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03-15-2019, 07:50 PM   #1
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M75-150/4 - a solution to a spotting scope problem?

I thought I'd share my recent thoughts on using a spotting scope convertor on camera lenses...

When I travel (FF & film) I usually take the following: FA20-35/4, FA43 & M135/3.5 which gives me a good range of options (I don't mind the gap between 43 & 135). The M135 is a very compact lens, has a built-in hood, takes 49mm filters and has enough reach for many subjects - as such it's a good companion to the others. I also take a pair of compact 8x30 binoculars but would also like to carry some kind of spotting scope. Some time ago I bought a Kenko 45 degree 'Lens2Scope' NEW KENKO LENS2SCOPE ADAPTER – Kenko Tokina USA (turns a camera lens into a spotting scope with a power of focal length divided by 10) but finding a suitable lens for it wasn't easy.

The Lens2Scope has it's own small tripod foot or if your lens has it's own you can remove it. With something like a 400 or 500mm tele with a tripod collar it can produce very good results (my Tamron 500/8 mirror is roughly optically equivalent to my 4.5" reflecting astronomical telescope at 45x - at a fraction of the size). The Lens2Scope small tripod foot limits the use of lenses without tripod collars to compact & light ones which won't overload the foot (or in all likelihood the small travel tripod I plan to take). With the M135 it gives a good 13.5x spotting scope, an increase over the binos but longer would be preferable. A zoom would also be preferable to allow easier alignment at lower power before zooming in.

Attempts to use the 70-210 zooms I have (Vivitar 70-210/2.8-4 QDOS & Tamron SP 70-210/3.5 19AH)* weren't very successful as they're too long and heavy for the tripod foot. This is where my recent purchase of the M75-150 comes in - it's compact and light enough to not overload the foot, has good reviews (I haven't had chance to test mine properly yet), has a built-in hood and takes 49mm filters. It also provides more range & reach than the M135, it is only slightly bigger/heavier and is almost as fast.

* I also have a non-SMC F 70-210 - although it works reasonably well as a spotting scope, I doubt it's optics are sufficient for photography so won't be travelling with it.

03-15-2019, 08:49 PM   #2
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Just a thought on using longer or heavier lenses. Would you be able to mount the tripod foot into a longer plate for better balance on a tripod?
03-15-2019, 09:04 PM   #3
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This is interesting, could you show a photo or two of the rig?
03-16-2019, 06:30 AM   #4
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Shots of the rig are below, I'd forgotten that the lens mounts upside down on the Lens2Scope for some reason - if you have a lens with a tripod collar, the collar must therefore revolve to 180 degrees to have the eyepiece vertical.

As this is intended as a travel setup with shorter lenses, I've shown those with the travel tripod I'll be travelling with - hama Traveller Mini Pro and the head supplied with it, which is very light (700g), rises to about 4 feet but isn't that sturdy (OK for a spotting scope, probably not shooting with a K-1). The 400 & 500mm lenses would overload the tripod foot and probably ball head - I've shown those on my Manfrotto 190Go, an old (but light) Uni-Loc 30 ball head. Aligning the longer lenses at 40x & 50x is not straight forward.

Pentax-M 75-150/4 (7.5x-15x):

Pentax-M 200/4 (20x):

Sigma KA 400/5.6 APO (40x):

Tamron SP 500/8 55B (50x):

Tamron SP 500/8 55B with an earlier 'straight through' monocular converter (50x):

---------- Post added 03-16-19 at 01:42 PM ----------

QuoteOriginally posted by Thagomizer Quote
Just a thought on using longer or heavier lenses. Would you be able to mount the tripod foot into a longer plate for better balance on a tripod?
You could probably mount it on something like an Arca-Swiss rail and slide it forwards/backwards, but the foot is only plastic and slides/clips onto the converter - too heavy a lens would break it or make it hard to lock it in position.

I don't have a lens between 200 & 400mm with a tripod collar, I think something like my Sigma 70-300 APO would be too heavy.

Last edited by johnha; 03-16-2019 at 06:54 AM. Reason: Added the magnification powers for clarity.

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