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Eyepieces collection for dob 12"?

zoneca

By zoneca
in Discussions - Eyepieces

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Moonshane

Moonshane

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I'd say (assuming it's f5) :

something between 25-30mm

something between 15-20mm

a further 2-3 between 6-15mm

Personally I have eleven eyepieces for three scopes and only two are lower powers (32mm and 26mm) and the other nine between 15mm to a 6-3mm zoom. (although I do hanker after a 17mm, and possibly a 20mm). it never stops

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zoneca

zoneca

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It very much depends on what you are most interested in looking at. What is the focal lenght of your scope and how much money can we spend.

Alan.

FL 1500 f/4.92

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alan potts

alan potts

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Posted

Zoneca,

You did not mention what sort of money you wish to spend but never mind, Estwing was straigth in there with some of the most expensive glass that you can buy, it makes best cyrstal wine glasses look give away prices. The chance are that the eyepieces that come with the scope are not that good and I would look to changing them in time, once you buy one really good EP you can judge for yourself what they are like.

Now as each one of the Ethos eyepiece costs almost at much as you scope I will avoid this option. Your scope is fairly fast so is going to be demanding on eyepieces, it will make cheaper eyepieces look fuzzy at the edges of the field of view, things there will not be in focus like in the centre of field. Myself I would follow the lines of Moonshane who has been doing astronomy a look time and has a scope a bit like yours but bigger.I have spent a good while in and around Jakarta a few years ago and I don't recall the seeing being that good on a night probablely due to the humidity in the air.. For this reason, unless I am totally wrong I would avoid a high magnification, well above X200, I would go no higher than 8-9 mm..

I was going to suggest you look at the Explore Sc brand or the Meade brand as they perform well for the money but not as good as the Telveu eyepieces Estwing mentioned. As it happenes both companies do a 8.8mm which will give you X170, high enough I feel. These eyepieces also have an 82 degree FOV which is good in a unguided Dobsonian, you can allow the stars and planets to drift through the field and you see them longer before having to nudge the scope.

Low end I would go for a wide 30mm eyepiece, even with the two companies I mentioned these are not cheap, Meade do a 30mm UWA for about 250 Pounds, how much this will be in Jakarta, I guess that is the only place you will be able to buy such gear, I don't know. This will work very well in your scope and give you a Mag' of X50 and also has this amasing 82 degree FOV.

For the mid range I would choose an 18mm from the ExSc range giving you X83 or a 14mm from either of the ranges giving you X107, it is up to you but I would go for the cheaper 14mm myself. There are other eyepieces you could buybut if I were you I would save and get what you can when you can and have some degree of quality in the focuser.

I hope this has been of some use to you and good luck.

Alan.

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zoneca

zoneca

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Thanks all especially Alan for the suggestion. Why does people mostly enjoy viewing galaxies using low power? Aren't they look too small to enjoy the view?

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Stargazer_00

Stargazer_00

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They are brighter when they are smaller because you arent stretching them. the more you increase magnficiation the dimmer objects get, so an already dim object will get even dimmer as you stretch it by magnfying it. Also by keeping them smaller they can be kept central of the eyepiece where the views are usually more clear and resolved compared to the outer 20-30% of the view.

It is a trade off, of course. You can get to the point where the magnficiation is so low you see nothing at all other than a small dot or a small line. Pointless looking at anything this low, and also the lower the magnification the more prevelant the light polluted orange glow becomes. At less than 30x I don't see dark sky backgrounds at all, its all orange wash.

My preferred galaxy magnficiation is 50x with a 82 degree 2" eyepiece. (24mm in my scope)

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Qualia

Qualia

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Ay, I imagine around 60x will be useful for large galaxies and for hunting them out in general. Depending on the night and the seeing conditions, many galaxies can take a lot more magnification. In general I'm using an exit pupil between 1.5mm to 2.5mm on the majority of DSOs and most of the time playing between 1.8mm to 2.4mm. I feel that on better quality nights this could be pushed to 1mm to 1.5mm exit pupil - depending on the galaxy or DSO being viewed, obviously.

A given eyepiece will give different magnifications with a different telescopes in virtue of having different focal lengths. So, no matter what size telescope you have, I'd keep your 25mm for now and look for an EP with a similar exit pupil as that suggested above, somewhere between that 1.5mm to 2.5mm. It is hard to say what is the best magnification because a lot of other factors come into play, but I honestly feel that an exit pubil around this range will end up being one of your most used EPs (along with a longer focal length for wider views and hunting).

Hope this helps a little.

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zoneca

zoneca

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Thank you stargazing00 & Qualia. From your both explanations, I come to a decision to collect a 2x barlow + 2 more eyepieces which are 30mm 82°& 8mm.

All in all I would have:

30mm 82° for locating dso

25mm come with scope

15mm (using barlow)

12.5mm (using barlow)

10mm come with scope

8mm for zooming

5mm (using barlow)

4mm (using barlow)

Please correct me if I am wrong. I'm not sure if the 4mm & 5mm can give clear view.

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alan potts

alan potts

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The barlowed focal lengths of 5mm and 4mm will give you a massive amount of power, you may be able to use the 5mm on the Moon but the 4mm I think will be too much but you can always try, it will cost no extra. I think as i said before your worst problem will be your seeing

Let me know what it is like, I guess Jakarta is not typical as the pollution is visible, brown sky in the morning from traffic. I notice you put where you are but this is a place I do not know and do not believe I have been there, I have only been to the Java Island and Bali and only one remember reasonable sky but this could just be the time of year on my 6 visits. I found the same true of Thailand too and I've been there many times.

Alan

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Qualia

Qualia

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Ay, I agree. I feel the 5mm and 4mm won't be used that often.

Personally, I feel the best plan of action is to use what you already have and see what you really enjoy viewing. Keep a little journal and note down what EPs are being used the most. With my own 10" f/5, to date I have found that EPs offering an exit pupil between 2.5 to 1.5mm are the most used on DSOs. While between 1.6mm to 1mm are more often being used for planetary and Lunar observing.

If it were me, and I had a little cash to spend on a couple of EPs for a 12" f/5, I'd be looking into a decent long focal length, wide field of view +/- 30mm EP and another tasty EP somewhere around 11mm to 9mm.

The Delos, Pentax XW and Explore Scientific spring to mind :p

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zoneca

zoneca

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Yeah Alan. Nice to hear that you've been to Jakarta. You are so right that Jakarta's sky is so polluted. Gratefully I'm not in jakarta. I live in the other island called borneo, and I'm in the west part of it which the city is known as Pontianak. I bet you ever heard about Pontianak aswell because this city is located right on the equator line 0°. I can't find people here that also interested in this kind of hobby, could be I'm the first one. Lol. Thats why getting the scope & parts is difficult. Luckily I founder one retailer that selling sw 12 dob. Just that the price here already sky high. It cost me about $1450. I checked the william optics UWAN 28mm 82° $460. Does it over price or reasonable? How about the quality?

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alan potts

alan potts

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This is a very good eyepiece indeed almost as good as a Televue. but the price is high.

Why not try a dealer in Singapore or Australia? I don't know one but I am sure there is one. You are in the same boat as me for costing but the Dealer here is very good to me now.. Your right I have never been to that island.

take care,

Alan

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  • 2 months later...
zoneca

zoneca

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After some carefully thought, I'm willing to spend $500 for eps in this coming end of june. I changed my mind to get only one better ep which made up this upcoming list of eps:

Barlow lens orient shorty 2x (buy) $119

Ultrablock filter / narrow band (buy) $95

25mm come with scope 60x

16mm William Optic UWAN 82° 93.75x (buy) $283

12.5mm (barlow) 120x

10mm come with scope 150x

8mm (barlow) 187.5x

5mm (barlow) 300x

Would it be a good investment going for William Optic? Whether this decision can cover dso & planetary observing? Will I get the WOW feeling from this ep?

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