Sony RX100 M4 Attached to Telescope

Prolog... | Eyepiece and Adapters | Camera Attached to Eyepiece | Camera Attached to Skymax-102 Telescope | Camera Attached to Skymax-102 Telescope as a Spotting Scope | Camera Attached to Skymax-127 Telescope | Camera Attached to a Telescope - Tips | References

On this page, I demonstrate how I attach the Sony RX100 M4 to a telescope eyepiece with a T-mount filter thread for taking astro photos using the projection technique. Projection technique means that the camera is mounted to the eyepiece, not directly to the telescope. The latter technique can only be used with SLR cameras where the body can be directly attached to the telescope - typically using a T mount adapter.

BTW: I mention the 1:50 method on this site several times. This is a simple variant of the projection technique - you hold the camera by hand to the eyepiece instead of attaching it firmly...

 

Prolog...

At the beginning a few warnings:

 

Eyepiece and Adapters

Here, you can see the Revelation 32 mm DigiScope eyepiece and the two adapters needed to mount the Sony RX100 M4 with Lensmate filter adapter to the eyepiece. A second adapter, a step-down ring 52-37*, is required, because there is no T-mount adapter available, which directly fits the filter thread of the Lensmate filter adapter (52 mm). You can remove the upper part of the eyepiece including the eyecup to reveal the T-mount filter thread.

*) The respective Baader DT ring adapter is no longer available. I found the step-down ring on the Internet, and it looks nearly like a DT ring (and works like one)...

         

Top: Baader Digital Camera T-mount adapter M37/M42 (#2408165); bottom left: Lensmate filter adapter for Sony (52 mm); bottom right: Step-down ring M37/M52

 

Top: Step-down ring M37/M52, left: Baader Digital Camera T-mount adapter M37/M42 (#2408165); right: Lensmate filter adapter for Sony (52 mm)

 

Ditto; bottom: Revelation 32 mm DigiScope eyepiece with eyecup

   

Left: Revelation 32 mm DigiScope eyepiece, T-mount thread visible (the eyecup lies below it)

 

Revelation 32 mm DigiScope eyepiece with nearly all adapters for mounting the eyepiece to the RX100 M4, Lensmate adapter still not screwed on

 

Dito, Lensmate adapter attached; now you just need to attach the camera to the Lensmate bayonet

 

Camera Attached to Eyepiece

Here, you can see the Sony RX100 M4 attached to the Revelation 32 mm DigiScope eyepiece:

    

    

 

 

Camera Attached to Skymax-102 Telescope

Here, you can see the Sony RX100 M4 attached to the Sky-Watcher Skymax-102 telescope (Maksutov-Cassegrain) and the Revelation 32 mm DigiScope eyepiece.

Attention: The small Dobsonian base (taken from the Heritage 100P) is extremely wobbly and shaky and therefore not a "recommendation," but only shown here for demonstration purposes. If I actually use this base, I hang the camera's shoulder strap around my neck to avoid the worst! Alternatively, I use a photo tripod for this configuration.

    

    

Skymax-102 on small Dobsonian base from Heritage 100P

 
 

Ditto, detail views

           

Skymax-102 with zenith mirror on a photo tripd

Results

    

Zoomed in (54 mm equiv.)

 

Ditto

 

Camera Attached to Skymax-102 Telescope as a Spotting Scope

Here, you can see the Sony RX100 M4 attached to the Sky-Watcher Skymax-102 telescope (Maksutov-Cassegrain) and the Revelation 32 mm DigiScope eyepiece. In addition, I use an Amici prism for getting a correct view for daylight.

Attention: The small Dobson base (taken from the Heritage 100P) is extremely wobbly and shaky and therefore not a "recommendation," but only shown here for demonstration purposes. If I actually use this base, I hang the camera's shoulder strap around my neck to avoid the worst! Alternatively, I use a photo tripod for this configuration.

    
    

Skymax-102 on small Dobsonian base from Heritage 100P

 
 

Ditto, detail views

       
     

Different zoom steps: wide angle (left), tele (right)

 
 

Skymax-102 with Amici prism on a photo tripd

Results

At Home...

         
         
 
 

Photo data: March 2, 2018, ISO 1600, focal length 50 mm (equiv.)

At the Binshof Lakes Near Speyer

         
         
   
         
 
 
         
   

Photo data: March 4, 2018, ISO 800, focal length 52 mm (equiv.)

 

Camera Attached to Skymax-127 Telescope

Here, you can see the Sony RX100 M4 attached to the Sky-Watcher Skymax-127 telescope (Maksutov-Cassegrain) and the Revelation 32 mm DigiScope eyepiece. It is mounted on my Sky-Watcher Star Discovery mount.

         
         
 
 
         
   

Results

Daylight

         

Zoomed in (50 mm equiv.)

 

Ditto

 

Dito

Moon

The following photos of the moon were taken on March 25, 2018 using the projections method, that is, with the Sony RX100 M4 attached to the eyepiece. I used ISO 800 and mostly underexposed EV -1 to avoid blowing the highlights. I used the Sky-Watcher Skymax-127 OTA with a 32 mm Digiscope eyepiece with T-mount.

    

2700 pixels

 

2700 pixels

The following photos of the moon were taken on March 29, 2018, two days before Full Moon, using the projections method, that is, with the Sony RX100 M4 attached to the eyepiece. I used ISO 400 and 200 and underexposed EV -2 to avoid blowing the highlights. I used the Sky-Watcher Skymax-127 OTA with a 32 mm Digiscope eyepiece with T-mount.

    

2200 pixels (ISO 400, 28 mm equiv.)

  2700 pixels (ISO 200, 35 mm equiv.)

Saturn

The following photos of Saturn were taken on August 3, 2018 using the projections method, that is, with the Sony RX100 M4 attached to the eyepiece. I used ISO 800 and 1600 and underexposed to avoid blowing the highlights. I used the Sky-Watcher Skymax-102 and Skymax-127 OTA with a 32 mm Digiscope eyepiece with T-mount.

         

Skymax-102 (brighter versions)

         

Skymax-127 (brighter versions)

 

Camera Attached to a Telescope - Tips

There are three things that can make life difficult with astronomy photos:

Focusing

Focusing requires two steps:

  1. Distance has to be set manually at the camera to "infinity."
  2. The telescope has to be focused using the viewfinder or LCD screen of the camera.

Setting the Distance to "Infinity"

Basically I set the distance to manual (MF) and then to "infinity" (unless there is an explicit "infinity" setting as Ricoh cameras have) for all my cameras that I use on the telescope. Not with every camera (example: Sony RX100 M1) you can easily and quickly check whether the distance is actually set to "infinity." Since the Sony RX100 M4 displays a rough distance scale as soon as you set the distance, this can be quickly done and corrected if necessary with this camera (even if I never know in which direction I have to turn the Control Ring).

Unfortunately, the Sony RX100 M4 has to be reset to MF and "Infinity" after certain operations or after switching the camera off, which is somewhat cumbersome. Maybe, you should save the camera settings you need to work with the telescope so that you can quickly recall them when needed...

Focusing the Telescope

Since the camera is set to infinity, the telescope takes over the focusing task. This is done using the camera's viewfinder or LCD display, often under poor lighting conditions. This is why focusing is less successful on surface structures, as I tried during the lunar eclipse in 2018, because the viewfinder image is often too dark for this. Stars or planets are better suited to to task.

Exposure

A bright object or even a small bright dot in front of a black background generally leads to overexposure when using the normal exposure controls (spot metering may work for larger objects). One option that I use more often is to use exposure compensation and underexpose 1 to 3 exposure (EV) steps. Of course, this requires some trying, but most of the time you have the time for it.

However, it is best to adjust the exposure manually according to the "eye impression" provided by your digital camera (according to the viewfinder image, especially during playback). I select an aperture that is not too small and then adjust the exposure time until the exposure "fits" (which is not always easy to see...). Bracketing is certainly one way to find the right exposure.

However, some cameras, such as the Sony RX100 M4 and M1, do not make it easy to set aperture and exposure simultaneously in manual mode (MF and M mode), especially when manual focus is set and a setting ring is occupied by this or another function. Unfortunately, only a look into the camera manual will help here! See next!

Setting Aperture in M Mode

Usually, you can use the Control Ring in M mode to set the aperture value and the control wheel to set the shutter speed. However, when you assign another function, such as exposure compensation or zoom, to the Control Ring or use the manual focusing, which is also controlled by the Control Ring, the latter is no longer available for setting the aperture. Since exposure compensation is not needed in M mode, the "bottom" button on the control wheel is in thos case used to toggle between setting shutter speed and setting aperture. That is really a brilliant idea - once you have grasped it!

Protection against Camera Shake

First of all, a photo tripod or a telescope mount is recommended if you want to take photos with a telescope. However, my tripods and mounts are not very stable and let the telescope and camera shake as soon as you touch them. In such a case, you should avoid touching the shutter as much as possible or separate the time of shooting from the time of shutter release (if this is possible and the equipment does not tremble for too long). You have the following options:

*) The cable release on my Leica M (type 240) caused camera shake due to the movement of the cable!

 

References

 

An den Anfang   Homepage  

gerd (at) waloszek (dot) de

About me
made by walodesign on a mac!
05.08.2018