said:

I wouldn't doubt it with the advances in low dispersion glass and improved Chinese lens polishing.

The question then arises, are their lens cells as well designed to hold collimation as temperatures drop for astrophotography?

The pre Starfire Astro-Physics Refractor that I used to own did not even have a collimatable lens cell.

John 

On 29/10/2020 at 17:26, johninderby said:

If you want to start a war on Cloudy Nights just say that the Chinese can make scopes just as good as Astro Physics. 😁😁😁

AP is just another import in the UK anyway. 🙂

Actually they can, my Skywatcher Esprit 150 is superior to a early (pre Starfire) 6in f8 Astro Physics Refractor that I used to own in terms of sharpness of the image, and vastly superior to it regarding colour correction.

John 

46 minutes ago, parallaxerr said:

 

Am I right in saying that using moderate 55°-68° EP's with the 8" would not necessitate the requirement for a coma corrector?

 

 

In my opinion you do not require a coma corrector for visual if you are using well corrected eyepieces (including the TV and ES 82 degree eyepieces) for scopes down to around f5, unless you are a fanatic  about the view being aberration free right to the edge of the field. You also need to be aware that some coma correctors are quite heavy as well and will potentially affect the balance of your scope, and partly for this reason don't usually bother using my ES Coma Corrector with my 14in f5 Newtonian. 

For photography however this is a different matter.

John