Archive for the ASTRO Category

A refractor is born

Posted in ASTRO on October 22, 2017 by maxpho

Sometime in September I’ve decided that an upgrade for solar imaging is a must.

The goal of such an upgrade would be to have a very portable yet powerful scope that can be easy to set up and without many of the problems encountered with other instruments I have. I’ve concluded that a diameter of 150mm is the minimum, and that the instrument will be a refractor due to lack of the collimation procedure required with a Newtonian for example. Other optical systems were considered but my budget aimed at a homemade instrument. That, again, pointed at an achromatic lens.

The main purpose of the instrument would be H-alpha solar work, but with the ability to do some white-light solar imaging also, and the occasional ISS transit. The Moon would also be fun for such an instrument, and perhaps some deep-sky views at the eyepiece.

I’ve decided that I should go with the iStar company (US based) and their 150mm F/5 achromatic lens. Unfortunately this lens was not on stock, so I’ve reconsidered and selected an improved version, an anastigmatic R50 slim lens. I was hoping that by the time the lens would get to Romania the instrument’s frame would be completed.

So…I had one month to put on paper, select materials, build components and assemble the “thing”.

September 22: The design was more or less selected. Initially I’ve built the lens and focuser flanges by hand, using an aluminum plate and sawing by hand the desired shape.


I was not happy with this setup, so I’ve decided to get some proper flanges built using Laser-cutting techniques. The process took quite a while, so at the end of September I was still lacking the main parts of the frame.

October 5: The new flanges arrived. Using some new components built the days before, I’ve assembled for the first time the frame of the instrument. The focuser system was also modified, with the electric motor now connected to the focuser by a pair of  toothed wheels.


A few more components had to be built by hand, and aligning/realigning the frame took some time.

October 15: One of the most delicate procedure of the entire project was to spray-paint the components. The job was done after 7-8 days of painting/drying/painting/correcting/painting/drying procedures:


Finally, the components were now ready to be permanently assembled.

October 17-18 (the night between): Like some furniture from IKEA or a LEGO set, the components of the soon-to-be optical instrument were “carefully placed” on the carpet:


And they were not left alone until the final shape of the refractor was formed:


Verifying the alignment showed me that the frame was stable and could now receive the main component: the lens.

October 20: The lens was in my hands. I must thank my friend Alin Tolea for the many talks and help with acquiring the lens from the US 😉

Now I was finally touching the “untouched” lens. No dust, nu scratches, no signs of ever being in contact with the air. The first and last time a lens would look like this…


Thanks to my friend Vlad Dudu for this shot.

Of course I’ve rushed back at work, drilled a few more holes, and went home only to start the final and most rewarding procedure: “put a lens on it”.


Now, this strange-looking piece of aluminum, was finally looking almost like an optical instrument. The Lunt 50mm ERF filter was also housed into a homemade cell, and mounted on the focuser; one more component finished.

Next phase: tests. Under the stars at first, to have a proper collimation and some first views of the sky.

The same evening I had the refractor ready, I drove to my usual observing site and had a go at the eyepiece of the new instrument. With a 32mm eyepiece the views of Dumbell Nebula and M 15 globular cluster were very nice, despite the very poor transparency due to cirrus clouds and some light pollution. I did not have much time to do the adjustments, but I did however acquire some frames of M 15 using the ASI 1600MM camera at the focal plane with no filters. This was before I had the lens collimated, so some defects are easily visible on the 50% resized image. Only 50% of the frame was selected due to the uneven star shapes (very normal for such a lens). Using no filters showed that the chromatic aberration is present, but at rather low levels compared to other achromats I’ve used (SkyWacther 150mmF/8, 100mm f/5, 90mm f/8). Of course no match for the Teleskop Service APO 115mm F/7, but again, deep-sky imaging was not the purpose of this lens, at least not in full-spectrum. Some H-alpha might be a possibility as soon as I find a suitable field-flattener. So, the M 15 shot (40 frames, each a 10 sec exposure, no binning, no calibration, just some mild Photoshop):


Pretty nice for a 6 minute-equivalent shot under poor conditions. This scope proves to be a very fast one.

Of course I had to wait a little longer for the true test…

October 21-22: Some H-alpha work was finally in sight. On Oct 21 the seeing was very poor, and the results were not confirming my expectations for the instrument…I was a bit disappointed actually. But on Oct 22 the conditions were not so bad, with some cirrus clouds and 4-5/10 seeing. The Sun had an altitude of only 30-35 degrees, which did not help much…

Still, the “first H-alpha light”looks promising:


Also, this was the first time I could actually see (on Oct 20 I was observing at night) the refractor onto the EQ6 mount. They look happy together 🙂


I still have to build a dew shield, a shroud and some lens caps, but the shape of the refractor will not change.

At the end, I can say that this 1-month project was very rewarding, as I could build the frame in time to receive the lens, and also test the instrument just before the arrival of  a bad weather front.

This time the well-known phenomenon “I’ve got a new telescope, so it will rain for days” did not occur 😉


 UPDATE (October 23):

I’ve managed to save a few more H-alpha shots from the first-light tests on October 21-22. All were acquired in poor seeing conditions…


ar2685 oct 21.jpg


2685 wlOct21.jpg

ar2685 oct 22 b.jpg


Lunar images – October 10, 2017

Posted in ASTRO on October 21, 2017 by maxpho

A few lunar shots from October 10 acquired under good seeing conditions with occasionally very good moments. For some of these shots the jetstream was a problem, but luckily only for about a quarter of the session. This session was around 4 hours long…with breaks due to poor seeing and a few clouds.

Equipment: 355mm F/5 Newton, ASI 174MM, Baader red filter.








Three craters in three days – October 10-13, 2017

Posted in ASTRO on October 17, 2017 by maxpho

On October 10, 11 and 13 this year I had the luck of some good to very seeing conditions while imaging the Moon. Following are three sets of images for three well-known lunar craters: Plato, Clavius and Tycho. On October 12 the clouds did not allow any lunar images. Equipment: 355mm F/5 Newtonian, ASI174MM, Red filter.




High resolution lunar images – October 13, 2017

Posted in ASTRO on October 13, 2017 by maxpho

A very frustrating lunar session this morning, with mostly fair seeing and the occasional very good to excellent moments. The problem was that the seeing was very good or above only when the wind was blowing from a certain direction, which also had a negative effect: dew…So each 1000-2000 frames I had to clean the secondary mirror, which slowed the image acquisition process quite a lot.

Nevertheless, a few nice results emerged. Some of which are my best shots of the imaged regions.

Equipment: 355mm F/5 homemade Newtonian, 2.5x and 3x Barlow lenses, ASI 174MM, Red filter. Seeing: 6-8/10.

Copernicus (my best image yet of this magnificent crater):


Rupes Recta and Rima Birt (again, my best shot of this region):


The image above shows the region under almost the same illumination as an older image of mine (from 2013, acquired with the C11 SCT), which at the time was also an LPOD.

Plato under a very nice illumination:


One of my favorite craters: Pythagoras.


Craters Pitatus with its complex floor rilles, nearby Hesiodus with two volcanic calderas, and the concentric crater Hesiodus A.


Tycho under low illumination.


Also, a highly enhanced view of the same image, showing the inner terraces of Tycho, visible by the reflecting sunlight coming from the opposite walls of the crater. I had had to sacrifice the normally exposed lunar surface in order to see “inside Tycho”.


Lunar images – October 11, 2017

Posted in ASTRO on October 11, 2017 by maxpho

“I choose to image the Moon, not because it is easy, but because it is hard…”

This was my motivating phrase for today’s lunar session. At only 2 degrees Celsius and  lots of fog, the imaging conditions were very good, but for a human that is also not used to get up very early in the morning (at 3 a.m. in this case), they were not so…comfortable.

The phrase in the introduction was, of course, modified from John F. Kennedy’s speech before the start of the Apollo Program. His original phrase is one of the most memorable ones for any lunar enthusiast: We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard (September, 1962).




One imaging project that was on my “to do list” for some time: crater Plato in RGB colors. The following image was combined from the October 11 Luminance image (acquired in very good seeing conditions) and the October 10 RGB data. This was rather difficult to do since from day to day the libration changes the aspect of craters quite a bit, especially towards the lunar limb. Nevertheless some good color data was extracted, in high resolution also. There are a few large purple areas on the floor of Plato that are in contrast with the surrounding regions.


Also, a rectified view of Plato, as it could be seen from directly above the crater:

Plato rectified view.jpg

One large mosaic showing the Alpes Mountains, crater Cassini (lower left), and the very photogenic couple Aristoteles (up) and Eudoxus (center-right). This region is filled with high contrast features when the illumination is right. The shadows and complexity of the Alpes offer a striking view of the lunar surface at the eyepiece in any size scope.


One image showing Ina volcano. This is my best view of this interesting feature yet.


Plato with many small craters on its floor and the Alpine Valley with its narrow rille:


One more mosaic showing Cassini and the trio of craters Archimedes, Aristillus and Autolycus:

From Archimedes to Cassini.jpg

Craters Walther and Deslandres under very good seeing conditions. Some dew on the secondary mirror interfered with the acquisition, but in the end the result is worth posting.


Crater Copernicus under a rather high illumination. Under this light the shadows are not quite yet dark, so details on the inner walls are still visible.


Triesnecker and Hyginus Rille.


Manilius area in above average conditions (seeing 7/10):


AR 2682 and 2683 – October 2, 2017

Posted in ASTRO on October 2, 2017 by maxpho

Some H-alpha shots from a quick session under rather good seeing conditions (considering the low altitude of the Sun). With the 115mm refractor, Quark filter and ASI 174MM camera.

First, a wide view of the sunspot groups (2682 to the right):


An inverted view of AR 2682:


And a large but somewhat faint prominence:


AR 2673 is back – September 24, 2017

Posted in ASTRO on September 24, 2017 by maxpho

After two weeks AR 2673 is still going strong. Despite the poor seeing a lot of interesting activity was observable around the re-emerging spot today.

Equipment: TS 115mm APO, Quark filter, ASI 174MM.

ar2673 is back.jpg