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JeremyS

First light with Takahashi FC76 DCU

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Had a chance to try the new Takahashi FC76 DCU on Jupiter last night for a couple of hours. I followed the GRS transit for quite a while. Seeing was very good tho not excellent, for the large part.
I’m used to using the Tak FS102 on Jupiter this apparition, but I was pleasantly surprised with the 76’s performance. There was plenty of detail to see in the cloud belts and the GRS was distinct and nicely coloured (but not quite as deep a red as I’ve seen it in the FS 102 – aperture wins!) lately.

I found best results with the Televue NZ eyepiece at 6 mm (95 x) – zooming higher didn’t bring out more detail. Looking forward to testing under even steadier conditions. The Fujiyama HD Ortho 6 gave a similar view, but with less eye relief. The Fujiyama HD Ortho 4 and 5 didn’t bring any additional benefit nor the Pentax XL5.2.

Needless to say, the low power views in Cygnus were stunning. This is my travel scope, so I’m Looking forward to taking this beauty to more southerly climes. As I’ll need to minimise ancillary equipment, it sounds like I might get away with the NZ and a widefield eyepiece in the 20 to 26 mm range. So far I’m really happy!
 

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Jeremy, Now I know why it is cloudy in 'Swindon, your 'Box of Clouds' escaped and went south!  I also looked at Jupiter last night, shining bright in the southern sky even made out alpha Libya (a constellation I have never really looked at?).  Happy viewing.

 

Peter

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It is a great scope.  Mine has traveled south of equator and provided some memorable DSO views under dark skies.  And so easy to transport as well.

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Posted (edited)

What a coincidence. I received also received my FC-76D objective module a few days ago. Which eyepieces and filters do you use for deep-sky?

 

P1130978_cut.thumb.JPG.36e31fe68d3b48915d737d4582103d92.JPG

Edited by marcus_z
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9 hours ago, marcus_z said:

What a coincidence.

Another coincidence is that I was in Euston Station yesterday and picked this month's Astronomy Now mag only to find a pic of the FC76 DCU in the front cover and a fine review by Matthew @DirkSteele inside. I was especially interested to read about his impression of the GRS through the scope, which is exactly as I had found a couple of days ago.

Are you planning to fit a finderscope, @marcus_z?

 

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12 minutes ago, JeremyS said:

Another coincidence is that I was in Euston Station yesterday and picked this month's Astronomy Now mag only to find a pic of the FC76 DCU in the front cover and a fine review by Matthew @DirkSteele inside. I was especially interested to read about his impression of the GRS through the scope, which is exactly as I had found a couple of days ago.

 

 

Thanks! Did not know it was going to be on the cover so was quite a surprise when it arrived on my doormat.

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58 minutes ago, JeremyS said:

Are you planning to fit a finderscope, @marcus_z?

No, I don't think I need one. For planets I just use the tube as orientation. For deep sky I might just use the lowest magnification eyepiece as a finder. A Panoptic 41 gives a 4.6 degree TFOV and 14x Magnification. That is almost like a finder, but with much better aberration control and eye relief. But I'm not 100% sure about the low mag eyepieces which I should use for travel...

 

I'm thinking about a Masuyama 45mm, which gives a 6mm pupil and should work good with filters. Maybe a 16mm Nagler for open clusters, but then I don't know which eyepiece to take between the two...

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16 minutes ago, marcus_z said:

o, I don't think I need one. For planets I just use the tube as orientation. For deep sky I might just use the lowest magnification eyepiece as a finder.

I also just sighted along the tube to find Jupiter, but I think it might be harder to find faint deep sky objects, so I've put a Tak 6 x 30 finder on the OTA. However, when I travel I might not take the finder as I'm keen to minimise accessories.

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On 13/06/2018 at 16:55, marcus_z said:

What a coincidence. I received also received my FC-76D objective module a few days ago. Which eyepieces and filters do you use for deep-sky?

 

P1130978_cut.thumb.JPG.36e31fe68d3b48915d737d4582103d92.JPG

That is absolutely beautiful. I love that scope set up. 

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Great report Jeremy. :) 

I've always used a 24 Pan as wide field eyepiece with my TV60, although I'm considering a Plossl 32mm as addition or replacement. You could also consider the new 24mm APM ultra flat field.  

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Posted (edited)

Last night the seeing was rather good, but again not perfect, the GRS was on show, so I thought I do some tests with the Tak FC76 and the Tak Extender Q 1.6 x

In its native format (f/7.5), the GRS was clear and pink and fine detail could be seen on various belts with the NZ at 6 mm (x95). Zooming to 5 mm (x114) and 4 mm (x142) didn’t bring out more detail and is was much more pleasant to view at 6 mm. I did have fine views with the Pentax XL 5.2 (x 110) and it was slightly more comfortable to observe with. But it’s a much bigger eyepiece, so for travelling the NZ is definitely the one to take.

I then put the Extender Q in place (f/12). I started with the NZ at 6 mm (x 152) but the mag was too high. I moved to a Pentax XL 10.5 (x86), which gave fine views, as did the XL 7 (x 130), but probably a bit too much mag. I would probably need something in between.
There is one main advantage with the Extender Q: viewing is much more comfortable especially over a longer period of time when waiting for those moments of really good seeing, presumably due to being able to use of longer FL eyepieces. 

So using the Extender Q has advantages, but for travel it’s yet another accessory to carry. But it will be interesting to see how it performs with Mars.
 

Edited by JeremyS
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This morning two further components of my travel kit arrived: a Neewer carbon fibre tripod and a TS-Optics Altazimuth Travel Mount.

I went for the Neewer because it is so light and low cost. It will be interesting to see how in performs in reality. The TS head is a lovely piece of kit.

IMG_9349.JPG

IMG_9347.JPG

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4 minutes ago, JeremyS said:

This morning two further components of my travel kit arrived: a Neewer carbon fibre tripod and a TS-Optics Altazimuth Travel Mount.

I went for the Neewer because it is so light and low cost. It will be interesting to see how in performs in reality. The TS head is a lovely piece of kit.

I agree about the TS head. It's a nice and light mount. :)

Great equipment BTW. I thought about the Neewer carbon fiber tripod for a while, but eventually got the Manfrotto, as you know. Looking forward to reading your thoughts about it. 

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5 minutes ago, Piero said:

Great equipment BTW. I thought about the Neewer carbon fiber tripod for a while, but eventually got the Manfrotto, as you know. Looking forward to reading your thoughts about it. 

I already have a metal Manfrotto, Piero. It's been around the world with me. But with tightening luggage restrictions on airlines (or perhaps that I have too much non-astro to carry!), I wanted to try the minimalist 

I am not too sure about the colour scheme of the overall I have ended up with. The Tak FC76 has the new Tak baby blue on the OTA, but I currently have the tube ring clamp and the finder in older Tak green (which I actually prefer). I am using the  narrower ring clamp which came from my Tak FS60 as it lighter than the recommended clamp. I do have one of these too: it's wider and quite a bit heavier, which again is not ideal for travel. Then there is deep blue on the tripod and bright red on the TS head. In the dark nobody will notice and accuse me of Tak bling.

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Posted (edited)

When I saw the first photo I thought the blue in the telescope and tripod is a nice match! 

Anyway, as long as it works well, colours are secondary.  :) 

Edited by Piero
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On 14/06/2018 at 10:24, marcus_z said:

No, I don't think I need one. For planets I just use the tube as orientation. For deep sky I might just use the lowest magnification eyepiece as a finder. A Panoptic 41 gives a 4.6 degree TFOV and 14x Magnification. That is almost like a finder, but with much better aberration control and eye relief. But I'm not 100% sure about the low mag eyepieces which I should use for travel...

 

I'm thinking about a Masuyama 45mm, which gives a 6mm pupil and should work good with filters. Maybe a 16mm Nagler for open clusters, but then I don't know which eyepiece to take between the two...

If you want a smaller lighter 40 for travel I recommend the Vixen LVW 42mm, some of whuch FLO have in stock.

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1 hour ago, JeremyS said:

This morning two further components of my travel kit arrived: a Neewer carbon fibre tripod and a TS-Optics Altazimuth Travel Mount.

I went for the Neewer because it is so light and low cost. It will be interesting to see how in performs in reality. The TS head is a lovely piece of kit.

IMG_9349.JPG

IMG_9347.JPG

Lovely looking stuff !

I'm on the lookout for a really light but sturdy tripod for my travel scope so I will be interested to see how the Newer does for you. What model is it by the way ?

 

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On 14/06/2018 at 10:24, marcus_z said:

No, I don't think I need one. For planets I just use the tube as orientation. For deep sky I might just use the lowest magnification eyepiece as a finder. A Panoptic 41 gives a 4.6 degree TFOV and 14x Magnification. That is almost like a finder, but with much better aberration control and eye relief. But I'm not 100% sure about the low mag eyepieces which I should use for travel...

 

I'm thinking about a Masuyama 45mm, which gives a 6mm pupil and should work good with filters. Maybe a 16mm Nagler for open clusters, but then I don't know which eyepiece to take between the two...

You might find a finder useful when going for the fainter planets and binary stars. I know that I do despite having some very wide angle eyepieces. I use a 6x30 RACI on my refractors and it's very useful.

On the subject of 40mm eyepieces in the 2 inch fitting, the Skywatcher Aero ED 40mm is a good combination of good performance and relatively lightweight for a 2" eyepiece. Same optics as the now out of production TMB Paragons. There are other clones out there under other brands too.

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1 hour ago, John said:

I'm on the lookout for a really light but sturdy tripod for my travel scope so I will be interested to see how the Newer does for you. What model is it by the way ?

Its a "Neewer Carbon Fiber 65 inches", John

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2 hours ago, Piero said:

I've always used a 24 Pan as wide field eyepiece

I have a Pentax XL 21 and an ES Maxvision 68, 24 mm. I have heard good things about the Panoptic 24, though. . 

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2 minutes ago, JeremyS said:

I have a Pentax XL 21 and an ES Maxvision 68, 24 mm. I have heard good things about the Panoptic 24, though. . 

The 24 Pan is a good eyepiece but with a lot of RD. With the TV60, it works well when observing a large open cluster. Due to RD, planetary targets look like ovals at the edge. At 15x this is not really an issue, though - apart from poetic observations of the Moon / Sun coming up from the surrounding trees. 

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Posted (edited)
25 minutes ago, Piero said:

The 24 Pan is a good eyepiece but with a lot of RD.

Do you mean distortion near the edge of field? There is some with the Pentax and the ES too, but it's not too bad. But they are both quite heavy (back to the theme of miminal weight/bulk). I think the Panoptic is lighter. But it's a lot to pay for another eyepiece when I already have two in a similar FL range. 

Edited by JeremyS

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14 minutes ago, JeremyS said:

Do you mean distortion near the edge of filed? There is some with the Pentax and the ES too, but it's not too bad. But they are both quite heavy (back to the theme of miminal weight/bulk). I think the Panoptic is lighter. But it's a lot to pay for another eyepiece when I already have two in a similar FL range. 

Interesting quote from another forum from Don Pensack, who knows a thing or two about eyepieces:

"And no two eyepiece designers seem to have the same idea when it comes to controlling astigmatism, field curvature, rectilinear distortion, angular magnification distortion, etc.
All designs appear to compromise on one or more of the above issues.
And what's acceptable to viewers seems to vary with the individual. I'd gladly accept pincushion distortion for well controlled astigmatism and field curvature. People who scan for comets or who use the eyepieces in spotting scopes abhor rectilinear distortion, yet can tolerate a bit of astigmatism.
Chacun a son goût (Each has his own poison)."

The trouble is, you need to try the various optical types out before you can reach a decision on what your particular preferences are. And that can be an expensive business :rolleyes2:

Personally, having tried the ES, Vixen and others of similar spec, I love the Panoptic 24 in my Tak FC-100DL and other refractors. In the 12" dob, it's the Ethos that get the vote :smiley:

 

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Posted (edited)
5 minutes ago, John said:

The trouble is, you need to try the various optical types out before you can reach a decision on what your particular preferences are. And that can be an expensive business :rolleyes2:

Personally I love the Panoptic 24 in my Tak FC-100DL and other refractors. In the 12" dob, it's the Ethos that get the vote :smiley:

Too true, John. £302 for that experiment! Moreover, the Panoptic 24 doesn't seem to be as widely available as other Pan's and not at huge discount either.

Maybe I should look for a second hand one, although people tend to hold on to them

Edited by JeremyS

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Posted (edited)
50 minutes ago, JeremyS said:

Do you mean distortion near the edge of field? There is some with the Pentax and the ES too, but it's not too bad. But they are both quite heavy (back to the theme of miminal weight/bulk). I think the Panoptic is lighter. But it's a lot to pay for another eyepiece when I already have two in a similar FL range. 

I mean that the 24 Pan shows a lot of rectilinear distortion (RD). TeleVue consciously introduced it in order to control astigmatism and angular magnification distortion (AMD) at the edge within a certain threshold (which I believe is 1%).  

RD does not cause issues when observing a large star field, and one can notice it when spanning along the Milky Way (pincushion distortion) or when large targets (e.g. Moon, Sun) are moved near the edge (they appear like ovals). 

 

Personally, and by some criticised, my preference for eyepieces is: 

- a trade-off between RD and AMD (the two are inversely proportional);

- zero astigmatism. 

The Docter UWA is an example of these kind of eyepieces. There is this long-lived belief that terrestrial eyepieces should minimise RD, whereas astronomical eyepieces should minimise AMD. Essentially, this is what TeleVue has done. To me this is down to one's preference and not something biblical. I prefer to see the moon as a sphere near the edge rather than an oval; whereas others prefer to see the separation between 2 stars to be constant within the field of view. One cannot have both for reasons concerning optical physics, but I just don't see anything wrong with having some AMD in an eyepiece used for astronomical purposes.

Just my 2 pennies.

p.s. hope this does not start an AMD vs RD war, with an army waving TV flags! :D   

Edited by Piero
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