info about Comet Hunter Phoenix WFT 204-6

[ivan86]

Hello to all,

im Ivan and i come from Italy. Nice to meet you all.

Im very interested about your big comet hunter because i love the observing of the night sky at low power.

Im a bit scared about the logistics of this big refractor so if possible i would like the know the weight of the Phoenix WFT 204 at f/6 with focuser, ring and dovetail included and the transport lenght with dew shield retracted.

Have you a sample in stock ready to be shipped in Italy?

Many thanks and best regards
Ivan

[Ales - iStar Optical]

Hello Ivan,
Excellent choice for deep space visual works. If I may suggest, you may be even happier with our brand new Asteria TCR 204-8 R35 scope. This one is more expensive but will offer much greater detail, amazing level of resolution so you will be able to resolve individual stars in most popular globular clusters and resolve even the tightest of the binary stars, etc...

....you got lucky that I looked at this forum today, normally we do not replyl via Istar Scope Club, it is not even part of Istar web pages. Istar Scope Club is a completely independent site created by our fans, amateur astronomers. So plase contact Mike Harden directly about the shipping cost from Florida to Italy, his email address is [e-mail] and if you dont hear back from Mike soon than write to me at [e-mail]
Have a wonderful day, talk to you soon,
best regards,
Ales

[ivan86]

Thanks Ales for your quick answer. I sent an email to Mike.

I need the biggest aperture in the shortest tube avaiable. I can manage a tube that have a lenght of 1.2 or 1.3 meters but no more so for me an f/8 is impossible to use. Ill travel with this tube and my car under dark sky so the dimensions are important.

Can you tell me please (or maybe some owner) which is the max usefull magnification for this tube? I mean, at which magnification about the image start to degrade at a level that every other increase give no advantage?
Ofc in DSO observation! so CA not a big problem, contrast is.

Thanks
Ivan

[jamesling1000]

Hi Ivan.....

I know why you want the F6 version.... cause I need to cut my F9 into two halves, so that i can load it into my car......

Regards

James Ling

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[Ales - iStar Optical]

Hello Ivan,
the laws of optics production give you a pretty clear answers on this. If you use an achromatic doublet in 200mm aperture and F/5 to F/6 ratio than your optimal magnification is 0,25D where D is Diameter of the lens in mmm. So in this case 204 x 0,25 %= 51x magnification. So ideal eypieces to use are 50mm, 40mm, 30mm down to 24mm. Do not use anythis below 20mm. The maximum usable magnification is based on surface quality producable in this aperture range. For F8 system you end up with 0,75D, for F10 approx 1,00D and for F18 around 2,0D (F15 can also reach 2,0D in most cases so for this aperture the maximum usable magnification by the book would be 408x). We have people commenting on using much higher magnificaitons but Im presenting you the AVERAGE numbers as per our experience, production capabilities and books about optics.
Best regards,
Ales Patrick Krivanek
ISTAR Optical

[ivan86]

Wow James! Beatiful work! This is exactly my problem

Thanks again Ales, i had for 1 year the TS individual refractor 152/900 and i can remember that the image start degrade from 170/180x.

Do you know maybe the definition of optimal magnification in the formula?

Maybe 50x for the WFT 204 f/6 is the limit for a APO like image where chromatic aberration is not visible but the telescope can reach 100/120x with still good contrast for deepsky object even if CA is noticable on brighter stars.

Someone in the forum have some "real life" experience with this tube ?

Many thanks
Ivan