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02-13-2009, 11:22 PM   #1
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K mount lens to a telescope?

Had anyone seen any adaptor that could convert a K mount lens (not a m42) to a 1.25" eyepiece holder?

If so, where could I buy one?

It's going on my tamrom 70-300mm.

Thanks

02-14-2009, 12:31 AM   #2
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They frequently turn up on eekbay every month or so.

Check out this site "Bojidar Dimitrov's Pentax K-Mount Page"

Pentax K-Mount Lenses and Lens Accessories



QuoteOriginally posted by Luciferase Quote
Had anyone seen any adaptor that could convert a K mount lens (not a m42) to a 1.25" eyepiece holder?

If so, where could I buy one?

It's going on my tamrom 70-300mm.

Thanks
02-14-2009, 02:31 AM   #3
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Hey, thanks for that.

But for one that is female K mount on one side and 1.25" on the other side, have you seen them before?

I did try looking on ebay but only found m42 treads, which I already got.

I also use T-mounts and adaptors for putting my camera on telescopes, but try out all combination and couldn't get my lens to stick to an eyepiece.

I'll pass on the duct tap and drilling holes to body cap method please!

So a direct link of where I can order one is nice.

Many Thanks.
02-14-2009, 04:48 AM   #4
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Sorry, I'll have to pass on a direct link finding one of these.

And hope one of our more learned members can help you out there.

All the best finding one, Wal'

02-14-2009, 06:51 AM   #5
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Let me be sure I understand.
You want an adapter to fit on the end of the 70-300 that will have a 1.25" snout?
02-14-2009, 07:10 AM   #6
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QuoteOriginally posted by Luciferase Quote
Had anyone seen any adaptor that could convert a K mount lens (not a m42) to a 1.25" eyepiece holder?
...
Which end of the lens do you want to attach to the adapter?

Do you want the eyepiece end to be a hollow tube that slips into an existing 1.25" eyepiece?

Or are you trying to convert a lens into a telescope (ie. the eyepiece end of the adapter accepts a 1.25" eyepiece lens?)

Male_K-> |adapter| -> 1.25" OD tube

Male_K-> |adapter| -> 1.25" ID tube

Which?
02-14-2009, 03:58 PM   #7
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QuoteOriginally posted by Luciferase Quote
But for one that is female K mount on one side and 1.25" on the other side, have you seen them before?
I've never seen a lens-mount to T-adapter, only a body mount to T-adapter. If I understand you correctly you'd end up with the side of the lens that is normally closest to the camera sensor facing the telescope instead. How would you then attach the camera?

There are filter-thread to T mount adapters which would allow you to attach the lens to the telescope via it's front filter thread:

Amazon.com: 49mm to T-mount Adapter: For mounting 49mm threaded Digital Cameras on a Telescope/Spotting Scope/Nightvision Scope: Electronics

...but if I understand you correctly that would orient the lens opposite to what you want.
02-14-2009, 06:41 PM   #8
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QuoteOriginally posted by Sean Nelson Quote
...but if I understand you correctly that would orient the lens opposite to what you want.
Hm, not sure whether there is another way of doing it. Could they be done by connecting to the front element end?

QuoteOriginally posted by newarts Quote
Which end of the lens do you want to attach to the adapter?

Or are you trying to convert a lens into a telescope (ie. the eyepiece end of the adapter accepts a 1.25" eyepiece lens?)

Male_K-> |adapter| -> 1.25" ID tube

Which?
Converting a lens to a telescope.

It should be like this

1. (filter tread in mm/ front) Lens (male K-mount/ back)

connect to back of 1

2. adaptor (female K-mount/ front) converter (1.25"ID eyepiece holder/ back)

connect to back of 2

3. 1.25" eyepieces of various sizes for different magnification

That functions like a spot scope.

I think my 70-300mm could give me some high magnification with a 8mm or lower eyepiece. The only thing I'm unsure is whether it'll focus at infinity.

Thanks

QuoteOriginally posted by wildlifephotog Quote
Let me be sure I understand.
You want an adapter to fit on the end of the 70-300 that will have a 1.25" snout?
Thats right. Seen or heard of them?

Many Thanks.

QuoteOriginally posted by wwwmorrell Quote
Sorry, I'll have to pass on a direct link finding one of these.

And hope one of our more learned members can help you out there.

All the best finding one, Wal'
Thanks for the link you send. There was actually a picture of a similar item I wanted, but just couldn't find a place that sell them.

02-14-2009, 07:32 PM   #9
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I want to help, but I am sorry, I am confused. Do you want to connect a K-mount camera to a telescope? I have one of those converters, and I can take a picture of what they look like for you.

Or:

Are you trying to use a lens as a telescope by connecting a K-mount lens to telescope eyepieces?
02-14-2009, 09:53 PM   #10
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QuoteOriginally posted by Luciferase Quote
Converting a lens to a telescope.

It should be like this

1. (filter tread in mm/ front) Lens (male K-mount/ back)

connect to back of 1

2. adaptor (female K-mount/ front) converter (1.25"ID eyepiece holder/ back)

connect to back of 2

3. 1.25" eyepieces of various sizes for different magnification
Ummm.... you haven't mentioned where the camera goes... Are you trying to take pictures through the scope?

I'm going to assume you want to take pictures through the scope as if you were holding a normal camera/lens combination up in front of a normal telescope/eyepiece combination, but instead of just hand-holding or putting the camera/lens on a tripod you want to actually attach it to the eyepiece.

This is not actually the way most people use eyepieces. When you use an eyepiece you'd normally project it's image directly onto the sensor without using a camera lens, as described here: An Introduction to Astrophotography

But if you really want to use both the camera lens and the eyepiece at the same time then here's what you'd need, IMHO.

1. The camera.

2. The lens, mounted on the camera as normal. For descriptive purposes I'm going to assume the lens has a 49mm filter mount. If not, then you'd need to find a whatever-size-filter-thread to T-mount adapter instead of the 49mm one.

3. A 49mm filter-mount to T adapter, such as: Amazon: 49mm to T-mount Adapter You'd screw this on to the front of the lens using the 49mm thread.

4. An eyepiece T-mount adapter such as: Televue Eyepiece Projection Adapter You put the eyepiece into the adapter tube, screw the camera/lens/t-adapter onto the eyepiece viewing end, and insert the other end into the telescope's eyepiece holder.

You'd have to use a little judgement regarding the lens and it's filter mount. A large or long lens may not have a sturdy enough filter mount to support the weight of the lens and camera.
02-15-2009, 04:03 AM   #11
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QuoteOriginally posted by Sean Nelson Quote
Ummm.... you haven't mentioned where the camera goes... Are you trying to take pictures through the scope?

I'm going to assume you want to take pictures through the scope as if you were holding a normal camera/lens combination up in front of a normal telescope/eyepiece combination, but instead of just hand-holding or putting the camera/lens on a tripod you want to actually attach it to the eyepiece.
Ya, no camera. I'm not/ dont want to take any photos with the lens. If I were taking photos, then I'll connect my camera (dSLR) to a T-mount then to my telescopes (8" Newtonian or 2" refractor) and a tracking equatorial mount/ GPS tracker OR connect my telescopes to a T-mount and to an eyepiece holder tube and to my camera (compact). I have all the above setups.

But my aim is to be able to convert all my K-mount lens to different telescopes!

Correct me if I'm wrong, isn't a slr lens (tele/ super tele) already half of a telescope (i.e. the objective piece). So to make a full telescope, one would need to add an eyepiece at a calculated length to create a projectable real/ inverted image?

Any idea?

Thanks

QuoteOriginally posted by PentaxPoke Quote
Are you trying to use a lens as a telescope by connecting a K-mount lens to telescope eyepieces?
That's right! Is that possible or had I got my theories mix up? I'm no optics expert, please correct me if I'm wrong.
02-15-2009, 04:49 AM   #12
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QuoteOriginally posted by Luciferase Quote
Had anyone seen any adaptor that could convert a K mount lens (not a m42) to a 1.25" eyepiece holder?

If so, where could I buy one?

It's going on my tamrom 70-300mm.

Thanks
No, the usual eyepiece adapters (original Pentax, Vivitar or whatever) all have a fixed 10mm eyepiece. The only 1.25-adapter for lenses, I have seen ready-made are those for M42 (BW Optics, Germany) or T2 lenses (Baader Planetarium). You could machine something yourself or get it done. I would use a simple helical focuser with the K-mount on one side and the eyepoiece holder on the other. The helical mount should help finding focus for different eyepieces. The whole assembly could get fairly long, if you use long fl eyepieces, though.

Ben
02-15-2009, 05:37 AM   #13
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QuoteOriginally posted by Ben_Edict Quote
No, the usual eyepiece adapters (original Pentax, Vivitar or whatever) all have a fixed 10mm eyepiece. The only 1.25-adapter for lenses, I have seen ready-made are those for M42 (BW Optics, Germany) or T2 lenses (Baader Planetarium).
Ben
Oh, ya, sorry I was referring to a telescope eyepiece (barrel diameter of 1.25"). There are plenty of eye relief ranges for them (for as low as 5mm to as high as 25mm). There are even those with zooms (8-24mm).

Such as:
Super Zoom Plossl Eyepiece 8-24mm 1.25" Telescope New - eBay, Telescopes, Binoculars Telescopes, Photography. (end time 16-Feb-09 09:00:00 AEDST)

As for custom design and drill work. I only wish I have that experience on metal work and know how.

Cheers.
02-15-2009, 11:11 AM   #14
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QuoteOriginally posted by Luciferase Quote
Ya, no camera. I'm not/ dont want to take any photos with the lens. ... my aim is to be able to convert all my K-mount lens to different telescopes!
OK, so by "K-mount lens to telescope" you don't mean "CONNECT K-mount lens to telescope" but rather "CONVERT K-mount lens INTO a telescope". In other words, you want to use the lens as the telescope's objective.

I don't know of anything that will connect to the mount side of the lens other than a camera, telephoto adapter, or extension tubes. You don't want to use the camera, and the telephoto adapter or extension tubes just give you another exact same mount to deal with, so they're not helpful.

You could use the filter thread adapter I mentioned above with the lens reversed, but I don't think this would work very well. Other than that, I'm sorry but I can't offer any suggestions other than to take an extension tube and modify it somehow.
02-15-2009, 11:28 AM   #15
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vivitar makes one or did many years ago

If I can find mine I will post a photo
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