Hermagis Eidoscope

[Marko Trebusak]

Also I found that the aperture of this type lens is scaled something like 5, 6, 7,14, 20..., does this mean the max aperture is f5, how can I change these numbers to modern stops commonly used today, such as f8, f11, f16 etc.

Thx,
firestar

If you type "french f-stop" into this forum's search engine, you'll find this thread.

Cheers,
Marko

[Jim Galli]

Wow, good resource, just found it.

I'm considering to get a Hermagis Eidoscope lens No.4 for my 4x5, based on your discussion, No. 4 will be 7 1/2", Anybody know if it can cover 4x5?

Also I found that the aperture of this type lens is scaled something like 5, 6, 7,14, 20..., does this mean the max aperture is f5, how can I change these numbers to modern stops commonly used today, such as f8, f11, f16 etc.

Thx,
firestar

You don't need to change anything, just get used to thinking in 1/3rd stops from they system you're used to. All the "action" with these lenses occurs before f8. After that they're just sharp. Very sharp. So f5, f6, f7 are all 3rd stops, f5 being close enough to 5.6 to be identical, f6 being 5.6 + 1/3, f7 being 5.6 + 2/3, f10 being f8 + 2/3, and f14 being f11 + 2/3. No big deal. If you paid the $$$ for one of these, you'll want to be down in the f5 f6 f7 world I would think.

[firestargps]

If you type "french f-stop" into this forum's search engine, you'll find this thread.

Cheers,
Marko

Marko, I've noticed that thread, but they are different stop system. Thanks, anyway.

[firestargps]

You don't need to change anything, just get used to thinking in 1/3rd stops from they system you're used to. All the "action" with these lenses occurs before f8. After that they're just sharp. Very sharp. So f5, f6, f7 are all 3rd stops, f5 being close enough to 5.6 to be identical, f6 being 5.6 + 1/3, f7 being 5.6 + 2/3, f10 being f8 + 2/3, and f14 being f11 + 2/3. No big deal. If you paid the $$$ for one of these, you'll want to be down in the f5 f6 f7 world I would think.

Very clear and superb helpful, 5 6 7 10 14 is really modern stop system although not aligned to normal used system 4 5.6 8 11 16 ..., thanks so much Jim. Sure, I'll leverage f5, f6, f7 for its special effect.

Salute!
firestar

[Scott Davis]

Sorry to resurrect an old thread, but does anyone have an idea of when the Eidoscope switched from waterhouse stops to a mechanical aperture?

[Steven Tribe]

No apologies needed! Better a continuation than a new start.

I can't answer the question, but will just mention that a number of makers advertised their lens in many versions at different prices at the same time. With/without shutters and with iris/WHS. Not always a matter of price differences, stereo pairs are best with WHS.

[renes]

I have never seen Eidoscope was selling with yellow/orange filter. It seems this one was originally sold with such filter, so, is it uncommon for Eidoscope?:

261853915401

Numbers work backwards on Eidoscop. 0=24" 1=19" 2=14 3/4" 3=11" 4= etc.

What FL are no. 4", 5" (6" = 150mm) ? Was there also no.7?

[renes]

Noted No.4 is 7 1/2"

Anybody knows what fl is no.5 Eidoscope?

[Jim Galli]

Noted No.4 is 7 1/2"

Anybody knows what fl is no.5 Eidoscope?

Perhaps they dropped the numbers after 4? The 150's were sold in a case as groups that were designed for standard Compur #1 shutters. I've not noted smaller than the 150mm ones Although cine versions would have been logical.

[renes]

Thanks Jim.