Modernising a 70s Towa 80mm F15

[philj]

Which scopes that on Rob?

Philj

[Leo.A]

Edit: Sorry, just noticed your reply in another thread that your tube is the 1200mm F15.

Pardon my ignorance, but I have an 80mm Tasco which I believe to be a near identical scope (without your great mods) originally purchased in 91. It's the 17TR, a 900mm focal length, 80mm objective, and a much modified, formerly horrid 1" focuser.

My question, what benefit if any to fitting more than one baffle?

I can see the obvious difference in your moon shots and am considering attempting this mod and the flocking myself. Now I'm not lucky enough to have access to a lathe (gave my Myford away when I moved, no room) and would probably make the baffle from multiple sections of rather thin aluminium (or ply??) I have and adhere them together for more strength. I see in other threads and other forums where members have fitted multiple baffles and wondering how exactly this improves the imaging.

As I said, pardon my ignorance. Been playing with cheap scopes for 20 years but actually know little through health constraints and a failing memory (Hair turns grey because it absorbs the grey matter from within, I'm positive of this) but I have taken some great moon photos (or so I think) with the standard scope. It now has the Vixxen ED lens and viewing quality is 10 fold over the original (or more), but I would really like to squeeze every possible bit of enhancement for viewing and photographic pleasure as possible, as long as it doesn't cost a great deal of money.

Sorry, not trying to hijack your thread here.

[philj]

Hi Leo

I added the baffle to this scope because I lost one when I swapped from the stock focuser, there is actually a baffle on the inner end of the original draw tube ; how that works throughout the focus range Im not sure. However I have noticed a marked improvement in contrast with the new baffle over the standard ones.

In theory if you only have one accurately positioned baffle which is dead flat black with absolutely zero reflectivity and no light gets past the baffle itself then I would imagine 1 would be all you needed. But like everything else in life nothing is perfect therefore an extra one or 2 baffles plus flocking will help cut down on internal reflections and cut out any stray light that gets past the 1st baffle.

I still havent fitted another baffle yet as I was intending, (too many other projects on the go:)) I will eventually, more out of curiosity than necessity because the scope performs superbly as it is, but I reckon another baffle will help a little.

Some manufacturers / ATMs fit 5 or 6 baffles and I reckon the benefit must go down exponentially the greater the number but there is a benefit and if its worth adding the extra couple of baffles over the standard ones is a choice I would take when the scope has good optics so I would definately give it a bash with a Vixen ed objective.

Philj

[Leo.A]

I'm now looking into fitting a crayford focuser but like you, am having all sorts of problems finding one which will fit the 79.5mm ID of the tube. Williams optics make a rather expensive (for me) unit which is said to fit anything from a 3" to a 6" scope. Now since 3" is 76mm, I'm thinking it should fit my scope. The only turn off is a price of $280 Australian where I can purchase a GSO unit for approx $120 Au but it won't fit my scope. I might have to look into taking the path you travelled and have a local machine shop make me an adaptor. I might even be able to save some money by supplying my own aluminium bar which I already have (I think it's the right size).

You have gotten me very interested in getting the most out of my scope and I have just fitted the first baffle and am in the process of making another. Once fitted, I will do my best to flock the tube (I see what you mean by the complexity of this task due to the small diameter of the tube). I have also made up 2 mount rings to fit it to my new EQ3 mount (got to beat the original wooden Tasco unit). The old tripod itself is OK with the accessory drive motor to keep basic alignment and I'm familiar with the advantage of the tripod not being affected by temperature change like the steel or alloy units but the equatorial head itself is rather flimsy. My EQ3 also has synscan GOTO so I can find objects I'm not familiar with.

[philj]

Sounds a good bet Leo to source your own ali as some machine shops charge over the odds fro materials. I now have a bigger lathe so am a bit more independent of them.

Yep the old mounts look elegant bit they arent really up to teh job and an eq3 knocks spots off them for rigidity.

Post a few pics of your project progress it'd be interesting to see how you get on and also what you think of the final product, bet youll be impressed.

Philj

[Leo.A]

Thanks Phil!

I ordered a William Optics digital display focuser (2" with reducer to 1.25") and also ordered the Philips C900NC webcam, modified with adaptor, IR filter and some software from ebay. Once my focuser arrives I will arrange getting an adaptor made up and start doing a bit of a write up, including the mod to the Vixen ED lens, complete with photos.

For the money I've just spent (thanks to my sons help) I hope to get good results, I probably could have gotten a new OTA for the money, but I'd still have to update it with the mount and other items anyway I guess.

[nightfisher]

Im looking forward to making similar mods to my towa 339 once i get it, i will be getting the crawmach focuser, and some tube rings to mount it on the EQ5 to start with

[philj]

Jules

If your scope came with teh mount you can save on tube rings by taking the scope cradle off the mount, (2 allen screws) then just bolt a dovetail straight on to it, (you may need to drill a couple of holes in the DT bar to suit).

Works a treat and only costs for the dovetail.

Phil

[nightfisher]

excellent phil, thanks for the tip, its important that i can mount this towa on the eq5, as it will be getting plenty of use

[Darkmatter]

Phil, excellent project I have bookmarked your site as I am too a refractor enthusiast, I hope to start restoring a 6" Irving at some point in the near future, but it will be a long process as I do not have the site to set it up properly, I gather the lens was reworked by Jim Hysom formerly of AE Optics and Hytel some years ago.

I love the 4" refractor project looks excellent