Lens for increasing magnification on Photron Fastcam SA-X2

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Sebs
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Post by Sebs »

@dickb, I am exactly going that route with just trying a teleconverter. Maybe that will give me sufficiently large magnification. I will get it maybe Saturady or Monday.

I also got a recommendation for higher magnification from Infinity Optics. They recommended:

Model K2 DistaMax Single-Port Main Body \
NTX Tube (2x)
CF-1/B Objective T2 Adapter Nikon F-mount

By adding another NTX tube, I can achieve even more magnification. So it would be a nice and flexible solution.

Bob-O-Rama
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Thats a tough one...

Post by Bob-O-Rama »

I have the K2-Distamax tube and the older K2-SC tube and the CF-1 ( but oddly enough the CF-1B is the only one I don't have ) which I set up last night with the NXT. At ~3x total I was around f/8 or a tiny bit better in terms of actual light collected.

The 150/2.8 will have a larger front element, so with both needing to be 200mm away, it should win on a NA basis. So it may be the winner by a stop. However I expect to get to 3x you need about 4x of rear converters.

If you have a port hole you are shooting through, make sure that is not going to act as a stop. If that's your situation draw out a ray trace of the peripheral rays from the subject plane, through the window, to the front element of your lens. I only mention this because I witnessed a very expensive mistake involving a big lens and a tiny porthole. It was laughable.

Anyway, fun puzzle for sure. Do you get to keep the $100,000 laser?

dickb
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Post by dickb »

Sebs wrote:@dickb, I am exactly going that route with just trying a teleconverter. Maybe that will give me sufficiently large magnification. I will get it maybe Saturady or Monday.

I also got a recommendation for higher magnification from Infinity Optics. They recommended:

Model K2 DistaMax Single-Port Main Body \
NTX Tube (2x)
CF-1/B Objective T2 Adapter Nikon F-mount

By adding another NTX tube, I can achieve even more magnification. So it would be a nice and flexible solution.
I am not familiar with this system, but looking at the images it seems like this may result in less light hitting your sensor, compared to your Sigma 150/2.8. NTX tubes are teleconverters, right? They may be high quality and robust, but if your goal is to gather more light then this may not be the way to go.

Sebs
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Joined: Tue Oct 15, 2019 3:26 pm

Post by Sebs »

Could I use 2 sigma teleconverters (one 2x and one 1.4x) with my sigma lens? I am really just considering the Infinity optics solution, if we want to go to higher magnifications.

Lou Jost
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Post by Lou Jost »

Again, if you need higher magnification via teleconverters, there doesn't need to be any light loss if you can concentrate your beam energy on the actual area being imaged.

A pair of good teleconverters can still give acceptable resolution. The Nikon 1.4x converter is superb. I'd go with that rather than the Sigma, just because I know it is great. I do not have experience with the Sigma.

enricosavazzi
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Post by enricosavazzi »

dickb wrote:[...] so maybe a manual focus 300/2.8 or even 400/2.8 with extension would work for you.
Large-format enlarger lenses could also become useful, although not especially fast. 240, 300 and 360 mm f/5.6 to f/8 are not difficult to find on the second-hand market. They require a very long extension from the camera to work at 2x or 3x, but this can be built with flocked plastic or cardboard pipes.
--ES

Sebs
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Joined: Tue Oct 15, 2019 3:26 pm

Post by Sebs »

Lou Jost wrote:
A pair of good teleconverters can still give acceptable resolution. The Nikon 1.4x converter is superb. I'd go with that rather than the Sigma, just because I know it is great. I do not have experience with the Sigma.
I am just not sure, if the Nikon Teleconverters are compatible with my sigma lens. The Sigma ones are.

I think the 200 mm Macro lens from Nikon would be optically superior and I might be able to use the Nikon Teleconverters with it.

Sebs
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Joined: Tue Oct 15, 2019 3:26 pm

Post by Sebs »

enricosavazzi wrote:
dickb wrote:[...] so maybe a manual focus 300/2.8 or even 400/2.8 with extension would work for you.
Large-format enlarger lenses could also become useful, although not especially fast. 240, 300 and 360 mm f/5.6 to f/8 are not difficult to find on the second-hand market. They require a very long extension from the camera to work at 2x or 3x, but this can be built with flocked plastic or cardboard pipes.
Making extension tubes would not be a problem. I have access to nice CNC machines and could easily design and turn one on a lathe. I just don’t have any experience with which of these lenses are good and then there is the concern of working distance.

enricosavazzi
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Post by enricosavazzi »

Sebs wrote:
enricosavazzi wrote:
dickb wrote:[...] so maybe a manual focus 300/2.8 or even 400/2.8 with extension would work for you.
Large-format enlarger lenses could also become useful, although not especially fast. 240, 300 and 360 mm f/5.6 to f/8 are not difficult to find on the second-hand market. They require a very long extension from the camera to work at 2x or 3x, but this can be built with flocked plastic or cardboard pipes.
Making extension tubes would not be a problem. I have access to nice CNC machines and could easily design and turn one on a lathe. I just don’t have any experience with which of these lenses are good and then there is the concern of working distance.
Enlarger lenses are fairly simple optical schemes, so no telephoto and no retrofocus designs, and entrance and exit pupils almost always are within the physical lens.

In practice, with these lenses the distance between lens and camera sensor plane is roughly equal to focal length when the lens is focused at infinity, twice the focal length when the lens is focused at 1x, three times at 2x etc.

Distance between lens and subject is roughly twice the focal length at 1x, and somewhere between 1x focal length and 2x focal length at magnifications above 1x.
--ES

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