Full Moon with Explore Scientific AR127

Scope: Explore Scientific AR127 refractor
Camera: Canon T3i unmodded
10 subs - 1/800 sec each at 100 iso
Stacked with Lynkeos
Cropped to Moon
Post-processed with Preview in Mac OS

Here is the full fame, single shot for comparison (before cropping)

DIY Repurpose Your Finder Scope into a Guide Scope Conversion

The final modified "finder scope now a guide scope"

Original Finder scope  50mm

How to DIY Finder Scope to Guide Scope Conversion for an Explore Scientific 50mm Guidescope

I wanted to make a guide scope out of the standard (and basically useless) Explore Scientific 50mm white guide scope that comes with most of their telescope (at least the 127mm model I got).
Useless because the crosshairs are invisible unless you are pointing it at the Moon or something equally bright.

But if you are doing astrophotography you need a guide scope not a finder scope.
Sure you can buy one but wouldn't it be great if you could re-purpose the standard guide scope?

Please read ALL the instructions below BEFORE attempting this easy conversion!

* Unscrew the eyepiece end of the finderscope

The interior diameter of the white tube is just a couple of mm wider than a standard 2" to 1.25" eyepiece adapter.

NOTE: The eyepiece adapter MUST have a very low "stop" when you put it into the white tube. The best one I found in my astro scrap pile (yes, never throw anything away, you never know when you will need it!) has only about a 2 mm "stop" that keep the adapter from going all the way into the white tube.

My junk box adapter has the eyepiece screw below the "stop". Most do not, however.
Most 2" to 1.25" eyepiece adapters have a THICK "stop" and that complicates matters because you will have to CUT the white tube down by the thickness your "stop" is in order to have any chance at reaching focus on your guide camera. So if your adapter is 10mm thick then you will have to chop off 10mm with a metal saw, keeping it as true to "level" as possible. Of course you may have to insert some kind of wooden dowel that is 2" in diameter into the white tube to keep it from warping in the process of cutting. I suggest that you test it first by taping it all together and testing it with your guide camera before cutting.

In my case I had to drill a hole (or may be two if your eyepiece adapter requires it) at the proper distance from the end of the white tube, a hole big enough for the screw(s) to hole an eyepiece or a guide camera in place.
However if your adapter is a thick one, the holding screw will not be necessary.

You will find that with just three layers of black electricians tape around the eyepiece adapter will make it fit snugly in. If after testing you decide you are "never going back to a finder scope" you might want to epoxy it in place permanently. Your choice...

Temporarily, especially for testing, I only held the whole eyepiece assembly in place with electrician's tape.

Now for the focusing test. I inserted an Astromania SGCMOS Series Telescope CMOS Camera (a ZWO ASI120MM Mini Monochrome Astronomy Camera will do just fine, too. Google this model.)

Hooking the camera up to my computer I had to vary the amount that I inserted the camera barrel into the eyepiece adapter so I could reach basic focus. Then I made the final sharp focus by twisting the objective lens at the other end of the finder scope then locking it in place with the smaller black ring.

Because I didn't have to cut the white tube (just drill a small hole) I was able to keep the original threads inside white tube and screw in the original eyepiece end. But I will likely never need to.

And just like that, you have repurposed your finder scope into a guide scope!

Shooting the Moon

 Copernicus (cropped)

 Copernicus region

 Plato (cropped)

 Plato region

 Tycho and Clavius (cropped)

Tycho and Clavius region

Scope: Meade LX200GPS 8"

Camera: PointGrey Grasshopper 5 megapixel gray-scale camera

Processed in AutoStakkert

Best 15% frames

Air fairly unstable

Two Galaxies: M 81 & M 82 - My Best Effort So Far

(click on the image for a larger view)

Last night's capture of M 81 & M 82

Scope: Daystar 480mm Doublet f/6

Camera: Canon T3i unmodded

Filter: Grosky Light Pollution Filter 2"

240 sec subs x 10 = 40 minutes stacked DSS

ISO 6400

Post processed with Luminar 2018

First Real Test of Guan Sheng Optical's RC 6" astrograph

M 1 - The Crab Nebula

First attempt but the collimation of the scope is off.

The image is not as sharp and detailed as it can be.

Got to work on that soon...

NGC 2239 The Rosette Nebula

Data: GS RC 6" telescope Canon T3i unmodded camera ISO 6400 360sec subs 8 to 10 subs Stacked in Sequator Post-processed in Luminar

Unexpected clear sky... at least for two hours!

Bode's Galaxy (M 81) near the Big Dipper (Ursa Major).

Got a surprise clear night!

DATA:
Celestron C6 with Meade .6 focal reducer
Celestron AVX mount
Canon T3i unmodded camera
28 minutes total exposure time
ISO 1600
10 subs, flats, darks, bias frames
Stacked with DSS
Post processed with GIMP and Luminar 2018
Cropped

RawTherapee app Conquers Chromatic Aberration!

While I have written before about this noisome issue of purple fringing on stars I have found that the RawTherapee (google it) app does a fantastic job of minimizing this chromatic aberration.

After few clear nights in a row here, I imaged the Rosette Nebula with a 200mm f/5.6 old Pentax telephoto on a Canon T3i unmodded.

The chromatic aberration as terrible... purple fringing on the edges of the brighter stars! Yuck! 

But RawTherapee photo program to the rescue! It has a function that can reduce/eliminate the objectionable color and rescue an otherwise useless image! You can see the difference is quite apparent! Then I was able to increase the color saturation without increasing the purple around most of the stars!