Skywatcher 127 - advice re: eyepieces please

[vocalis]

Hi everybody. 

I'm a newbie to astronomy having returned to it after a while.  

I bought  a used  Skywatcher 127 which came with the entry level 10mm and 25mm wide angle long eye relief lens.

I read that these are the ones that most definitely needed upgrading so I went for a used set of BST Starguiders eyepieces which were available for a good price and had seen recommended here.

I have a 8mm, 12mm, 15mm and 18mm

Would it be worthwhile to upgrade the 25mm eyepiece? If yes what would people suggest? A 32mm Plossl?

I read also that the diagonal could do with an upgrade and I should get a good 2x Barlow, as the one which came with the scope seems rather basic.

My budget is not unlimited but would like to do justice to the scope.

Thanks in advance!

[Louis D]

First, don't bother with a 2x Barlow given the f/12 focal ratio and 1500mm focal length.  The 8mm will provide just about the highest usable power with your scope.

The 25mm BST or a 32mm Plossl would work well for widest field.  The BST would be wider and would fit in well with the rest of the BSTs.

If want to go wider, you can put a SCT thread adapter on the rear thread, install a 2" visual back on it, and then use a 2" diagonal.  With a 2" diagonal, you can use wider 2" eyepieces.  There is some vignetting and some odd reflections of bright stars with them, but I've found it actually works very well.  Here's an image comparing the difference:

[Zermelo]

The stock Skywatcher 25mm has a quoted 50° apparent field of view and 21.8mm of eye relief. It is giving you 0.83° true field of view in the Skymax.
It's a "modified achromat" design - not awful, not great either.  Your Skymax at F/11.8 will give it a good chance. I found some obvious pincushion distortion on my F/5.

You would certainly notice the difference with the BST (60° APOV, 16mm eye relief) which is well corrected for most aberrations. Some have reported a little edge distortion on faster scopes. It would give you a TFOV of 1°, which is about the best you can get unless you go for 2" format as described above.

Now that you have used the other BSTs, you should have a better idea on whether you think it's worth the spend for the difference in performance (and the wider view).

 

 

[vocalis]

19 hours ago, Louis D said:

First, don't bother with a 2x Barlow given the f/12 focal ratio and 1500mm focal length.  The 8mm will provide just about the highest usable power with your scope.

The 25mm BST or a 32mm Plossl would work well for widest field.  The BST would be wider and would fit in well with the rest of the BSTs.

If want to go wider, you can put a SCT thread adapter on the rear thread, install a 2" visual back on it, and then use a 2" diagonal.  With a 2" diagonal, you can use wider 2" eyepieces.  There is some vignetting and some odd reflections of bright stars with them, but I've found it actually works very well.  Here's an image comparing the difference:

Thank you Louis D, good advice.  With the 2" diagonal I would need to change all my 1.25" eyepieces, right?

[vocalis]

8 hours ago, Zermelo said:

The stock Skywatcher 25mm has a quoted 50° apparent field of view and 21.8mm of eye relief. It is giving you 0.83° true field of view in the Skymax.
It's a "modified achromat" design - not awful, not great either.  Your Skymax at F/11.8 will give it a good chance. I found some obvious pincushion distortion on my F/5.

You would certainly notice the difference with the BST (60° APOV, 16mm eye relief) which is well corrected for most aberrations. Some have reported a little edge distortion on faster scopes. It would give you a TFOV of 1°, which is about the best you can get unless you go for 2" format as described above.

Now that you have used the other BSTs, you should have a better idea on whether you think it's worth the spend for the difference in performance (and the wider view).

 

 

Thank you Zermelo. Any suggestions regarding the diagonal?

[Louis D]

22 minutes ago, vocalis said:

Thank you Louis D, good advice.  With the 2" diagonal I would need to change all my 1.25" eyepieces, right?

No, pretty much all 2" diagonals come with a 2" to 1.25" adapter/reducer.  However, the increased optical path length of the 2" diagonal will cause an increase of 200mm or possibly more to your native focal length, so you're best to stick with 1.25" accessories unless you really want that wider field on occasion.  I already have a bunch of premium 2" eyepieces that I wouldn't be able to use on the 127 Mak without a 2" diagonal, so I'm good with the increased focal length.

[Tiny Clanger]

That seems an expensive way to get the 127 mak to be a wider field 'scope ... I just looked on FLO, and taking the very cheapest options for each component would cost £36 for a 2" visual back, £99 for a 2" diagonal and £70 for a single 2" eyepiece. I've read that some newer SW maks do not need a thread adapter, but if your model does add the cost of that , which looks like at least £30, so all together at least £235 .

For that you could by a 150mm aperture, 750mm focal length  OTA which comes with a 2" focuser and get a 25mm BST too !

Heather

 

[Zermelo]

13 hours ago, vocalis said:

Thank you Zermelo. Any suggestions regarding the diagonal?

Sorry, I wouldn't want to comment on that.

[Steve Clay]

When I had the 127 Mak I found a 32mm plossil a great tool for getting on target. I then used the exact same combo of starguiders as you. For the cost of converting to 2 inch you would be better off looking for something like a used Ed 80 then you have a nice wide field and a lunar/ planetary set-up 

Steve

[Nik271]

I have a 127 SW Mak and frankly I don't think converting to 2inch visual back is worth the extra cost in diagonal and eyepieces.

The opening at the back is less than 30mm, i.e its optimised for 1 and 1/4 eyepices. Sure you can put 2 inch accessories with adapters but there will be vignetting as people have pointed out already. 

This only makes sense if you have the gear already, so it does not come at extra cost.

[Louis D]

15 hours ago, Tiny Clanger said:

That seems an expensive way to get the 127 mak to be a wider field 'scope ... I just looked on FLO, and taking the very cheapest options for each component would cost £36 for a 2" visual back, £99 for a 2" diagonal and £70 for a single 2" eyepiece. I've read that some newer SW maks do not need a thread adapter, but if your model does add the cost of that , which looks like at least £30, so all together at least £235 .

For that you could by a 150mm aperture, 750mm focal length  OTA which comes with a 2" focuser and get a 25mm BST too !

Heather

 

I already had multiple 2" diagonals and eyepieces for other scopes, so I just added a 2" thread adapter and visual back for about $60 ($25/$35 for each).  The second used 127 Mak I bought for my daughter already came with both, so no additional cost there.

Without a 2" diagonal, I couldn't use some of my favorite eyepieces like my 12mm and 17mm ES-92s, 22mm NT4, or 30mm APM UFF with the 127 Mak.  A $60 upgrade to use my existing eyepiece collection seemed like a no brainer.

Your second point misses the point that if this is a travel scope (camping, for my daughter), you don't want to bring along multiple scopes just to get a wider field.  I added a 60mm finder scope to my daughter's Mak so it can take in wider views of around 6 degrees while star hopping.

[Tiny Clanger]

12 minutes ago, Louis D said:

I already had multiple 2" diagonals and eyepieces for other scopes, so I just added a 2" thread adapter and visual back for about $60 ($25/$35 for each).  The second used 127 Mak I bought for my daughter already came with both, so no additional cost there.

Without a 2" diagonal, I couldn't use some of my favorite eyepieces like my 12mm and 17mm ES-92s, 22mm NT4, or 30mm APM UFF with the 127 Mak.  A $60 upgrade to use my existing eyepiece collection seemed like a no brainer.

Your second point misses the point that if this is a travel scope (camping, for my daughter), you don't want to bring along multiple scopes just to get a wider field.  I added a 60mm finder scope to my daughter's Mak so it can take in wider views of around 6 degrees while star hopping.

The OP didn't mention camping, or use as a travel 'scope , and doesn't say they already own any 2" eyepieces , or already have multiple spare 2" diagonals .

I'm not suggesting it was a poor decision in your case, you are missing the  point that  I was addressing the original poster's query. Hence the current UK costing for each individual component which they would have to buy .

[vocalis]

Thank you everybody for your comments. Food for thought!

[Tiny Clanger]

1 hour ago, vocalis said:

Thank you everybody for your comments. Food for thought!

I've not commented on the stock 25mm vs a 32mm plossl vs a 25mm BST before now, because although I own them , I'd never compared all three in my SW mak 127 ... the stock EP  I originally replaced with the plossl  ( a skywatcher super plossl, not fabulous, but at about £30 what I could afford in the summer when I started observing) .and subsequently snaffled a second hand BST .

Tonight though, I had a couple of hours of clear sky, and with the Moon wrecking my chances of seeing what I'd like to , I set the mak up and tried the trio against each other. Pointed at the Moon first, and there was a distinct increase in sharpness and contrast when going from the stock 25mm to the 32mm plossl. Going from the 32mm plossl to the 25mm BST gave another step of improvement , everything was clearer , sharper, brighter and just nicer to look at . Exactly as you'd expect from the steps up in price . As well as the better image, I find the BST easier to position my eye over.

The bright moonlight was washing the sky out somewhat, but I tried all three EPs in the vicinity of the Orion nebula , and as before the plossl and BST performed better and had wider views than the stock EP. I saw no 'kidney bean' effect in stars near the edge with the BST or plossl , I recall having seen that effect with an eyepiece in my 150 dob, but I can't recall which !

I'm no expert , and have probably described what I've seen through the three EPs in imprecise terms, and it is all very subjective, but in this 'scope, to my eyes, the relative costs of the 3 ( £not much , £30, £47) accurately reflected the quality of the views they give.  For me,  the BST is worth the extra over the plossl, but the plossl is perhaps a bigger jump in quality from the stock 25mm.

This illustration is from the FLO page on the BST, you can add or remove any listed eyepieces to see a mock up of various views with any listed 'scope

[vocalis]

Thank you very much Tiny Clanger. Your post is extremely helpful and gives me a very good idea of what to expect from the different EPs

I think I will go for a 25mm Starguider to complete the set I have already.

Will check the FLO page you mentioned: I didn't know about it.

As a matter of curiosity did you buy a better 1.25mm diagonal than the one supplied with the mak 127?

Like you I took the chance to get my scope out last night mainly to test the SynScan WiFi adapter I recently aquired. 

It was so freezing cold that I thought I might end up just like Jack Nicholson in The Shining!

 

 

[Tiny Clanger]

23 minutes ago, vocalis said:

Thank you very much Tiny Clanger. Your post is extremely helpful and gives me a very good idea of what to expect from the different EPs

I think I will go for a 25mm Starguider to complete the set I have already.

Will check the FLO page you mentioned: I didn't know about it.

As a matter of curiosity did you buy a better 1.25mm diagonal than the one supplied with the mak 127?

Like you I took the chance to get my scope out last night mainly to test the SynScan WiFi adapter I recently aquired. 

It was so freezing cold that I thought I might end up just like Jack Nicholson in The Shining!

But ... you are a penguin ! 🐧 The weather should be ideal for you 🙂

I think that EP comparison tool is on every eyepiece page on FLO's site (not that I've looked at the Tele Vue Ethos 21mm for a mere  £810 of course ... curses, gave myself away ! Look, it's been so cloudy , I had to do something ) It is very handy.

I had read that the standard diagonal was not great, and when the 'scope arrived it did seem a bit flimsy, but it's my first ;scope which uses such a thing, so had nothing to compare it with. I decided a slightly better dielectric star diagonal would be a good eventual upgrade, and noted there are two identical models on FLO at identical prices , currently £69  https://www.firstlightoptics.com/diagonals.html

which look like better made items without being silly money . I'd added them to my wishlist when a chance at a second hand one came up on the buy/sell here so I went for it. It has a much nicer engineered feel to it, is sturdier, and has one screw and a collar arrangement to hold the eyepieces rather than the original's  screws which might scratch the eyepiece barrel.

Exactly as with the 25mm eyepieces I've not taken the time to actually compare the views between the two diagonals, the better one was simply obviously better ! If I'd bought it new from a dealer, I would have compared them as I'd be able to return it if I didn't think it worth the expense. Which, by the way, is somethng you can do with eyepieces , distance selling reg.s in the UK give you that option. For the BST 25mm it might be worth checking if Alan at Sky's the Limit has any in stock, he is a good chap and responds to emails . https://skys-the-limit-108154.square.site/shop/1-25-bst-starguider-ed/8

After coming in last night and typing my reply aboutthe eyepieces, I stayed up and went out again with my 150 heritage dob after the Moon set at 2am ... the 25mm BST is really not as nice in it , star shapes were distorted around the edges of the view,  I found the 15mm BST better to use.  The mak 127 is f11.8, the little dob f5, so the dob is showing up shortcomings which do not bother the longer focal ratio mak .

Oh dear, I may have to look around for a better ( for better ,read expensive) low mag EP specifically for the dob now !

Heather

[Louis D]

22 minutes ago, Tiny Clanger said:

noted there are two identical models on FLO at identical prices , currently £69

Just be aware that if they are the same as the WO and other brandings, there's a 22mm or so lip inside that will vignette widest field eyepieces.

I've got the same type, and can verify the unnecessary baffle.  Since I only use it with binoviewers of 22mm clear aperture, it doesn't matter much to me.

Perhaps @FLO can verify if the StellaMira version does not have it.

[vocalis]

23 hours ago, Tiny Clanger said:

But ... you are a penguin ! 🐧 The weather should be ideal for you 🙂

True! I must have forgotten....  🙂

 

[vocalis]

23 hours ago, Tiny Clanger said:

I had read that the standard diagonal was not great, and when the 'scope arrived it did seem a bit flimsy, but it's my first ;scope which uses such a thing, so had nothing to compare it with. I decided a slightly better dielectric star diagonal would be a good eventual upgrade, and noted there are two identical models on FLO at identical prices , currently £69  https://www.firstlightoptics.com/diagonals.html

which look like better made items without being silly money . I'd added them to my wishlist when a chance at a second hand one came up on the buy/sell here so I went for it. It has a much nicer engineered feel to it, is sturdier, and has one screw and a collar arrangement to hold the eyepieces rather than the original's  screws which might scratch the eyepiece barrel.

Exactly as with the 25mm eyepieces I've not taken the time to actually compare the views between the two diagonals, the better one was simply obviously better ! If I'd bought it new from a dealer, I would have compared them as I'd be able to return it if I didn't think it worth the expense. Which, by the way, is somethng you can do with eyepieces , distance selling reg.s in the UK give you that option. For the BST 25mm it might be worth checking if Alan at Sky's the Limit has any in stock, he is a good chap and responds to emails . https://skys-the-limit-108154.square.site/shop/1-25-bst-starguider-ed/8

After coming in last night and typing my reply aboutthe eyepieces, I stayed up and went out again with my 150 heritage dob after the Moon set at 2am ... the 25mm BST is really not as nice in it , star shapes were distorted around the edges of the view,  I found the 15mm BST better to use.  The mak 127 is f11.8, the little dob f5, so the dob is showing up shortcomings which do not bother the longer focal ratio mak .

Oh dear, I may have to look around for a better ( for better ,read expensive) low mag EP specifically for the dob now !

Heather

Interesting Heather! Thank you once again for your time and good advice.

Raff 

[vocalis]

23 hours ago, Louis D said:

Just be aware that if they are the same as the WO and other brandings, there's a 22mm or so lip inside that will vignette widest field eyepieces.

I've got the same type, and can verify the unnecessary baffle.  Since I only use it with binoviewers of 22mm clear aperture, it doesn't matter much to me.

Perhaps @FLO can verify if the StellaMira version does not have it.

Thanks Louis D. Good to know!

[KP82]

On 22/01/2021 at 15:36, Tiny Clanger said:

Oh dear, I may have to look around for a better ( for better ,read expensive) low mag EP specifically for the dob now !

Heather

Look for a Tele Vue 32mm plossl or ES68 24mm. These are probably the cheapest eyepieces with good edge correction at f/5 and max possible fov in 1.25 format.