Have been looking for a larger aperture finder scope to find those deep fuzzies. Currently use a Tak 7x50 but would prefer a correct image Finder with a 90 deg prism. Came across a 13x80 finder f3.75 from stellavue + APM and wondering if anyone else had used these before or could recommend another type. In these you are able to change to different 1.25" eyepieces which is a bonus as well. Use a tsa 102 as my main scope, would this be a miss match or overkill as a finder/scope combination ?
I have the F80M and use it to complement my C9.25 SCT and Telrad. I originally had the 23mm pulse illuminated crosshair but found the pulse distracting when looking for faint fuzzies. Stellarvue recommend a highly corrected eyepiece such as a Nagler for the f3.75 focal ratio and I tried a 16NT5 and it is a great combo giving 19x and 4 deg sharp field. I don't miss the crosshairs and 19x is great for identifying some of the smaller DSOs and 4 deg matches nicely with the outer ring of the Telrad. The number of stars visible in 80mm is great for star hopping in barren star fields like Virgo when galaxy hunting.
I leave a 20mm low cost wide field eyepiece in it and use during the day for bird watching in my backyard. Stellarvue make a camera tripod adaptor for it.
The finder is light for its size but still requires extra counterweights on either an SCT or Newtonian. The 60mm may be a better choice if weight is an issue and the 50mm is lighter again. Yes you can use any 1.25" eyepiece that will reach focus.
I have a nagler 13 t6 that would work for now and a Le 30mm(an excuse to buy another nagler perhaps), and the weight shouldn't be an issue either, use a steel pier and dm6 mount.
I've tried the 24mm & 19mm Panoptic in it but much prefer the view with the Nagler as it looked better corrected and the higher power is nicer to me at least. I think the wide field stop of the 24mm was wider than the clear aperture of the Amici prism. The 19mm was closer to the 16mm but I still prefer the 16mm.
One word of caution, check for excess grease inside the helical focuser as it may come in contact with the barrel of the eyepiece. I had this issue and wiped any excess away before using my Nagler in the finder again. I've not tried the 13mm so maybe I'll give it a go too next time.
Having had the pleasure of using a Tak 11x70 finder recently, I would recommend it IF you can find one (it's discontinued). Certainly well able to see fuzy targets with it.
An Orion ST-80 works very well at low power. The ST-80 OTA weighs about the same as a Nagler 31mm.
You can pick up 2nd hand ST-80's in the classifieds for $100-$150.
They come with a 1.25" focuser so if you stay with that focuser, you'll be limited to plossl's and narrower fields 5 deg with a 40mm and 4 deg with a 30mm plossl. As a finder, you don't need a fantastic focuser for it so you could remove the 1.25" R&P and replace with a custom machined simple Aluminium or a 3D printed plastic 2" sleeve focuser.
With a 30mm 2" superview eyepiece, you'll get a 13x80mm finder with a 6mm exit pupil and a 5 degree field. With a 40mm 2" superview you'll get a 10x80 finder with an 8mm exit pupil and ~6.5 degree field.
It is also pretty easy to install your own cross hairs and led illumination on a large finder and you can easily get adjustable guidescope rings for them.
That's interesting about the Tak 11x70 I didn't realise that they use to make them that size.
When were they discontinued? LewisM
I'll have to do a bit of research and see if I can find one before I commit to anything just yet.
Yeah I was thinking about that as well Matt, gives me another option. Save my
pennies a bit longer and get a 41pan or 31 nagler. The panoptic gives me about 3.1deg true field, nagler 2.9 but the Finder scope will give me even more about 4.1 deg. Something to think about I guess.
