During the photographic work, I use the following equipment.
The astrophotographic instruments.
Click on the image for an enlarged view.
- Synta 100/900 (f/9) ED apochromatic refractor in home made tube
- Zeiss-Sonnar 2,8/180 (6x6) objective
- Synta HeQ5 pro telescope mount with Synscan (goto)
- Synta 70/500 (f/7,1) achromat — performs as guider
- Canon EOS 350D DSRL camera, with Baader UV/IR internal block
- Sbig ST4 autoguider
- Vixen 0,67X Field flattener/reducer
- Vixen, illuminated guider eyepiece adapter
- Vixen 150/750 (f/5) Newton-reflector
- Synta 90/910 (f/10,1) achromatic refractor (for Sun-observations)
- Synta EQ3 mount, with motorized RA axis
- Starlight Express MX5 C ccd camera
Most of mentioned accessories have been modified or are fully home-made. In the following section I sum up the main modifications I’ve made to synchronize all of the different devices.
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The 100 ED apo originally draws a flawless image at APSC format, but during my photographic work, I found the f/9 stop to slow, so I purchased a Vixen ED reducer/flattener. The 2” apochromatic optic reduces the focal length by 1/3. The FOV stays corrected up to the corners and increases from 1,6° to 2,2° in diagonal. For fainter objects I use this combination. The original tube of the 100 ED had a large couple of problems. Firstly, the reduced focal length required a shorter one. The new aluminium tube is 588 mm long with 2 mm walls. Inside I placed velour cover and new blends specially made for the light cone of my used FOV. The objective has internal heating and 30 cm long, home-made lens hood to prevent dew consideration. The air spaced apochromatic lenses generally have three tiny rectangular discs in 120° around the endge of the objective. They keep distance between the two glass surfaces. The shadow of these discs appears on the images around the brighter stars. To hide this effect, I made an aluminium ring for the edge of the outer lens, that occults the three discs. (Instead of replacing them with a ring) Finally, the cameraside is equipped with a 2” Baader crayford focuser. The adapters of the ED reducer allow to reach the correct focus at f/6 with the reducer and at f/9 without that. So actually, I have two telescopes in one.
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The currently used EOS 350D (Rebel Xt) camera has only the well-known modification. The original internal blockfilter is replaced with Baader’s UV/IR, that passes the 656 nm Hydrogen-alpha wavelengths.
The new peltier-cooled EOS 300D is under construction.
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