Too big spectrum

[pixueto]

Sorry for taking up your time with this basic question. My spectrum is too big and I want the zero order to appear on screen too. I am using a 2X barlow and a philips spc 880 webcam. Would a 3X barlow make things better?

Thanks

[jsandse]

Assuming you are using a star analyser I would try the opposite - not using a barlow lens at all.

If you still have problems then the following advice from the star analyser manual should help

Problem: The spectrum is too long to fit across the field.

(Take care not to confuse the infra red end of the wanted spectrum with the blue end of the next order spectrum which will be much fainter but will overlap.)

This is because the dispersion (The amount by which the light of given wavelength is deflected) is too high. The Star Analyser100 is designed to work with the majority of cameras and nosepieces. You may however run into this problem with cameras with smaller sensor chips and/or longer than average nosepieces. For example most Toucam owners may find it difficult to include the complete infra red end of the spectrum. (See the FAQ for more information on the optimum distance) There are several solutions to this.

a) Rotate the Star Analyser so the spectrum falls diagonally across the camera field. This increases the available length by 25%. The spectrum image can easily be rotated back to horizontal with any image processing package.

Reduce the distance between the Star Analyser and the sensor by using a shorter nosepiece. (Some camera suppliers can supply shorter nosepieces which are designed primarily for use with focal reducers and where focus travel is limited)

c) Move the star image off to the side of the field. (Note this has the disadvantage of making the calibration more difficult, as the star image represents the zero wavelength point (see calibration)

[pixueto]

Thank you for your help. One last thing: how do I attach the star analiser grating to a SLR canera? I'm using a skywatcher with a Direct SLR Camera Connection. I understand that the T ring is enough for this scope to take pictures but my star analiser filter is 1 25. Should I get an adapter for it?

Thanks

[jsandse]

It sounds like you need an adapter

There are several solutions out there including some at this site:

Adapters for Star Analyser and Rainbow Optics Spectroscope gratings : RSpec / Real-time Spectroscopy

Jack if your reading you may want to chip in with what you use.

cheers

John

[Merlin66]

It may be easier to buy a 1.25" nosepiece (with a filter thread) and use this to mount the camera body and grating to the focuser....

[Jack Martin]

jsandse yes indeed I'll chip in,

I had a threaded barrel made up to mount my RO Star Spectroscope inside my Orion tele extender attached to an Olympus OM1 SLR now using a DSLR. pixueto what film are you using?

Regards,

Jack

[pixueto]

jsandse yes indeed I'll chip in,

I had a threaded barrel made up to mount my RO Star Spectroscope inside my Orion tele extender attached to an Olympus OM1 SLR now using a DSLR. pixueto what film are you using?

Regards,

Jack

I've been using a webcam with a star alalyser but got hold of a Nikon D1 and I would like to have a go. It's an old digital camera.

Thanks for your help

Juan

[Jack Martin]

pixueto,

Have a go with the Nikon D1 and post your results.

Good Luck.

Regards,

Jack