Barlow, Powermate, & Magnification

[Brycepj (Peter)]

Hi everyone, It's been awhile but I still have questions. lol

A recent discussion with some other amateur astronomers relating to image magnification with the discussion turning to Barlow and Powermates.
This no doubt has been covered before, ie which one is better and is it worth spend the extra $ for the televue?

The other part of my question I have relates to putting a 5x Barlow into a 2x barlow which was part of the discussion that leads on to focal length. and magnification.
Ok now I'm lost. The comment was that in doing the above (looking a a fuzzy image of saturn) that..."there is probably not enough focal length to achieve focus" ....

Lets use looking Saturn as an example.
So from this with my 10" dob with a 1200mm focal length if I put a 2x barlow into a 5x barlow and then using 6mm eyepiece will I get a crisp clear larger image of Saturn in the field of view, am I also limited by eye piece i use.?
Which now brings me to my next question the magnification limits of my scope which the specs tell me,
Highest useful mag.300x
Highest theoretical mag 508x

Whats the difference??

I also have 20mm, 15mm & 10mm eyepieces.

Hope this makes sense, just want to be sure before I spend $

I also notice 5x barlow/popwermate prices as follows:

Bintell Barlow 5.0x =$69
Orion High power Barlow 5.0x 4 element = $269
Televue Power mate 5.0x = $319.

Is spending the extra dollars worth it? Would you spend the extra $ and buy the Powermate?

Thanks and regards
Peter

[Atmos (Colin)]

Ultimately you are going to be limited by your seeing conditions, relative humidity, secondary mirror (mass produced primaries are pretty good these days) and the ability of your newt from not being disturbed by your body heat

In short your view will be worse at 12,000mm focal length than 1,200mm.

[glend (Glen)]

Save your money, you wil not get a very useful 12000fl out of that gear due to Seeing limitations. In fact powerful EPs on their own regardless of brand, are often useless in normal Seeing conditions. I had a couple of very nice high powered Televue EPs and eventually sold them, as i simply never got to use them.
I would suggest, for now, you stay with good EPs down to 9mm, and you can 2x barlow that if you have really good Seeing. If you want really long focal length in a scope, and its mainly visual, the SCT design can get you there, and they are not hard to collimate.

[dannat (Daniel)]

i doubt you will get very few opportunities to use a 5x, even with your 20mm that will make it a 4mm, giving you 300x -only useful for moon or dbl stars.
a 3x barlow is the most many users use for visual -keep the 5x for planetary imagers

[Atmos (Colin)]

Also depends on what you're looking at. I personally find an exit pupil below 0.55mm for Saturn starts to get too dim. 0.4mm on Jupiter is still okay.

~300x is about as high as you'd want to go on many nights, going further sometimes reduces contrast.

[Brycepj (Peter)]

Thanks everyone for the sound advice and the extra bit of education.
One last question though how about getting a 3x Barlow?
The eye pieces I have all 1.25(I do have a 28mm 2" as well)
20mm
15mm
10mm
6mm
2X Barlow.
The 20mm and the 15mm are Televue plossl, the others re Orion's own brand.

Thanks for all your help.
Regards
Peter

[raymo]

A single eyepiece will always give at least a slightly better viewing
experience than an EP+ barlow. Given that, if you look at what a 3x
does for you, this is what you get.
Your 20mm + barlow becomes 6.66mm which you already have covered
with your 6mm EP, so no point.
Your 10mm becomes 3.33mm which would give a magnification that
could be used only occasionally when the seeing permitted.
Your 6mm becomes 2mm which would give a magnification too
high to ever be used.
raymo

[Brycepj (Peter)]

Thanks Raymo
I guest buying better quality eye pieces may be the way to go
Peter

[cletrac1922 (John)]

When doing school and scout presentation with SAS, I use a 17mm or 15mm wide angle eyepieces on my 10" collisionable dob
At Star Stuff 2017, had the 15mm wide angle on my PST, and gave a perfect image. Have issues when attempt to use 2" Barlow on my dob, as unable to get scope to focus, even when using adjustable extension tube

[AEAJR (Ed)]

For WIW I have moved away from single FL eyepieces using zooms as my primary eyepieces in all of my scopes.

For over a year the Celestron 8 to 24 mm was my primary eyepiece being matched up with a barlow when higher mag was needed. I did add EX 82 8.8 and 6.7 for high power wide views on my dob, which does not track. My two ETX scopes do track.

I upgraded to the Baader Hyperion 8 to 24 recently and it has replaced the Celestron as my primary eyepiece and my eyepieces are falling into neglect.

I my 8" Dob this gives me 50 to 150X. Add a 2X barlow and I have 100 to 300X which is about all I can use 98% of the time. Most nights I can't push over about 240X.


So I suggest you consider the BH Zoom and forget about magnification gaps. Zoom plus barlow and you have ALL magnifications based on 24 mm to 4 mm or 24 to 2.7 mm depending on what barlow you use.

All of them!

• I never expected the zoom eyepiece to become my primary eyepiece, but it has.
• The Celestron is good and comparable to my Plossl eyepieces but the Baader Hyperion is great and comparable to my Explore Scientific eyepieces
• Watching doubles split as I rotate the barrel is wonderful
• One filter serves over a wide range of magnifications, no screwing and unscrewing to try other eyepieces
• The Baader is a 1.25" zoom but it has its own 2" collar so, in my XT8i 2” focuser I can move from my 2" low power eyepieces to the zoom and a wide range of magnifications without playing with adapters.
• Moving smoothly from and between small changes in magnification helps when seeing is not the best
• Sharing the view with others is easier, especially in my manual tracking Dob - I can hand it over at low mag so it stays in the view longer, and then have them zoom back in to whatever magnification works best for them rather than for me.
• Kids love the zoom
• My eyepiece case has been greatly simplified

[Brycepj (Peter)]

Aearj (Ed)
What great advice will investigate and seriously consider.

For everyone else please also comment on my other thread regarding "filters"
Thanks

[AEAJR (Ed)]

These are the zoom eyepieces I use

Celestron 8-24
http://agenaastro.com/celestron-8-24...-eyepiece.html


I have the older version of this one
http://agenaastro.com/baader-8-24mm-...-eyepiece.html