F30070 Telescope – a review

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Barnacle
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F30070 Telescope – a review

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Post by Barnacle »

F30070 Telescope – a review
F30070.jpg
F30070 b.jpg
F30070 a.jpg
I picked up this very common no name made in China scope recently second hand as an el cheapo finder scope for my frac.

The tabletop tripod is not my testing subject, only the optics ad the optical tube assembly will I be commenting below.

The specification sticker on the scope’s focuser says the scope is a 70mm focal length 300mm coated lens telescope, so a focal ratio of F4.3! I am keen to test this claim, as it is very fast.

The focuser is a 1.25 inch barrel, but the plastic eyepiece adapter ring is super thick, and stop the opening down to fits its two 0.965 inch Huygenian eyepieces of H20mm and H6mm.
stop down eyepeice adaptor ring 1.jpg
stop down eyepeice adaptor ring 2.jpg
First thing I notice is that the objective lens does not look coated.
Inside the looking glass.jpg
I can see there is a baffle inside the scope tube, not far from the objective lens, and the focuser draw tube reach not far behind the baffle with its own baffle inside and quite far towards the objective end.
Remove the objective look.jpg
focuser baffle.jpg
I did a light test with the stock 0.965 H20mm eyepiece to see if it operates at full aperture out of the box?

The torch light test shows the telescope tube baffle acts as an aperture restrictor, stopping the scope down to 50mm!
50mm stop down!.jpg
I then did a test on the focal length of the objective lens, it is 350mm, not 300mm.
350mm focal length.jpg
Therefore, the manufacturer has the scope operating at 350mm/50mm = F7 straight out of the box. The label should be F35050 telescope instead. :)

After taking the scope apart and darken the doublet objective lens edges with a sharpie, I moved the baffle as far back as possible towards the eyepiece end by flipping it around and changing over to a shorter focuser draw tube and swapping over to a 1.25 eyepiece adaptor ring, the light test shows the scope operating at 60mm, a 10 mm improvement.
Flip the baffle and push it down.jpg
focuser compare.jpg
You can use instead a Stanley knife to slowly scrape off the plastic to ‘open up’ the eyepiece adaptor ring from 0.965 to 1.25 inch if you do not have a 1.25 inch eyepeice adapter to swap with.

The only way to reach full aperture of 70mm for this scope was to remove the telescope baffle altogether and to swap over to a shorter focuser draw tube, as the telescope tube length is just too short. This means I rely on the drawtube baffle but I find it was sufficient for me. If you do not have a shorter focuser draw tube, you can cut the tube shorter but you will need ‘Knead it’ to rebuild the rack and pinion focuser knub.

The doublet achromat optics on this ‘F35070’ scope is fine operating at full 70mm aperture at F5. I saw the Moon after the above DIY, I did not see any blue edge on the lunar horizon. I am yet to check for astigmatism with a bright star.

To focus without a diagonal with the shortened focuser draw tube, I use those made in China 2 or 3x plastic shorty barlow lens to lengthen the barrel to achieve focus.

In summary, after the above modifications, it is a much more capable 70mm scope or finder scope.

PS: My scope comes with a 5x24mm finder scope, but the objective lens on the finder scope is a singlet plastic lens and the finder scope has been stopped down to 12mm with a baffle. I find the plastic singlet lens operates better than the glass singlet lens when operating at full aperture due to its different refractive index. By using a Stanley knife, one can enlarge and scrape off the finder scope baffle insider the finder scope barrel to let the finder scope operates at its full aperture of 24mm, with minor loss of crispness in the focus as a trade-off.
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StarBru
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Re: F30070 Telescope – a review

#2

Post by StarBru »

Interesting review, Barnacle. You said it was a no-name scope, so do you know who the distributor is? Thanks!
Bruce
12 telescopes, 9 mounts, a couple binoculars, various eyepieces, barlows, filters, gadgets......
Barnacle
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Re: F30070 Telescope – a review

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Post by Barnacle »

No idea Bruce. Each country will have their own distributors.

The seller I bought my scope from got this unit from eBay, and I got it second hand off him.

In this case, the distributor likely rest in China, as it was likely shipped out of China.

Thanks.
Barnacle
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Re: F30070 Telescope – a review

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Post by Barnacle »

Found a weblink with interesting photos of the assembly manufacturing these 70mm short tube fracs!
https://m.made-in-china.com/product/Ref ... 35075.html
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Lady Fraktor
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Re: F30070 Telescope – a review

#5

Post by Lady Fraktor »

I like the image of the 150mm f/8 on a aluminium tripod and EQ-3.
That would be a very shaky platform.
Proper Telescopes: Antares 105 f/15, Bresser 102 f/13.2, Celestron 150 f/8, Stellarvue NHNGDX 80 f/6.9, TAL 100RS f/10, TS 102 f/11, UR 70 f/10, Vixen SD115s f/7.7
Mounts: Berlebach Planet w/ 410mm pier, Celestron AS-GT, Celestron CG-5 w/ Argo Navis & tracking motor, SLT w/ 250mm pier & tripod mods, Manfrotto 028b w/ SV M2C, Mantrotto 055Pro w/ 128RC, Skywatcher EQ-5 w/ dual drives, TAL MT1C w/ wood tripod, Vixen SXP w/ HAL-130 & 200mm half pier
Diagonal: 2" A-P Maxbright, 2" Baader Herschel Wedge (P), 2" Zeiss/ Baader Amici Prism (DX2), 2" Long Perng Amici Prism, 2" Stellarvue DX, 2" TeleVue EverBrite
Eyepieces: Antares to Zeiss
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Barnacle
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Re: F30070 Telescope – a review

#6

Post by Barnacle »

Good pick up!

Yes, looks like they compromise their large cannons by having all of them shaking on stilts at these bargain-basement prices.

https://www.barride-optics.com/product/ ... Telescope/
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