Lens upgrade?

[Starbuddypal]

I have a Celestron Powerseeker 70EQ with a GSO 1.25" SuperView Eyepiece - 20mm. I attached photos I took with my iPhone. I can’t see details of Mars and Jupiter but I can see the moons of Jupiter. I can see Saturn easily due to the rings but no details. Do I need to upgrade my lens so I can see better details or am I just doing something wrong? I’m still somewhat new to this.

[Astrid]

There is this rule: use the eyepieces with the smallest number for planets and the eyepieces (EP) with the biggest number for DSO (deepsky objects).

Why? Well planets are small but very bright, so in order to see their details you need EP that magnify by a lot.

And deep sky objects (nebulae and galaxies) are very faint but big, so you need low magnification EP.

 

Ex: the formula for magnification is the telescope's focal length divided by the eyepiece focal length. So do the math from here. By the way, I recommend checking the max magnification your telescope could approach. (the bigger the telescope, the larger the range of EP you could get). For example, with a small telescope a 5mm EP would do nothing but make the image bigger and fuzzier, without details. 

Here is a good calculator: https://astronomy.tools/calculators/magnification

(the formula for the max mag of a telescope is the telescope's aperture in mm (diameter) times 2.5. I think this is an empirical formula - though i'm not sure- but it works.)

Edited November 17, 2020 by Astrid

[Jiggy 67]

The simple answer to that is yes, though there are no easy answers when it comes to eyepieces!

 I have no experience of your scope but a basic principle is to spread out the range of focal lengths and double that with a 2 x Barlow lens. A Barlow basically doubles the magnification of an eyepiece so.......I would consider a high power, medium power and a low power, something like a 6mm, 18mm and a 32mm . With a Barlow added you get 6 focal lengths for the price of 3.

As to which type/brand that is personal choice dependent on the depth of your pocket, preferred eye relief, field of view and other factors, have a read up on these on the internet. A well well respected brand are the BST Starguiders which many recommend on this forum.

Dont worry if you make a mistake with a purchase because eyepieces are easy to sell on but like anything you get what you pay for so buy the best you can afford ......enjoy the shopping 🛍 

[DaveL59]

another thing to consider, did your Astromaster come with a star diagonal or an erecting one? If erecting then it's also worth getting a proper star diagonal as the erecting ones use prisms and will lose some detail. They are fine for terestrial use and ok on the moon but beyond that not so much. Looking at images online I'd say it is a very similar scope to the LT70AZ I have, 70/700 and the plastic spherical body diagonal which is an erecting type.

Eyepieces I use a 7-21mm zoom with a star diagonal, both SVbony, which give good views and then barlow for more magnification. Max mag on the scope is quoted as x165 and the zoom at 7mm barlowed will push that mag to x200 so may not give the best view depending on how well you have focus and the quality of seeing conditions.

[Zermelo]

Hi,

so your Celestron is a 70/700 refractor. The 700mm focal length means that your 20mm eyepiece gives you a magnification of 700/20 = 35 times.
That's not going to show you very much detail on planets; you'll see the rings of Saturn (when open, like now) and the four largest moons of Jupiter. Also, be aware that Jupiter and Saturn are not well positioned (Sagittarius) for Northern hemisphere observers at the moment. The lower they are in the sky, the more difficult it is to observe them - there is more atmosphere in the way, and in many locations there is sky glow from artificial light near the horizon.
Mars is better positioned, higher in the sky and not far from its closest to Earth. But Mars is a small disc, and with low magnification you are not likely to see any detail.

The other limiting factor is the "70" in your 70/700 specification - the diameter of your main "objective" lens. It's this that determines how much light you are gathering, which in turn limits how much you can magnify an image while remaining useful (it also places a limit on the amount of detail you can see). Planets are bright objects so they will stand a good deal of magnification without becoming too dim - the limits are more likely to be set by other constraints. One factor is how favourable the observing conditions are; if the air is turbulent, or humid, this will make a magnified image too unstable to be useful. The elevation of the object also matters (see above). Another factor is that your refractor will introduce some "colour fringing", especially on brighter objects like planets. This will degrade the image to some extent.

A rough guide to the maximum magnification you can expect is to double the size of the objective (in mm) - so 140 in your case, for which you would need an eyepiece of focal length 5mm. Note, this is the maximum achievable under excellent conditions - in practice, you will usually be limited by the other factors. I see your scope also comes with a 4mm eyepiece. I too own a 70/700 refractor which came with a 4mm. I found that in most situations it was not usable - it's just asking too much from a scope like this, and in addition, eyepieces supplied with telescopes are rarely quality designs. I'd suggest that you should be aiming for something more like 100x, which won't be too much for your scope and will show a bit more on planets, when they are suitable. That would be around 7mm focal length. As pointed out above, you could get this either with an eyepiece on its own, or with a different eyepiece used with a "barlow" - for example, a 14mm with a 2x barlow. You could then of course use the 14mm on its own, which would give you a useful 50x mag. Or something close, if those exact lengths aren't available in the range you're considering. As mentioned by Jiggy 67, the BST Starguiders are good value for money and will be a noticeable improvement on the eyepieces that came with the scope (but may be known by other names in the US - possibly "Astrotech Paradigms"). Though you may be in for a wait for any order, as almost all suppliers seem to be out of stock due to Coivd.

Do persist with your 70/700 - I saw a lot with mine - but you may need to manage your expectations as far as planets go.

 

[Starbuddypal]

It's certainly frustrating trying to look at Mars and Jupiter and just seeing a bright dot with no discernable features. I have an app to help me find everything. Objects like Neptune and Uranus are hard to find even if I use my app. I can identify the general area where some things like Neptune are but finding those are difficult. I never got a star diagonal I have been meaning to get one. Nebulas and galaxies I haven't even tried looking at because I just figure I won't be able to see them.

I forgot to mention that I got my telescope at a Goodwill and it had no eyepieces. The GSO 1.25 lens I purchased separate since I didn't have any eyepieces to begin with. From what everyone is saying I should get a lens with 6mm or something low in that range AND a 2x barlow lens?

[Kyle Allen]

A 6mm and 2x Barlow will give you an effective 3mm, which will be too high magnification for your telescope. You can either get a short focal length eyepiece or Barlow a medium focal length eyepiece, which has the benefit of giving you two effective focal lengths and increased eye relief.

Keep trying though because seeing detail on the planets depends mostly on the seeing conditions, which vary night to night. Observing as often as you can will allow you to take advantage of any nights where the seeing is good. 

[Starbuddypal]

On 18/11/2020 at 02:24, Kyle Allen said:

A 6mm and 2x Barlow will give you an effective 3mm, which will be too high magnification for your telescope. You can either get a short focal length eyepiece or Barlow a medium focal length eyepiece, which has the benefit of giving you two effective focal lengths and increased eye relief.

Keep trying though because seeing detail on the planets depends mostly on the seeing conditions, which vary night to night. Observing as often as you can will allow you to take advantage of any nights where the seeing is good. 

If I were to get this: https://www.amazon.com/Celestron-Omni-2X-Barlow-Lens/dp/B00008Y0TM/ref=pd_sim_421_5/145-3371215-1829265?_encoding=UTF8&pd_rd_i=B00008Y0TM&pd_rd_r=3417272a-ed41-47c7-b8ff-f1bb76eebb77&pd_rd_w=DCJHs&pd_rd_wg=m6giF&pf_rd_p=8958999c-906e-4b6b-80aa-4bc1f740ed92&pf_rd_r=R30H2P1RYQWG7A9MEYQW&psc=1&refRID=R30H2P1RYQWG7A9MEYQW

and combined that with my GSO 1.25" SuperView Eyepiece - 20mm....would that be suitable?

 

I'm also leaning toward these two:

-https://www.amazon.com/Celestron-Omni-2X-Barlow-Lens/dp/B00008Y0TM/ref=asc_df_B00008Y0TM/?tag=hyprod-20&linkCode=df0&hvadid=309836137809&hvpos=&hvnetw=g&hvrand=1465836525062899768&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9011454&hvtargid=pla-403917110347&psc=1

-https://www.amazon.com/Celestron-93230-24mm-1-25-Eyepiece/dp/B0007UQNV8/ref=asc_df_B0007UQNV8/?tag=hyprod-20&linkCode=df0&hvadid=309822971200&hvpos=&hvnetw=g&hvrand=15649631866367199766&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9011454&hvtargid=pla-434892205575&psc=1&tag=&ref=&adgrpid=70157059668&hvpone=&hvptwo=&hvadid=309822971200&hvpos=&hvnetw=g&hvrand=15649631866367199766&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9011454&hvtargid=pla-434892205575

 

[Kyle Allen]

20mm + 2x Barlow gives you 70x, which is a bit low for the planets. As a general rule, you can magnify twice the aperture of your scope in mm. Since your telescope is 70mm this means that a 5mm eyepiece should be your maximum (140x). However, you might find that slightly less magnification gives you a sharper view. You could look at getting a 6mm (117x) or 7mm (100x) eyepiece instead.

Another option is to get something in the 10-14mm range and use a 2x Barlow to reach higher powers. 

[Zermelo]

9 hours ago, Starbuddypal said:

If I were to get this: https://www.amazon.com/Celestron-Omni-2X-Barlow-Lens/dp/B00008Y0TM/ref=pd_sim_421_5/145-3371215-1829265?_encoding=UTF8&pd_rd_i=B00008Y0TM&pd_rd_r=3417272a-ed41-47c7-b8ff-f1bb76eebb77&pd_rd_w=DCJHs&pd_rd_wg=m6giF&pf_rd_p=8958999c-906e-4b6b-80aa-4bc1f740ed92&pf_rd_r=R30H2P1RYQWG7A9MEYQW&psc=1&refRID=R30H2P1RYQWG7A9MEYQW

and combined that with my GSO 1.25" SuperView Eyepiece - 20mm....would that be suitable?

 

I'm also leaning toward these two:

-https://www.amazon.com/Celestron-Omni-2X-Barlow-Lens/dp/B00008Y0TM/ref=asc_df_B00008Y0TM/?tag=hyprod-20&linkCode=df0&hvadid=309836137809&hvpos=&hvnetw=g&hvrand=1465836525062899768&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9011454&hvtargid=pla-403917110347&psc=1

-https://www.amazon.com/Celestron-93230-24mm-1-25-Eyepiece/dp/B0007UQNV8/ref=asc_df_B0007UQNV8/?tag=hyprod-20&linkCode=df0&hvadid=309822971200&hvpos=&hvnetw=g&hvrand=15649631866367199766&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9011454&hvtargid=pla-434892205575&psc=1&tag=&ref=&adgrpid=70157059668&hvpone=&hvptwo=&hvadid=309822971200&hvpos=&hvnetw=g&hvrand=15649631866367199766&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9011454&hvtargid=pla-434892205575

 

The Celestron omni is not their premium model, but it has been good for me so far, and probably a match for your likely choice of eyepiece, in price/performance terms. I recently bought a Baader Q Turret and I could see no difference in image quality, at least when used with the other kit I have.

The Celestron seems to be on sale here, and they claim to have stock (a lot of outlets won't at the moment).

 

 

 

[Alan64]

You don't have to get Celestron-branded eyepieces and accessories to work with your Celestron telescope.  Brands are unimportant.  One should look beyond such in the choosing...

https://agenaastro.com/meade-series-4000-126-1-25-2x-short-focus-barlow-lens.html

With that 2x-barlow, inserted into the diagonal, then the eyepiece into the barlow, the magnification is doubled.  If you insert the barlow into the telescope first, then the diagonal and eyepiece into the barlow, an approximate 3x multiplier is had, which triples the magnification...

https://agenaastro.com/gso-12mm-plossl-eyepiece.html

[Alan64]

Jupiter is too bright at the lower powers to see much if any detail.  You can dim the planet's brightness down a bit with this...

https://www.bhphotovideo.com/c/product/1485009-REG/ice_ice_vp_125_1_25_variable_polarizer.html

Or, ramp up the magnification until it dims on its own.  In either case, you may then begin to discern the planet's features.