Reductor de Focal para Newton f/5 + QHY6

[zonalunar]

Hola.

Pues eso, que reductor de focal f/3.3 me recomendais para usar con un Newton de 200mm a f/5 y la cámara QHY6.

Un saludo.-)

[Nazgull]

Para un newton lo suyo es un corrector de coma, no me suena que vendan reductores de focal para newtons, de los que yo tengo referencias son todos para SC y refractores

Edito: A quien venderian los de Takahashi y ASA sus newton ultrarapidos y ultracaros si se pudieran conseguir esas relacciones focales con un reductor de focal

[plutarko]

A lo mejor podrias poner un reductor de focal 0.5 de atik, de los que van roscados como filtro. Pero creo que en tu configuracion de focal no te iba a funcionar bien. Si ya tienes una focal de 1000mm dejarlo en 500mm es un poco bestia y seguro que te da problemas de coma y enfoque.

Los reductores estan mas pensados para los SC con su relacion focal 10.

[eb3bjd]

Puedes probar con este, no tengo ni idea de si funcionara bien pero es barato GSO 1.25" 0.5x Focal Reducer

copio las especificaciones:




GSO's popular 1.25" 0.5x focal reducer screws on to any accessory such as eyepieces, camera adapters, etc. that accepts standard 1.25" threaded filters and provides a nominal reduction of 0.5x. Use of this focal reducer effectively halves the focal ratio of your telescope, resulting in a wider field of view and significantly shortened exposure times for astrophotography. For example, use of this reducer will convert an f/10 telescope into an f/5 scope.

The 2-element reducer features fully multi-coated optics in a black-anodized aluminum filter cell. It also has additional 1.25" female threads so you can screw/stack additional 1.25" filters on to this reducer. This focal reducer will work well for visual use too when coupled with the right kind of eyepieces and telescopes; it is not recommended for very fast scopes or very wide angle eyepieces for visual applications.

Note that the use of any optical element like barlows and focal reducers changes the focus point of your telescope, requiring additional in-focus or out-focus travel. The exact amount of focus travel required will depend on the optics and mechanics of your specific set-up (telescope, diagonal (if used), barlow/reducer, and eyepiece). Hence, be aware that you may not be able to reach focus with all eyepieces or in all configurations with a given barlow/reducer. In our tests, when screwed into an eyepiece, this focal reducer required approximately 8mm of additional in-focus travel so please make sure that your focuser can accommodate this travel requirement.

Focal length (estimated) = 101 - 103mm (3.98 - 4.06")
Total item length (including external thread) = 13mm (0.51")
Total item length (excluding external thread) = 10mm (0.39")
Clear aperture = 22mm (0.87")
Weight = 0.5 oz.
Made in Taiwan

Varying the Reduction Factor of a Focal Reducer

The actual reduction will vary a little over or under 0.5x depending on exactly where the focal reducer is placed in the optical path. The exact focal length specification of this reducer has not been provided by the manufacturer, but we estimate it to be approximately 101-103mm. Hence, the "working distance" of this specific reducer is estimated to be 51mm, i.e., this reducer will provide a reduction of 0.5x when the center of its lens assembly is placed 51mm from the focal plane of the eyepiece or imaging device. Move the focal reducer closer to the eyepiece/camera and its reduction factor will increase. Move it away and the reduction provided will decrease.

By using additional spacers or extension tubes (sold separately), you can vary the amount of reduction you obtain with this reducer as follows:

Extra Spacer Length Nominal Reduction Provided
0" / 0mm 0.50x
0.25" / 6.4mm 0.44x
0.5" / 12.7mm 0.38x
0.75" / 19.1mm 0.31x
1" / 25.4mm 0.25x

However, do not be tempted to buy only the longest spacer tube to get the most reduction. A focal reducer will provide good results as long as it is placed "close" to its working distance. For example, it is possible that a 0.5" spacer will provide good results, a 0.75" spacer will provide acceptable results, and a 1" spacer might be unacceptable for your telescope/eyepiece combination. You will usually have to determine this by trial and error for your set-up, so you might want to consider buying more than one spacer.

Copyright Notice: This description was developed by Agena AstroProducts. It was NOT provided by the supplier/manufacturer of this product. Please do not copy for personal or commercial use.