Illuminated Reticle EP's

[iceman (Mike)]

Hi all.

Can someone tell me everything I need to know about illuminated reticle eyepieces?

I'm thinking I should start using one to properly align my EQ platform to eliminate star trails when doing long exposures with my 350D, and also so that the planets will stay in the FOV longer without having to babysit it the whole time.

1. What focal length do they come in?
2. How are they powered?
3. Where do you get them from?
4. How much do they cost?
5. Does anyone have one they don't want?
6. Is there any particular object you should align on, or in any particular part of the sky?
7. Is there a DIY alternative?

Thanks for your help.

This is the one I use Mike. Bintel have them for $245. They also have an Orion for $285. Works very well.

http://www.optcorp.com/product.aspx?pid=30-155-1778

[Striker (Tony)]

Mine is similar to Peter's but in the 12mm giving me a magnification of 235x.

The meade works fine but I know Mark Hodson had some constent problems with the illumination lines going all course and dissapearing.

Powered by 2 x small watch batteries...cheap only $1.50 each.
Most astronomy shops have them.
Mine was about $150
I align with a star fairly high in the sky...maybe within 20 degreez of Zenith.

[[1ponders] (Paul)]

If its just the x-hair ones then usually 12mm and 9mm. For your platform Mike 12 would be enough. Besides if its not then you can always barlow it.

Mine was about $150 from Bintel but that was 12 months ago.

As for aligning your platform: This is the technique I use to rough polar align my Losmandys
1. Just ball park the north and south using previously determined landmarks. If none known then magnetic north/south will do. My mag dev is around 11 degree so I "nudge" it a bit further east.

2. roughly set my alt (though for me that doesn't change much once initially set up)

3. Slew my scope to 0 deg dec and close to the meridian. and center a star in the reticle.
4. Watch how quickly the star drifts in dec. (Ignore RA drift) If you are a long way out the star will drift pretty quickly. If it does then crank the Az adjust (or move in Az) at least a degree or two. Slew to recenter a star again and watch how quickly and in which direction it drifts.

If it drifts slowly only over a period of time and in the same direction as previously then you are nearly there. Repeat with a smaller Az adjustment in the same direction.

If the drift is in the same direction and quicker then you need to adjust your az in the opposite direction the same as your initial adjustment and then some more.

If the drift is in the opposite direction but only slow then you have to go back in small increments.

The idea is to stop the star drifting off the Dec cross hairs as much as possible. BTW initially try to line your reticle up so that the cross hairs are in alignment with the ra and dec directions.

Once you've minimized the drift at Az, move to Alt adjust.

5. Center a star about 15 - 20 degrees above either the Eastern or Western horizon close to 0 dec. Watch for drift. When the star drifts adjust your alt adjust to bring the star back to the center of the line. You can ignore any RA drift. Keep drifting and adjusting until there is no more dec drift.

6. Slew back to the meridian at 0 dec again and repeat the Az adjustments again. You shouldn't need much adjustment but if you've moved your Alt more than a couple of degrees then you will most probably need to adjust your Az.

I don't know how accurate your platform is Mike or how accurate your RA drive is but using this method I was able to take 3 min unguided images of Andromeda through my Orion on Saturday night. I did add a few more iterations of AZ and Alt though just to fine tune it. Hopefully piggybacking and manually guiding your should be able to achieve something similar. If you can get at least 1-2 minutes of the star not drifting off your reticle center line you would be able to expect at least that if not longer with no rotation.

[seeker372011 (Narayan)]

but do you really need an illuminated reticle just for drift aligning? why not use K3CCD and the Toucam?

[[1ponders] (Paul)]

Yep I agree that's still my favourite for fine tuning after getting it rough Narayan. Or I'm in the backyard and I put the tripod back on my marks. I find it can be a pain though if I'm a long way out of polar alignment. I can spend too much time reaquiring an alignment star at times if I loose it by making a large adjustment, though slewing while I'm adjusting does help. If I loose it though, especially in Az adjustument I have to pop out the toUcam, put in the eyepiece, center a star, put in the ToUcam, measure the camera angle, watch for movement, adjust, loose star if I make too big an adjustment and back to point one if I loose the star again. Nowadays I do my rough initial drift using the reticle if I'm at a different site and fine adjust using K3 once I've got it rough. Saves me heaps of time.

Your point is well taken though, plus Mike coule use K3 for manual guiding by simply watching the graph and adjusting RA as its needed rather than the reticle. Though I think in Mikes case it might be a bit like using an elephant gun to shoot a sparrow if all he is doing is wide field imaging.

It's nice to have lots of options though

[gbeal]

Mike,
most have answered the questions you pose.
Astromart is the best source, as with used you are less likely to lose.
I have a pair of them, so if you want to "borrow" one sing out. (I don't want to sell it).
I built one from an old binocular eyepiece ages ago, Robby has (or had) it. I may still have an etched reticle that you could use if you DIY.
Seekers idea has more merit.
Gary

[Striker (Tony)]

I am only using the reticle out in the field at the moment because I dont have a laptop...otherwise Like Narayan said...I use K3 with the toucam for my Observatory set up with my PC.

[33South (Chris)]

I use a Lumicon Illuminated 12mm Kelner with double crosshairs, variable illumination, adjustable focus for the crosshairs with pulseguide that controls on/off time for illumination. Bit OTT and pretty old now but great for centering autostar/synscan guide stars and drift align, wouldnt part with it.

They are still available now with 12.5 ortho about 100USD + 50usd for pulseguide option.


Chris