M42 - 30mm - 23.2mm eye tube adapter warning.
- blekenbleu
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M42 - 30mm - 23.2mm eye tube adapter warning.
This Cnscope adapter seemed ideal for adapting a 23.2mm centering telescope to 30mm eye tubes,
https://www.ebay.com/itm/224158403124
...but the i.d. is nearer 26mm, too loose a fit IMO.
This was remedied using bits of HVAC pressure-sensitive aluminum tape:
https://www.ebay.com/itm/224158403124
...but the i.d. is nearer 26mm, too loose a fit IMO.
This was remedied using bits of HVAC pressure-sensitive aluminum tape:
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
It says it's a C-mount internal thread = 1" = 25.4mm?
Louise
Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo
- blekenbleu
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
There are internal threads, for about 6mm, in the tube at the end opposite the T flange.
It could not be used for a C-mount camera in a 30mm eye tube.
I lack C-mount stuff to verify that thread.
Tube length is about 28mm.
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
Yeah, I have some similar ones - more for astronomy really. The C-mount is probably intended for a filter. I think maybe the advert is incorrect though! If the od is actually 30mm it could maybe fit a 30mm microscope eyepiece tube. I've seen similar adapters that have an od of 23.2mm to fit a standard EP tube. My one actually has an od of 31.6mm so slightly too big to fit a 30mm EP tube but ok for a commonly used 1.25" astro fitting https://www.ebay.co.uk/itm/394107226337 ... BMjvHO5tJg. It has an id of 27.5mm. The one in your ad can't be both C-mount and 23.2mm for an EP and od of 30mm so is wrong. It could be the advertiser intended to offer a choice between 30mm and 23.2mm viz: https://www.ebay.co.uk/itm/334149957114 ... BMpKHd5tJg rather than an impossible hybrid! Still, at least they don't cost much!blekenbleu wrote: ↑Fri Aug 12, 2022 11:32 pmThere are internal threads, for about 6mm, in the tube at the end opposite the T flange.
It could not be used for a C-mount camera in a 30mm eye tube.
I lack C-mount stuff to verify that thread.
Tube length is about 28mm.
Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo
- blekenbleu
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
I was unaware of C-mount filters; thanks! I had supposed that
there might be some application for converting C-mount to M42x0.75 with 28mm of extension...
It is and does, now working for my 23.2mm centering telescope in a Nikon UW head 30mm eye tube,If the od is actually 30mm it could maybe fit a 30mm microscope eyepiece tube.
as intended.
I found an old JVC video camera with C-mount; it does fit, and the rest now also fits 23.2mm eyepieces.The one in your ad can't be both C-mount and 23.2mm for an EP and od of 30mm
Even before shimming, 22mm of the tube had a smaller i.d. than that final C-mount threaded 6mm, just not small enough.
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
I bought adapters as well.
I my case the OD on one of them was 33mm. Managed to turn it down to 30mm but spent 2 hours using a hand drill as a lathe, in the sink, with 400 grit sandpaper.
I my case the OD on one of them was 33mm. Managed to turn it down to 30mm but spent 2 hours using a hand drill as a lathe, in the sink, with 400 grit sandpaper.
- blekenbleu
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
And I thought using a drill for turning down rubber and plastic was a hassle;
two metal turning opportunities await...
two metal turning opportunities await...
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
23.2mm for an EP normally refers to the OD for the adapter to fit into the microscope standard EP tube. e.g. this add shows a 30mm one and 23.2mm one side by side https://www.ebay.co.uk/itm/140938461878 ... xyzHxRSxd~blekenbleu wrote: ↑Sat Aug 13, 2022 2:41 pmLouiseScot wrote: ↑Sat Aug 13, 2022 9:02 am
I found an old JVC video camera with C-mount; it does fit, and the rest now also fits 23.2mm eyepieces.The one in your ad can't be both C-mount and 23.2mm for an EP and od of 30mm
Even before shimming, 22mm of the tube had a smaller i.d. than that final C-mount threaded 6mm, just not small enough.
Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo
- blekenbleu
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
I have seen those, but never understood their purpose;LouiseScot wrote: ↑Sat Aug 13, 2022 5:16 pm23.2mm for an EP normally refers to the OD for the adapter to fit into the microscope standard EP tube.
e.g. this add shows a 30mm one and 23.2mm one side by side https://www.ebay.co.uk/itm/140938461878
what optic fits inside such a tube with 23.2mm o.d.?
How does a camera focus down an empty eye tube without some lens?
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
I guess could use direct projection to a camera (though I never have) https://www.amazon.co.uk/Microscope-Eye ... C61&sr=1-8blekenbleu wrote: ↑Sat Aug 13, 2022 6:16 pmI have seen those, but never understood their purpose;LouiseScot wrote: ↑Sat Aug 13, 2022 5:16 pm23.2mm for an EP normally refers to the OD for the adapter to fit into the microscope standard EP tube.
e.g. this add shows a 30mm one and 23.2mm one side by side https://www.ebay.co.uk/itm/140938461878
what optic fits inside such a tube with 23.2mm o.d.?
How does a camera focus down an empty eye tube without some lens?
Or may interface to a trinocular tube.
Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo
- blekenbleu
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
Direct projection wants a camera sensor is at a focal plane,
which, by design, is below the first lens in oculars or photo relays.
Refocusing objectives to increase their tube length 40mm or so exacerbates aberrations.
I just took these otherwise unedited 1:1 crops from images using the same APS-C camera, objective, target and illumination.
The first is from that 30mm-M42 adapter in an empty Nikon trinocular UW eye tube: .. which required major objective refocusing from ocular focus.
The second is parfocal with oculars using a CF PL2.5X photo relay lens: ... which IMO has less chromatic aberration, despite requiring a speed booster lens
on the camera to get back to roughly comparable magnification and field of view.
A 5X objective was used (because easier to refocus),
but which is less liable to aberrations than high n.a. objectives.
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
I didn't say it was a good idea! But would work ok with an adjustable trinocular which could a suitable projection eyepieceblekenbleu wrote: ↑Sat Aug 13, 2022 9:12 pmDirect projection wants a camera sensor is at a focal plane,
which, by design, is below the first lens in oculars or photo relays.
Refocusing objectives to increase their tube length 40mm or so exacerbates aberrations.
I just took these otherwise unedited 1:1 crops from images using the same APS-C camera, objective, target and illumination.
The first is from that 30mm-M42 adapter in an empty Nikon trinocular UW eye tube:
MTeyetube.jpg
.. which required major objective refocusing from ocular focus.
The second is parfocal with oculars using a CF PL2.5X photo relay lens:
CFPL2.5X.jpg
... which IMO has less chromatic aberration, despite requiring a speed booster lens
on the camera to get back to roughly comparable magnification and field of view.
A 5X objective was used (because easier to refocus),
but which is less liable to aberrations than high n.a. objectives.
Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo
- blekenbleu
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
Indeed, Nikon's photo tube is 3 pieces screwed together;
unscrewing the top 2 would make the focal plane below photo relays
available for direct projection to mirrorless camera sensors. Sadly,
Nikon applied some sort of cement to those threads
that I have yet to overcome.
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
I was thinking more of the Amscope cheapo, basic but adjustable trinocular tubes.blekenbleu wrote: ↑Sat Aug 13, 2022 10:47 pmIndeed, Nikon's photo tube is 3 pieces screwed together;
unscrewing the top 2 would make the focal plane below photo relays
available for direct projection to mirrorless camera sensors. Sadly,
Nikon applied some sort of cement to those threads
that I have yet to overcome.
PhotoTubeUW.jpg
Louise
A Nikon CF plan 20x; A Swift 380T; A DIY infinity corrected focus rail system with a 40x/0.65 Olympus Plan, a 10x/0.30 Amscope Plan Fluor, and a 20x/0.75 Nikon Plan Apo
- blekenbleu
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Re: M42 - 30mm - 23.2mm eye tube adapter warning.
I lack Amscope experience; perhaps this tube is comparable e.g. when used with Nikon F-trinocular:
https://www.ebay.com/itm/274696367794
... as suggested by @Scarodactyl.
Nikon's F trinocular (presumably intended for fluorescent photomicography)
https://blekenbleu.github.io/microscope ... scope-head
adds no glass between objectives and APS-C mirrorless camera sensor
for truly direct parfocal projection. It seems less popular than trinocular T or UW heads,
because lacking simultaneous ocular and camera viewing
and unusual twist-to-switch operation,
but final focus e.g. by HDMI monitor works well after finding and composing objects in oculars.
Metaphot, Optiphot 1, 66; AO 10, 120, EPIStar, Cycloptic