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Planetary Eyepieces


bosun21
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What is a decent eyepiece for magnified views of the planets and moon?. Should I consider a decent Barlow or extender?, or am I best aiming for short focal length EP’s?. I have a 8mm and 5mm Starguiders, Baader Hyperion Zoom 8-24mm. I was also thinking about orthos. That’s the thing I’m finding about astronomy, is that there are so many roads to take, with multiple doors at the end of them.

PS:- Looking for directions 

I have an 8” Dobsonian and a 127 Maksutov 

Edited by bosun21
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The 8mm will give 187x in the Skymax. Assuming the dob is an 8" @ 1200mm focal length the 8mm will produce 150x mag and the 5mm 240x.

Tbh in the UK a sensible max planetary magnification most nights given average seeing conditions is about 150-180x so realistically you don't really *need* more eyepieces.

When using the zoom what focal lengths seem the best to you? Which feel easier on the eye or seem to give the most clarity? What is it you don't like about your current eyepieces or what do you think you're missing? Sorry for the questions, but rather than just encourage you to spend more money it's wise to find out what your expectations are.

 

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I know all this about focal length and magnification etc. In theory my Dobsonian would be 2 x 200mm = 400x and my Maksutov 2 x 127 = 254x. What I’m asking is for any decent short focal length eyepieces and whether a Barlow or extender is feasible, or am I better sticking to the EP’s alone and forgetting the Barlow etc 

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3 minutes ago, ScouseSpaceCadet said:

The 8mm will give 187x in the Skymax. Assuming the dob is an 8" @ 1200mm focal length the 8mm will produce 150x mag and the 5mm 240x.

Tbh in the UK a sensible max planetary magnification most nights given average seeing conditions is about 150-180x so realistically you don't really *need* more eyepieces.

When using the zoom what focal lengths seem the best to you? Which feel easier on the eye or seem to give the most clarity? What is it you don't like about your current eyepieces or what do you think you're missing? Sorry for the questions, but rather than just encourage you to spend more money it's wise to find out what your expectations are.

 

Thanks and I obviously vary the fl of the zoom depending on the seeing conditions. What I’m asking is would a Barlowed high quality flat field EP of say 18mm be better than a mediocre 9mm. So if I bought several higher fl EP’s and a good Barlow etc could i save myself having to buy higher quality short length EP’s?

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If you were using short focal length eyepieces such as plossls and orthoscopics, then because of the short eye relief of these eyepiece designs, you would be better using a barlow with a longer focal length eyepiece of this type. This is because a barlow lens will increase the magnification but not effect the eye relief. However there are more modern eyepiece designs such as planetary type eyepieces that have much more comfortable eye relief. Your BST eyepieces are like this, they basically have an inbuilt barlow lens already.

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1 minute ago, Franklin said:

If you were using short focal length eyepieces such as plossls and orthoscopics, then because of the short eye relief of these eyepiece designs, you would be better using a barlow with a longer focal length eyepiece of this type. This is because a barlow lens will increase the magnification but not effect the eye relief. However there are more modern eyepiece designs such as planetary type eyepieces that have much more comfortable eye relief. Your BST eyepieces are like this, they basically have an inbuilt barlow lens already.

Yes I did notice this in the BST eyepieces. I have bought the full set of the Starguiders( apart from the 3.5mm) and also the Baader Hyperion Zoom. I’ve got enough to be getting on with and have decided to now build my EP collection one high quality addition at a time. In regards to my planetary question, it’s contrast I’m chasing. Not FOV or ER. Are the orthos or TMB’s contenders?

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29 minutes ago, bosun21 said:

In regards to my planetary question, it’s contrast I’m chasing. Not FOV or ER. Are the orthos or TMB’s contenders?

Orthoscopics are the traditional high contrast eyepieces for planetary observation. Typically with an AFoV of 40-45deg. Baader have a modern take on these in their Classic range, 18mm,10mm and 6mm BCOs and have 50deg AFoV. They are reasonably priced and recommended. There is less glass in this eyepiece design and the name orthoscopic means 'free from aberations'. Search on SGL for BCOs, there is an excellent review by @John.

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If you are OK with the FoV and ER, orthos provide excellent contrast and light scatter control for a reasonable price. If you would like a little more viewing comfort (20mm eye relief plus a significantly larger eye lens) I found the Vixen SLV's compared extremely well with high quality orthos. In fact I could see no differences at all when I compared the Baader Genuine Ortho 6mm with the Vixen SLV 6mm on a number of occasions when observing Saturn, Jupiter and Mars.

I seem to prefer a bit longer eye relief and a wider field of view these days :rolleyes2:

 

 

 

Edited by John
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4 minutes ago, John said:

If you are OK with the FoV and ER, orthos provide excellent contrast and light scatter control for a reasonable price. If you would like a little more viewing comfort (20mm eye relief plus a significantly larger eye lens) I found the Vixen SLV's compared extremely well with high quality orthos. In fact I could see no differences at all when I compared the Baader Genuine Ortho 6mm with the Vixen SLV 6mm on a number of occasions when observing Saturn, Jupiter and Mars.

I seem to prefer a bit longer eye relief and a wider field of view these days :rolleyes2:

 

 

 

As a rule of thumb for myself, I am also inclined to lean towards the more comfort aspects you mentioned. However I don’t mind making the sacrifices when it comes to planetary viewing. I noticed that there’s a 10mm BCO in the buy & sell for £40. I’ll have a look at it or i may just buy a new one for £49

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If I was considering another 10mm then the Svbony 10mm Ultra Flat would be on the list at £45. Amazon have already sold out and their Ebay store are down to 5.

https://www.ebay.co.uk/itm/284532210530

 

22 minutes ago, bosun21 said:

As a rule of thumb for myself, I am also inclined to lean towards the more comfort aspects you mentioned. However I don’t mind making the sacrifices when it comes to planetary viewing. I noticed that there’s a 10mm BCO in the buy & sell for £40. I’ll have a look at it or i may just buy a new one for £49

 

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37 minutes ago, bosun21 said:

As a rule of thumb for myself, I am also inclined to lean towards the more comfort aspects you mentioned. However I don’t mind making the sacrifices when it comes to planetary viewing. I noticed that there’s a 10mm BCO in the buy & sell for £40. I’ll have a look at it or i may just buy a new one for £49

The 10mm BCO punches way, way above it's asking price in my opinion (and others).

 

 

 

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5 minutes ago, ScouseSpaceCadet said:

Please let us know how you get on with those eyepieces. 😉

Regarding the BCO line. I'm very impressed with the 6mm. The eye relief is very short indeed but I can cope with that. Great clarity and light weight too.

I have only had a short time with the 18mm last session before the clouds intervened and I was pleased with what I was seeing. I’ll wait for my 10mm to arrive and then I’ll put them both to use. I’ll let you know how I find them 

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I have read the more glass the worse the view but I think that is wrong, I think it depends on the eyepieces and the Barlow you use. I rarely barlow but when I do I dont use my BST`s I use a old vixen silver top 10mm and a couple of TMB`s the 6mm especially my barlow of choice is my Tal x2. 

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35 minutes ago, wookie1965 said:

I have read the more glass the worse the view but I think that is wrong, I think it depends on the eyepieces and the Barlow you use....

I think that used to be valid but modern glass types and optical coatings have evened the balance up.

If you look at what are considered to be the very best planetary eyepieces there are low glass designs (eg: Zeiss ZAO ortho, TMB Supermonocentric) but the Pentax XO, which is right up there, has 5 elements, the Takahashi TOE 6 elements and the Vixen HR 7 or 8 elements.

Of these, only the Tak TOE are still in production I think.

 

 

 

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4 hours ago, John said:

I think that used to be valid but modern glass types and optical coatings have evened the balance up.

If you look at what are considered to be the very best planetary eyepieces there are low glass designs (eg: Zeiss ZAO ortho, TMB Supermonocentric) but the Pentax XO, which is right up there, has 5 elements, the Takahashi TOE 6 elements and the Vixen HR 7 or 8 elements.

Of these, only the Tak TOE are still in production I think.

 

The Vixen HR is a 5 element, 3 group design (ref: https://www.vixenoptics.co.uk/Pages/hr_eyepieces.htm).

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To the OP: 

There are so many good eyepieces nowadays, that I am not sure the definition of `planetary eyepiece` still applies, unless one just intends something like "I want a focal length to observe planets with my telescope X". 

I would rather consider a telescope with larger aperture rather than a set of ultra expensive / famous eyepieces. Besides, planets are visible for about 1 season in one year and from UK latitudes they are also quite low.

 

Regarding the 10mm BCO, my copy bought new was functional but nothing special. Possibly, its low cost is due to poor QA?

Edited by Piero
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