New Dob 8 owner question: Barlow 2x or high power EP for mag experiments

[furio]

Hello everyone, i'm new on this forum.

I am proudly a new owner of a Dob 8 (SkyWatcher Classic Dob). I am using the stock 10 mm and 25 that came with the scope and i'm amazed by what i see so far! I was able to see a lot of Messier objects so far as well as Jupiter and a beautiful early morning moon.

Now i would like to try to magnify some objects a bit, mostly the moon and planets. My local speciality shop advice is to keep observing with my current EP for a while before spending on anything. I don't want to go over my head and buy a lot of EP.

I was thinking about a barlow 2x or a 5 or 6 mm EP to test out more magnification... The good thing i think about the barlow is that i think it could help simulate the results i could get with say... 5 or 12.5 mm EP?

What do you guys think and what would be a good start?

[LukeSkywatcher]

Hi Furio and welcome.

I do agree with your local shop. Get used to your new scope and EP's before you consider upgrading. You can and will get what you want (magnification) by ivesting a small amount on a barlow.

Wit a 2x barlow you will end up with a 5,10,12.5 and 25mm EP collection.

Thats what most of us have started out with (as most scopes come with a 10,25mm EP). 

The Moon should look outstanding in a 200mm Dob using the 10mm+2x barlow. Jupiter should be great using the 10mm alone.

There is an online app that allows you to type in the scope you use and the EP size and give you a good idea of thow stuff will look. I dont have the link to hand but if you search for "FOV calculator", you should find it easy enough. Someone else may post a link.

What barlow to buy? Thats the question. I'd say a TAL 2x but they have been discontinued and are like gold dust.. If you find one second hand............brilliant. They retail for about £30.

Revelation ones retail about the same and are good. Also, i think the Celestron "shorty" is held in high regard.

To be honest though.......................a fixed focal length EP would be a better choice, as the less amount of glass you have in the "train", the better. You will learn that over time and as you gain experience. 

It really boils down to your budget. Most people however do own a barlow.

Hope this helps.

Paul

[brantuk]

I agree with all Paul's points. I can only add that eyepiece choice is a personal thing related to each individuals eyes and which scope they're using. I'd suggest joining a local astro club and go out observing with them. You'll find folks are mostly happy to let you try out eyepieces from their collections in your scope.

You'll soon get to know what you like and what does/doesn't suit you. A good barlow is also a good idea in the early days - you can double what few eyepieces you start with until you collect a range of fixed stop pieces at intervals you require. 4mm or 5mm difference between each one is a reasonable interval.

There's a vast range of eyepiece sizes and qualities - it's always good to try before you buy.

[Charic]

It gets a lot harder to follow the target at higher magnifications. You`ll get far less time to view as It glides across your view.

I have the Revelation 2.5X  and Looking at the Moon at 375x with the 8mm BST is just frikin awesome, especially when you hit the edges between light and dark, but the Moon is such a bright and large target to look at. Jupiter on the other hand, the weather  bands are just visible to my eyes, and I still haven't seen the GRS (Great Red Spot), more due to the poor weather conditions and lack of observation. I've probably not been out since the middle of January?

I think Al Nagler once said pick, any lens that just frames the target and be happy with that ( or something similar) The problem to that is, as you go to the larger focal lengths, the space you can see gets wider, but the image  is smaller  within that space ( and vice versa)  What were wanting is the highest magnification and the biggest image. I think the bigger images  for me will only come  from bigger apertures, but I have no intentions to buy a bigger scope for a long time yet, but  I may invest in a 2x Barlow just to bring my magnification down for the Planets?

[furio]

Thanks a lot guys for your advices! I think I will go for a barlow to start with then i'll keep observing with what i have for a while!

There is no club that i'm aware of close to me but will check further. Of course if I can try before buying I will do that! That's exactly what i did with my scope.... i was able to rent one before buying (then substract the renting fee on the price tag). Too bad ghat the shop isn't offering the same thing for the EP

[furio]

Oh and as for the barlows models, my shop keep a cheap Skywatcher, 3 Celestron and 1 Televue (which is too pricey for me).

In my price range:

- Skywatcher barlow/adapter for camera (40$ can)

- Celestron Omni (50$)

- Celestron X-Cel (90$)

I may lean towards the Omni if the quality is there (2 elements vs 3 for X-Cel), mainly because of the price.

[Charic]

Thanks a lot guys for your advices! I think I will go for a barlow to start with then i'll keep observing with what i have for a while!

There is no club that i'm aware of close to me but will check further. Of course if I can try before buying I will do that! That's exactly what i did with my scope.... i was able to rent one before buying (then substract the renting fee on the price tag). Too bad ghat the shop isn't offering the same thing for the EP

There is a site here in uk that will allow you to buy two lenses to allow you to compare side by side. If you don't want one of them, you return it for a full refund. Its the nearest thing to try before you buy, but you buy first. Its also free postage to receive the goods in UK but a small fee to return. If you check this out http://www.skysthelimit.org.uk/index.html and check their *bay site at http://www.ebay.co.uk/itm/1-25-8mm-BST-Explorer-Dual-ED-eyepiece-Branded-Starguider-/161134743886 for example. For posting to Canada its £3 about 5.5 Dollar. If you like both lenses, you`d just keep them. If you decide you buy the 5mm BST & 6mm TMB II  and decide to return the TMB, you would have to pay the return postage too . again about 5.5 Dollars!. BST eyepieces are fairly good for the money.

[Blazar]

What barlow to buy? Thats the question. I'd say a TAL 2x but they have been discontinued and are like gold dust.. If you find one second hand............brilliant. They retail for about £30.

Not discontinued....just not imported. Our friend here is in Canada, and there is a guy in Michigan (Roman) who owns TALteleoptics, and imports all TAL goods from Novosibirsk. So the Americans and Canadians can get the x2 and x3....

And indeed I just ordered a set from them.  Do a searh for TALteleoptics and you will find them. or follow this link here

Remember TAL=Not dead (just yet)

Regards

[furio]

Charic: Thanks for the link i'll check it out.

Paul A.K.A Luke: I found a website that simulate views with your scope specs and the EP sizes you want, and you can even simulate a Barlow 2x on top of them. It's in french but really well made: www.stelvision.com

It's seems that you guys around here are all sold to TAL optics. So I have a question for all of you: what make them better than the ones I mentionned above?

And yes I'm from Canada. I didn't realize this is a U.K. forum until I posted a couple of posts!

Thanks guys!!

[Charic]

Charic: Thanks for the link i'll check it out.

Paul A.K.A Luke: I found a website that simulate views with your scope specs and the EP sizes you want, and you can even simulate a Barlow 2x on top of them. It's in french but really well made: www.stelvision.com

It's seems that you guys around here are all sold to TAL optics. So I have a question for all of you: what make them better than the ones I mentionned above?

And yes I'm from Canada. I didn't realize this is a U.K. forum until I posted a couple of posts!

Thanks guys!!

The freeware program Stellarium allows you to do similar. This will give you an idea, especially the FOV (Field of View) your likely to see through the telescope. Its how I chose my 32mm lens.

As for TAL, I think it was just the build quality of the Russians. Solid and reliable. However the TAL 2xbarlow is like Hens teeth, pretty rare to find over here in UK,  people just keep hold of them. I believe this place still supplies them http://www.talteleoptics.com/finderscopes.html.