5x Barlow?

[luishidalgo]

Dear All,

I have a Skywatcher 200/1000 Newtonian (200PDS EQ5 PRO) and I was recently purchasing a Televue 2x Barlow to be used with a TS 5mm planetary EP. The results are satisfactory, but I expected to have more definition when looking at Saturn (at least being able to see the Cassini Division. The sky conditions were perhaps not the better, but decent and I found that I got not so much contrast to be able to see some details at Saturn... Instead, excess of bright (despite of use of filters) did not allow for a good observation.

I was thinking about using a 5x Barlow and wait for a good sky any of the next sommer nights, but I have serious doubts about the performance of a Televue 5x with my OTA... Of course, I should use perhaps a 6 or 7mm planetary EP as with my 5mm I am already on the theoretical limit of the Telescope (x400)... I read anywhere that I should not expect to go for good observation over x300, but i am not 100% sure about this extent...

I would really thank some advice, referred in particular to my OTA and the best performance optics for planetary observation.

Thanks a lot in advance!

[luishidalgo]

Sorry about the above post,

I meant that with a 5x Barlow I would need a 12mm EP instead of 6 or 7mm....

Thanks!

[OscarTheGrouch]

I have a 2x and a 3x Barlow.  I find that combined with the 20/10/6mm eyepieces, that gives me the magnification I need. 

[John]

I think you are already pushing things too far with the 5mm / 2x barlow combination to be honest with you. 250x is a much more practical and useful power or just possibly 300x when the seeing conditions are really good. I have a 12" dobsonian and find 225x - 300x the most useful range on Saturn. You will get much better views using the 5mm eyepiece without a barlow. Not larger but sharper and with more contrast, which is what matters.

So your doubts about the 5x barlow are very well founded !

[JED-E3]

It's easy to get into the trap of thinking more magnification will or should give more detailed views but it almost never does, I had my best ever views of Saturn last week with cloud bands and the Cassini division clearly visible, all at a lowly 150x magnification.

The best advice I can give is to use whichever eyepiece gives the most contrasty view and then stick with it, over a period of probably half an hour there will be moments of clarity that come and go.

[JamesF]

As a general rule (which means there are exceptions) I tend to consider barlows with large multiplication factors as imaging devices rather than for visual.

I think you may find that you've just not had a night with decent seeing yet.  It can make a huge difference.

James

[StarryEyed]

Your time and money would be better spent on collmination. 5x power mates are for fast scopes with excellent optics not saying you scopes not but your collmination will be your biggest problem before anything else. They works best for imaging in my experience in any case.