Rodenstock Rodagon 150mm f/5.6 rear diamater?

[JKT]

The title says it all.

I found a catalog, which gave the length of the rear part and flange distance, but the diameter is open. The question is whether I can squeeze it inside T2 extension tube.

[Sym P. le]

http://www.rodenstock-photo.com/Archiv/ ... __8230.pdf

Screw thread for 150mm f/5.6 Rodagon listed as M50x0,75

[JKT]

Thanks, but that catalog I had. The problem is the part that extends behind that M50x.75 thread and there are no dimensions for that except how far behind it extends.

[Sym P. le]

I admit that answer was a little too easy. Your question makes more sense to me now. I guess if the sizing is close, scaling off a photo can only take you so far as well.

[RobertOToole]

The title says it all.

I found a catalog, which gave the length of the rear part and flange distance, but the diameter is open. The question is whether I can squeeze it inside T2 extension tube.

Hi JKT,

Depends on the tube. I have a 5.6/150mm Rodagon here. I tried it on a M42 and there is a little baffle inside that blocks it. The rear cell OD is 40mm.

Better go M52 tube.

Best,

Robert

[JKT]

Thanks Robert!

The ID is 38, so no-go. Back to the drawing board...

What is the position sensitivity for the Rodagon? Does it matter at all if it is say 3 mm off in either direction?

[RobertOToole]

Thanks Robert!

The ID is 38, so no-go. Back to the drawing board...

What is the position sensitivity for the Rodagon? Does it matter at all if it is say 3 mm off in either direction?

Hi JKT,

The position depends, for use as a tube lens or taking lens?

From my experience this week testing a 135mm tube lens (Componon-S), for a couple of hours, focus at infinity was very sensitive, like a 1/4 turn of the variable tube.

But the difference in the results was not that important.

Short focus, or past infinity (less extension). Almost exactly 3mm less extension turned out to be best for the test. I am sure you could use a setting even closer than that but I ran out of travel with my variable tube!

I would guess the Rodagon should react similarly since the designs are so similar, all the 135mm enlarger lenses use a similar design but I don't know for sure.

Best,

Robert

[JKT]

Thanks Robert! I was thinking as a tube lens. With the short focus results you've had I thought it should be fine, but I don't have the lens ... yet.

[RobertOToole]

Thanks Robert! I was thinking as a tube lens. With the short focus results you've had I thought it should be fine, but I don't have the lens ... yet.

Anytime.

As an alternative the 135mm Rodagon, and that would fit in the M42 tube for sure but you have to be careful of corner shading with a full frame sensor.

Too bad you are not closer to California, I have lots of extra tube lenses!

Let me know if I can help.

Best,

Robert

[JKT]

The Rodagon 135 has one flaw - it is too close to Raynox 250, which I already have. I don't need that fine magnification steps ... at least not yet.

The other steps are Canon 100 L IS Macro and Raynox 150 for ~175 & 208 with the Century +4 as next step when I find one.


Corner shading could indeed be a problem as I plan to use T2 adapter inside SM2 tube. I have to do it that way if I want to use DCR-250 with same base system as others. The 77mm SM2 is so long that Raynox goes a bit inside it. I chose the long SM2 in order to get enough distance between clamps. If there is too much shading with others, I'll have to revert to camera base fixing for DCR-250.

[RobertOToole]

The Rodagon 135 has one flaw - it is too close to Raynox 250, which I already have. I don't need that fine magnification steps ... at least not yet.

The other steps are Canon 100 L IS Macro and Raynox 150 for ~175 & 208 with the Century +4 as next step when I find one.


Corner shading could indeed be a problem as I plan to use T2 adapter inside SM2 tube. I have to do it that way if I want to use DCR-250 with same base system as others. The 77mm SM2 is so long that Raynox goes a bit inside it. I chose the long SM2 in order to get enough distance between clamps. If there is too much shading with others, I'll have to revert to camera base fixing for DCR-250.

A trick for corner shading?

I was trying to sell my MakroSymmar 5.6/80 for a couple of years...no one was interested. Than I realized I never tried it as a tube lens, and first try was impressive in the center but the vignetting was really bad, then it hit me to try short focus....that did it, corners were fine, so I'm keeping the MakroSymmar

Also I've found some lenses like distance between the two lenses, 2 or 3 inches, like the Raynox, then other lens pairs have to almost be touching.

Best,

Robert

[Chris S.]

Robert,

Regarding short focus of a converging lens, I keep wondering if it will have a detrimental effect with a high-NA objective. We have theory that it might be problematic, but I don't recall seeing any tests.

You have a Mitututoyo 100x/0.70, don't you?

--Chris S.

[RobertOToole]

Robert,

Regarding short focus of a converging lens, I keep wondering if it will have a detrimental effect with a high-NA objective. We have theory that it might be problematic, but I don't recall seeing any tests.

You have a Mitututoyo 100x/0.70, don't you?

--Chris S.

Good memory Chris! I do have one, I had to double check.

I might have time tomorrow to play around with it. I was just finishing up on a little interesting project I will post tomorrow.

When you pull down a lens with short focus you can pull some lenses down quite a bit but all will eventually suffer IQ loss in the corners. I think this might happen sooner than later with a high-NA lens.

Robert

[Chris S.]

When you pull down a lens with short focus you can pull some lenses down quite a bit but all will eventually suffer IQ loss in the corners. I think this might happen sooner than later with a high-NA lens.

Robert, I was thinking more about spherical aberration and perhaps other issues. There was a post on the topic of using converging lenses at focus points other than infinity. I can't find it right now, and am pretty sure it was written by Rik. The post referenced this graphic. While the data in the graphic were compiled by varying tube length with finite objectives, my recollection is that we should expect similar results when varying converging lens focus with infinite objectives. The upshot was that with low NA objectives, we can get away with considerable change in tube length (or focus of a converging lens). But as the NA of the objective goes up, tolerance of this change goes down.

I'm interested in this because on my rig, with its Mitutoyo MT-1 tube lens, I've shortened focus by 2-3mm to eliminate a variable-length tube that wasn't as robust as I like. I regularly work with a Mitutoyo 100x/0.70 objective, and have never seen any obvious degradation. An NA 0.75 objective that I tested also behaved splendidly. But I wonder, at those larger NA's, if I'm leaving some smidgeon of quality behind. I don't have an easy way to test. . . .

--Chris S.

[RobertOToole]

When you pull down a lens with short focus you can pull some lenses down quite a bit but all will eventually suffer IQ loss in the corners. I think this might happen sooner than later with a high-NA lens.

Robert, I was thinking more about spherical aberration and perhaps other issues. There was a post on the topic of using converging lenses at focus points other than infinity. I can't find it right now, and am pretty sure it was written by Rik. The post referenced this graphic. While the data in the graphic were compiled by varying tube length with finite objectives, my recollection is that we should expect similar results when varying converging lens focus with infinite objectives. The upshot was that with low NA objectives, we can get away with considerable change in tube length (or focus of a converging lens). But as the NA of the objective goes up, tolerance of this change goes down.

I'm interested in this because on my rig, with its Mitutoyo MT-1 tube lens, I've shortened focus by 2-3mm to eliminate a variable-length tube that wasn't as robust as I like. I regularly work with a Mitutoyo 100x/0.70 objective, and have never seen any obvious degradation. An NA 0.75 objective that I tested also behaved splendidly. But I wonder, at those larger NA's, if I'm leaving some smidgeon of quality behind. I don't have an easy way to test. . . .

--Chris S.

That would be easy for me to check with the Thorlabs variable tube setup I have. I'll give it a shot later on today and see what I find out.

The most time consuming part of a test would be find the appropriate target that is flat enough for the 100x. Not having to stack would be save me a lot of time.

I'll report back.

Best,

Robert