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Slimmest M42-helicoid
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PostPosted: Sat Oct 27, 2018 1:02 am    Post subject: Slimmest M42-helicoid Reply with quote
Which length has slimmest helicoid with M42-thread? if slimmer also bigger mount accepted.


PostPosted: Sat Oct 27, 2018 8:44 am    Post subject: Re: Slimmest M42-helicoid Reply with quote
europanorama wrote:
Which length has slimmest helicoid with M42-thread? if slimmer also bigger mount accepted.


Ready available some 10-12mm, custom made some 8mm (but company no longer exists who made mine)


PostPosted: Sat Oct 27, 2018 10:20 am    Post subject: Reply with quote
want to mount special lens with 25,5mm register mounting on nikon Z. maybe M42 helicoid is too narrow. could vignet. is there a larger helicoid also with 8mm extension? will see the Z right now this afternoon.


PostPosted: Sun Oct 28, 2018 3:39 pm    Post subject: Reply with quote
europanorama wrote:
want to mount special lens with 25,5mm register mounting on nikon Z. maybe M42 helicoid is too narrow. could vignet. is there a larger helicoid also with 8mm extension? will see the Z right now this afternoon.

M42 mount was designed for 35mm film so shouldn't cause any vignetting issues with the vast majority of lenses.
As well as the new helicoids available it is possible to use the helicoid from a junk lens after removing the lens elements, possibly even having the mounting flange of your lens recessed quite some way into the helicoid. Some of the modifications I've seen on-line do this to make use of the iris from the old lens with an adapted lens that doesn't have an Iris.
I suspect the biggest issue will be getting the helicoid mounted on the Z mount - I've not seen many adapters yet.


PostPosted: Mon Oct 29, 2018 4:17 am    Post subject: Reply with quote
Novoflex has a very slim adapter but it will not make the 8mm helicoid shorter. max. 9.5mm to reach infinty would be the goal.
no- lens cannot be altered. rearlens alnmost in a line with end of body. mounting on lensside also is not a big problem. only register. maybe i will have to accept hyperfocal distance and not getting real infinity. if overall thickness of adapters and helicoid will be 2.5mm longer than the 9.5mm-ending at 12mm. with highspeed lens this could be a problem when no stopped down. It could last longer till i will have a Z. like focus-peaking better in R than in Z. Canon has an additional wings-like flag. when wings are coming up vertically to vertical line focus is signalled with the line in green. white when not in focus. when not infocus pattern like an upside down T. of i dont err.
beside this both cams shown the same old focus-peaking meachnisme.
on Canon R during manual focus-peaking on cannot zoom-in. how is Z? i didnt go back to check at nikon-stand.


PostPosted: Mon Oct 29, 2018 8:17 am    Post subject: Reply with quote
europanorama wrote:
Novoflex has a very slim adapter but it will not make the 8mm helicoid shorter. max. 9.5mm to reach infinty would be the goal.
no- lens cannot be altered. rearlens alnmost in a line with end of body. mounting on lensside also is not a big problem. only register. maybe i will have to accept hyperfocal distance and not getting real infinity. if overall thickness of adapters and helicoid will be 2.5mm longer than the 9.5mm-ending at 12mm. with highspeed lens this could be a problem when no stopped down. It could last longer till i will have a Z. like focus-peaking better in R than in Z. Canon has an additional wings-like flag. when wings are coming up vertically to vertical line focus is signalled with the line in green. white when not in focus. when not infocus pattern like an upside down T. of i dont err.
beside this both cams shown the same old focus-peaking meachnisme.
on Canon R during manual focus-peaking on cannot zoom-in. how is Z? i didnt go back to check at nikon-stand.


Well there is an old trick I have used when I was still using NIKON cameras Twisted Evil

It is what I call, "the sunken mount", i.e. take a quite larger helicoid and make a front inset, which allows the lens to dive into the front of the helicoid hence shortening the optical distance. Conveniently there are now cheap M65 helicoids available which were made to mount larger lenses, so this should be much easier than what I had to do years ago.

Here what I had done with my mechanic: http://photographyoftheinvisibleworld.blogspot.com/2010/12/ultraslim-helicoid-allows-infinity.html

I reached an effective optical length of minimum 5.3mm then Wink

As I said, this is not DIY, you need an experienced and skilled mechanic with a lathe for that...


PostPosted: Mon Oct 29, 2018 12:18 pm    Post subject: Reply with quote
Hab genau da drangedacht. Vermutlich ist die linse zu dick. werd dann halt gezwungenermassen fixe ringe machen lassen also min, und max. zb. oder drei. novoflex hat einen sehr dünnen ring. rsp zwei für gfx und Z. mal schauen.
Thought about the same using larger helicoid 65mm. think about using fixed-lenght tubes. maybe three versions. all within 12-9.5mm approx. in total. 9.5, 11 and12 or longer.


PostPosted: Mon Oct 29, 2018 12:24 pm    Post subject: Reply with quote
europanorama wrote:
Hab genau da drangedacht. Vermutlich ist die linse zu dick. werd dann halt gezwungenermassen fixe ringe machen lassen also min, und max. zb. oder drei. novoflex hat einen sehr dünnen ring. rsp zwei für gfx und Z. mal schauen.
Thought about the same using larger helicoid 65mm. think about using fixed-lenght tubes. maybe three versions. all within 12-9.5mm approx. in total. 9.5, 11 and12 or longer.


Like 1


PostPosted: Mon Oct 29, 2018 2:43 pm    Post subject: Reply with quote
kds315* wrote:
europanorama wrote:
Novoflex has a very slim adapter but it will not make the 8mm helicoid shorter. max. 9.5mm to reach infinty would be the goal.
no- lens cannot be altered. rearlens alnmost in a line with end of body. mounting on lensside also is not a big problem. only register. maybe i will have to accept hyperfocal distance and not getting real infinity. if overall thickness of adapters and helicoid will be 2.5mm longer than the 9.5mm-ending at 12mm. with highspeed lens this could be a problem when no stopped down. It could last longer till i will have a Z. like focus-peaking better in R than in Z. Canon has an additional wings-like flag. when wings are coming up vertically to vertical line focus is signalled with the line in green. white when not in focus. when not infocus pattern like an upside down T. of i dont err.
beside this both cams shown the same old focus-peaking meachnisme.
on Canon R during manual focus-peaking on cannot zoom-in. how is Z? i didnt go back to check at nikon-stand.


Well there is an old trick I have used when I was still using NIKON cameras Twisted Evil

It is what I call, "the sunken mount", i.e. take a quite larger helicoid and make a front inset, which allows the lens to dive into the front of the helicoid hence shortening the optical distance. Conveniently there are now cheap M65 helicoids available which were made to mount larger lenses, so this should be much easier than what I had to do years ago.

Here what I had done with my mechanic: http://photographyoftheinvisibleworld.blogspot.com/2010/12/ultraslim-helicoid-allows-infinity.html

I reached an effective optical length of minimum 5.3mm then Wink

As I said, this is not DIY, you need an experienced and skilled mechanic with a lathe for that...


I thought I must have seen something on sunken mounts previously - they are something I've often considered but never really tried. They do look like an very useful accessory as long as the aperture control doesn't become impossible to adjust, or the lens isn't recessed so much the helicoid becomes visible.


PostPosted: Sun Jan 13, 2019 1:02 pm    Post subject: Reply with quote
There are some 58, 65 and even 82mm helicoids, but they will cost an arm and leg Very Happy
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