Reticle eyepiece?

[FPM]

Hello

For aligning a finder scope & RDF on a Dobsonian, do I need a reticle / crosshair eyepiece?

Thanks

[FPM]

… and if so, low or high power..?

[bosun21]

I use a 12.5mm illuminated reticled eyepiece for doing accurate star alignment and conducting star tests. For this it's invaluable to me however if your dobsonian is manual then I wouldn't bother with one. Just centre the target in the eyepiece as near as you can and adjust your finder reticle to match. Same with the RDF.

Edited Friday at 13:45 by bosun21

[Zermelo]

With even a low powered eyepiece, if you judge the centre of the field by eye, that will be close enough to then align the finder(s). The ends of TV aerials are good targets.

Edited Friday at 13:21 by Zermelo

[FPM]

Many thanks.

[wookie1965]

I defocus so I get a bigger surface area to centre the star makes it much easier. 

[rl]

Viaually I find crosshairs or a reticule only make locating faint targets more difficult.

A normal eyepiece with a linited field of view, say 40 to 50 degrees is easier and accurate enough to guess the middle.

Astrophotography with a small sensor...that,s a different matter.

 

[FPM]

Thanks everyone.  My concern was whether I could estimate the centre of the view through the scope well enough for aligning with finders.

[Mr Spock]

I just use a normal eyepiece in my 60mm finder. I don't find it difficult to estimate where the centre is.

Some of the cheaper finders have crosshairs so thick they could almost hide the moon!

[seven_legs]

9 hours ago, FPM said:

Hello

For aligning a finder scope & RDF on a Dobsonian, do I need a reticle / crosshair eyepiece?

Thanks

A simple finder that normally comes with a Dob with have a cross hair in the finder which is all you need to align a star and centre your scope field of view, nothing fancy.

 

[Louis D]

To get back to your initial alignment question, if you are trying to align your various finders to your main OTA, start at low power to get things roughly aligned.  Next, jump up about 3x in power on your OTA and refine your alignment some more.  If you're still not satisfied, jump up another 3x and refine one more time.

Just remember, every time your remove your finders from your OTA, you'll need to refine your alignment again when every thing is put back together.  However, you can probably start at the mid-power level the next time.

Edited Saturday at 12:39 by Louis D