127mm APO First light

[h0ughy (David)]

Originally Posted by Stephen65

Colour may be caused by the eyepiece, many eyepieces show green/yellow on the Moon's rim when the rim is placed towards the edge of the FOV. The purple halo on Jupiter is a bit harder to explain though.

The best way to test for colour correction is to find a bright star and focus in and out and see how much colour there is in the in and out of focus images.

because I didn't use the EPs that came with the scope I borrowed Alan's series 4000 26mm Eyepiece - I do suggest that it was the EP to a large extent. I deliberately took jupiter at 30seconds just so as to see any colour in the spikes and how it handles bright objects. I am happy with it and consider this the bargain of the century I rate the scope 10/10 for value

[h0ughy (David)]

Originally Posted by JohnH

Here are a few images from my first attempt with this new scope last night. The nearly full moon really did not help with the swan shot but I did not want to use filters as the idea was to see how the scope perfomed - in particular wrt SA and CA. I imaged with the Canon 20D (unmodded) at prime focus.

Before I imaged I had a look at the moon, Jupiter and Omega C with the supplied eyepieces (20mm and 10mm). The views were stunning (to me at least - I have never looked through a big refractor before). I found the focus crisp visually and the action smooth (I did have to take a little tension off). The cloud belts on Jupiter were very evident at 20mm with 4 moons nicely frames, with more cloud detail showing at 10mm. I did not notice any false colour.

Then to the moon - very, very bright! I did notice a thin blue edge to the bright edge of the moon but it did not interfere with a tour of the terminator with really sharp views. I noticed the the colour fringe was more pronounced if the focus was off and varies in colout to green if my eyeline was off centre to the eyepiece. Once these issues were addressed I found that there was no noticeable false colour. Omega C resolved nicely in the 20mm ep with many pinpoint stars, I did not try my Vixen eps out to see if they gave better results as I was anxious to start imaging.

I connected the 20d and shot the moon at iso 400 and 1/1600s and then Antares and the Swan at iso 1600 and 180s. No flats were used but ICNR was on, I have only adjusted levels in PS.

I seems the scope is performing well but would benefit from a flattener - the outer 15% or so of the frame has some SA - I think the WO 0.8x mkIII flattener would be a good match?

Bottom line for the $$$ this is a wonderful scope.

you must have shot the moon a little later than me, but all I can say is we have the bargain of the century. best of luck those that follow in our footsteps, and if your gear turns out like what we have you have a winner my eta shot was a single 2 minute shot canon 20D - obviously Modded (care of Eric lo incorporated enterprises patent pending.....). This will be a delight to use with my cooled Canon 350D 'O how I am looking forward to Qld Astrofest

There should be enough shots now for the Plebeians out there to make a decision now

[renormalised (Carl)]

Takes nice shots and it's a nice looking scope...how much was it??

[h0ughy (David)]

Originally Posted by renormalised

Takes nice shots and it's a nice looking scope...how much was it??

mine was $1137US - delivered - so use the AUD-US converter and work out the AUD cost. mine was around the $1240 mark AUD

[Astrod00d]

Mine was relaeased released from Customs on the 21st - just in time to get it sorted for the new moon

I look forward to testing the 127ED with the QHY8. Which DSO should I aim at first??

Cheers,

Rob

[[1ponders] (Paul)]

Will someone puhleeeeaasse lock this thread.

[toyos]

Originally Posted by renormalised

Takes nice shots and it's a nice looking scope...how much was it??

Or you can take mine after a few weeks since I don't intend to spend too much time with those 'triplet semi apo's'

My orders should be shipped MUCH sooner (probably within a week, not 40 days if you know the trick of the trade).

[h0ughy (David)]

Originally Posted by Astrod00d

Mine was relaeased released from Customs on the 21st - just in time to get it sorted for the new moon

I look forward to testing the 127ED with the QHY8. Which DSO should I aim at first??

Cheers,

Rob

the first one you see in clear skies

[h0ughy (David)]

Originally Posted by [1ponders]

Will someone puhleeeeaasse lock this thread.

[Astrolabe]

Originally Posted by Astrod00d

Mine was relaeased released from Customs on the 21st - just in time to get it sorted for the new moon

I look forward to testing the 127ED with the QHY8. Which DSO should I aim at first??

Cheers,

Rob

Hi Rob and congratulations to you and to all other owners of this new refractor.

I would like to look through it next time I see you at Linden. Most likely I will go up on Tuesday subject to weather conditions. I will give you a ring on Tueday afternoon in any case. I hope that the images you get with this refractor are as good if not better than the previous ones.

Best regards

George.

[JohnH]

More Test Images - Rigel Kentarus region. These are 4 full size crops from the corners of a shot taken with the 20D. I have only adjusted the levels to minimise the noise, I think some of the distortion I was seeing earlier might have been due to poor focus - the corners look pretty good to me ...of course the clouds are back now to ruin my fun!

[miki63au]

Hello everyone,

I find the original prototype test:
http://www.astro-foren.de/showthread.php?t=9585

I not understand German (and have trouble with Eanglish...)
but, what I understand is the triplet is ok on Red, but just 1/3 wave
on the green, where the eye is most sensitive.
Now this is a triplet, and I can't see any small shim to separate the elements to a proper gap in a air spaced design. Which mean, I guess
is the gap is made with plastic rings. So my theory is, the manufacturer
not spending the money, time to fine tune each assembly for best spherical
aberration at green. It's about luck what you get. I had a 5" achro before,
and play with it a lot, try to get the best correction with different gaps.
Well, unfortunately one of the surface had a zone, at 70% dia. Actually it was a different radius from there. It was impossible to optimize.
With the triplet it would be daunting task without proper gear to get the
right settings between the elements.
But after all it's still a good deal, especially for wide field photo.

[seeker372011 (Narayan)]

Originally Posted by miki63au

Hello everyone,

I find the original prototype test:
http://www.astro-foren.de/showthread.php?t=9585

I not understand German (and have trouble with Eanglish...)
but, what I understand is the triplet is ok on Red, but just 1/3 wave
on the green, where the eye is most sensitive.
.

There is a thread on this subject in Cloudy Nights-started by me, I'll admit -which has become quite heated but this specific issue is addressed. It is in fact suggested that the null point was delibrately set to colour correct better in red.

http://www.cloudynights.com/ubbthrea...l/fpart/1/vc/1

[JohnH]

Thanks seeker - your views are coincident with my results! This scope performs well if it is correctly focused. It really does seem critical - just inside focus mine will yield blue halos.

I noted your comments about an FR - you are suing the TV unit yes? I was thinking the WO MkIII would also be suitable (I think it is a lot cheaper!) but now I am not sure - it is 0.8 but a flattener as well, ant thoughts. Have you figured out the thread on the draw tube - none of my adapters fir and I prefer to have my camera screw mounted than use the push in?

I already own a Vixen 0.63 FR for my VC200L - that is a pure FR - do you think it would be useable? I guess I could just try it - if I could figure out how to mount it...

[Astrod00d]

The 127ED was delivered this morning, all parts are included and appear to be in good condition.
The carry handle on top of the rings is cast metal and has a lengthwise slot so I can mount a guide scope directly with little or no flexure.

First light on Tuesday if the sky is clear.

Cheers,

Rob

[Terry B]

I finally got a "proper" first light last night rather than daytime images.
I took 7 x 5 min exposures of the trifid and of eta carina.
They were taken using an unmodded 40D quided with my QHY guider and guidemaster. Flats, darks etc and processed in Iris. No deconvolution filters have been used just stacking and a asinh stretch.
So the outcome.
Visually the scope is wonderful. I can't see any false colour with a 10mm eyepiece. Through the camera it isn't quite the same. There is certainly a small voilet halo around the bluer stars.
I will try to deconvolve the blue channel to see if it is removeable.
The field is not quite flat.There is a small amount of smearing on the ouside of the frame but it isn't visible at the magnification of these images.
There is very little vignetting. I have posted a flat frame to demonstrate this.
How does it compare to my VC200L.
The psf of the stars is about the same but the VC200L has no halo. It does however have difraction spikes. Is this good or bad? I quite like them.
A similar eta taken with the VC200L is here.
The field of the 127mmAPO is much wider and the contrast visually is higher. I'm not sure if this extra contrast makes up for the lesser aperture. However there is no way I could ever afford a 200mm refractor so probably the comparison is unfair.
The only other scope I have to compare it to is my 120mm achromat guidescope. It has lots of false colour and is not a patch on the new scope.
I am very happy with the scope but it isn't perfect. It seems to be worth the money.

[Stephen65]

Some people like diffraction spikes, even to the extent of adding them using software if the scope doesn't have a spider, some people don't. I like them but I wouldn't bother adding them.

Very nice images with just a touch of violet halo.

[JohnH]

Nearly full moon messed this up rather but it is still only a test shot - 16*3 mins at iso 800 ICNR.

Terry, I find the blue halos are present if you are a little inside focus try racking out a 1/8 turn or so, should not mess up the FWHM. I have a VC200 as well and the APO is sharper and the colour correction as good (subject to focus being spot on) the there is a little SA in the corners - but a decent FR/Flattener should remove that. The contrast is better on Jupiter.

I had a second 10:1 focus knob set in my box, did everyone get this?

[Terry B]

Originally Posted by JohnH

Nearly full moon messed this up rather but it is still only a test shot - 16*3 mins at iso 800 ICNR.

Terry, I find the blue halos are present if you are a little inside focus try racking out a 1/8 turn or so, should not mess up the FWHM. I have a VC200 as well and the APO is sharper and the colour correction as good (subject to focus being spot on) the there is a little SA in the corners - but a decent FR/Flattener should remove that. The contrast is better on Jupiter.

I had a second 10:1 focus knob set in my box, did everyone get this?

Yes I have the same focuser. I must admit I found focusing difficult. I'm use to using the diffraction spikes as my focus aid. I will have to make a little wire cross to sit on the front of the scope instead.
My shots were taken before the moon rose last night so the sky was dark.

[h0ughy (David)]

Originally Posted by JohnH

................................... ......................

I had a second 10:1 focus knob set in my box, did everyone get this?

no