Finder scope or long fl eyepiece?

[fwm891]

I'm having a one person debate at the mo and can't seem to come to any reason for / against in either direction.

I'm currently building a 16inch f5 dob and wondering whether I need a finder scope. I will have a x1 rdf and my though is/has/was to use a 40mm eyepiece as a 'finder' before switching to a higher mag. I've been trying most eyepiece makes/varieties in simulations to get a 'feel' for what fov such an eyepiece would yeald. A lot comes down to eyepiece design really wide fields come at a huge price and are not being considered. I like the ES 68° 40mm apart from it's weight, the pentax XW 40mm also seems a good option...

But would a finder scope be a better option especially for hopping to targets...

Any thoughts please especially from the larger scope brigade out there - what is/was your solution to getting to your chosen target.

Cheers

[Starwatcher2001]

I've got the Pentax and it's one of my favourites. In your dob it will give ~1.38 degrees 51x.  In my view that's border line for a finder, unless you've got good skies and the RDF will get you close to your target.

[Mark at Beaufort]

Francis I use an 80mm finderscope on my 12 inch. I am happy for you to try it out once your scope is complete. I can come over to Kingstone or you can bring it to Fownhope.

The 80mm really helps with star hopping.

[niallk]

I use a Telrad, a 31mm 82° Nagler ... but also Push-To on my 15": no explicit optical finder.  Tbh, if I didn't have push-to, I think I'd want an optical finder, the N31T5 fov is a bit narrow - it's not a replacement.

My decision to forego a finder was driven by balance: I mounted the Argo Navis unit conveniently by the focuser, so I traded the weight of a finder as I also use a P2 and Ethos EPs.

[Piero]

I have a rigel finder and an Antares VS-60 RACI finderscope on my 16" f4 Newtonian.

Whether or not using a magnifying finder depends on the darkness of your sky and well as your observing style. In my case, I generally keep my (12.5mm) medium power eyepiece in the PC2 when star hopping. So the latter is done at the eyepiece of the finderscope first, but then at the eyepiece directly. After observing at medium power, I go for medium high. My low power eyepiece is used almost only for large DSOs, like extended nebulae. The large exit pupil plays a role in those targets too.

If you get a finderscope, I would suggest one which allows you to change eyepieces. Personally I find that the default eyepiece delivers a too large exit pupil. They are also not particularly well corrected. My long term plan is to use something like a 16mm 70-80 deg  eyepiece with my VS-60. That would give almost 15x, a darker sky due to the lower exit pupil and still sufficient FOV.