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New f/15 CFF 300 -- almost here

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#1 MJB87

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Posted 08 April 2019 - 10:24 AM

Catalin is waiting for clear skies to test out the new telescope. If all goes well, I'll have it installed by the end of the month and will report back on its performance -- weather permitting.

 

2AA374A8-31B2-4281-B1D8-E8329B97EFBE.jpeg

 

This will be mounted side-by-side with my Astro-Physics 130mm GTX.  Total weight will be about 85-90lbs.  George assures me the AP1100 mount can handle it.

 

Given historical precedent, fellow observers in the Maryland area can expect cloudy skies for an extended period starting late April, exactly as the new telescope arrives. Just the way things seem to work out :)


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#2 aneeg

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Posted 08 April 2019 - 11:19 AM

A fun little scope :-)

 

Arne


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#3 macdonjh

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Posted 08 April 2019 - 01:14 PM

Welcome to the club.  I really enjoy my CFF 14" f/15.  I don't know if DJHanson is still active here (I thought I read a post that said he was signing off), but he has a 14" f/17 that he uses for planetary photography.  Ours are both really sharp scopes.

 

Post some photos when you get it installed, please.  



#4 rcg

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Posted 08 April 2019 - 10:35 PM

Waiting for first light, this would be my largest able to handle dream scope, what mirror substrate did you go with?



#5 Wouter D'hoye

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Posted 09 April 2019 - 12:44 AM

You'll love it. Catalin takes his time to make sure everything is up to par. But it will be more than worth the wait.

 

Love the blue accents.  Mine has red accents. but that goes well with the PM-MX it sits on. Mine has the FLT 132 piggyback. and works just fine. so your 1100 will be quite fine with the AP130.

 

Make sure to show pictures and a first light report.

 

Wouter.


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#6 MJB87

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Posted 09 April 2019 - 05:24 AM

Thanks, everyone.

 

I went with the cellular glass option, for two reasons. First, it will reach thermal equilibrium more quickly and my observing sessions often end relatively early.  Second, it saves me 2.1 kg in weight which is helpful for a variety fo reasons.

 

I will certainly post images from first light, most likely toward the end of the month.

 

MJB



#7 rcg

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Posted 09 April 2019 - 12:47 PM

MJB,

I think the cellular substrate is supposed to take a better polish also … another plus ...



#8 MJB87

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Posted 09 April 2019 - 02:07 PM

That was my understanding as well.

 

Well, the photo I showed is slightly incorrect. It has a straight spider. Catalin was going to put on a curved spider to minimize diffraction spikes.  He is in the process of making that change now.

 

MJB


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#9 rcg

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Posted 09 April 2019 - 02:29 PM

That's interesting to note about the curved spider, I notice Mewlon went to 3 vane spider … I was wondering about that effect also … great to know Catalin works with custom ideas. He worked some magic for me on my 165 frac also.


Edited by rcg, 09 April 2019 - 02:31 PM.


#10 payner

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Posted 09 April 2019 - 05:27 PM

The Mewlon 210 and 250CRS both have four vane spider.  I'm not sure about the new 180 Mewlon.

 

Randy



#11 salico

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Posted 10 April 2019 - 06:08 AM

The M180 C has a three vane spider.



#12 MJB87

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Posted 10 April 2019 - 08:34 AM

This was positioned by Catalin as a trade-off between rigidity and image characteristics. My primary setup is used about 100% for imaging so I chose the option that would limit the diffraction spikes.  Others could easily make a different choice.


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#13 rcg

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Posted 14 April 2019 - 11:54 AM

https://www.cloudyni...hi-mewlon-250s/

 

Here's where I saw the 250 Mewlon with a 3 vane spider ...



#14 MJB87

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Posted 18 April 2019 - 09:02 AM

Well, the telescope has arrived! Packaging appears to be in excellent shape. I'll need to organize a side-by-side setup with the A-P 130mm Starfire GTX.  Yeah, that's a pretty fancy finderscope for the new reflector.

 

In the end Catalin and I agreed to stick with the straight spider. He was worried about the fragility of the curved spider design should the telescope be mishandled at some point.

 

If all goes well I'll have first light Monday and will report back. I'll do the standard checks for collimation and any optical aberrations. If seeing is adequate I'll check out some double stars. Let me know if there is anything else I should do for the initial reporting.

 

MJB


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#15 payner

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Posted 18 April 2019 - 04:55 PM

https://www.cloudyni...hi-mewlon-250s/

 

Here's where I saw the 250 Mewlon with a 3 vane spider ...

Yes, the previous model of the 250 was three-vane design.  The current 250, 250CRS, is four-vane.  The four-vane is preferable, imho.



#16 Procyon

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Posted 18 April 2019 - 05:24 PM

So where does one buy one of these nice scopes? Are they for visual?

#17 junomike

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Posted 18 April 2019 - 05:57 PM

Yes, the previous model of the 250 was three-vane design.  The current 250, 250CRS, is four-vane.  The four-vane is preferable, imho.

Why (holds collimation better?)



#18 Tyson M

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Posted 18 April 2019 - 06:49 PM

Why (holds collimation better?)

I have the three vane. It survived UPS internationally shipped and remained in collimation! 

 

That to me, is incredible. 


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#19 MJB87

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Posted 19 April 2019 - 07:00 AM

Catalin's concerns were more about the curved nature of the proposed spider vanes and how any shocks would potentially misalign the secondary.  I shouldn't speak for him but I think he'd favor three straight vanes to four curved ones.



#20 junomike

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Posted 19 April 2019 - 12:33 PM

I have the three vane. It survived UPS internationally shipped and remained in collimation! 

 

That to me, is incredible. 

Hence my curiosity about the 4 vane being preferable?


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#21 Tyson M

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Posted 19 April 2019 - 12:38 PM

Hence my curiosity about the 4 vane being preferable?

I'm curious too. I thought it had to do with individual preferences to diffraction spikes. I believe the 3 vane has six tiny spikes all around the star, where the 4 vane has four longer spikes.

 

I cant see it making a discernable difference in planetary views regarding contrast, but the subdued spikes with 3 vane may be aesthetically pleasing to those who dislike spikes...

 

I'm just speculating at this point.


Edited by Tyson M, 19 April 2019 - 12:39 PM.


#22 junomike

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Posted 19 April 2019 - 01:19 PM

I'm curious too. I thought it had to do with individual preferences to diffraction spikes. I believe the 3 vane has six tiny spikes all around the star, where the 4 vane has four longer spikes.

 

I cant see it making a discernable difference in planetary views regarding contrast, but the subdued spikes with 3 vane may be aesthetically pleasing to those who dislike spikes...

 

I'm just speculating at this point.

That makes sense.



#23 payner

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Posted 19 April 2019 - 05:28 PM

It was based on the four-vane being quite rigid and stable given the four-point orthogonal secondary housing structure.  So, collimation is very stable once dialed in, even in transport.  The four-vane is my preference for the reason stated, the four diffraction spike vs. six diffraction spike presentation on bright objects; though, the four-vane diffraction spikes are a bit brighter.



#24 TG

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Posted 20 April 2019 - 01:29 PM

It was based on the four-vane being quite rigid and stable given the four-point orthogonal secondary housing structure. So, collimation is very stable once dialed in, even in transport. The four-vane is my preference for the reason stated, the four diffraction spike vs. six diffraction spike presentation on bright objects; though, the four-vane diffraction spikes are a bit brighter.


The three *straight* vane spider is just as rigid as the four vane one. I think people are confusing three *curved* vane spiders with straight vane ones. Due to the lack of tension in the curved ones, they're inherently less stable, no matter what the number of vanes.

Tanveer (own a 250 with a 3-vane spider)
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#25 payner

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Posted 20 April 2019 - 07:35 PM

Well, when Takahashi went to the CRS model, in the design they wanted to reduce diffraction spikes, compared to the three-vane design.  That was their statement; and while they may be a bit brighter, I prefer that to six a bit dimmer diffraction spikes.  I would also prefer the four-vane for the reasons already stated, ymmv.

 

in the end, either model is an outstanding telescope.

 

Randy




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