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upgrading eyepiece

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upgrading eyepiece

Postby orchininla on Fri Nov 06, 2009 9:23 am

I have a meade telescope with series 4000 DS Super Plossl 9.7mm and 26 mm eye pieces. They just aren't enought to see much more than the moon. Any suggestions on eye pieces that would be sufficient for more spectacular viewing? I know absolutely nothing about eye pieces so I do not know what to look for as far as quality or magnification or field of view. I need HELP!
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Re: upgrading eyepiece

Postby Neophyte Astronomer on Fri Nov 06, 2009 9:26 pm

I can not speak for OpticPlanets, but I can mention my experiences and offer some suggestions and/or opinions since I just started viewing the sky in February of 2009. (I know how important it is to receive feedback since you are probably excited about the hobby and Joanie K may not be able to respond until possibly Monday. Furthermore, you could read my questions for her on 09.30.09 and might explain some of the statements below concerning eyepieces.)

What type of telescope do you have? Before you can decide what eyepiece to consider, there is a little bit of calculations you have to do because of the different aspects of your scope that can change based on the eyepiece you are using such as magnification or power. Also, the FOV (field of view) can change and the exit pupil for the cone of light. There is also true and apparent FOV (AFOV). All of this did not make sense to me several months ago BTW.

Since we do not know what type of telescope you have, it is harder to make a recommendation for the eyepiece to chose. (If it is a department store telescope, a quality eyepiece will not probably solve your problem – I was there just in February of 2009 and was disappointed until I ordered a SkyWatcher Ten Inch Dob from Optic Planets that totally blew my mind.)

Before going forward, sometimes it is good to learn some of the constellations – even with a pair of binoculars – to see what your personal preference is going to be such as deep sky objects or planetary objects. It actually makes a difference between choosing an eyepiece such as Televue Panoptics or Neglar if you want to spend a couple of hundred dollars. (There are other great choices as well other than Televue products. ;-) The skills involved with this are only using binoculars – which I did not do at first – that will provide huge dividends.)

One of the biggest lessons I learned within the past nine months is that someone new to this hobby expects to see pictures from the Hubble Telescope processed so many times it makes your head spin. This is not going to happen!!!! I almost gave up the most wonderful hobby in the world because of this until I realized how many times these images are “processed.”

The second biggest lesson I learned is to not blame the eyepiece and/or telescope for certain things. I have fallen into this trap within the last couple of months. Here are some of the problems I had:

1. I did not realize how the local chemical plants such as Union Carbide, DuPont, etc. played in my area until I visited a friend’s house out in the country. I went from seeing only about thirty stars with the naked eye to several hundred even though I do NOT have very much light pollution in my area.
2. The air currents in the tube. If you have a Dob, you need to let it adjust to the outside temperature since it can affect the wavelength of light.
3. Just like point number one, the atmosphere can play a significant role.
4. Did you let your eyes adjust for at least thirty minutes? I never did this at first and got totally frustrated and it was actually my fault.
5. I thought high magnification is the way to go and actually learned this is one of the most common mistakes ppl make and put down the hobby for good. Therefore, after making some calculations - which is key - you will find it is best to stay within 20X to 60X of your telescope as a beginner before trying the highest levels of USEFUL magnification. (To be honest, several months ago, I had a hard time finding Saturn and/or Jupiter and it was one of the brightest “stars” in the sky.) Since I do not know how much you know, most magnification will be done at low levels for a telescope around three inches or less (which you probably have) with the consideration of not going past 150x for the next several months – this is just an opinion BTW.
6. I saved the “worst for last.” One of the problems I had was ensuring the collimation of the scope. This is one of the most intimidating things of all esp. if you have a Dob. Once I learned to collimate my scope correctly, it was like having a Televue Ethos eyepiece (which cost $500 or or more for one one eyepiece compared to the factory eyepiece.) If you have a scope that requires this, this could change everything for you.

In the end, I would wait for Optic Planets (Joanie K) to reply and ensure you have a telescope that can have the recommended viewing pleasure and provide the appropriate suggestion of an eyepiece. OTOH, I hate to say it…but department store telescopes do not cut it and I almost gave up on this wonderful hobby several months ago. In addition to that, I would consider if your viewing pleasure would be planets or deep sky – Believe it or not, it makes a big difference between the eyepiece(s) to purchase.

Ummm…In case you did not know (which I did not know until recently and still can not figure it out for all of it), the following is the formula stated at the beginning you should consider to use: f/ratio = focal length / aperture. I still do not understand what that means sometimes. I just plug and play an eyepiece after finding what works best after going to a to a local star party/astronomy club and find what works best for my scope. (If you are inquisitive, the fascination and the learning will never stop!!!!)
"Imagination will often carry us to worlds that never were. But without it we go nowhere.” ~ Dr. Carl Sagan
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Re: upgrading eyepiece

Postby Jne_K on Mon Nov 09, 2009 9:11 am

Hi

Good points. Couldn't have said it better, myself on things that can affect image quality.

The first thing you should always buy with a serious telescope are more eyepieces. Does not have to be the same brand as your telescope.

I generally recommend a range of magnifications in the low, medium and high range. Maximum should not exceed what your scope is capable of supporting. Large telescopes can handle higher magnifications better than smaller scopes, but once you hit 200x with any telescope, the atmosphere becomes a limiting factor. Even the largest scope is humbled when seeing conditions are poor. Again, use high magnifications for the moon and planets, but keep magnifications on the low side for nebulae, star clusters and galaxies. To calculate magnification with any eyepiece, divide the focal length of your telescope by the focal length of the eyepiece.

Magnification has much less to do with astronomy than beginners think. Astronomy is more about seeing faint objects, not about magnifying them and seeing faint objects is more about telescope aperture, in terms of mirror or objective size, rather than magnification. If you want to see fainter objects and therefore more objects, you use less magnification, not more. If your scope is not seeing enough detail and/or fainter objects, it usually means you need a bigger scope, not more magnification. If you want to see fainter objects and therefore more objects, get a bigger telescope, not another eyepiece.

Since telescope eyepieces are the most important accessory for any telescope, you may also wish to do more reading with my article, Ten Telescope Eyepiece Questions
Thanks for posting with us
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Re: upgrading eyepiece

Postby FLYcrash on Mon Nov 09, 2009 10:31 am

Hi! It is worrisome if you can't see anything but the moon with even a modest Meade scope and the Super Ploessls. You should at least be able to see Jupiter's bands even under moderately bad light pollution.

I recommend, however, that you get a 2x barlow, which will double the magnification of each of your eyepieces. Depending on the scope, the barlowed 9.6mm eyepiece might be too much magnification, but the barlowed 26 should give a very useful magnification.

Beyond that, please do some research. I won't try to rehash what others have said better, so I'll just tell you to look up the meaning of and mathematical relationships between the following: telescope focal length, telescope aperture, eyepiece focal length, exit pupil, f/ratio, magnification, apparent field of view, and true field of view. Don't worry, it's not hard; mostly division. You'll catch on in hours at the most.

Once you learn this material, read the following essay/blog post I find very useful for eyepiece selection. Hope it is OK for me to post it; it isn't commercial as far as I know.

http://www3.sympatico.ca/cuir/ep.htm
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Re: upgrading eyepiece

Postby Jne_K on Mon Nov 09, 2009 10:34 am

Hi

The article I listed on eyepieces also contains those math basics.
Thanks for posting with us
Joanie K - Your personal optics expert

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Re: upgrading eyepiece

Postby FLYcrash on Mon Nov 09, 2009 11:05 am

Yes, I do like your article, Joanie.

Maybe my point got lost in my rambly post...the Meade 4K Super Ploessls are good eyepieces. My club's eyepiece case is dominated by them (along with TeleVues), and the Meades throw up beautiful views with the century-old 6" refractor we have in our observatory. More expensive eyepieces may give bigger fields of view and better edge correction in fast scopes, but if one can't see anything but the moon with a 26mm Super Ploessl, an eyepiece upgrade will not fix that. Some other part of the optical train - bad sky, bad scope, bad eyes, or lack of experience - is to blame, and more detailed troubleshooting is in order.
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Re: upgrading eyepiece

Postby Jne_K on Mon Nov 09, 2009 11:09 am

I agree. A series 4000 is not a premium grade eyepiece, but it has been a long standard for a basic eyepiece.
Thanks for posting with us
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Re: upgrading eyepiece

Postby Neophyte Astronomer on Mon Nov 09, 2009 7:11 pm

Thanks for the links!

After reading the provided links, I realized how much more I need to learn for this great hobby.

There is so much information to process that it never gets dull. :D
"Imagination will often carry us to worlds that never were. But without it we go nowhere.” ~ Dr. Carl Sagan
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Re: upgrading eyepiece

Postby Jne_K on Tue Nov 10, 2009 6:43 am

You are very welcome.

I've been doing it for forty years and still learn something new just about every time I get to look through a telescope or binocular. No, never gets dull for me.
Thanks for posting with us
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Forum: http://www.opticsplanet.com/msgboard
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Re: upgrading eyepiece

Postby orchininla on Wed Nov 18, 2009 9:11 am

I read all your posts and links but it all is greek to me. The following is specs for my Telescope
Optical Design Refractor - Optical Diameter 70mm (2.8")
Eyepieces (1.25") MA9mm, MA25mm - Viewfinder 5x24 Viewfinder
Focal length, f/ratio 600mm; f/8.5

Can any of you make specific suggestions, given the above information, as to what type of eyepiece or barlow that would be useful for increased viewing pleasure. I am not interested in trying to see the surface of Jupiter, just a slight bit more magnification. Also what should I be able to see with the eyepieces that I have, given optimal viewing conditions?
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Re: upgrading eyepiece

Postby Jne_K on Wed Nov 18, 2009 9:20 am

Right now, your 9mm is giving you 66x.

The most popular high grade eyepieces for planetary viewing have been the Televue Radians. I would not exceed 150x in that telescope and even that much would require a night of excellent seeing conditions. That would translate to a 4m Radian. if that is not in your budget, I would try a Celestron X-Cel 5mm for 120x
Thanks for posting with us
Joanie K - Your personal optics expert

Forum: http://www.opticsplanet.com/msgboard
Blog: http://blog.opticsplanet.com/
Store: http://www.opticsplanet.com/

Phone: (800) 504-5897
Fax: (847) 919-3003
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