Piggy back what lens size is best ??

[ASTROSTUART]

Hello Folks, Im new to most of this but loving it apart from the fact weve not had clear skies here for months.. anyway ive got a 12 " Meade LX90 and would like to try some astrophotography using a DSLR in the piggyback mode. i would love to get some nebula pics and also later in the year some planets too, but i simply dont have a clue what lens to use and what sort of exposure and aperture settings work best, so any guidance would be very welcome.

Many thanks and please send some clear skies !!

[steppenwolf]

Assuming that by 'piggy-back' you do mean mounting the camera on top of the telescope with no optical contribution from the telescope itself, a 200mm telephoto lens is a popular option as it doesn't put too many demands on the mount for guiding yet will capture good detail in many nebulae.

[ASTROSTUART]

Just bought the book Thanks !

[springbok]

@Steve,

Just received your book via FLO. I beilive you send the FKLO orders out directly, so thanks for the super wuick delivery.

The book looks just what I need as a complete novice. I have information overload from jumping all over the web the last 2 weeks.

Thnaks again,

Grahame.

[pete_l]

ive got a 12 " Meade LX90 and would like to try some astrophotography using a DSLR in the piggyback mode.

Yes, a 200mm prime lens is considered by many (me included) to be the sweet spot for DSLR + lens photography. If you can manage it, the F/2.8 is nice.

One thing though. Your LX90 is a fork-mounted telescope. Do you have a wedge to make it rotate around the polar axis? Without that, the telescope will only track left-right and up-down. As stars and DSOs move across the sky - around the polar axis (constellations, too) they rotate as well as moving. Unless your telescope matches that rotation, then long exposures will show some blurring due to the difference in the way the telescope moves, compared to the way the DSO moves.

[michael.h.f.wilkinson]

I got some nice results using my 85mm F/1.4, but also a 135mm F/2.8, a 200mm F/3.5, and a 400mm F/5.6 lens, depending on the required FOV. Generally, I stopped the lens down by one F-stop, to reduce vignetting, but that was using slide film. With a DSLR you can correct for vignetting with flats.

Note that the LX 90 will have problems with field rotation, unless you use a equatorial wedge.

[steppenwolf]

I beilive you send the FKLO orders out directly, so thanks for the super wuick delivery.

My pleasure.

Just bought the book Thanks !

Thanks - you'll see the 200mm telephoto lens in action then as well as a discussion of the field rotation issue mentioned above.

[Davey-T]

I use 450d piggy backed on my 10"LX200 ,works well with 200mm Canon lense using the Meade piggyback bracket but with wider angle lenses you may need adapter to raise camera

away from scope as I found I could see the dew shield in the image.

Davey-T