Mak the Night

That's interesting. From what I can gather Nagler eyepieces inter alia were influenced by 100° FOV (or more) optics originally developed for German U-Boat periscopes.

They were my father's, he bought them secondhand before I was born. He was a trained engineer and stripped them down many years ago to clean and service them. I'm pretty sure the 'x' scratched into the left monocular front plate (which can be seen here) was made by him when he took them to pieces to facilitate cleaning them. As far as I can tell the optics are not coated. I use the binoculars regularly and they are as good to use today as I remember from using them when I was a child (when my dad let me lol). I've used a fair few pairs of binoculars, yet I've never found any to rival these. The wide angle view is quite spectacular. I don't know much about the history of them but my dad always maintained that they only ever had one previous owner who purchased them new in the early 1930's and possessed them through WWII until the 1960's when he sold them to my father.

Vintage pre-WWII Carl Zeiss 8x30 Wide Angle

I think Celestron sometimes refer to that AstroMaster Kit 'Kellner' as wide angle, so that slightly extra field stop size was probably what I was noticing. It got me started alright; I started to buy wide angle TeleVue eyepieces lol! Next, an Ethos I think.

I think it was the field stop of that Kellner (if it is a true Kellner and not modified by Celestron somewhat) that intrigued me the most. It seemed so wide compared to the Plossls I had. It's objective lens does seem too far from the end of the barrel compared to the diagram to be a Kellner even though Celestron describe it as one. I'm pretty sure the Celestron erectors are intended for terrestrial use, although I used mine for planetary viewing in a Newtonian once or twice, albeit combined with a TeleVue 3x Barlow!

The 20mm erecting eyepiece usually supplied with AstroMaster telescopes seen here to the right of the Kellner. I'm not sure what type the erecting eyepiece is but the Kellner differs from the Plossl in design. This probably explains its wider field of view.

Well, you can't go wrong with the Omni Plossls, they're pretty good. I never use a Moon filter and I view the Moon a lot. I find after a while I can adapt to the brightness and if I'm lunar viewing I usually don't try to observe anything else. Where I live in the greenbelt, as light pollution isn't a real problem, a Full Moon tends to light up the whole viewing area (aka my back lawn lol) anyway often negating the need for a red-light torch. I usually lunar observe with my 102mm Mak so when I get a 9.25" SCT early next year I may need a filter with the bigger aperture. I'm also planning on acquiring binoviewers essentially for lunar and planetary observing so I've been thinking about filters in general. If I were you, I'd invest in some decent eyepieces first and look at filters later. Oddly, I really used to like viewing the Moon with the 15mm Kellner from the AstroMaster Kit. You can see it has a large subjective lens and it also had a large AFOV and field stop, which I believe is often the case with Kellners. I think you can pick the AstroMaster Kit up for around 50 quid. The Barlow is good quality and has a removable element. The kit also has a Moon filter and a red and a blue Kodak Wratten filter. I'd get the Omni Plossls and a Barlow though rather than the AstroMaster Kit. I so want a Terry's Chocolate Orange now lol!

Yeah, it's terrible having new gear with rubbish weather. Welcome to astronomy lol! If you've got the Celestron Eyeopener Kit (the one in the big silver shiny box) it's actually pretty good as a starter kit. I believe it's been through a few incarnations over the years but I liked mine. The 13mm, 17mm and 32mm Plossls are good quality and apart from the fact that they are a different colour seem more or less identical to the Omni range. The 6mm and 8mm have the same quality but many find them difficult to use, although I thought the 8mm wasn't bad considering the limits of eye relief and field stop on such a short focal length. The Barlow is basically the same as the Omni equivalent although you can't remove the lens element like on some Celestron kit Barlows. Optically it's fine. There are seven Kodak Wratten colour filters consisting of an #80A Blue, #58A Green, #56 Light Green, #25 Red, #21 Orange, #12 Yellow and a #0.9 Moon Filter. This PDF may be useful: http://sas-sky.org/wp-content/uploads/2011/09/SAS-The-Use-of-Astronomical-Filters1.pdf I found the orange useful for daylight lunar viewing as it turns the blue sky dark. The Moon tends to resemble a Terry's Chocolate Orange though lol. Like this (by courtesy of the Virtual Moon Atlas and PhotoFiltre 7): The Eyeopener Kit looks like this new: The ABS case is aluminium framed and looks 'Jason Statham' hard. I still find the case useful, albeit modified a bit.

You're welcome. There are probably really good 3x Barlows other than the TeleVue, but the quality both in build and optical is hard to beat IMO. The TV 3x Barlow was the first TeleVue EP I ever bought. It was worth the money.

TeleVue explain Barlows better than I could: http://www.televue.com/engine/TV3b_page.asp?id=52&Tab=_back Like John says above, there are constraints with Barlows depending on atmospheric conditions and telescope specifications. With your 5.1" aperture AstroMaster you should get a decent maximum resolution at around 300x. With good optics you could get around 60x magnification for each inch of aperture on your scope (this only applies to scopes 6" or under). So as long as you don't exceed that rough rule of thumb with any combination of eyepiece/Barlow or other amplifier you should get a relatively sharp image. Conditions are important though and so is the angle of the target object. Objects low in the sky, particularly in the plane of the ecliptic, like the Moon and planets are viewed through many more kilometres of sky than objects nearer the Zenith. Thermal heat rising can also be a factor in distorting views of lower objects particularly. Due to the nature of the atmosphere it's well nigh impossible to get much more than 300x anyway and unless you actually live in low Earth orbit anything above 350x is unrealistic. In fact, I believe that although you may be able to exceed 350x with a big enough aperture you can't actually see any more detail, just a larger image. My 10mm Luminos in a Barlow would give me 260x on my 102mm/4" Mak, with its 241x resolution limit, and Saturn looks impressive but a bit grainy with it (I live in the green belt so have little light pollution) so if I use the Luminos I tend to thread a Barlow element straight into the eyepiece magnifying by only 1.6x instead of 2x. Although I tend to prefer to use a TeleVue Powermate 2.5x combined with a 16mm T5 Nagler for those sort of magnifications these days. I have experimented with the Luminos with a 3x Barlow on my Newtonian although the result was a tad heavy! It gave me 270x magnification, although as I hadn't set up the clockdrive even with an 82° AFOV any target moved quickly out of frame. The quality of Barlows varies considerably, I prefer the TeleVue ones but they can be expensive. My Powermate (not strictly a true Barlow) cost more than my Newtonian scope including mount, tripod and motor drive. The Celestron Omni Barlows are good, I'm not sure if they do a 3x Omni Barlow. With an AstroMaster 130 a 3x Barlow would be a great help to improve magnifications with longer focal length EP's. I can't recommend the TeleVue 3x enough if you are worried about quality of viewing. It really is superb. http://www.telescopehouse.com/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2etelescopehouse%2ecom%2findex%2ehtml&WD=televue%20barlow&PN=TeleVue_3x_Barlow_1_25__%2ehtml%23aBLW_2d3125#aBLW_2d3125

I have the Omni 12.5mm and 15mm Plossls, plus the Omni 2x Barlow, they are very nicely made Plossl EP's with a generous eye relief on the 15mm. Eyepieces are usually 1.25" or 2" in barrel diameter. I'm pretty sure your AstroMaster has the 1.25" eyepiece focuser. There is even an AstroMaster Kit available, although the Omni EP's bought separately would be better. Above you can see the AstroMaster kit case where I have replaced the original contents with my two Omni EP's, a 17mm Celestron Plossl and a 20mm Celestron erecting eyepiece. You will very probably be given the same erecting eyepiece with your AstroMaster scope. It's predominantly for terrestrial use and has a plastic body. It can be useful though if the upside-down world of Newtonian telescopes is disorienting at first and I used to use an erector on my Newtonian sometimes to help me acquire targets. Your AstroMaster has a focal length of 650mm, which means that if you place a 10mm eyepiece into the focuser you will get a 65x magnification. If you divide the focal length of the telescope by the focal length of the eyepiece it gives the magnification. The 20mm erector will give you 32.5x magnification. For sweeping star fields around 30x is OK, but for lunar or planetary observing you will want at least 65x and preferably twice that. You should see the rings of Saturn at 65x for example. You can double (or more) the magnification by using a Barlow lens which is placed into the focuser and the eyepiece then placed into the Barlow. Above, Omni and standard Celestron Barlow lenses. I think the Omni Barlow is well worth the money (although I did get a deal on mine lol). The problem with Plossl eyepieces of much less than 13mm focal length is that you may have the magnification that you need but you will have a smaller field stop and field of view, which many find uncomfortable. Which is why the only 10mm EP I use much is a Celestron Luminos wide angle. They can be around £100 though. And 3/4 of a pound in weight! lol As you increase the magnification the target will move in the field of view more quickly due to the Earth's rotation (Right Ascension), so a wider eyepiece field of view is easier to view the object in frame. The 12.5mm Omni should give you a 52x magnification with the AstroMaster, which you could potentially double with a Barlow lens. The 15mm would only give you about 43x but again, you could double that with a 2x Barlow. You can even triple it with a 3x Barlow. I have a 130mm scope with a 900mm focal length and I would often use a 15mm EP placed into a 3x Barlow for planetary viewing with it. I'd also look at the Omni 32mm Plossl as a low power sweep/search EP. I have a Celestron 32mm which is more or less the same as the Omni (not as pretty lol), although I prefer my TeleVue 32mm these days, the Celestron is nice though. The large field stop/apparent field of view of these larger Plossls is very aesthetically pleasing for viewing star fields and objects like open clusters. I hope this was some help. http://www.celestron.com/browse-shop/astronomy/telescopes/astromaster-130eq-telescope

There was a time when this Celestron AstroMaster Kit was my eyepiece case. Now it's still useful and usually carries a Celestron 17mm Plossl, Omni 12.5 & 15mm Plossls and a Celestron 20mm erecting eyepiece.

It's a shame about your 17mm Plossl, maybe it is defective. The best EP's in the Celestron Eyeopener Kit were the 17mm and 32mm Plossls IMO. The 13mm wasn't bad but the 6 & 8mm were virtually unusable.

That Celestron Kellner is pretty well made, although the plastic barrel lets it down I think. I believe it's difficult to apply paint blackening to plastic. The subjective lens is large (as you can see in the jpeg) and the field stop rivals a 32mm Plossl, or seems to. I got such good views of the Moon and Jupiter with it it inspired me to shell out on wide angle EP's. TeleVue Plossls are very well made, but I actually find the Celestron Omni Plossl 15mm easier to use than the TV 15mm with its 12-13mm eye relief compared to the TV's 10mm. These are all 15mm except the end Celestron Plossl, which is 17mm. The Celestron 15mm and 17mm Plossls are nearly identical. Although when directly compared the 15mm gives a slightly bigger image as would be expected. The TeleVue at the extreme left gives the biggest and sharpest image yet has the smallest eye relief. The size of the Kellner's subjective lens is readily apparent. Its eye relief seems the same as the 15mm Omni. The Kellner has the biggest AFOV. Weird or what?

Very interesting. Before I acquired more expensive eyepieces I found that the relatively inexpensive 15mm Kellner and the Barlow from a Celestron AstroMaster Kit worked very well in my 102mm Mak with its f 12.7 and 1300mm f/l. The Kellner was plastic barreled but had a huge field stop with a nice AFOV, far more than the 15mm Omni Plossl that I supplemented it with later. I got the Omni on sale for less than half price. 15mm Celestron Kellner Kellner and Omni Plossl 15mm AstroMaster Barlow With the Barlow I could turn the 87x magnification into 173x, a very useful mag for lunar and planetary observing with decent FOV and eye relief. I had a 32mm Celestron Plossl for the low magnification. I also had a 13mm Plossl and slightly later a 12mm Omni Plossl. None of them were particularly expensive. All in all it gave me a decent range of around 41x to around 216x magnification. These were perfectly good to great views of Saturn and the Moon.

I have two medium sized cases I usually take out with me, an Orion and a modified Celestron.