cross hair eyepice?

[Fatbloke-Dim]

Is there such a things an attachment to screw into the bottom of an inch and a quarter eyepiece with cross hairs? I find that even if the finder and the 30 mm two inch eyepiece are in agreement,when I put more"mag" in that the target is still not visible,leading me to conclude the finder is not aligned accurately enough. Such a widget may help me to achieve better accuracy.Anyone know of anything like this?

[hobsey]

I was trying to find such a thing a couple of months ago.

I gave up in the end and purchased and illuminated eyepiece.

[bambuko]

TAL makes one (or at least used to make one).

There is one for sale on Astro Buy & Sell (not mine btw), but there is no guarantee that it will fit in your eyepiece?

[dmahon]

You need a reticule eyepiece - there are some decent 12mm ones around for about £40 I think.

[ian_bird]

I keep saying this - but no one ever seems interested.

You don't need an illuminated reticule eyepiece. Just defocus until the target star is showing as a large donut. Then center that. Has the added advantage that only the brightest star will show.

Once you get it vaguely centered - defocus even more so that the donut pretty much fills the FOV. Then refine that.

It is so much easier and quicker than any other way of centering a star.

Hope this helps. But I don't hold out much hope - no one ever picks up on this technique.

I got it from one of the mods on the cloudynights forum. One of the best bits of advice I ever got.

Cheers

Ian

[L8-Nite]

TAL makes one (or at least used to make one).

There is one for sale on Astro Buy & Sell (not mine btw), but there is no guarantee that it will fit in your eyepiece?

Yes, as bambuko says, they are made by Tal. I am aware that there are two different thread versions. We have the version which fits standard 1.25" eyepieces. Here are a couple of photos of what it looks like. 

Edit: correct photos. 

Edited December 25, 2013 by L8-Nite

[ian_bird]

See. Told you. No one every picks up on the defocus technique! ;-)

Cheers!

Ian

[Fatbloke-Dim]

yeah?ellI'try that defocus technique, and give it fair go. If that don't work,then the TAL one will get a go.Than for the help with this,folks.

[ian_bird]

It does have the advantage of costing nothing! ;-)

Let me know how you get on with the defocus technique.

Cheers

Ian

[Astro Imp]

I have to be honest Ian I had read about that technique before and then forgot about. Will give a try next time I'm out.

Thanks for bringing it to my attention AGAIN.

[Prador]

I keep saying this - but no one ever seems interested.

You have another satisfied customer Ian. I will certainly give this a go on my next outing.

Seems quite obvious too 

[Fatbloke-Dim]

Bah! Blasted Android tab......half the typed letters go missing , some go awry some other way! Tech ,eh? Or maybe the beer . The defocus technique  works when the obj is vivible , and it can be defocussed to just about fill the field of the e.p. Just concerned that my interpretation of being centered may be a bit off ,hence the cross-hair thing would ( ought to ) be absolute . Ish. Anyhoo , if the damn rain and gales leave me alone , I'm off to try again . It's not a deal-breaker , by any means , I'm still loving getting a face full o' universe, 's just that I value convenience a great deal . Read.......I'm just damn "Bone " !!!!!!!  Easier is better , no ?And now I have a new project , too . Making some upgraded bolts for the alt adj on my eq6, at ess than half the cost of those you can buy. Cheap? Me? Never. Not often anyway . And a levelling base for me big Dob. And to think I hated woodwork at school ,on the odd occasions I was there .

Mods......

Can we get an "edit" button on here somehow , I hate to commit my spelling gaffes to eternity !

[bambuko]

 Mods......

Can we get an "edit" button on here somehow , I hate to commit my spelling gaffes to eternity !

Just use "preview" button and check it before posting (until you get edit option - which on this forum will happen when you reach 250 posts).

[DannyHarvey]

Hi Ian

Just stumbled across this thread whilst looking for a good reticule ep!

I have just purchased one of your defocussed eye-pieces for zero pounds for aligning my scope! ;-)

thanks for the advice!

Dan

[CumbrianGadgey]

I keep saying this - but no one ever seems interested.

You don't need an illuminated reticule eyepiece. Just defocus until the target star is showing as a large donut. Then center that. Has the added advantage that only the brightest star will show.

Once you get it vaguely centered - defocus even more so that the donut pretty much fills the FOV. Then refine that.

It is so much easier and quicker than any other way of centering a star.

Hope this helps. But I don't hold out much hope - no one ever picks up on this technique.

I got it from one of the mods on the cloudynights forum. One of the best bits of advice I ever got.

Cheers

Ian

I really love simple ideas. I for one will remember this, rest assured!

[Fatbloke-Dim]

I finally tried this de-focus thing , and yep ,it worketh . But I still got me cheap-ish illuminated double cross-hair 12mm Plossl . Belt an' braces an' all that.........for when the batteries in me eyes go flat !

[allen g]

I find it extremely helpful in the alignment and it has been helpful in training my eye to center without it. I use a 12.

[Alan White]

Thread revival, what a great technique.

I will try this on the next cloud free night, I like simple, I like free 

 😀

[Jiggy 67]

Love @ian_bird second post 😂😂

[Marvin Jenkins]

On 26/12/2013 at 18:49, ian_bird said:

See. Told you. No one every picks up on the defocus technique! ;-)

Cheers!

Ian

Brothers in arms, I use it every time and it works a treat. See. There are three of us including the Cloudynights astronomer.

Marv

[tomato]

But it would be tough manual guiding without the crosshairs and a focussed star, trying to see which way and how far the star has drifted.

Oh, just remembered, nobody manually guides anymore...😎

[Don Pensack]

I can't see the stars in the field of an illuminated eyepiece until the reticle is so dim I can't see the reticle.

I started using the defocused star in the early '60s--defocus a star until the crosshairs appear black crossing the donut shaped star image.  Works great.

But, about 10 years ago I realized I could estimate the center of a circle well enough I didn't even need crosshairs.

On my refractor, I can center the star in the field of the finder (no crosshairs) and it's in the field of view of a 3mm eyepiece.

Perhaps 57 years of doing this have given me the ability to line things up without crosshairs--I also align my DSC with just a visual estimate of the center of the field in the eyepiece,

and my alignment error is almost exactly the same as when I used to use a crosshair eyepiece--the trick is to use a very high power eyepiece to align the finder to the scope.

Lower powers all will appear centered.

Of course, that's for visual use.  Guiding a photograph is a whole different thing.

[bomberbaz]

I have been using a crosshair for aligning my pushto for a long time now, always get it to within +/- 0.2 accuracy.

My method is to use a telrad (RDF will do) to get your target star, then to the crosshair 9x50 finder scope to get it almost bang on and then use the crosshair to finalise alignment.

FYI the whole process takes no more or less than using other methods in my opinion.  It just works for me.

The telrad is used as I don't always use the pushto and quite often will use the telrad + finder scope to find my object.