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View Full Version here: : Celestron Ultima 1.25" barlow opinions?


skies2clear
23-02-2007, 12:35 PM
Anyone have any thoughts or first hand experience on the performance of this barlow?
Most info I found so far was pretty positive. How would it rate to the best out there? Is the best around something like the Televue powermates? Does anyone know if the TV barlows are apochromatic? Lots of questions I know!

Thanks in advance.

Clear Skies

Edited: Celestron 2X Ultima barlow that is!

ving
23-02-2007, 01:14 PM
i havent used one but the ultima range as a general rule is top notch. I have a 7.5mm ultima EP and it is better IMO than the equivilent televue but other would disagree. the celestron give a warmer colour i am told... but this is getting off track.
it is a good barlow.

janoskiss
23-02-2007, 02:32 PM
No need for "apo" barlows. My Televue "achro" barlow has less off-axis false colour (ie none) than the Orion Shorty Plus "apo" I used to own (which is very simular to the Ultima). AFIU, having an apo or ED lens in a barlow is either solely for marketing purposes or perhaps sometimes to allow the use of a very short barrel while still maintaining good colour correction.

Powermates are not necessarily as good as well made more basic 2-element long barrel barlows like the TV barlows. Have a read of this comparison from someone with a fair bit of experience:
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/523562

Starkler
23-02-2007, 03:50 PM
In short, much better than a cheapie and just a notch behind the best ones.
It seems to be a clone of the Orion Shorty Plus. The orion is good value and IMO at the sweet spot on the price/performance curve. With Celestrons name on it its much more expensive.

skies2clear
23-02-2007, 05:32 PM
Thanks Ving. I wouldn't dare ask a question about TV that might start a war or something! :P

skies2clear
23-02-2007, 05:40 PM
Interesting Steve. I'm still wading thru the CN link above. From what I understand so far, for on axis sharpness, contrast and transmission, you can't beat simpler 2 element designs, of course, as long as they are designed well and made with good glass/coatings, etc. Off axis performance may be a different issue though, and it could be that a well designed apo barlow may perform better off axis? And then, when it comes to imaging (though not my pursuit so far) , it could weigh towards the apo type barlow as well.

It's a bit like comparing simpler design narrower field eyepieces, to wide field complex/many element types. What do you think? I noticed you said your "acro" barlow was still better off-axis for colour than the Orion Shorty plus.

Clear skies.

skies2clear
23-02-2007, 05:41 PM
Thanks Geoff,
do you know how much a Shorty Plus normally costs?

CS

janoskiss
23-02-2007, 05:59 PM
S2S, I really don't know. All I know is that my good barlows do not introduce false colour - actually they usually improve colour correction near the edge of field of widefield EPs.

I have a Televue 1.8x barlow and a Japanese 2" 2x barlow (equiv to UO 2" or Orion Deluxe 2"). They are both excellent. I also have a Meade #140 3-element apo barlow which is defective and I use it only as an extension tube with lenses removed - bad astigmatism on and off axis. And I also have a 5x powermate that is waiting for a webcam + laptop (not much use for visual but tried it with 25mm Antares plossl and it works well).

Some imagers swear by the Powermates and are getting excellent results as you can see from the Saturns and Jupiters they manage to capture. Bird uses a powermate to image planets. I reckon he would know if and why it's better than a normal barlow.

casstony
23-02-2007, 07:21 PM
orion shorty plus $135 http://www.sirius-optics.com.au/barlowe_pieces.htm

Starkler
23-02-2007, 07:40 PM
Thanks Tony, saved me the trouble ;)

matt
23-02-2007, 09:17 PM
I have a Celestron Ultima 2x barlow, Televue 3x barlow, and 2.5x and 4x Powermates.

I do almost all my imaging with the 3x.

For visual the Ultima is very nice although from memory I seem to recall it being just a smidge "warm" in terms of introduced colour. Haven't barlowed visual for quite some time.

I do seem to remember Jupiter looking very impressive through the 24mm Panoptic in the 2x Ultima... in the 9.25

It just seemed to tint things slightly.

The Powermates are superb imaging tools also.

skies2clear
24-02-2007, 10:14 PM
Thanks everyone so far for your valuable input. It seems the Orion is slightly less expensive than the Celestron, if you get the Celestron discounted (about $140).

I just had a chance to look thru one and it seemed to work well, but I have nothing great (barlow) to compare it with, except comparing a 14mm XW with 2X barlow against a 7mm XW with no barlow. The losses seemed small, but I didn't have a really great night/ seeing conditions to be conclusive. However at F5, the 14XW barlowed, was sharper at the edge of field than it normally is. No surprise there really.

I'm interested in using a barlow on those rare nights for planetary use, and thought the better the barlow, the less it gets in the way of the final image.

I had a chance some time ago to get an old TV 1.8X barlow for a good price. Should have tried it!

When I can be more conclusive about the comparison, I'll give my 2 cents worth,

Clear skies

skies2clear
01-03-2007, 08:55 AM
I managed to have a relatively quick look through a Celestron Ultima 2X barlow a couple of nights ago in a 6" F8 refractor. Was mainly looking at the Trapezium and looking for the 5th and 6th stars. Seeing wasn't great, but would occasionally steady up. We compared a Pentax 14 XW barlowed with a 7 XW not barlowed. The Celestron Ultima held up very well actually. Losses were very small.
Also looked at Saturn. Colour issues were non existant with this barlow too.

However, being critical, it doesn't completely get out of the way. I noticed a very slight loss of definition and transmission, but it was slight! It was just that bit easier to see the 5th star without the barlow. I can certainly see why this type of barlow has had such widespread positive comments. Every now and then, you see them for sale second hand at great prices. So it would be great value for money.

In the past, I didn't see the need to spend much on a really good barlow, and I obtained one of those GSO 2" ED barlows. My gut feeling is the Ultima is better than that unit, although I have to be honest and say I didn't do a side by side comparison.

My next wish is to try a Televue Powermate and 2X Barlow and see how those go.

The quest continues....

Clear skies

astronut
02-03-2007, 04:23 PM
S2C,
Up until last year I'd used F15 refractors and my Meade shorty barlow worked really well. This time last year I purchased my 12"LB. After speaking with Harry Siebert of Siebert Optics I learnt that fast scopes (F5 and faster) have a much larger light cone than the slower scopes. To be able to enjoy this larger cone needs a barlow that can swallow up the complete light path.
The Meade and similar barlows waste a large amount of light because of their configuration. This will give you a dimmer image.
The Televue Powermates and Siebert Ultra's are the two best choices
The Siebert site is www.siebertoptics.com (http://www.siebertoptics.com) :D

skies2clear
02-03-2007, 04:38 PM
Thanks John,
I didn't even think about Seibert. I have one of his Binoviewer OCS's and it works extremely well. The comment about the steep light cone is interesting, so I'll investigate. Perhaps I wasn't seeing that particular effect though in the F8 refractor? And I guess the steep/larger light cone issue is more of a problem with lower powers and wider fields.

clear skies

casstony
02-03-2007, 04:57 PM
Even at 100mm in from the primary mirror focal point, the light cone width is 20mm in an f/5 scope; I can't see how a 1.25" barlow would impinge on the light cone? Are there factors other than clear aperture that come into play?

janoskiss
02-03-2007, 05:02 PM
Right! Every manufacturer has some spiel about why their product is better than the competition. One needs to take these things with a grain of salt.

astronut
02-03-2007, 05:16 PM
Yes fellows, there are a lot of spiels out there.
So I tried it out with a side by side test which proved Harry Sieberts advice.
Sieberts advice was not only aimed at his products but to the other Premium brands as well.
You have to see it to believe it:D My two cents.