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New M42 to M42 Iris available on ebay (test added)
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seta666



Joined: 19 Mar 2010
Posts: 860
Location: Castellon, Spain

PostPosted: Thu May 19, 2011 1:53 am    Post subject: New M42 to M42 Iris available on ebay (test added) Reply with quote

Hello,
few weeks ago I asked ebay seller jinfinance if he could build a M42 Iris; with the rigth adapters it could be used on bellows with any microscope lens
The Iris is ready 140547138653 ; I asked him to make several adapters for mitutoyo BD 40mm, nikon bd infinity 27mm, Mitutoyo/nikon BD, and RMS, also a M25 adapter would be nice for those Nikon lenses that use that thread. I askd him to make them ring type so the lens will stay close to the iris
Regards
Javier
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Last edited by seta666 on Wed Jun 29, 2011 12:49 pm; edited 2 times in total
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RogelioMoreno



Joined: 20 Nov 2009
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Location: Panama

PostPosted: Thu May 19, 2011 12:46 pm    Post subject: Reply with quote

Thank you.

Rogelio
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ChrisLilley



Joined: 01 May 2010
Posts: 680
Location: Nice, France (I'm British)

PostPosted: Thu May 19, 2011 4:15 pm    Post subject: Reply with quote

Adding an iris is an interesting idea.

I'm puzzled why this is M42-M42. The jinfinance adapters for Nikon CFI etc are to 52mm filter thread. So either this needs 52mm-M42 and M42-52mm adapters, or it needs new objective-M42 adapters ...

Since an infinite objective is used with a tube lens and tube lenses typically don't have M42 mounts on the front, I assume then that this is aimed at finite objectives used on (M42?) bellows.

I see the iris is available separately, which may be a better idea for use with infinite objectives.
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seta666



Joined: 19 Mar 2010
Posts: 860
Location: Castellon, Spain

PostPosted: Fri May 20, 2011 3:54 am    Post subject: Reply with quote

ChrisLilley wrote:

Since an infinite objective is used with a tube lens and tube lenses typically don't have M42 mounts on the front, I assume then that this is aimed at finite objectives used on (M42?) bellows.

I see the iris is available separately, which may be a better idea for use with infinite objectives.


Hello,
I asked an M42 Iris because as you say I use my lenses on Bellows; but I think that the iris makes more sense with infinity lenses, as the use of an iris with these lenses producers no vigneting
I use the bellows with adapted tube lenses (morfanon and somco 240mm) which are fitted inside M42 tubes, so adding the Iris in between is very easy
I already use Iris from stripped down enlarging lenses but is a pain to find the right thread, with this M42 iris and the right adapters I will be able use any microscope lens
I have ordered adapters for 40mm (mitutoyo bd), 27mm (nikon BD infinity) 26mm (mitutoyo BD) and RMS (nikon infinity EPI); custom made for this iris so the lenses will stay as close as possible to the iris
Regards
Javier
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dmillard



Joined: 24 Oct 2006
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Location: Austin, Texas

PostPosted: Sat May 21, 2011 7:46 am    Post subject: Reply with quote

Thanks Javier - this looks very useful.

Regards,
David
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Craig Gerard



Joined: 01 May 2010
Posts: 2877
Location: Australia

PostPosted: Mon Jun 13, 2011 12:13 am    Post subject: Reply with quote

Thanks Javier,

Yep, I'll be adding some of those pieces to my box'o'things in the near future.

The additional adapters that couple with the M42 iris assembly are now available Smile

Some of the listing images show the iris assembly in the photos; but the iris assembly is a separate piece.

Here is the M42 iris assembly:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140547138653

and here are the additional adapters

http://cgi.ebay.com/thin-M42-Nikon-CFI-M25-microscope-objective-adapter-/140563723217

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200619040662



Craig
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seta666



Joined: 19 Mar 2010
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Location: Castellon, Spain

PostPosted: Mon Jun 13, 2011 2:21 am    Post subject: Reply with quote

Thank you Craig,
I was going to update the post today, you did first ;-)
Mine is on the way with some of the adapters, I requested to build adapters for mitutoyo BD plans M40, Nikon BD infinity M27, mitutoyo m plans and nikon BD finite M26; nikon infinity CFI M25 and RMS

Also a M42 to BD flat adapter is now available rathar than just the cone shaped

I hope it works as expected

Regards
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BugEZ



Joined: 26 Mar 2011
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PostPosted: Mon Jun 13, 2011 4:19 am    Post subject: Got my new Iris last week Reply with quote

I purchased the iris mentioned above and installed it in my rig. I am very pleased. I use M42 extension tubes to support my microscope lenses and it installed with no difficulties.

Thanks for bringing the iris to my attention!

Keith
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seta666



Joined: 19 Mar 2010
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Location: Castellon, Spain

PostPosted: Wed Jun 22, 2011 3:18 am    Post subject: Reply with quote

Yesterday I recieved the iris and adapters for mitutoyo BD, nikon BD infinity, mitutoyo M plan / nikon BD and RMS
The Iris is beautifully round, closes to 1mm and has 14 blades; only con would be the blades being a bit more reflective than desired but yesterday I did a quick test and did not notice any contrast lost
The thin adapters allow the rear element of the objective to be 5mm to the Iris, the Mitutoyo BD M40 adapter is thicker in desing and stays 11mm awy from the Iris
From right to Left the iris with mitutoyo BD plan 20/0.42, nikon BD 20/0.46 oo, Mitutoyo M plan 10/0.28 and nikon Epi 50/0.55 ELWD 00 with their adapters

Here the Mitutoyo BD 20/0.42, Iris and Morfanon lens tube inside cheap chinese M42 tubes


As soon as I can run some test I will let you know
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Craig Gerard



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PostPosted: Wed Jun 22, 2011 4:29 am    Post subject: Reply with quote

Javier,

Thanks for the update.

Looking forward to your report.


Craig
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Harold Gough



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PostPosted: Wed Jun 22, 2011 5:41 am    Post subject: Reply with quote

It was jinfinance who supplied (ready made) my X-Pan to micro 4/3 adapter. Nice kit.

Harold
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ChrisLilley



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PostPosted: Wed Jun 22, 2011 11:46 am    Post subject: Reply with quote

I can see that the thin objective adapters, screwing into the body of the iris housing, give a shorter distance between the objective and the iris than would be provided with the existing objective to m52 adapters.

For use with infinity objectives and (non-M42-mounted) tube lenses, M42 macro reversing adapters can be used such as this item

http://cgi.ebay.com/Macro-Coupler-Reverse-Ring-52mm-42mm-1-0-M42-/290324995025
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ChrisLilley



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PostPosted: Wed Jun 22, 2011 12:15 pm    Post subject: Reply with quote

seta666 wrote:

The Iris is beautifully round, closes to 1mm and has 14 blades;


Here are some back of the envelope calculations, I would be interested to see if I have got them right.

A 10x/0.25 objective has an effective aperture at 10x of m/2NA = 10/0.5 = f/20

with a 20μm CoC c, and 550nm wavelength λ, in air (n=1),
DOF = (λ/NA^2) + c(1/mNA))
= 16.8 μm

A 10x infinity lens designed for use with a 200mm tube lens has a focal length of 200/10 = 20mm.

An iris of 1mm diameter on a 20mm lens is f/20 nominal aperture. (20/20=1).

Treating the objective as a 20mm objective, and pretending it is on 220mm of extension to give 10x, stopped down to nominal f/20 would give an effective aperture of
F * (1+m) = f/220
and a DOF = 2Fc((m+1)/(m^2)
= 88 μm

However, the objective is actually a 20mm lens stopped down to f/20 then mounted on a 200mm lens and I don't know how to work out the effective aperture or DOF of the combination.

Maybe I should instead be converting the nominal f/20 back to NA? So NA =1/2F = 1/40 = 0.025

A 10x/0.025 objective at 10x is effective f/200 and the DOF is 960 μm.

Really? almost a millimeter of DOF?
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lauriek
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PostPosted: Wed Jun 22, 2011 12:28 pm    Post subject: Reply with quote

Close to 1mm of DO'something' - not much focus at f200...
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seta666



Joined: 19 Mar 2010
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Location: Castellon, Spain

PostPosted: Thu Jun 23, 2011 12:10 pm    Post subject: Reply with quote

I do not intend to use the 10x at f200, but the iris can be usefull to close a few stops for last shots
closing down to 1mm will allow the iris to be used with my 50x lens, with very smallrear element
one more use for the iris is making objectives work with smaller apertures than they were designed for
I can turn my 10/0.28 into a 10/0.20 or my 20/ 0.46 into a 20/0.35 for subjects that may require that kind of lens (hairy subjects or deep stacks)
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