telescope adapter

I have a Minolta adapter that you put on the back end of the lens to make it into a Telescope/Spotting Scope. It works very well with such lenses as the old 300mm f/4.5 MC/MD lens. I now have a Sigma 600 f/8 mirror lens that I wish to use as a spotting scope, its mount is not Minolta MC/MD but Konica AR. Was a similar adapter made for this mount? I am getting an adapter AR to FX for use on my Fuji X-Pro1 but would still like to use the 600 Sigma as a spotting scope.

I don't know if telescope adapters were made in Konica mount. They are also known an monocular converters, which may help when doing internet searches.

I don't know if telescope adapters were made in Konica mount. They are also known an monocular converters, which may help when doing internet searches.

 

Thanks John. I was struggling for the correct name. I did a search on Ebay and came up with a bunch of items just like my Minolta one, but none for Konica AR. My next idea is to remove the Minolta mount and replace it with a Konica AR mount from a 2X multiplier and hoping the registration is the same so I can focus at infinity!

According to most charts the Minolta MC/MD registration distance is 43.72mm and the Konica AR is 40.5mm

According to most charts the Minolta MC/MD registration distance is 43.72mm and the Konica AR is 40.5mm

 

OK, then if I am correct and I can replace one with the other, then the AR version will be closer to the lens and I will be able to focus at infinity as a spotting scope. The close focusing will be much less, but this less important than the ability to infinity focus. I have a 2x converter coming from Ebay next week and will try to do this.

 

Or, did I get my reasoning backwards???

If you have 3mm of extra extension to play with, is there a Minolta to Konica adapter available?

 

IIRC, some of those telescope adapters have a focussing eyepiece, so you may not have to be over-precise with the registration from lens to monocular device. The makers almost certainly wouldn't have made the optics camera-specific, so there must be some adjustment somewhere.

I have found two types of telescope adapters - direct, which focus a direct image on the film plane without a lens or eyepiece, and digiscoping adapters, which use both a camera lens and eyepiece. The digiscope adapter centers the camera on the eyepiece in the same way.you would position your eye.

 

Direct adapters are easily found to fit standard 1-1/4" and 2" astronomical telescopes, and have the effect of a lens with a fixed focal length. These adapters usually fit a T-mount adapter for a specific camera lens mount. Since they're passive (no optics) they are relatively inexpensive, accurately centered, and give the best image quality. I have T-mounts for Sony, Nikon and Canon, which fit the same 1-1/4" tube adapter.

 

While you can digiscope with any camera, the security of the mount is questionable. You take advantage of additional magnification from the telescope eyepiece. You focus on a virtual image, with the camera set at infinity, focusing with the telescope only. Centering and distance from the eyepiece is critical if you want the widest field of view. Most people use them with a smart phone, which is lightweight, and gives you a live view. Since you usually have to touch the phone to take the shot, use a 10 second or longer delay to allow vibrations to settle. You can also set up a sequence of shots. My results have not been satisfactory to date, but the setup is rather fussy and I haven't put enought time into getting it right.

 

I have the Novagrade smart phone adapter, with is mostly metal, adjustable, and clamps firmly on the eyepiece with bushings for various sizes. Once set up, it is fairly easy to re-attach it to the telescope and fine tune the position.

 

Novagrade Universal Standard Digiscoping Adapter for Smartphones (Boxed)

Here are two of the breed - the one is a Spiratone T-mount which could be adapted to most older lens mounts/

 

The other is a Soviet TURIST which also works pretty well (actual Praktica mount M42x1).

 

 

Old Photo.net post

Adapter for lens to use as a telescope

I misread the OP, which asked about converting camera lenses into telescopes.

 

To digress, a 1.25" eyepiece tube vignettes in direct view on a FF camera, as does a 2" tube. When digiscoping, you have the advantage of magnification by an eyepiece, which can have a visual field of view up to 80 degrees, enough to fill the frame. The sensor is not exposed to air in a catadioptric or refracting telescope, because the tube (including the eyepiece tube) is closed to the outside. A Newtonian telescope (reflector) is open to the air, but the sensor is largely shielded due to length of the eyepiece tube.