wide view eye pieces vs standard plossels

[neil groves]

ok so after months of bugging people on this site I finally made a purchase last night:

http://www.amazon.com/gp/product/B004Q78OHY/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1

Now I know this comes with 2 eye pieces but I have read a lot about 'wide view' and 'super wide view' eye pieces, I know I want to purchase a 2" eyepiece just to experience the 'head in the stars' feeling I have read about but what are the advantages of the wide view eye pieces apart from the wider view which I assume is the same as fitting a wide angle lens to a camera, you get more in the FOV but everything is smaller? I imagine wide field eye pieces are good for 'surfing the sky' but I could use my finder scope for that surely? what are the visual differences for example between a 20mm eyepiece and a 20mm wide angle eyepiece, does the magnification and the amount of detail seen stay the same or is everything pushed further away?

I bought this scope mainly for observing but may venture into some photography at a later stage. I just bought the canon T3 for that purpose, is that a good choice?

Neil.

[John]

Thats a nice scope - I have an ED120 and really enjoy it ! 

Basically a wide field eyepiece shows objects the same apparent size as normal ones but you see more sky / space around the object. In the case of really large objects (eg: The Andromeda Galaxy) you can fit more of it in with a wide or ultra wide eyepiece than you could with a normal field eyepiece of the same focal length.

Whether those are the sort of views you will crave is a personal decision mostly. You generally pay more for wide and ultra wide eyepieces because producing a nice, undistorted view across a wider field takes more glass, more care in manufacture and design and sometimes needs a 2" barrel to allow the width of field.

You will see from all the eyepiece threads on here that wide, ultra wide and even hyper wide (100 degree) eyepieces are very popular although not universally to be fair.

I was observing the moon with a 100 degree eyepiece last night at 400x (with my 12" scope) and it was like flying across the lunar landscape in a spacecraft 

[swamp thing]

Hi Neil

If I use my 20mm 82deg 2" eyepiece I get the same field of view as a 32mm 50deg 1.25" plossl at the same magnification as a 20mm plossl. This means I get the same nice wide field as the 32mm at the increased contrast and higher mag of the 20mm.

My 12mm 82deg gives the same performance as a regular 12mm 50deg plossl with the field of a 20mm.

For me this means I can replace all plossls between 12 and 32mm with two eyepieces. I also have a Powermate this means I can replace plossls from 6mm to 32mm with two eyepieces and a Barlow.

As I rarely observe planets the requirement of tuning power to the seeing conditions is largely un-needed.

[neil groves]

Thanks guys.....very well explained and yes.....i NEED a couple lol

Am thinking maybe a Q70 or somthing, i am going to my local Orion store on Saturday so will look at there selection and get some more advice, may even pjck up a barlow though my main interest is open star clusters, starfields and nebula so may not need one.

Thanks again

Neil.

[Charic]

neil.....Hi, The Canon T3,  Not a good choice?

Only kidding, its the way you posed the question, it humoured me . You bought it, then ask if its any good?  rather than ask first then buy, but thats your choice, not ours!

Most modern DSLR cameras should work well on your telescope. They need to work in manual mode, if your removing the camera lenses, and fitting to the telescope, as the camera wont know / accept the telescope, so dont be puzzled, by the cameras negative response to any auto or programmed settings. Thats only for prime focal use. There is the Afocal method, that still uses the camera lens. the other issue to overcome, is getting the cameras sensor right at the focal plane. Adaptors and extensions will allow/correct for this. Ive got a Nikon DSLR, and have used it a couple of times on my telescope. Dobsonian mounts don't really cut the mustard for astro-photography, but some of my images have worked ok. My image scale is just a little to small, but working on that. I own a book called "Making Every Photon Count" That and other reference books are from people who have overcome the problems you may come across when starting out in astro photography. 

[neil groves]

will I need a wide field eyepiece to get the entire M31 in a single FOV with this scope?

how do I work out or find out how much sky in degrees a certain telescope/eyepiece combo will cover?

Neil.

[John]

If you want to fit the whole extent of M31 in you will need something that gives 4 degrees. I don't think there is an eyepiece that will do that with your scope. The closest would be the Vixen NLVW 42mm which will show you 3.3 degrees of sky. That would show a large proportion of M31 that is visible with a 120mm aperture scope but not the whole thing.

[Stu]

Whilst this is a case of marketing overkill to a degree (calling it a 'majesty factor', this link on the Televue site has some good info and a nice comparative image of the benefits of Widefield eyepieces.

http://www.televue.com/engine/TV3b_page.asp?return=Advice&id=114#.U0eVou29LCQ

Also, Andromeda is quoted at just over three degrees on its longest axis so you would just about fit it in with an LVW 42mm. It would be best at a really dark site in your scope as you can then begin to see the really faint outer parts to it and appreciate the size.

I use my f6.5 106mm with a 31mm Nagler which gives a 3.68 degree field, very nice :-)

Enjoy your scope :-)

Stu

Sent from my iPhone using Tapatalk

[neil groves]

Stu...where is that little diagram from?....looks useful

Thankyou

Neil.

[Stu]

Stu...where is that little diagram from?....looks useful

Thankyou

Neil.

It's from SkySafari. I have just upgraded to the Pro version which allows you to display field of view circles based on your own kit, very useful. The plus version lets you define different sized fov circles so can achieve a similar thing but slightly less flexible.

A couple more screen shots to show how it works a little more. There is a selection screen where you can chose which kit to select and display

You set all your kit up in the equipment list.

And it displays like this

A great app, very handy, and I've recently started to use it to control my mount too, amazing what is possible.

Stu

Sent from my iPhone using Tapatalk

[rwilkey]

will I need a wide field eyepiece to get the entire M31 in a single FOV with this scope?

how do I work out or find out how much sky in degrees a certain telescope/eyepiece combo will cover?

Neil.

Hi Neil, it is unlikely you will get the whole of M31 in one ep, it's just too wide, however, the outer arms are almost impossible to see because they are very feint, the central core is what most people see, can be seen with the naked eye from my back garden a mile from the town centre on crisp clear nights.  On your question of working out scope maths on how much sky you can see with a particular ep, you can put the details of an ep or intended purchase in this website and it will tell you how many degrees of sky you can see, and also stuff like transit times etc:  http://www.stargazing.net/naa/scopemath.htm

[alan potts]

Robin,

Very true it can be seen from a back garden with the naked eye, but not mine, it has not stopped raining for 2 days, the neighbour said it was to stop me feeling homesick.

On M31 I have always found it better at low power as I have a very dark site but as you say unlikely to see all of it but it is one target that many get superb photos of with inexpensive equipment.

Alan.

[rwilkey]

M31 is great at low power, in fact I use low power most of the time, as one of my favourite targets is open star clusters rather than galaxies, but always great to see when you find them.  Where's all that nice weather you had Alan?  We are now getting some clear skies so I will shoot out middle to late evening, Jupiter and Moon currently good targets from my back garden.

[AndyWB]

Thanks Stu, I'd been trying to figure that FoV setting in SkySafari out.