that big prom 7/16 (and a heuge mosaic)

[Kitsunegari]

I happened to see the crazy big prominence today while doping around with some unconventional optical experiments..

 

it was very faint today, but was certainly still massive.

 

 

 

I am attempting to build an a-focal calcium magnifier using many many many extension tubes.  MY first test run  actually worked well , and now I am in the process of calculating the required distance to get a high definition solar limb image out of my basler 1920-155um.   I want something like 5000mm    

 

I built the extension support out of fuel pump mounts.  (unconventional doping)    https://www.ebay.com/itm/Alloy-60mm-Fuel-Pump-Filter-Mounting-Bracket-Clamp-Cradle-Holder-Silver-USA/174332539016

The extensions were imported from china a few years ago. I bought about 100 of them for $1.00 each ,  these  have a 58mm thread on the front and  with a 52mm thread on the back.  They fit perfectly inside the fuel pump mount.!   

https://www.ebay.com/itm/52mm-Metal-Screw-in-Hood-Shade-for-Standard-Lens-with-58mm-Lense-Cap/264635047847

 

I utilized TWO coronado pst cak objectives, for the a-focal relay optics.   The rear of the pst objective has a standard 46mm camera thread, and the front has a standard 52mm camera thread.  Perfect for integrating into optical systems with off the shelf parts.

I retro-reflected the solar image back toward the objective using TWO , 2" diagonal mirrors.     

At the objective, is where my camera is mounted, using a 48mm to 52mm stepping ring,  attached to a standard 2" to 1.25" telescope  eyepiece reducer

 

Why am i doing this?   Because my televue powermate 2.5x , and meade 2x barlow are producing newton rings and its very annoying.

 

These PST objective lens optics have completely eliminated my newton rings!  So that is worth it.   

 

Secondly , i believe if i experiment with filter placement i can squeeze out narrower bandwidth with the crazy long telecentric operation.

 

Again, my final goal is to get something like 5000mm running into my basler 1920-155um camera so I can get a nice high resolution closeup of the spicule layer for everyone!    While i am getting amazing results on the  little imx 287 chip with its 720x480 resolution at 350 frames per-second.   I really want something astoundingly detailed and large.

 

Like this mosaic for instance!    

This mosaic came out of this first experimental run.    (its pretty huge)    I used a different filter here.     I have not attempted many mosaics, but i am happy with this.

 

Edited July 17, 2020 by Kitsunegari

[Kitsunegari]

mosaic pieces zipped up and shared here if anybody wants to show me how to smooth it out so its even.  I used "imerge"

 

 

0014.zip

[Kitsunegari]

and for the curious, some close ups of my pump mounts attached to the extensions,  camera, mirrors and telescope.

This first image shows the Camera , very close to my 127mm objective, with the 2" to 1.25" eyepiece adapter. (52mm to 48mm stepdown camera adapter is attached as well)

 

 

Second photo here is a close up of the "pump mount"  that uses a rubber gasket to retain the 52mm - 58mm extension tubes.   It is mounted to my OTA with the top thread of the scope rings via "aluminum window screen framing"

 

This aluminum framing is very cheap extremely light weight and rigid enough to build a great optical rail mount.  only $5.00 for an 84" section from homedepot.

https://www.homedepot.com/p/Screen-Tight-5-16-in-x-84-in-Aluminum-Screen-Frame-MSCF5167/100069982

 

 

 

Here is the second Coronado pst CaK corrected achromat that I cannibalized from a coronado pst .  It is attached to the 52-58mm extension tubes via 52 to 46mm step down camera ring.     The front of the dewshield already has 52mm threads so its very easy to integrate without custom made parts.

A close up of the aluminum window screen frame, and another pump mount.

 

 

There are three pump mounts total on this extension assembly, and they are very easy to just bolt on to any flat telescope.  It is firmly set in place and does not shake, or sag.  The pump mounts are made of aluminum so they are fairly light weight.

 

Here you can see the first Pst CaK achromat, again attached to a 52mm to 46mm step down ring;  i am using a self centering 2" eyepiece extension barrel here attached to the mirror.  The thumbscrew has been removed from the second mirror so the focuser of the telescope can still operate.  The polished chrome barrel on the base of the 2" eyepiece barrel does not snag on the mirror, so the telescope focuser still functions smoothly.  There is just enough clearance to allow focusing through this adapter while it is attached to all the pump mounts. 

 

The pump mounts are all fixed and do not move,  they hold both objectives securely to the top of the explore scientific telescope.

 

I am using a second 2" nosepiece extension threaded onto one of the 52mm extension here (there is a 52mm to 48mm step down ring to allow a standard nosepiece mounting onto the 52mm extension).  This allows the Coronado CaK objective lens to integrate with the self centering 2" eyepiece barrel directly into the mirror assembly.

Somewhere in here there is also a "reverse thread" adapter .  This is commonly called a "gender changer" in the camera world.

 

All industrial standardized parts are used on this.  All i had to do was drill holes in the aluminum window trim, so i could bolt it to my OTA..

 

 

Edited July 17, 2020 by Kitsunegari

[Kitsunegari]

Here is some vital information that was provided by televue.com. These formulas are essential to make this "a-focal relay" work the way I desire.   There really is no "difference" between eyepiece and objective lens other than the greater focal lengths used.  In the world of optics, a lens is a lens.  As long as you know the focal length, and diameter you can achieve great magnifications by simply "mating" the focal points together. You can then calculate distances, to achieve an expected amount of mangnficaition/ or reduction..

http://televue.com/engine/TV3b_page.asp?return=Advice&id=85

 

(4) Focal Length Extended by Using Eyepiece Projection

• Camera lens must be removed.
• Focal length extended by eyepiece acting as a relay lens
• f/# slowed by projection magnification
• Magnification of focal length determined by Relay Ratio (see diagram left):
  Relay Ratio  = A ÷ B
• focal length = Telescope Focal Length x (A ÷ B )
  Where A and B are determined from the formula:
  

   
  
  Where F = eyepiece focal length
• Example with 600mm focal length (TV-85 telescope) using the Tele Vue Eyepiece Projection Adapter with Tele Vue 11mm Plössl eyepiece: if the Plössl is 12mm from Telescope focal plane and 150mm from Film or CCD Plane, the relay ratio is 150/12 = 12.5. 600mm x 12.5 yields 7500mm focal length.

(5) Afocal Imaging (Also Called "Digiscoping")

• Camera lens remains attached.
• Focal length of camera lens extended by telescope magnification where:
  magnification of Telescope = objective Focal Length ÷ eyepiece focal length
• Example: 600mm focal length telescope (TV-85 telescope) with 10mm eyepiece = 600/10 = 60x. If camera uses 50mm lens, above equation yields 3000mm focal length.

• An alternative way of determining effective focal length considers the camera lens and eyepiece combination acting as a relay system. Using the example above, the 50mm camera lens with the 10mm eyepiece gives 5x relay magnification. 5x600mm telescope objective focal length yields 3000mm focal length.

 

Edited July 17, 2020 by Kitsunegari

[Kitsunegari]

Here is my optical schematic for what is happening with this right now.  Currently this layout is producing a relay magnification factor of just 1.0775.    This has changed my prime focus / focal length to 1293mm.      

 

 

 

 

Now Calculating for "ccd critical focus" of my basler aca1920-155um camera to get optimal performance.  A prime imaging focal length of 4650mm is required for a 127mm objective; operating at 393nm wavelength.   http://www.wilmslowastro.com/software/formulae.htm#CCD_Sampling

 

Now displaying the schematic with the added 1550mm extension to achieve critical focus, by boosting magnification to 3.875x .

 

Because the total length of this modification will exceed 3000mm,  it will require two additional diagonal mirrors to redirect the image back down to the focuser.

Edited July 17, 2020 by Kitsunegari