40mm Selsi f/20?

[Sumpy]

I ran across this mid-70's Selsi branded 40mm telescope in an online auction, and after sending $8 + shipping it was on my doorstep a few days later. I enjoy tinkering with these old, slow Japanese built refractors, and have rescued and given away several over the years to any aspiring young astronomers that show interest. I was a little surprised at how complete this one was, down to the last washer, and while it is certainly nothing special, it is a good looking little guy perched on the alt/az mount.

As best as I can tell, this isn't a Towa scope but rather a Dai-Ichi Kogaku (DK). There is some yellowing of the OTA, and oddly enough it appears to be PVC? Strange, for sure. Other than the yellowing it seems to be in perfect condition, however.

The sun actually peeked out this morning, and after I grabbed my Ha image, I thought why not? So behold the incredible prowess of the 1974(?) Selsi 40mm x 800mm f/20 achromat. (As you can tell, I don't have mosaics quite figured out yet).

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[DeepSolar64]

Brian,
I love well made traditional Japanese refractors. It closely resembles my 40 year old Japanese made Traq F12 60mm refractor. Mine has Tanzutsu , <Z> optics. Most of those are only rated fair but I got a really good example. The objective gives really sharp low CA images and I have used it at high as 175x with very good results. A friend of mine had a Jason F15 60mm which was also excellent. It had a Towa objective. The downside to both of these scopes was the cheap .0965 eyepieces they came with and I generally dislike the .0965 focusers anyway since it's now hard to find good eyepieces for them. And their finders were cheap stopped down singlet objective things that were only useful on really bright objects. And what ever happened to the wood tripod that came standard on these refractors!?? I prefer them over metal and now if you want one you have to pay a premium for it!

I wish most refractors were still made in Japan! I don't think you can find an achromat made outside of China anymore unless it's iStar which I think are European. Takahashi has the StarBase 80 which is their only achromat. It's of course Japanese.


https://www.skyatnightmagazine.com/revi ... tor-mount/

https://optcorp.com/products/takahashi- ... -telescope

But unlike traditional Japanese refractors the Starbase 80 lacks the stock wooden tripod. :-(

James

P.S. I notice the tiny white dots across the disk in the image. I have never heard of a 40mm scope picking up granules without a short wavelength filter being used. They look similar to the dots seen on your SV70 image I seen a few days ago but less distinct. Are these indeed granules, artifacts or noise?

And my friend's Jason had a built in mirror flip finder which was awesome unlike my Focal and Traq refractors that had cheap singlet finders.

[Sumpy]

I love well made traditional Japanese refractors. It closely resembles my 40 year old Japanese made Traq F12 60mm refractor. Mine has Tanzutsu , <Z> optics. Most of those are only rated fair but I got a really good example. The objective gives really sharp low CA images and I have used it at high as 175x with very good results. A friend of mine had a Jason F15 60mm which was also excellent. It had a Towa objective. The downside to both of these scopes was the cheap .0965 eyepieces they came with and I generally dislike the .0965 focusers anyway since it's now hard to find good eyepieces for them. And their finders were cheap stopped down singlet objective things that were only useful on really bright objects. And what ever happened to the wood tripod that came standard on these refractors!?? I prefer them over metal and now if you want one you have to pay a premium for it!

I wish most refractors were still made in Japan! I don't think you can find an achromat made outside of China anymore unless it's iStar which I think are European. Takahashi has the StarBase 80 which is their only achromat. It's of course Japanese.


https://www.skyatnightmagazine.com/revi ... tor-mount/

https://optcorp.com/products/takahashi- ... -telescope

But unlike traditional Japanese refractors the Starbase 80 lacks the stock wooden tripod. :-(

James

P.S. I notice the tiny white dots across the disk in the image. I have never heard of a 40mm scope picking up granules without a short wavelength filter being used. They look similar to the dots seen on your SV70 image I seen a few days ago but less distinct. Are these indeed granules, artifacts or noise?

I've had a couple of Towa's come through over the years, as well as a few I was never able to identify. Seems like there were more brands of these Japanese made small refractors than I was ever able to keep up with. This one isn't a particularly good example of the era - plastic focuser, plastic ota, and obviously built to a price point. It does seem to be much better built than your typical $50 department store telescope of today, however. The wooden tripod and cast metal mount head make it very solid considering the ota length. I'll gift it along to someone and hopefully it'll get to see regular use again.

I pulled up the raw image data, and indeed that is noise. I'm guessing that is the case for the Stellarvue 70 image as well. I think it is being introduced during the ImPPG step? I guess I need to drop LR sigma lower, even though I have it down to almost nothing. I don't seem to be able to push the sharpening on WL images nearly as hard as I can Ha images. I've still got a lot to learn on all this - apologies for the confusion!

Oh, and I had no idea Takahashi made an achromat! That is one nice looking 80!

[DeepSolar64]

Back in those days Japanese refractors varied a lot in quality. Many were good, some very good. Others were not. My first scope was a 50mm F12 Focal refractor, Focal was a brand exclusive to K-Mart and the scope was gifted to a 14 year old me back in 1978. It was a decent scope. All metal focuser and a metal housed diagonal too. Wooden tripod. It's images were ok but the scope came only with a cheap 12.5mm eyepiece which gave about 50x. The scope needed a lower powered wider field eyepiece badly. I got by this by using a pair of 10x50 binos to find objects, mainly deep sky and used the scope for closeup views. I have fond memories of seeing M13 for the first time in these instruments even though it was just a dim fuzzy ball! The focal 50mm had a cemented doublet for an objective unlike the later Traq 60 which had an air-spaced objective.

I was trying to find an article called " Coping with the Scope of Death " which I read several years back about someone successfully coping with a cheap Focal Japanese refractor. I cannot seem to find it anywhere. I found it a very entertaining read. He used it successfully for years.

Not all department store refractors were bad. I bought my Traq 60 at Brendle's department store in 1982 and it turned out to be a real performer despite the cheap eyepieces that came with it. I upgraded to Kellners. It served me well and I still have it. The biggest gripe I have with it is the .0965 focuser. I wore the original focuser out and replaced it about two years ago with another .0965. I bought a 1.25" for it hoping to upgrade it but I could not get it to come to focus.

James

P.S. And both of the scopes came with eyepiece solar filters. I used them for years without issue until I found out about the dangers of using them. And the Starbase 80 is made at a different factory than the apochromatic Takahashi's. I wonder if it's a Vixen plant.

Traq 60 and Coronado 60.JPG (5.31 MiB) Viewed 811 times

[ffellah]

Nice thread, good looking scopes put back to work…

Franco

[MAURITS]

Very nice to see Brian.

[DeepSolar64]

I love old refractors. I certainly welcome posts on them on SolarChat. Japanese or otherwise!

[Montana]

Wow! it's long but it takes a neat white light image

Alexandra

[DeepSolar64]

Did anyone ever notice that the 40mm was an ASTORONOMICAL telescope?

[Sumpy]

Did anyone ever notice that the 40mm was an ASTORONOMICAL telescope?

This brand made the same mistake on their 60mm telescope labeling as well from the images I've found online.

[DeepSolar64]

It's a simple label missprint that wasn't caught or allowed to be let go. No biggie. Does is say anywhere when the scope was made?

[JochenM]

Now that's a bargain alright. Looks great.

[Sumpy]

Does is say anywhere when the scope was made?

Not that I can really find. There is an 'alternate selection' label on that bottom of thee box that has a date code of '74, but that could have just been the last time the label was modified and not necessarily when the telescope was manufactured. I've found some supporting information online that does seem to point to the mid to late 70's.

Are we allowed to post links to other forums here? There is a thread on CN where someone restored one of these.

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[DeepSolar64]

Yes, certainly 1970s. While some department store telescopes were certainly junk others were quite good scopes. A user can use them at what magnifications they work best at and ignore the super high magnification claims and upgrade the eyepieces if they come with Huygens or Ramsden ones IF you can find .0965 eyepieces these days! Did it come with an eyepiece solar filter?

James

[Sumpy]

Did it come with an eyepiece solar filter?

It came with everything - no missing pieces at all. Of course I'm not planning to use this solar filter! Almost wondering if I should toss it in the trash to prevent someone else from trying it in the future?

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[DeepSolar64]

Both of my old refractors came with the filter but not the projection apparatus. I do wonder if that eyepiece filter would be safe with such a small aperture.

[Sumpy]

I do wonder if that eyepiece filter would be safe with such a small aperture.

Not sure. I've sure read quite a few warnings about these type of filters, though - too many for me to try it!

I had another go with a mosaic this morning using this little guy.

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[DeepSolar64]

This is very nice Brian! It's noticeably sharper than the first image and is without the numerous white dots. It they would have been granules they would have shown up even more in this shot. So they must have indeed been noise or processing artifacts.

The scope does really well for such a small aperture. I would have trouble selling this one or giving it away.

James

[DeepSolar64]

Brian,
Does the Selsi have a 1.25" focuser? If not how are you getting the ASI178MM camera to work with it?

James

[Sumpy]

The scope does really well for such a small aperture. I would have trouble selling this one or giving it away.

Indeed, the optics on this are actually better than I expected. I'm looking forward to getting it out under the moon as well!

Does the Selsi have a 1.25" focuser? If not how are you getting the ASI178MM camera to work with it?

It does not - it is the typical 0.965 focuser of the era. For now I used a 3d printer to whip up a quick adapter. A coat of black paint and a nylon 1/4-20 wing bolt from an RC airplane finished it up and had it ready to accept 1.25" accessories.

My camera can reach focus straight out the back with no issue with this adapter in place. When I want to use a diagonal with an eyepiece, I have to screw a barlow lens on the snout of the diagonal to reach focus due to lack of in-focus. I've read that a star/prism diagonal may allow me to remove the barlow lens, but I don't have one on hand to try at the moment.

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[DeepSolar64]

I tried making an adapter for my Traq 60mm many years ago. I had focusing issues with it and vignetting. I have thought about buying a commercial one to see if one of those would work. A 3D printer is handy!!

James

[Sumpy]

I tried making an adapter for my Traq 60mm many years ago. I had focusing issues with it and vignetting.

Yea, the design above adds around 1" or so to the light path. Add in the diagonal on top of that and it pushes this little guy to the point of not achieving focus. I've not noticed any vignetting with my plossls , but I do see odd 'dark half moon' type distortions in the eyepiece if I have my eye positioned wrong. This may be due to exit pupil?

I think if I design a new 0.965 nosepiece for the diagonal that threads directly into the body, it'll free up enough spacing to allow me to reach focus without the barlow when using it. I'll try that today if I get time.