Do you need a filter to see Nebulas?

[Eardrum73]

Hi there,

Do you really need a Nebula Filters to see Nebulas? Can you actually see the colour of the Nebula or is it just more cotrast but in B & W? :confused: Are they worth the money? :confused:

So far I have been trying to see Nebulas with little success. (I have a 12' dob)

I have only ever seen these 3 filters advertised for sale and that is the:

Astronomik OIII 2' by Bintel for $440
Sirius Optics 2' by Andrews for $179
Baeder 2' by York Optical for $210

Are they worth the money? does the $440 Astronomik filter provide better visuals then a $210 Baeder one? or Sirius Optics?

[astroron]

Hi Eardrum, go to the thread started on this forum by Asimov dated 23/09/05 which gives you a good overview of what members think of filters. this forum has lots of threads on filters. regards astroron :thumbsup:

[mickoking]

Eardrum 73,


With a 300mm (12") Dob you should be able to spot many nebulae and with your size 'scope many of them will be very bright. Most nebulae appear green of grey thru a telescope. But the Orion neb (M42) may show traces of crimson red with a 300mm Dob at a dark site.

Nebula filters do indeed improve the visability of Nebulae but different viewers seem to have different experiences with them. These filters however don't bring out the colour in neb's they just allow the wavelengths of light that nebulae emit the most to be transmitted and block extaneous (ie non nebula) light. I personally have 2 filters. Lumicon OIII (oxygen 3) and a broad band filter (Its a lumicon filter but I can't remeber its name:doh: ). I really rate the OIII filter as it results in improvement on most emission and planetary nebulae.

The links section of this web sight will give you the details of retailers that will be able to help you with filters if you wish to purchase one but first, Find that first nebula, you wont be dissapointed.:thumbsup:

chill

[ving]

like micko said... you dont need a filter to see nebs. you will see heaps in your scope. a filter will make them stand out more tho.

:)

[astroron]

Some nebulae are not improved by filters,and in fact are much better without, also it can depend on the accuity of the observer. astroron :thumbsup:

[davidpretorius]

Hi eardrum, check with asimov on this one.

Off the top of my newbie head, i can think of 4 nebula which i can see in my 10" dob without filters. I have little light pollution and so i am very happy with the nebula viewing.

lagoon in the milky way, tarantula near the large magellenic cloud, keyhole below the southern cross and the brightest is orion.

If you can wait up until 1am and you have clear skys, Orion is rising in the east.

Look for the saucepan and look at its handle. I suggest you take that as a reference point. I you can see the greyish clouds and are happy with that then don't bother spending heaps. If however you want to track down harder to see nebulas, go for it!. To get the lovely coloured version, well that is where long exposure imaging comes in. The eye can't see, but the camera can!

A nebula filter for me is low in priority, barlows and a really good eyepiece are next due to mars getting so big!!!

[acropolite]

The NPB filter from DGM optics comes highly recommended and can be had for around $80 (1.25 inch) landed here in OZ. Mine's only just arrived so I can't give you any impressions, but Mike and a couple of other IISers have them and a recent US Astro mag review rated them very highly.

[iceman]

I used mine (DGM Optics NPB Filter) again on the weekend, in both my scope (10" dob) and hector (20" dob). I used it on the Tarantula (NGC2070) and a nice planetary NGC246 in Cetus.

On NGC2070, the filter showed wisps of nebulosity that couldn't be seen without the filter, with the tradeoff that you lose the view of the nice starfield next to the tarantula.
The view of NGC246 was substantially improved with the filter, giving more contrast and showing more detail than what could be seen without the filter. It gave an almost 3D appearance to the circular looking planetary. I'm very happy with mine, for AU$80 to my door. The 2" version is obviously more expensive, but still significantly cheaper than the upmarket alternatives (astronomik/lumicon etc).

As others have said, you don't need the filter to see the nebula, but when used, it can enhance areas that you can't see visually, as well as increase contrast to give a different view of what you could see before.

Filters will sometimes give you false colour, making things look greenish or blueish, depending on the filter.

HTH

[Eardrum73]

Thanks all for your responses,

From the look of things, it sounds like I can see nebulaes without the filters. I have defintely come across some small greyish "brush marks" in the sky but I wonder if those are nebulaes....

Iceman.... DGM NPB... what do these stand for and where can I get them for $80??? If the 1.25' is $80 I am guessing the 2' would be a whole lot cheaper as well.

What about the Sirius Optics or Baader ones that go for $180 or $210 respectively? Has anyone had any experience with these?

I will have to go for the 2' ones... only because I wear glasses and I sometimes find it hard to look into 1.25 inch eyepieces, especailly the small diameter ones like the 6.9 mm..., I almost need to look at it from an angle to see venus! Most times it really hard to see objects as it is very dim, and constant adjustment is needed to keep it in its FOV, with a dob it can be a real nightmare.

Speaking of 2'... what is the lowest 2' eyepeices thats available? The lowest I have seen is the 26mm..... I have not seen any 2' with better maginication than this....

As long as the price is relatively inexpensive, I wouldn't mind getting my hands on a 2' 6.9 mm for example....

[janoskiss]

I can vouch for the DGM NPB (narrow band pass) as well. I have very limited experience but I was amazed how well it worked from light polluted skies. It does not add colour to anything, it just dims everything except the light coming from gaseous nebulae. Well worth the $AU80 I paid for the 1.25". Ordered it from DGM optics, got it in under 10 days.

http://users.erols.com/dgmoptics/

[Starkler]

I think you have the impression that 2 inch format eyepieces automatically come with longer eye relief. This isnt the case.

Examples of 1.25" eyepieces with long eye relief:
Pentax XL and XW, Vixen lanthanium, Televue radian, ED2 eyepieces, Synta LER.

Eyepieces in 2 inch format are usually longer focal length, which normally means longer eye relief but its not always the case.
The Meade UWA eyepieces have quite short eye relief.

[Eardrum73]

Hi all,

I have an impression that 2' eyepieces are (if everything remains constant) better than the 1.25' eyepieces.
hence a Widewview 15mm 2' will look better than a wideview 15 mm 1.25'.
When ever I look through my 2' compared to my 1.25' the view appears alot brighter, the 1.25 ones just looks dimmer.

I am currently thinking of which barlow to get... a 2' one or a 1.25'.

Lately I 've been having lots of cloud, so have not been able to see much. I do want to see Davidpretorius' nebula before I make a decision on going for the filters.

Judging from your responses, the DGM ones look like the ones to go for. For both its price and its quality;)

[janoskiss]

The brightness difference is not due to barrel size but focal length. Lower magnification (longer focal length) gives a brighter the image because more light is illuminating the same apparent field (image plane).

You only need the 2" format for EPs with longer focal lengths and wide apparent fields of view. The 2" allows for a larger field stop needed by longer focal length wide view eyepieces (approx FL>23mm, AFOV=70deg). Otherwise it makes no diff. It's like putting a larger diameter dew shield on your scope, or a bigger chrome pipe on the end of your exhaust pipe. Might look more impressive but does nothing for the performance.

The 1.25" format is more versatile, with cheaper accessories (filters, barlows etc). If you ever decide to get into binoviewing then you'll almost certainly want 1.25" EPs.

[davidpretorius]

mate, i had immaculate conditions last night and orion and the keyhole down south and tarantula were beautiful.

Orion and tarantula filling up the eyepiece in the 12mm

it was like looking at clouds! No colour, but very very pleasing.

Well worth the look at orion!

[janoskiss]

A review of 20 or so filters in the August issue of Astronomy put the DGM NBP well ahead of all others tested, including those you mention. The second highest rated was Orion's nebula filter. But it's worth keeping mind that this is just one (experienced) reviewer's subjective evaluation.

[Eardrum73]

Ok, from what I gather for eye pieces...

Eye relief is important for me as I wear eye glasses so I am thinking anything above 15mm eye relief for my next eye peice.

Focal length determines the brightness, can you get a high magnification eye peice with high focal length? or are they negatively correlated?

Its hard to find the focal length of eye peices as the online shops like Bintel and Andrews don't give such information.

I am considering the one below....

<TABLE cellPadding=1 border=0><TBODY><TR><TD class=ProductDescription vAlign=top>Meade 5000 06.7mm (1.25") </TD></TR><TR><TD class=desc vAlign=top>The new six and seven element Series 5000 Ultra Wide Angle eyepieces deliver extremely high resolution, contrast and full-field sharpness over an astounding 82° apparent field-of-view.



Fully Multi Coated. 7 lens elements

Eye relief: 15.7mm Weight:250g

</TD></TR><TR><TD vAlign=top></TD></TR><TR><TD> </TD></TR><TR><TD vAlign=top></TD></TR><TR><TD vAlign=top>$285.00


Is this good? It has 15mm eye relief, but it doesn't say the FL so i am not sure as to how bright the image will be....
and the price is like 1/3 of my scope?!?!?!? Is it worth it to spend so much on an eyepeice?
Is there a cheaper alternative I can get which offer similar results?

BTW I have 12' GS Dob..... FL 1500.

</TD></TR></TBODY></TABLE>

[davidpretorius]

Mate,

I am about to get a list of as many eyepieces that will be there at snake valley and who will allow me to look at and review from my noobie status.

List the ones you are looking at, the details like eye relief you are looking for and i will do my best to check it out at what is a great opportunity to review lots of great equipment.

[Eardrum73]

Man am I so confuse now....

After reading treads and calling up shops for advice... it seems that there are different eyepieces that will work well with different telescopes. Some eyepieces that will work well with the SCT will not work well with the dob and so on.

I spoke to someone at Bintell and as I ask them what they thought of a 4 x powermate and a number of 2' eyepeices (26mm, 30mm, 40mm etc...), and he said that I would not be happy with the image. He said that for a powermate to work, i would need to get high quality eyepieces.

Guys, any thoughts on this?

My original thought process was to get a powermate x 4 and then get some cheaper 2' eyepieces. To save cost overall. Instead of getting many wide view 1'25 eyepieces which will cost me more than the scope at the end.

Now it looks like that is not even going to work... I'm so confuse as to what eyepieces I should get now.......:ashamed:

Davidpretorius I wouldn't even know which eyepieces to list for you now... it seems that different eyepeices work well with different scopes.:confused:

[ving]

I wouldnt go for a 4x barlow for visual work (dependin on the fl of the eps you have) a 2x would be much more useful :)

[asimov]

Visual use a 2X barlow is nice, IMHO forget the 4X unless you want to do imaging. I purchased a 2" 30mm EP recently to see what all the fuss was about. Perhaps it's an aquired thing to get used to or something because I just didn't like the views. Sold it. I like my 1.25" 24mm ultima best for wide view low mag viewing.

Perhaps if I looked thru a high end 2" my opinion would change. My experience on this subject is limited.

[janoskiss]

The focal length is always specified along with the eyepiece make & model. For e.g. the Meade you've quoted above:



Here 6.7mm is the focal length.

Magnification = focal length of scope / focal length of eyepiece.

[Eardrum73]

ohhhh so thats the focal length...

lol i alawys thought that number was the eyepeice apeture or something....

Me = noober :whistle:

[acropolite]

Eardrum, I would try any Meade EP in your dob before you buy, because they don't always perform in fast scopes (e.g. your dob) That's not to say they're poor quality, but most seem to agree that they're optomised for Meade SCT's which are generally f8 and higher.

[RAJAH235]

Eardrum, I have Meade 4000 SP's & they are 5/6.4/9.7/12.4/15/32 & UWA 14mm, + #140 barlow. I also have a 7.4mm Televue plossl + 18 & 25m MA cheapies. They all work extemely well in my 10" 4.5 DOB.
Why not pick a brand & stick with it? You can always buy Naglers or Panoptics later if nec/needed. HTH. :D L.

[Eardrum73]

Hi all,

Thanks for all your responses....

Reading elsewhere in the forum it is said by many that 200x is the limit in terms of visual magnification.

But after reading an article about mars in Sky & Space Megazine (October issue) it said that for larger scopes we should try an get 300 to 400x magnification for observation.... this kinda of contridicts the 200x is the max rule... can anyone shed any light on this for me?


As for eyepeices,

what do you think of the following setup? (I have a 12' DOB, with FL 1500)

Option 1
1)Meade 5000 6.7mm 15mm eye relief with Orion Shorty Plus Barlow which should give me 447x magnification.
This will set me back $385 from Bintel.

Will this work to see the details in mars? (instead of a round orb of light like I am getting now.) will the meade eyepeice perform well with my GS dob?


Option 2
2) Andrews Ultrawide 2' 12mm, 80 FOV eyepeice. (Don't know what the eye relief is yet....) with a Andrews 2' Barlow at $79. This should give me 250x maginification.
This will set me back $298 from Andrews.

The only thing with this is that it is not 400x magnification liek option 1 and I am unsure of the quality of the barlow and the eyepiece.....

Sky and Space megazine said 300x to 400x should be good viewing for mars when it peaks in late october... but I am worried that if I spend $385 and realise that I can't make use of the magnification that all that money would be down the drain... which option should I go for (or perhaps none of the above, you can see a better option) and why? pls help.

[janoskiss]

Magnifications of over 300x can very rarely be achieved. I'd say don't spend so much money on something you could use for no more than a few hours a year.

The long eye relief requirement limits your choices at shorter focal lengths (FLs). The ED2's are an option you might like to consider at $79 each from AOE (http://www.aoe.com.au/eyepieces.html), with FLs as short as 2.3mm. Then there are the GSO superviews at medium and FLs. At FLs of 20mm or more, Ploessls will also have at 15mm eye relief or more. These are all sensible budget options. If you've got money to burn Televue Radians or Pentax XWs seem to be the most highly praised choices (20mm eye relief).

[davidpretorius]

from the televue website
"
HIGH-POWER VIEWING
Once you’ve selected an eyepiece set based on field stop sizes, calculate the magnifications produced with your scope. For planetary or double star observing, you’ll want an eyepiece in at least the 150x range. For determining maximum power, a good rule of thumb is to use no more than 60x per inch of aperture for scopes with apertures up to 6". Higher magnifications may still be pleasing but will not likely reveal any additional detail. Realistically, the atmosphere will usually limit your planetary observing to a maximum magnification of about 300x, no matter how large your telescope aperture.

Basically, you’ll be choosing low and medium power eyepieces by field stop increments to "frame" the subject, and high power eyepieces by magnification increments (based on your scope’s aperture), to reach the optimum contrast and resolution for viewing planets and double stars. "

[square_peg114GT]

The ED-2s are reported to be very fussy about eye placement, blacking-out if if you don't keep your eye positioned just right.

Unless you have an astigmatism, try removing your glasses for viewing. Also, at higher powers the resulting smaller exit pupils may fall inside of the astigmatic portion of your eye. Remember:
EPmm = Dmm / Magnification;


where EP is exit pupil in mms
D is the objective diameter (again in mms)
Magnification is the effective focal length of the objective divided into
the focal length of the eyepiece.

300x in your 300D scope produces a 1mm EP, which may not be effected by an astigmatism.


Another trick for those needing long eye relief is to get to high powers by barlowing longer FL eyepieces. A barlow changes the effective focal length of the telescope not the eyepiece, so the eyepiece retains it's eye relief when barlowed. Ex. - a typical plossl has eye relief = ~.75xFL, so a 15mm eyepiece with a 3x barlow results in the same 300x (in your scope) as a 5mm eyepiece, but with longer eye relief (11.25mm vs. 3.75mm).

In general, I think the new owner of a fast dob (< f/5) should buy a few stop-gap eyepieces to tide you over until you invest in some quality wide-field eyepieces. Celstron Ultimas, Orion Ultrascopics or Orion Highlights (not sure what equivalents you have down under) should do just fine. Avoid the bargain wide-fields - You're gonna end up replacing them. JMHO

[iceman]

The 6.7mm on its own (without the barlow) will be your most used eyepiece for the planets. As Steve said, it's very rare that the seeing will allow the type of magnifications you're going for. Most times you try it, you'll end up with a fuzzy out of focus ball and you won't see any fine detail on the planet.

Of course you want to be able to push the magnification when the seeing IS great on those rare nights, but usually you'll be around 200x or less.

You'll want a barlow for every focal length - so getting one of them is a must. The Orion Shorty Plus is a great choice - it's really the best of the middle priced range, after the Televue range.

I'm not a fan of the ED-2 series, as Pegster said, they're fussy about eye placement and I found that the 14mm I tried didn't perform well in my f/5 10" dob. They might be better at shorter focal lengths (asimov likes them (http://www.iceinspace.com.au/index.php?id=42,231,0,0,1,0)) but if you could try before you buy, that would be the best bet.


As I said above, 300x or higher will only be possible on nights of really good seeing. So don't spend a fortune going for that - spend you money on a good eyepiece to get you around 200x, and the barlow for nights of GREAT seeing. As I said, you'll use the barlow for your other eyepieces too.

So Option 1 looks like a good deal.

The Meade s5000 range don't appear to be quite as good as the s4000 range (at least in the Ultra Wides), but they're at a reasonable price and the plossls or super wides might be better than the 14mm ultra wide i've tried.

[Eardrum73]

Thanks for the help and feedback guys... I think your post help me heaps...

Eye placement is a crucial factor for me. I have Andrews 1.25' 40mm with 25mm eye relief and it actually cast a "shadow" or a "black shade" depending on where I place my eye. it actually has to be pretty exact, any slight movement will bring about the shadow. With eyeglasses its just a nightmare!

the other plossils don't have this problem. My most comfortable eyepiece is the GS 2' 26 mm with 30mm eye relief.... no shadows, easy to view, clear.... but unfortunately only 58x magnification.
Perhaps I will try and find a 3x barlow as Square Peg said and see if it can increase it 170x.

The Pentax UW or Televue Raidians with 20mm of eye relief sounds like something i should look into.... (I just hope they are not the wallet lightening types.....)

Iceman... you mean option 2 is the better choice don't you?

[iceman]

No, I don't think Option 2 will be the best way to spend your $$ as you'll need to upgrade to something sharper before long (imo).

Option 1 is good because you'll use the 6.7mm on it's own for the planets, and the barlow for when the seeing is GREAT. Both are good quality items that you won't need to upgrade and you'll get plenty of use out of them.

[Eardrum73]

Ahhh I see... thanks for that!!!!!!!!!!

[Starkler]

I think many of the writers talking about very high magnifications are people living in places with exceptional seeing that most of mortals dont experience, such as Florida in the US.

In my Melbourne based experience, times are rare that going over 200x gains me anthing. My most used planetary combo is a 14mm barlowed which gives me 196x.
200x corresponds to a focal length of 7.5mm in your scope.
If you buy say a 15mm and a 12mm quality plossl such as televue, along with a good barlow, you will have a flexible set of medium powers for dso viewing, and medium and high planetary magnifications all giving quality views.

[davidpretorius]

Geoff, a noobie question?

Is 15mm and 12mm too close together. Is it a double up?

[janoskiss]

Eardrum, one more thing to keep in mind. Barlowed long FL eyepieces might have problems with eye placement too, because the Barlow actually extends the eye relief. My 25mm GSO Ploessl is comfy on its own but real touchy in the Shorty Plus. In my limited experience, the barlow can also accentuate some of the design/build flaws of an eyepiece, like internal & stray light reflections.

Dave, I'd say no, 15 and 12mm are like 30 and 24mm in a scope with twice the FL. 30 & 24 don't sound like doubling up at all, do they? ;)

[davidpretorius]

thats true!!

[Eardrum73]

Hi all,

Over the weekend I had a chance of looking through a GS 68 degee eyepeice vs a Meade Wide view, both projected crisp clear views ( Although I was looking at the sign across the street on a spotting scope) and for the same FL they looked exactly indentical. perhaps with the more experience eye maybe you guys can spot the diffrence. But I will have to say its a very minute difference.

The meade eyepieces for its price seem to project about the same image as the GS ones. For almost 3x less the price, i would go for the GS wide view eyepieces anyday! (thats if I was heading down that path....)

I am begining to think that I should follow - the all or none law!

Either get the cheap stuff (which is GS eyepeices whoes quality seems comparable to eyepieces at 3 to 4 times its price ).... or go for the top of range like a televue.....

I haven't had a chance to look through and compare so I can't make any comments..... but I hear Televues are suppose to be the best of the eyepieces.... also the best bank busting one.... at 500 quid a pop!:sad:

[davidpretorius]

Eary,

hang five and let me try all the eyepieces i can lay my hands on at star camp.

Three categories, cheap=series 500 and gs, moderate = meades etc and premium = televue.

Each will be compared back to a series 500 at the same target at roughly the same time on the f5 dob

Mars will be out and so will saturn and dark skies will show up the dso's ie orion!

Which is the best planetary, best dso, double star resolution.

I will try and repeat on another sct etc, to see if there is any difference.

I want to know for all three ranges of eyepiece; contrast, image quality across the entire eyepiece, eye relief, barlow potential, double barlow potential etc. What is the overall feeling for the eyepiece etc.

I was able to double up a 2.4x and a 2x barlow and my 12mm series 500 worked well on mars ,the 6.5mm didn't work at all.

Hopefully, there will be a comprehensive list from a newbies point of view of where they all sit, and is there a good feel for value for money?

[Eardrum73]

11 days eh? I look forward to reading it..... should be interesting reading. Can't wait actually!!!!

But wow it sounds like a mountain of work...

Maybe I sould email Sky and Space megazine and see if they want to buy an eyepiece review article by an author named Davidpretorius...

[davidpretorius]

iis can sell the royalties, for every mag sold!!!!

except greg bryant's mates, cos he is a top bloke!