Discussion of Collodion Emulation

[photoni]

I re found these photos of the cactus flower set with the 20x25 cm camera.

and the "ambrotype" positive photo on black anodized aluminum.

 

There is also a negative photo on clear glass, this was used for the blueprint of page 1

 

it seems to me that with there are not a UV signals, when they bloom I will try with the A7 full spectrum

[colinbm]

Lovely flower, great equipment.

[photoni]

today my neighbor's cacti are in bloom

I took some pictures, the most significant are with BG39 which looks a lot like normal vision and BG25 + BG39 to see if there are UV signals ... it doesn't seem to me!

[ulf]

Those pictures look good and are well white balanced Toni.

My guess is that the image with BG39 only might lack a little bit of the red compared to how it looks in real life.

It must not be so, but the BG39 do cut away the deepest red wavelengths and if there were any seen from the flower they will have been removed in the image.

 

Such flowers on cacti are very rarely seen here.

They look beautiful. Do they have any scent?

[colinbm]

Nice work Toni on a lovely flower.

[photoni]

Nice work Toni on a lovely flower.

 

Col.. is there an empirical way to see if a lens sees up to 325nm?

I have a micro Nikkor 60mm AFD f2,8

a Nikkor-H 50mm f2

a PC35mm f 3,5

a nikkor-H 24mm f 2,8

and some rodagon magnifying lenses for printing

Thanks

Toni

[colinbm]

Col.. is there an empirical way to see if a lens sees up to 325nm?

I have a micro Nikkor 60mm AFD f2,8

a Nikkor-H 50mm f2

a PC35mm f 3,5

a nikkor-H 24mm f 2,8

and some rodagon magnifying lenses for printing

Thanks

Toni

 

Hi Toni

The simplest way is to make-up a UV Sparticle. You can search for 'Sparticle' on UVP & you will see some examples.

A UV Sparticle is a collection of small 10 - 12mm UV pass filters.

I have mounted 4 x 10mm filters in a rubber disc, mounted in a 52mm filter ring, that I can screw onto a lens.

Three filters, say 320, 340, 360nm narrow pass filters will show you what your camera & lens combination is capable of.

Stefano said this seller has a range of narrow band UVA filters.

https://www.aliexpress.com/item/33050407116.html?spm=a2g0o.store_pc_home.productList_613361818.subject_0

 

 

[ulf]

Nice build there Col.

 

One thing to be observant about here is that all BP-filters are not alike.

Some might have a bad out of band OD giving a false positive result.

For this kind of test the need for a good OD is not as high as for proper UV-photos but as camera sensors are much more sensitive for VIS and IR than for deeper UV-A it is still essential to have a reasonable OD

[colinbm]

Yes thanks for reminding me, Ulf

Toni I would now do this test under the Badder U filter to cut the IR & be sure of the result.

[photoni]

Thanks Col

I was hoping there was an easier and cheaper way.

the "mini" filters cost € 25.66 each.

I thought I was buyng from tangsinuo.com

UG11 = U-340 = ZWB-1 (see a lot of red)

UG1 = U-360 = ZWB-2

and try them with the flash light of my old Elinchrom generators with tubes without yellow anti UV coating (I don't think they emit IR)

.

By applying the Sony F.S. behind the large format,

(placing the filter in front of the Sony camera)

"I would like to see" how large format lenses work.

I have two Petzval from 1860 and some more modern lenses like Industar 37 - 300mm,

and its similar Carl Zeiss Tessar 360mm and 400mm

I have seen that a "new 1980" Rodenstock Sironar with multilayer loses a lot of light with the wet platter.

.

P.S. remember it is sensitive ... around 325 to 510 nm

[photoni]

perhaps the easiest thing is to take a thick ZWB-1 , 8mm filter :)

do you have any idea how much a Ø 72mm costs

[colinbm]

" Thanks Col

I was hoping there was an easier and cheaper way. the "mini" filters cost € 25.66 each. "

 

It depends on how badly you want the answer ?

[colinbm]

perhaps the easiest thing is to take a thick ZWB-1 , 8mm filter :) do you have any idea how much a Ø 72mm costs

 

tangsinuo.com

[colinbm]

I tested my 130mm quartz lens on my Full spectrum Sigma fp with my UV Sparticle & a BaaderU & CWB.