daiwelly52
Member
Hi have been recently left a Optolyth TBG 80 I have a complete range of 1.25 lenses for my Skywatcher 200mm Dobson is there any way I can use them on the Optolyth
-
Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.
Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
Optolyth (1 Viewer)
- Thread starter daiwelly52
- Start date
Hi have been recently left a Optolyth TBG 80 I have a complete range of 1.25 lenses for my Skywatcher 200mm Dobson is there any way I can use them on the Optolyth
Hi,
yes, there's an adapter part number ZUB - 24068.
http://www.optolyth.de/english/products/accessories/adapters/index.php
The focal length of your TBG 80 is 445mm. It depends on the eyepiece if you're able to reach focus at infinity with your spotter - the focusing range is usually not too long in spotters.
Joachim
JerryLogan
Well-known member
Hello,
Joachim knows this world! My only question would be the focal lengths of your eyepieces. Since the dob has about 2.7 times the focal length of the Optolyth and 120mm more aperture - there's a danger that perfectly suitable eyepieces for the dob will yield unsuitable magnification/exit pupil mounted on the Optolyth.
I expect an 8mm eyepiece (60x) and longer (15mm for 30x) would be best. Anything shorter isn't going to make a very nice view. And anything longer is just going to be kind of a one-eyed, tripod mounted, binocular barrel. I think you'd definitely be disappointed with 5mm or smaller eyepieces.
Best,
Jerry
Joachim knows this world! My only question would be the focal lengths of your eyepieces. Since the dob has about 2.7 times the focal length of the Optolyth and 120mm more aperture - there's a danger that perfectly suitable eyepieces for the dob will yield unsuitable magnification/exit pupil mounted on the Optolyth.
I expect an 8mm eyepiece (60x) and longer (15mm for 30x) would be best. Anything shorter isn't going to make a very nice view. And anything longer is just going to be kind of a one-eyed, tripod mounted, binocular barrel. I think you'd definitely be disappointed with 5mm or smaller eyepieces.
Best,
Jerry
Last edited:
Hi,
well, a 24mm Panoptic or equivalent ES68 would give a nice 18.5x view with a 3.7 degree tfov and 4.3mm exit pupil - not quite rich field under dark skies but not too shabby.
I have a 5mm on my old Kowa which is useable but narrow at 84x - unfortunately my 5mm Nagler doesn't fit the Kowa. If the Optolyth is the fluorite version and 60x is good, I would certainly try for more - especially if you have the EPs anyways...
Joachim
well, a 24mm Panoptic or equivalent ES68 would give a nice 18.5x view with a 3.7 degree tfov and 4.3mm exit pupil - not quite rich field under dark skies but not too shabby.
I have a 5mm on my old Kowa which is useable but narrow at 84x - unfortunately my 5mm Nagler doesn't fit the Kowa. If the Optolyth is the fluorite version and 60x is good, I would certainly try for more - especially if you have the EPs anyways...
Joachim
daiwelly52
Member
Thanks for all the advice I have the following lenses 32mm pannaview, starguiders: 25mm,15mm, 8mm, 6mm and 3.2mm I may as well maximise there usage if at all possible!
JerryLogan
Well-known member
Joachim,
I completely agree about the wide field 24mm eyepieces - would be very good if he owned one. For sure the 3mm is unusable and 75x (6mm) in the Optolyth is going to look a lot dimmer than 75x (15mm) in the dob. But, you are correct, since he already owns them there's no reason not to give them all a try!
Best to you,
Jerry
JerryLogan
Well-known member
I believe Joachim is right. The 20468 mates astro eyepieces to Optolyth scope. The 20469 and 20470 mate Optolyth zoom and wide angle eyepieces to regular telescopes. OP needs the the 2046 8 as Joachim advised.
Best,
Jerry
Last edited:
Yes, I saw that when I was playing around with a Baader lens on my Optolyth scope about 12 months ago. They must have changed the aperture on the later scopes, because on mine, the astro lens wouldn't fit in. Mine narrowed down about halfway in, so the lens would only go in part way. If the later Optolyth scopes can take a astro EP you have a top quality scope with loads of EPs to choose from. I think the picture on the Optolyth website shows the Optolyth to Astro though.
Last edited:
A good 77mm or 80mm to 85mm spotting scope in good alignment can usually take 120x to 150x magnification. A good Kowa fluorite can probably take 180x.
I keep a complete range of orthoscopic and Kelner eyepieces in the old 24.5mm, 0.965 inch maybe, fitting.
These fit many scopes.
I use the back end of a 45 degree angled Pentax 500mm mirror lens spotter, which has a T2 mount thread which fits many old large lenses. This also takes 24.5mm eyepieces with wiggle room.
High magnifications are usually most useful on planets, but in good conditions also terrestrially.
I find that 60x is too low for me with most 80mm spotting scopes.
I do also use low and medium powers, but I like to have the complete range.
P.S.
One can unscrew the barrels of 1.25 inch eyepieces and make or cobble up an adaptor for spotting scopes. That is if they don't fit as is.
I keep a complete range of orthoscopic and Kelner eyepieces in the old 24.5mm, 0.965 inch maybe, fitting.
These fit many scopes.
I use the back end of a 45 degree angled Pentax 500mm mirror lens spotter, which has a T2 mount thread which fits many old large lenses. This also takes 24.5mm eyepieces with wiggle room.
High magnifications are usually most useful on planets, but in good conditions also terrestrially.
I find that 60x is too low for me with most 80mm spotting scopes.
I do also use low and medium powers, but I like to have the complete range.
P.S.
One can unscrew the barrels of 1.25 inch eyepieces and make or cobble up an adaptor for spotting scopes. That is if they don't fit as is.
Last edited:
DRodrigues
Well-known member
Older Optolyth scopes don't reach focus with astro 1.25" eps but more recent do - see the info and photo at the end of http://www.pt-ducks.com/cr-telescopes.htm#Test%20of%20100mm%20telescopes
There you also have a link for a company that produced a compatible adapter with lower cost and already with screws to hold the astro ep - didn't found the present correct link but you can ask them.
However you can test if your model focus or not, before purchasing an adapter: - just remove the Optolyth ep and insert the astro ep and see if it focus ...
There you also have a link for a company that produced a compatible adapter with lower cost and already with screws to hold the astro ep - didn't found the present correct link but you can ask them.
However you can test if your model focus or not, before purchasing an adapter: - just remove the Optolyth ep and insert the astro ep and see if it focus ...
daiwelly 52,
I looked up the Starguider eyepieces.
They seem to be good quality and should work very well on the Optolyth 80mm scope, so long as you can reach focus.
Sometimes a barlow lens can extend the focus position to enable eyepieces to be used that seem to be impossible, maybe removing the barlow tube and just using the optics, or shorten the tube.
In this case the 3.2mm is too high magnification, but otherwise 140x shoud be fine.
One needs a good heavy tripod.
P.S.
The amplification of a barlow lens depends on position.
A 2x barlow can be 3x with a different tube length.
It could be only 1.5x closer to optics than usual.
So the actual eyepiece magnification changes with barlow lens position, as does the final focal ratio of the scope.
I looked up the Starguider eyepieces.
They seem to be good quality and should work very well on the Optolyth 80mm scope, so long as you can reach focus.
Sometimes a barlow lens can extend the focus position to enable eyepieces to be used that seem to be impossible, maybe removing the barlow tube and just using the optics, or shorten the tube.
In this case the 3.2mm is too high magnification, but otherwise 140x shoud be fine.
One needs a good heavy tripod.
P.S.
The amplification of a barlow lens depends on position.
A 2x barlow can be 3x with a different tube length.
It could be only 1.5x closer to optics than usual.
So the actual eyepiece magnification changes with barlow lens position, as does the final focal ratio of the scope.
Last edited:
