39 replies to this topic

[Carl N]

My understanding from Joel Short, www.buckeyestargazer.net, whom I bought my APM 115 from is that the Astro Physics flattener and reducers he didn't have as much luck with. He reccomended the Tak or Riccardi. I assumed it was because the AP stuff was designed for the oil spaced lenses. That is my interpretation not what anyone said.

[John Anthony]

Sell a TMB 130SS for a........ Ok while I can't really give any expertise advice that can help you with your question I can say this, selling a TMB 130SS is just wrong, I really mean wrong.

I hope this helps, I really do. :-).

[mfarrell]

Matthew, 

Thanks for that info.  Did you ever try the AP 2.7" reducer?  I wonder how it compares to the Riccardi on the TMB 130.  I did manage to find some images from one person who used it with a large sensor but he was using an AP155.  Although his stars wheren't perfect, I think it would be acceptable enough to use while I saved up for something like a FSQ106.  

 

Phil, no I have not used the AP 2.7" reducer.

 

Here's a 100% center and corner crop from the TMB130SS + Riccardi on my 5D MkII at ~2 arcsec/px over a 3.0 x 2.0 deg field of view.  Only processing was to apply a flat frame and do a linear Levels stretch in Photoshop on the linear, debayered raw output from Digital Photo Pro.  0 Sharpening, 0 noise reduction, etc.  Exposure was 300 seconds, autoguided.

 

The lower left and upper right corners show stars that aren't perfectly round, and I suspect my camera sensor wasn't perfectly orthogonal since the upper left and lower right corners look great.  You can also see a little green/purple fringing around the brightest corner stars, which is characteristic of lateral chromatic aberration similar to what you'd see in a wide angle camera lens (although not bad at all and easily processed out).  Note that in a few cases, what appears to be a non-round star is actually two unresolved stars right next to each other, but I'm sure you figured that out already.

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[mfarrell]

And here's a flat frame from the TMB130SS + Large Riccardi run through CCD Inspector.  It's about 22-24% vignetting at the long edge (36 mm circle) and I would estimate about 30% in the far corners.  It's hard to tell for sure since I think I'm getting some mechanical vignetting from the 48mm T-ring I'm using and the steep light cone, as well as from the DSLR itself (the mirror's shadow shows up along the bottom).  In any case, really good for a 0.75x reducer on a 36x24 mm sensor!  I would imagine that your 54mm thread interface would avoid some of the DSLR vignetting issues, assuming your filters are appropriate diameter, etc.

 

Edited by mfarrell, 03 March 2015 - 12:47 AM.

[mfarrell]

Again, here's the TMB 130 SS + Large Riccardi on 5D MkII.  Single frame run through CCD Inspector.  Min FWHM: 5.1", Max 6.1".  You can see how one corner has higher FWHM, suggesting that the sensor or flattener was tilted slightly.

 

That reminds me...It's a good idea to purchase the tip-tilt adjuster that APM sells so that you can adjust out any tilt in the imaging train.

 

[mfarrell]

For comparison, here's the same analysis for the TMB130SS with the William Optics 68mm FLT flattener (no reduction).  Stars are nearly perfect across the entire frame, although again I can see what appears to be tilt in my camera since one corner has higher FWHM than the others.

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[mfarrell]

Matthew,

Can you give me a breakdown of what other parts/adapters would be needed?  I know you're using a DSLR and I'm using a CCD, but it should be close since my camera is set up in such a way that I already have 51.5mm of back focus taken up by the camera and filter wheel, and where your're using a T-ring, I'll need an adapter that can connect to the M54 thread on my filter wheel.  

 

Hi Phil, for the Riccardi reducer you would need a FT35 endcap -> M82 thread adapter.  Then optionally add a tip-tilt plate that has M82 threads on both sides.  Then the Riccardi itself.  Then you need to adapt the Riccardi's M82 thread to your M54 thread and take up the remainder of the backfocus.  Markus could machine one for you or there is also Precise Parts.  Basically it would be a single part 74 or 75mm - 51.5mm, or ~23mm long with M82 thread on one side, and M54 on the other.

[aorion314]

aorion314 here, it is this simple, I would divorce my wife before I would sell my TMB 130SS, respectfully submitted.

Edited by aorion314, 07 March 2015 - 12:29 PM.

[John Anthony]

aorion314 here, it is this simple, I would divorce my wife before I would sell my TMB 130SS, respectfully submitted.

If I had a TMB 130SS and I sold it I would want my wife to divorce me, it would be proof I lost my mind. :-)

[stevew]

Sell a TMB 130SS for a........ Ok while I can't really give any expertise advice that can help you with your question I can say this, selling a TMB 130SS is just wrong, I really mean wrong.

I hope this helps, I really do. :-).

Agreed!

I have number 0006...

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[olivdeso]

I would sell the TMB only to grab either a TAK TOA130 with 4" focuser, or AP140 with 4" focuser.

 

But I would never sell it to buy a NP101is. The NP101is will also require a flatener for the 11K sensor. Same for the NP127is. The NP127is is a great imaging scope, with super wide field and aperture. This could also be my choice for imaging, but only after having seen a test picture which demonstrates sharp stars at each corner, which is not always the case on these refractor. The collimation mecanism is not so reliable not easy to tune by the end user. 

 

I would prefer the FSQ106 over the NP101is for both its better mechanical side, and its much wider corrected field, which does not require any corrector. on top of that, the much larger FSQ focuser allows the use of a large reducerwhichh covers the 11K sensor at F3.6. The FSQ106 is a great tool for wide field imaging, perfect if you like narrow band imaging neabulae. For galaxies, globulars, planetaries and other smaller objects, the 130 is more apropriate and will do a better job.

 

The new Vixen 100mm F3.8 seems also very interessting for large sensor and wide field, even wider than the FSQ for a 24x36 sensor : narrower corrected field than the tak, but still much larger than the 11K sensor, and shorter focal length and faster focal ratio. There are already some nice picture avalaible on the net. Not cheap either, but native F3.8 and even faster with the dedicater reducter at F3.0, faster than the FSQ.

 

Now, if the use is not 100% imaging, the 130mm aperture is the sweet spot to me : still lightweight, not requiring a large mount, already very good in planetary viewing and even decent in planetary imaging. For visual use, aperture rules. Also a 130F7 will have less longitudinal chromatism than the FSQ. For deep sky imaging, the moderate focal length gives access to many different objects : neabulae using the reducer (the marginal corners chromatism will even desapear will doing narrow band) 

 

The x2 powermate can also be used with great succes on planetary nebulae

 

So all in all, a 130 F6 to F7 very good all around telescope, for both imaging and visual use.

 

These TMB1300SS and its small cousin the Astrotech 106 are awesome imagers. The AT106 only laks of a FT focuser, but the optics is just perfect, much better than many far east competitors (no spikes nor blue halo, which is not so common except at Astrophysics and some of the Tak). put a 2" astrotech FF on it and you have a perfect imager for medium sized sensors, like the TSA102, with similar picture quality, but 1,5x faster.

Edited by olivdeso, 07 March 2015 - 11:27 PM.