TheSkySearchers

Hi All,

I acquired another second hand Tasco 9F 60mm scope in better condition than the first.

http://www.astronomyforum.net/astronomy ... rture.html

Again, the baffle on this unit acts as an "aperture stopper" from 60 mm to 50mm, so the Tasco 9Fs are all set to operate at 50mm on manufacture.

Attached are photos of the scope with light test showing it is operating at 50mm due to baffle being set too forward towards the objective lens.

The second photo shows inside the tube, the ring is where the baffle used to be located, with no matt black paint after I pushed towards the eyepiece end, so bare unpainted metal shinning thru.

The new location of the baffle can be seen in the crescent slit looking down the tube, now sitting right in front of the two screws that house the flip prism finders cope casing.

Third photo shows the full opening at 60mm after the baffle got pushed down the tube towards the eyepiece end.

Final photo shows the light test with the opening at 50mm.

Hope everyone can make the most of their Tasco 9 F by unscrew at the objective end and push down the baffle, as the Tanzutsu objective lens is very good.

They should not be set to perform at 50mm, and should be deployed at its full aperture at 60mm instead. It makes a huge difference for such small aperture scopes! You can see how much large the circle is at 60mm versus at 50mm.

PS: I haven't check yet if the objective lens on this second unit requires rotation to eliminate astigmatism, hope not as the aluminium retainer ring looks hard to remove without professional lens ring openers.

Kind regards,

Bill

Great report Bill! This is something that I have to do with my red Tasco 9F - haven't taken that out in a while...

Interesting Bill, thanks for that post. I have two Towa 700mm f/l 60mm's; a '61 Tasco 12TE and a Sears 4331-4. Both of them have a baffle just ahead of the finderscope's screw towards the front, as you put yours. I wonder when and why the "move the baffle forward" thing happened. Good for you on noticing that; most people would not!

Nice looking scope, been searching for one for a while. That finderscope is just so unique!

Nicely done and all the best,

Thanks Terrynak and The Fat Kitty,

Thanks for your posts and my apology, have not been back to the site until today.

Hope everyone is keeping safe and well with COVID-19 being house-bound.

Not sure why Tasco moved the baffle to restrict the aperture to 50mm for their 9Fs, other than to increase f ratio from 13 to 16, which is to increase sharpness of the objective lens when they don't bother with rotating the crown and flint objective lens elements to ensure their alignment and remove astigmatism. The loss is to operate these units at 50mm instead of 60mm, and is a massive and inexcusable loss when light gathering is quintessential on such small units on the astronomical front.

Presumably this aperture stopper tactic is to remove the need to maintain quality control, but is such a waste when they apply it on Tanzutsu objective lens.

Do a torch light test even if the baffle is set just in front of the findscope housing screw, in case the width of the baffle ring is such that it still truncates the light path and reduce its aperture. This is common with small aperture refractors when they want to do away with quality control. You see this a lot on Chinese scopes, especially binoculars, which I hope to write about shortly in this forum, but as these Tasco 9Fs were made in Japan, one would expect better...

PS:
Yes, this flip finder is unique and nifty. In the Tasco 9Fs, they are both prisms that deflect the light path in my units. I have not yet own that blue Tasco Lumina (made in China in the 1990s) with the same flip finder, so can't see if they have replaced with a mirror instead of the prism or whether the baffle on this Tasco Lumina also acted as an aperture restrictor. I bought the Lumina on eBay but the seller renege on the deal, ie, didn't want to sell at the highest bid price despite I was higgest bidder.

https://www.pinterest.ca/pin/265149496790598286/

Thanks.

Take care and keep safe everyone.

Kind regards,

Bill

@Barnacle, words cannot describe how awesome you are - this is amazing detective work, which makes these 9Fs really sing!

I have a hilarious addition to this thread - I just this weekend "inherited" a Tasco 9F from a local bread maker (!) - he told me it had been sitting outside in his backyard for years, and was about to throw it away when I told him I'd take it and see if it was worth rebuilding.

I spent this entire weekend first researching the 9F (including THIS thread!), then un-yukking it - it was in disastrous shape - hundreds of rolly-polly bug shells inhabited the box, the crevasses, the accessories, and yes, the tube! The in-line finder scope was missing, so there were insect carcasses throughout the primary tube! Fortunately nothing was wet, and the components were strangely high quality - steel tubes, fine threadings and all the gear worked more or less. Many screws were missing, which I found replacements for (even the primary mounting screws) The Tanzutsu primaries are an air-spaced doublet, easily removed for gentle cleaning - with your advice I marked orientation and direction, so as not to rotate them. After 8 hours of steady cleaning and refurbishing, this F9 was ready for re-assembly and test.

Testing: Rock steady mount, quality fine controls for an alt-az, and the optics were surprisingly good. I spent the evening (5/3/2020) on the Moon and Venus (no finder, remember?) and the views were spectacular. The only salvageable accessories here were the 20mm Kellner (which yields 40x from the 800mm focal length) and the loooong Barlow - they were below par, but even they couldn't disrupt the Tanzutsu lenses from their pinpoint sharpness. Over an hour with an alt-az on the moon at 80x, tiny eye relief, no problem. Some of the best lunar observing I've ever done! Venus yielded a bit of coloration at 80x, but still super sharp images, which move awful quickly through the tiny fields of view. All told, exceeding expectations was an A+. And all this with a big open hole in the tube!

Some important things to note about the 9F:
- I took your advice on how to gently push back the pressure-fit baffle to regain the full 60mm of Tanzutsu aperture - I did it and it makes a huge difference for this scope! Higher brightness, no loss in sharpness. THANK YOU!

- most of the included accessories are pretty bad. The 90 degree splitter, the Kellner eyepieces, the Barlow and the zoom lens are nowhere near the quality of the optics and should be abandoned immediately. The first addition to my 9F will be a 0.965-1.25 converter.

- The important pieces of this 9F are very high quality. I was impressed by the Tanzutsu primaries, the focuser rack and pinion, the slow motion controls, and most unexpectedly, a terrific tripod. Just take a small screwdriver and gently tighten each and every tripod screw and you will have a pretty darn stable mount for high power work (which this thing excels at). Also the fire-engine red paint job was miraculously undamaged and, once polished, looks great.

- My only major problem remaining is that the bizarre/cool inline finder is missing, and I still have a big hole in the top of the tube! If anyone knows where I can find one of these crazy things, please let me know - right now I'm tube-sighting everything (good thing my background is in Dobsonians).

- Rescued from a terrible fate, it's now just a lovely, classic telescope, sitting there dressed in hot-rod red. And this one can dance! Will update when eyepiece converter shows up and I can use my Plossl's on this. Did I mention it was free? (not counting the billable hours!) A surprising example of a high quality, long focal length refractor.

p.s. if I can figure out how to post pictures, I will!

p.s. the nice thing about having a HOLE in my telescope is that I had a pretty clear view of the pressed-in baffle causing the aperture stop! This may give you a better feel for where it is and what it looks like - it's actually pressed into the draw tube way down at the other end...

Great find and restoration Dozerbolt.

BTW I did the math on the aperture stop - opening the primary lens from 50mm to 60mm is a 30% increase in light - wow!

FYI my Tasco 9F Refractor restoration is almost complete! Here's an updated picture with it's inline finder we found...
Just a few screws to go!

@DozerBolt: Great to learn and see you found and restore a Tasco 9F back to its mint condition!

The 9F telescope tube has a baffle, and it is this baffle (which acted as aperture restrictor from 60mm to 50mm) I moved towards the eyepiece end, to the point of hitting the screws of the prism flip finder housing.

The baffle ring you shown in the photo is in the focuser draw tube, there are two of them from memory in the focuser tube, as the focuser tube is not painted matt black but left in bare metal, these focuser baffles did not act as aperture stopper in the Tasco 9F. I inserted a rolled up slip of black photocopy paper to darken the focuser draw tube to improve contrast anyway,

May I ask what tool you use to open the retainer ring on the Tasco 9F to access the clown & flint Tanzutsu objective lens?

I was unable to unscrew my retainer ring to rotate the objective lens my first unit without destroying the retaining ring and chipping the edge of the objective lens on my first unit. I am yet to test my second unit (the one I took photos with and share on this forum), as the first unit needed a clean real bad and then to rotate the lens to achieve perfect alignment.

There is not must love lost though, the first Tasco 9F unit was out exposed in the weather when I bought it from the original owner, tripod rusted and bug shells everywhere. The objective lens were opaque in yellowish mud/gunk. The objective lens also lost the bluish coating. To remove the ancient stains on the lens, basically I had to add quite a few scratches to it. Having withstood all that to restore clearness to the lens, I was able to split Rigel and observe its faint binary companion with this Tasco 9F, so the Tanzutsu primary is a really good quality lens compared with the now Chinese made 60mm scopes, which I cannot find Rigel's binary with.

PS: The scope came with two original eyepieces of 0.965 aperture, both are Tanzutsus. One is labelled a Huygenian 23mm (exceptionally narrow 25 degrees field of field by design), the other is a SR4 (symmetric ramsden) 4mm (but really huygenian when I took it apart). I like the SR4 better as it has a wider filed of view.

As I have two of each 23mm and 4mm eyepieces when I have two Tasco 9F units, making use of the eyepiece housing design, I modified the 23mm by moving the two plano convex eyepiece lens closer together to have a higher magnification and wider field eyepiece around 15mm.

Having said that, I use a 0.965 to 1.25 diagonal and use 1.25 inch eyepieces instead on this scope to max the utility of the Tanzutsu objective lens on this Tasco 9F.

Keep safe and enjoy your classy and superb red Tasco 9F!

Bill

Hello,
I was referred to you all by another member. Not sure if anyone is still monitoring or replying to these messages?
I need some expertise on how to re-install this part on my scope. I acquired this scope as a gift from a neighbor, who had no manual or interest in using. I would like to use it if possible...
This piece was loose inside of the Optical Tube, that was discovered while cleaning. I can't figure out how to re-attach?
Is there anyone knowledgeable about this scope that can help me?

Any advice would be greatly appreciated!!

DR