Accessory advice for bintel 10" dob

[Cris]

Hey guys,

I just signed up tonight after purchasing my new telescope and I've got a few questions about accessories. Here's the specs first off:

Aperture: 254mm
Focal length: 1250mm (f/5)
Eye pieces: 9mm, 15mm, 30mm plossl

Tonight I did some viewing from my backyard (suburban) and I believe I was viewing mars at about 7pm (to the right of the moon). It was orange/red and when viewed through 9mm plossl it was quite a small blurry point (slightly larger than a pin head). At the moment I can get a 139x magnification, would a 6mm or 4mm plossl help see detail on mars due to a larger magnification? What are good eye pieces/filters for viewing planets?

Also, are DSO's going to be hard to see? I mean mars was such a small point how could I resolve a galaxy, nebula or globular cluster like what is promised about this telescope?

BTW I didn't let the telescope cool down enough (realised this after reading some other posts) so this may be why mars was blurry.

[barx1963 (Malcolm)]

Hi Cris and welcome to IIS!!

Congratulations on your new scope, and well done on getting a target. Mars is always a tricky one. It is veeeeery small and this apparition has not been a great one although it was quite high in the sky at it's best. Now though it is getting smaller and lower in the sky which makes it more subject to poor seeing (turbulent atmosphere)
On a more positive note, a 10" dob is a great starting scope for DSOs and the thing you may not realise is that many DSOs (btw by DSO I mean Deep Sky Objects such as nebula, open clusters, globular clusters and galaxies) are actually quite large. Mars this opposition only reached a maximum size of 15" which is really small. This chart, http://www.nakedeyeplanets.com/mars-...ns.htm#oppdata shows the relative sizes of the planet for the next few apparitions. DSOs are quite large, Omega Centauri by comparison is 36' in diameter, effectively over 70x bigger, although the outer edges are fairly faint so you may not see it as large.
So do not despair! And with eyepieces my usual advice is get used to the ones you have and what works or doesn't work for you before spending money on more. And I wouldn't bother getting a plossl shorter than the 9mm you have for a couple of reasons. 1. They are harder to use, very tight eye relief and small exit pupil once down under 9mm and 2. Power or magnification is not always good. It also magnifies any poor seeing or movement of the scope and can be very tricky to get good focus.

Malcolm

[Allan_L (Allan)]

Hi Chris,
Welcome!
As Malcolm said, congratulations on your new scope, a 10" DOB is a great scope.
Mars is not very good target at the moment, and is difficult to extract any detail at the best of times.
Saturn is far more satisfying an object and should look pretty impressive through your scope.
Jupiter, likewise, is a good target for your scope (as far as planets go) but it is just about over for this season, now setting very early after sunset.

To help find and identify stuff, you should download Stellarium, it is FREE and very good.

You will be able to see quite a few DSO's but they are called "faint fuzzies" for a reason. For best results you will need dark skies (away from light pollution, and as little moon glow as possible).

Try to find a observing group in your area and head along there fro some help with your new scope and to learn from experienced friendly people.

Read as much as you can (on this website, library, other) and please ask many questions. There are quite a few guides on here about southern hemisphere objects to look for as well as stuff to make it easier to find.

Enjoy

[astro744]

For more wow factor, try for Saturn. You can find it about half way between Mars (Ares) and Antares (Rival of Mars) tonight. On 6/7 the Moon will be just to the right of Mars. On 7/7 it will be between Mars and Saturn and on the 8/7 it will be just to the right of Saturn.

Antares is often the same colour and brightness as Mars hence its name. Antares is the brightest star in the constellation of Scorpius which is one of the few constellations that looks like what it represents and one of the easiest.

I highly recommend Stellarium for finding your way around.

For a deep sky wow, try Omega Centauri high in the south.

[Cris]

Originally Posted by barx1963

Hi Cris and welcome to IIS!!

Congratulations on your new scope, and well done on getting a target. Mars is always a tricky one. It is veeeeery small and this apparition has not been a great one although it was quite high in the sky at it's best. Now though it is getting smaller and lower in the sky which makes it more subject to poor seeing (turbulent atmosphere)

Going to have to wait until next time when its larger! Thanks

Originally Posted by barx1963

On a more positive note, a 10" dob is a great starting scope for DSOs and the thing you may not realise is that many DSOs (btw by DSO I mean Deep Sky Objects such as nebula, open clusters, globular clusters and galaxies) are actually quite large. Mars this opposition only reached a maximum size of 15" which is really small. This chart, http://www.nakedeyeplanets.com/mars-...ns.htm#oppdata shows the relative sizes of the planet for the next few apparitions. DSOs are quite large, Omega Centauri by comparison is 36' in diameter, effectively over 70x bigger, although the outer edges are fairly faint so you may not see it as large.

I thought this may be the case but I wasn't sure. I guess DSO's would be hard to see with the naked eye, even though they are large? And that is where the light gathering capabilities of the DOB come in?

Originally Posted by barx1963

So do not despair! And with eyepieces my usual advice is get used to the ones you have and what works or doesn't work for you before spending money on more. And I wouldn't bother getting a plossl shorter than the 9mm you have for a couple of reasons. 1. They are harder to use, very tight eye relief and small exit pupil once down under 9mm and 2. Power or magnification is not always good. It also magnifies any poor seeing or movement of the scope and can be very tricky to get good focus.

Malcolm

Ok what is meant by "tight eye relief" and "small exit pupil"? So, if I wanted more magnification I would need to move away from a plossl? what are my other options (I realise eye pieces get really expensive).

Thanks for the info Malcolm!

[Cris]

Originally Posted by Allan_L

Mars is not very good target at the moment, and is difficult to extract any detail at the best of times.

Pheww, thought my scope wasn't working as it should :p

Originally Posted by Allan_L

Saturn is far more satisfying an object and should look pretty impressive through your scope.
Jupiter, likewise, is a good target for your scope (as far as planets go) but it is just about over for this season, now setting very early after sunset.

To help find and identify stuff, you should download Stellarium, it is FREE and very good.

I will definitely try and have a go at saturn on a clear night. I already have stellarium (used it in astronomy class a few years back and its great) and it seems Jupiter is quite close to the sun (from our perspective). Mercury and venus are always near the sun, is there any way of viewing them?

Thanks for the advice Allan

[Renato1 (Renato)]

Hi,
I always attach a 1X red dot finder or a Telrad on my telescopes, because for me it makes it so much quicker to get something in the field of view of my finderscope.

Your 15mm plossl is fine for the faint (but not that faint) DSOs. Your 9mm is okay for most faint galaxies in suburbia, though out in the country I'd prefer a 10mm eyepiece that delivers a 2mm exit pupil. I suspect that at some stage you'll get annoyed with pushing your scope around so often with the 9mm, and you'll want to replace with a wide angle or ultra wide angle 9mm or 10mm eyepiece.

The 4 and 6mm eyepieces giving roughly 300X and 200X are a good idea, and the plossls will do in a pinch - but they have shallow eye relief and a small field in your telescope, which you may find frustrating (especially the 4mm plossl - with my one, I had to take the rubber eyecup off to see the entire field).

Much better are the wide angle, long eyerelief eyepieces. I'm quite happy with my budget TMB ones - which cost two to two and a half times the price of budget plossls - and there are other budget ones which do a similar job. Or you may want to go for more expensive ones. Or, if eyerelief isn't a problem for you and you don't mind cleaning them every now and then, perhaps consider ultra wide ones (which while expensive, aren't as dear as they used to be even 15 years ago).
Regards,
Renato

[barx1963 (Malcolm)]

Originally Posted by Cris

I thought this may be the case but I wasn't sure. I guess DSO's would be hard to see with the naked eye, even though they are large? And that is where the light gathering capabilities of the DOB come in?


Ok what is meant by "tight eye relief" and "small exit pupil"? So, if I wanted more magnification I would need to move away from a plossl? what are my other options (I realise eye pieces get really expensive).

With the first point DSOs are faint rather than small, although come are both small and faint. So your telescopes main function is to collect light to make them brighter. Magnification is less important. With my 12" I did most of my observing at 67x or 113x, very rarely needed to go higher. In my 20" mostly I use 150x.
Tight eye relief means you have to get your eye closer to the EP to use it it which can be uncomfortable or difficult if you wear glasses especially. Better EPs will often have more eye relief (EG Ethos have 15mm regardless of the focal length of the EP, but cost more than your scope each!).

Malcolm

[Cris]

Originally Posted by astro744

I highly recommend Stellarium for finding your way around.

For a deep sky wow, try Omega Centauri high in the south.

Thanks for the info

[Cris]

Originally Posted by Renato1

Much better are the wide angle, long eyerelief eyepieces. I'm quite happy with my budget TMB ones - which cost two to two and a half times the price of budget plossls - and there are other budget ones which do a similar job.

Where can I buy the TMB eyepieces. There's someone on ebay selling TMB planetary II for $72, but they are from the UK. When buying eyepieces do I have to worry if they will be able to focus in my particular telescope?

What about the Orion expanse range, they have good eye relief and FOV? Will they work in my telescope?
http://www.bintel.com.au/Eyepieces-a...1/catmenu.aspx

[astro744]

Originally Posted by Cris

Pheww, thought my scope wasn't working as it should :p


I will definitely try and have a go at saturn on a clear night. I already have stellarium (used it in astronomy class a few years back and its great) and it seems Jupiter is quite close to the sun (from our perspective). Mercury and venus are always near the sun, is there any way of viewing them?

Thanks for the advice Allan

Venus is north-east about 10 degrees high in the morning right now and heading back toward the evening sky where it will be visible in the west after sunset around Christmas (strong twilight though) and will make a nice pairing with Mercury in the first two weeks of 2015. Venus is visible during the day if you know where to look. No telescope needed! Do NOT use a telescope or binoculars when Venus is near the Sun. Too dangerous and not worth the risk!

Venus get to between 45 and 47 deg. elongation before it starts back again toward the Sun in a cycle from superior conjunction to inferior conjunction and maximum elongation morning (west) and evening (east) either side.

[Cris]

Originally Posted by barx1963

Tight eye relief means you have to get your eye closer to the EP to use it it which can be uncomfortable or difficult if you wear glasses especially. Better EPs will often have more eye relief (EG Ethos have 15mm regardless of the focal length of the EP, but cost more than your scope each!).

Malcolm

Eye relief seems to be important to me as I wear glasses. As stated in one of my other posts, what do you think about the orion expanse range. Good eye relief and FOV

[Renato1 (Renato)]

Originally Posted by Cris

Where can I buy the TMB eyepieces. There's someone on ebay selling TMB planetary II for $72, but they are from the UK. When buying eyepieces do I have to worry if they will be able to focus in my particular telescope?

What about the Orion expanse range, they have good eye relief and FOV? Will they work in my telescope?
http://www.bintel.com.au/Eyepieces-a...1/catmenu.aspx

I've bought all my TMBs from Ebay, some from Australia and some from the UK. Postage from the UK is quite reasonable and it gets here in around 8 days or so.

Here is the blurb from the TMB website about the 6mm eyepiece which only has 12mm eyerelief - and it says you won't see all the field with eyeglasses on.
http://www.tmboptical.com/itemsRecor...=40&cat_id=62&

That said, unless you have some strange eye problem, when using high power eyepieces with 2mm or 1mm or less exit pupils, wearing glasses doesn't make much of a difference. I've got terrible astigmatism , but I don't really notice it till I get to a lower power 3mm exit pupil. I don't think about wearing glasses until I get down to 4, 5 or 6mm exit pupils.

I don't actually mind short eye relief at high power, except that eyelashes eventually dirty the eyepiece halfway through a session - and it becomes annoying to look through.

Anyhow, the Expanse eye relief figures cited in your link seem akin to the TMB ones.

One doesn't have much focuser range in a dob. I have several eyepieces that don't work in my 14.5" dob, including the 2" GSO Superviews except for the 40mm one. I imagine that they would all work in a GSO scope like yours, so it is pointless my saying that if my TMBs work in mine, they will also work in yours (though the probability is that they will).

When you've decided what you want to buy, it can't hurt to post a separate post here asking other owners of your telescope if and how well the eyepieces you were thinking of buying works in theirs.
Regards,
Renato

[Cris]

Originally Posted by Renato1

One doesn't have much focuser range in a dob. I have several eyepieces that don't work in my 14.5" dob, including the 2" GSO Superviews except for the 40mm one. I imagine that they would all work in a GSO scope like yours, so it is pointless my saying that if my TMBs work in mine, they will also work in yours (though the probability is that they will).

Renato

I have a bintel 10" dob not a GSO. So I may have similar issue as you. I might email the guy from bintel that helped me out with my scope purchase. I just wanted to get some other opinions on this.

BTW great information Renato, I really appreciate the help and advice.

[Allan_L (Allan)]

Originally Posted by Cris

I have a bintel 10" dob not a GSO.

I believe the Bintel DOB is a GSO DOB, rebadged.

Re: Glasses, I wear glasses but I take them off when using the telescope. You just adjust the focus to account for the eyesight adjustment.
I (and many others) find that more satisfying.
It just means you have to adjust the focus if others with good vision are sharing your views.

I am not sure what sort of finder your DOB has (I have a skywatcher), but as Renato says, I also think the combination of BOTH a Red Dot Finder and a (Right Angled) magnified finder scope (mine is 9x50) is the best way to go.

[noeyedeer (Matt)]

have had no troubles with the 32 and 30mm 2" eps nor the 5mm and 4mm TMB IIs in my 10".

safe bet and easy on the eye with the TMBs .. not premium but better then a plossl

matt

[Renato1 (Renato)]

Originally Posted by Cris

I have a bintel 10" dob not a GSO. So I may have similar issue as you. I might email the guy from bintel that helped me out with my scope purchase. I just wanted to get some other opinions on this.

BTW great information Renato, I really appreciate the help and advice.

No problem. It's good to see that Matt and Allan have chimed in and answered what I couldn't be 100% certain about.

Good quality eyepieces have never been cheaper than now. 20 years ago paying $50 or $60 for a reasonable 2" eyepiece as one can now do from Andrews and Bintel, was impossible. And the even better thing is, if you outgrow them or just want something you think may be better at a later time - you can recoup part of your cost, by easily flogging them off here or at Ebay.

Have fun.
Cheers,
Renato

[Suzy]

I own an Orion Expanse 15mm. It was my favourite eyepiece (before I got premiums) in my 6" dob. And now a favourite in my 4" dob. But it wouldn't perform in my 10" dob- seagulls everywhere .
My 10" is a Saxon (so was the 6") if that makes any difference with focus issues because I bought a TMB 6mm and it wouldn't come into focus. So I sent it back and the seller re-tried in his scope even taking a video of the views and posting it to me- it was perfect for him .

I agree with Malcolm in suggesting you should wait a little bit longer before buying eyepieces. If I can suggest spending some time reading the masses of eyepiece threads in the eyepiece forum on here, you will get a great education before you buy. Two of my threads come to mind (links below) which were highly educational but there are many, many on here which are too.
The Best 5mm Under $200 and
Help On Choosing A Premium 14mm Eyepiece.

I'm surprised no one has mentioned Explore Scientific or Andrews widefield eyepieces yet .
Try and get a 10mm in a widefield. The higher the magnification, the more the field of view is reduced so objects like Omega Centauri don't fit in a plossil. And 10mm is a popular choice for planets- though using a plossil on planets you will find that they zoom out of the field of view (fov) very quickly, whereas widefield ep's (eyepieces) give you much greater time to view them. A plossil can end up becoming a lot of work with pushing and nudging a dob trying to keep the objects within the fov.

There is a reason people suggest waiting- it takes time to find out what's important in an eyepiece, and sometimes what's important can cost you a lot of money- hundred of dollars in fact. Read up, and do your research.

I know many people have issues using a 5mm on planets, but here in my light polluted backyard, I use it often with success. Though you'd never use it if the planet was wobbling about and blurry (due to seeing conditions) in a 10mm.

"Also, are DSO's going to be hard to see? I mean mars was such a small point how could I resolve a galaxy, nebula or globular cluster like what is promised about this telescope?"

Are you sure it was Mars?
I've just been checking your time observing at 7pm on the 2nd July and Mars was a good 40 degrees above the moon- not to the right. Arcturus however was more right and closer to the moon, and it is large, bright and orange in colour. Why I suspect this also is that you referred to it as a point source. Stars are more like a point source and planets have a more resolvable disc shape .

The quality of DSO viewing will be dependent on the seeing conditions. This applies to planets as well. Some nights will be magical showing up a great amount of detail, while other nights you'll barely see anything and that is why it's worth constant re-visits to the same objects. And don't view DSO's when the moon is out as it it'll just wash them out. Moon interference won't affect planetary viewing but the seeing conditions still stand. Also, the more you observe DSO's, the better you will become at picking out the detail so consider your eyes in training now .

All the best with your new telescope- lots of fun nights ahead!