New Telescope / dirty eypieces

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Barry B
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New Telescope / dirty eypieces

Post by Barry B »

Hi All,

I've recently purchased a Skylight 100mm f13 refractor, I have not yet had any clear nights to do any observing, but whilst alighning the finder on a distant daylight object I was aware of the FOV being full of small blurred spots.
My first thought was that the scope had a fawlty object glass, or that I had some eye problem, however, by rotating the eypiece the spots also rotated. I tried several eyepieces all of with the same result. I have not noticed this to the same extent when using the same eyepieces in my 10'' f6.3 Newtonian.
All of my eyepieces appear to have clean field lenses but the eye lenses do show some dust and a finely speckled appearance to the coatings. I have tried cleaning, with limited success, using a fine sable haired brush and a photographer's blower brush.
Can anyone suggest a safe way to remove the dust and also the mottling of the coatings, also any ideas why this should be more noticable in the refractor than the reflector?
Finally, the new scope has an achromatic object glass made in Japan by Carton, has anyone ever heard of this maker?

Regards Barry B
David Frydman
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Re: New Telescope / dirty eypieces

Post by David Frydman »

Hi Barry,
What type and focal lengths are the eyepieces?

Is the mottling actually fungus?

If coating faults not a lot you can do, but should not affect view.

If the objective and scope are good suggest you buy some good quality new eyepieces.

Do you wear glasses?

If just dust and grease Baader optical wonder fluid plus good microfibre cloth suggested by others here.

I use lens cleaner and Kleenes for Men white tissue.

regards, David

I might gave heard of Carlton but not Carton. If Japanese may be very good.

Maybe the longer focal ratio gives greater depth of focus, so spots more visible ??
brian livesey
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Re: New Telescope / dirty eypieces

Post by brian livesey »

CARTON refractors get very good reviews. If you can't shift the lens specks, it might be a problem of staining due to condensation or something else. Or there might be miniscule bubbles in the glass, I've seen this before.
Are the eyepieces original to the refractor?
brian
David Frydman
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Re: New Telescope / dirty eypieces

Post by David Frydman »

The 100mm f/13 Carton has wonderful reviews, sounds like a great find, maybe c. 1980.

I hope it is in good condition and you enjoy great views of planets and double stars.

My 100mm f/12 Pentax c. 1980 was fantastic, I hope the Carton is as good.

regards, David
Barry B
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Re: New Telescope / dirty eypieces

Post by Barry B »

Hi,

The eyepieces I have used as follows:-

8mm & 22mm Vixen Lanthanum W/A's
13mm Nagler
35mm Panoptic

The worst affected are the Vixens, but they are also the most used. I am wondering if the speckling of the coating is caused by grease or abrading by my eyelashes and eyebrows, which are quite bushy.

The dust seems to be stuck to the surface although I have as yet only lightly touched it with a brush.

I was also wondering if the fact that the problem appeared more obvious through the refractor was due to the increased focal ratio. I also have a pair of Zeiss 10x40b binoculars which I have had for many years and are at least as dirty as my eyepieces yet they show no sign of the problem. Would the appearence of dust on the eye lens be more noticable on negative rather than positive eyepieces due to the image being formed internally.

The telescope is new and beautifully made in South London.

Thanks for your help

Barry B
David Frydman
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Re: New Telescope / dirty eypieces

Post by David Frydman »

Baader Wonder optical fluid plus microfibre cloth, First Light Optics £14? should do the trick for all optics, but clean with care.

Nice binocular.

It may be that for some reason the offending marks are more in focus with the refractor.

regards, David
Lady Isabella
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Re: New Telescope / dirty eypieces

Post by Lady Isabella »

Barry

The skylight instrument is a superb telescope. I've been to Richard's (Skylight) house in London and seen
these instruments and the care that Richard puts into each telescope.

I know of only Two proper Carton 100mm f/13 OTA's and Equatorial mounts in the U.K
(I know that Richard had one of them). Back in the day, these were usually kept for the Japanese market and to import
one was incredibly expensive.

Richard fits the objective glass into his own tubes. I bought a Carton 100mm f/13 lens and fitted it
into a tube made from plastic soil pipe.
These lenses are real sleepers. I've had my scope side by side with some of best APO scopes out there,
i.e. Lzos, Takahashi, Televue and the Carton is right up there. My scope also showed better contrast
and sharpness than some other APO scopes on the market.

The lens shows a tiny amount of C.A., and a very slight over-correction in the star test.
The over-correction appears to be normal for the Carton, going by reviews by other observers.
In focus the views are wonderful. I was using mine by the side of a Takahashi-102, and the
detail visible on Jupiter was the same in both scopes. The same results were obtained over several
other nights of testing.

I hope you manage to get the eyepiece problem sorted out, as you have a stunning lens
with the Carton.
David Frydman
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Re: New Telescope / dirty eypieces

Post by David Frydman »

Lady Isabella,

Have you tested the Pentax 100mm f/12 c. 1980?

I could find no real faults.
It worked superbly on planets and double stars at 300x with Pentax eyepiece and did not break down at 400x Clave in superb Seeing.

Regards, David
Barry B
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Re: New Telescope / dirty eypieces

Post by Barry B »

Hi all

Thanks for your help and comments, I shall obtain some Baader cleaning fluid and go to work on my eyepieces.

I concur with Lady Isabella's remarks regarding Richard Day's skill and artistry in producing these 'scopes. I too have visited his home and workshop and I am very impressed, his latest batch of 4" f15's are using Teleview object glasses.

As soon as the sky clears I shall try out the 'scope on Jupiter and report back on how it performs.

Regards

Barry B
Lady Isabella
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Re: New Telescope / dirty eypieces

Post by Lady Isabella »

David

I have only tried the smaller 80mm Pentax, which was a very nice
scope. The larger 100mm scope was much harder too find, however I Seem
to recal seeing a second-hand in the old Broadhurst Clarkson shop on Farringdon Road
about 10 years ago.

What I find really interesting about the Carton lens is that mine appears to have a single
coating of Magnesium Fluoride, yet it gives eyepiece views that are every bit as good as
the latest multi-coated APO scopes.

The views of double stars with the Carton are wonderful. I have seen the companion to Sirius several
times this year with this scope. I have even found that the Carton has given better views of some
doubles like the stars E and F in the Trapezium. Side by side with a Takahashi FS-102, I found the F
star easier to see with the Achromat.

For my Planetary viewing, I always use a slight yellow filter and Bino-viewers, here again I found the Carton
gave the same detailed views as those seen with the Takahashi.
brian livesey
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Re: New Telescope / dirty eypieces

Post by brian livesey »

The BAADER Semi-Apo filter gives good results with achromatics. It's colour neutral too.
brian
David Frydman
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Re: New Telescope / dirty eypieces

Post by David Frydman »

The 100mm Pentax was in a camera shop window in Helsinki for 3 years.
I lusted after it but at well over £2,000 c. 1980 could not afford it.

I plucked up courage and asked if they would take an offer.
They said it belonged to Pentax and was on loan.

I contacted the Pentax director went on the tram to see him, and in Finnish said I was an astronomer and would he take an offer. One of the set of eyepieces was missing as well as the original packing.

I said I could raise £250 cash (in Finnmarks).

I was sure he would refuse but he spent ten minutes going through his paperwork.
It was probably written down every year and to my amazement he accepted it.

He said I should take the cash to the camera shop, so I went and collected the scope handed over the cash and took it in a taxi to my flat.
The shop owner was furious. He lost his toy and I paid about a tenth of the retail price.

The scope was the Pentax demonstrator, probably specially selected as the best Pentax could make, perhaps the only one in Finland.

It was I think single coated and used 24.5mm Pentax eyepieces and exquisite on its equatorial mount.

I could only compare it to the observatory 135mm f/16 refractor which I used a lot and taking into account the aperture difference they were equally good, with the Pentax probably having better contrast.

I have not used a modern 100mm APO but the Pentax may have been equal to the best. I don't know.
I have never seen Sirius B.
I used the Pentax quite a bit, but my 150mm Maksutov was more portable for a flat dweller.

The Seeing in Helsinki in autumn is sometimes better than the very best I have seen in England. Rock steady for long periods at high power.

regards, David
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