PINHOLE test with sunflower & UV filters

[photoni]

PINHOLE test with UV filters

 

The potted sunflowers have arrived.

How to try Tangsinuo's filters?
Theoretically, only a pinhole has no lens limits.
the problems are the necessary power and the reflections of the glass
(it would probably be better to put them behind the pinhole)

 

Sony A7 f.s. focal distance approx ~ 45mm ~ f: 300
0.15mm pinhole (non laser, abrasion technology for microscope use)

All photos are with 1000w full power studio flash
I didn't add saturation, just a brightness and contrast curve.

 

- the first image is with a nude pinhole
- QB39 - 50iso
- TSN575 + QB5 - 1600iso
- TSN575 + QB29 - 1600iso
- TSN575 + ZB2 - 1600iso
- TSN575 + ZWB3 - 6400iso
- TSN575 + ZWB2 - 12800iso
- TSN575 + ZWB1 - 12800iso

 

Thanks
Antonio

 

 

 

[OlDoinyo]

That is very good image sharpness for digital pinhole images..

[colinbm]

Good pinhole comparisons.

[Nate]

Great images, I'm thinking of a way to get a pinhole closer to my sensor as my mirrored cams are no go as is.

[photoni]

@Nate I mounted the pinhole on a Nikon AI ring
has the same focal distance on Nikon DSRL and Sony A7 with AI lens adapter
it is the same concept as the "caps" for sale

 

according to the (constant Lord Rayleigh ... 1.9 = ø 0.30 = fl 45.33mm = f: 151)

a pinhole of 0.15 is suitable for a focal length of 27.6mm
in fact I have another mounted on the Leica much closer to the film

[photoni]

these are the versions with L. Meritar 50mm f: 2,9 @ f: 11

 

the first "naked" version is missing

the 3 and 4 are with two similar filters QB29 and BG25Jena (with Tsn575)

 

Surprisingly, there are no major color differences

 

 

[Yves W]

Thanks Antonio, very interesting 

[Doug A]

@photonilove seeing these comparisons. Lots of info to take in. Appreciate your skill and time put into these tests.

 

The pinhole images are some of the sharpest pinholes I've seen. The Meritar matchs the color range of the pinhole. Amazing performance.

 

Thanks for sharing,

Doug A

[ulf]

On 4/26/2022 at 8:18 PM, photoni said:

- the first image is with a nude pinhole
- QB39 - 50iso
- TSN575 + QB5 - 1600iso
- TSN575 + QB29 - 1600iso
- TSN575 + ZB2 - 1600iso
- TSN575 + ZWB3 - 6400iso
- TSN575 + ZWB2 - 12800iso
- TSN575 + ZWB1 - 12800iso

The image sets are very nice for comparison of different filter effects.

 

However the description of the filters is lacking essential information.

They only tell what filter glass material is used.

With these kinds of technical filters it is essential to state both the glass material and the thickness to give a meaningful indication of the filters transmission characteristics.

Different glass thickness of the same glass material normally affect the image appearance much more than batch variations in the glass.

 

Here are an example from my filter collection of a few filter glass types in different thicknesses:

UG2A (white on dark pink label): 2.0mm 1.0mm and 0.7mm

ZWB3 (blue on white label): 3.0mm and 2.5mm 2.0mm

UG5 (gold on black label): 1.5mm and 1.0mm

 

[photoni]

thanks @Yves W thanks @Doug A thanks @ulf very nice and practical your filter holder

 

I finally got to the final stage of my project.

I don't have scientific methods for measuring photographic lenses and filters ... and I don't need to measure them.
I just need to understand my tools and use them for what they are.

for filters ... whether they are 1.5mm 2 or 2.5 thick it doesn't matter, I care what they do, I won't buy others, so I need to understand the best stack to emulate the wet plate (collodion) with what I have.

 

the same thing is for the lenses, I thought you needed dedicated lenses, but I realized that there are no big differences with these filters, between a pinhole and a discrete lens.

yesterday I found in a drawer an old lens for photo enlarger, an Astron 150mm f4.5 (new costs € 49) and I saw that it works well ... (probably it's a triplet)
this weekend I won an auction in England for a Prinz Galaxy 35mm f:3,5, it should be a good Koei clone, we'll see.

 

ULF ... Tangsinuo wrote that all filters are 2mm thick.
in this photos I have always used the TNS575 filter for IR blocking
QB39 (~ BG39) 1.5mm thick does not work :(
(I also tried a BG18 Jena 2mm thick that blocks IR well but is darker)

 

these are the technical information of the photos taken with the L. Meritar f: 2,9

1 - QB39 (50iso - f16  ~16w?!)
2 - TNS + QB5 (50iso - f11 - 125w)
3 - TNS + QB29 (100iso - f11 - 125w)
4 - TNS + BG25 (100iso - f11 - 125w) Jena 2,2 thick
5 - TNS + ZB2 (200iso - f11 - 125w)
6 - TNS + ZWB3 (200iso - f11 - 500w)
7 - TNS + ZWB2 (200iso - f11 - 1000w)
8 - TNS + ZWB1 (200iso - f11 - 1000w)

 

 

[ulf]

59 minutes ago, photoni said:

 

for filters ... whether they are 1.5mm 2 or 2.5 thick it doesn't matter, I care what they do, I won't buy others, so I need to understand the best stack to emulate the wet plate (collodion) with what I have.

59 minutes ago, photoni said:

 

 

ULF ... Tangsinuo wrote that all filters are 2mm thick.
in this photos I have always used the TNS575 filter for IR blocking
QB39 (~ BG39) 1.5mm thick does not work :(

(I also tried a BG18 Jena 2mm thick that blocks IR well but is darker)

 

these are the technical information of the photos taken with the L. Meritar f: 2,9

1 - QB39 (50iso - f16  ~16w?!)
2 - TNS + QB5 (50iso - f11 - 125w)
3 - TNS + QB29 (100iso - f11 - 125w)
4 - TNS + BG25 (100iso - f11 - 125w) Jena 2,2 thick
5 - TNS + ZB2 (200iso - f11 - 125w)
6 - TNS + ZWB3 (200iso - f11 - 500w)
7 - TNS + ZWB2 (200iso - f11 - 1000w)
8 - TNS + ZWB1 (200iso - f11 - 1000w)

 

 

Tony, I fully understand your point of view for the filters.

 

However it is essential for the understanding of less experienced members to realise that it is the combination of material and thickness that gives the final transmission characteristics. They might want to replicate what you have done and fail if they do not have the same filter thicknesses.

 

That is why I am nagging at you to always include the thickness information.

 

Your QB39 failed because it is too thin. It might have to be 2.0mm or even 2.5mm to work the way we want it to do.

Stacking two 1.5mm filters gives enough rejection, but the extra surface losses increase the needed exposure time by ca 10% and the extra 0.5mm thickness beyond 2.5mm adds even more exposure time

The real BG39 has a sufficient density to work well at 2.0mm

 

The reason I have so many different thicknesses of the same glass types is that they perform differently and sometimes the illumination characteristics give a need for a different filter that typically used.

 

The UG2A, 2mm stacked with a S8612, 2mm or a BG39, 2mm is dense enough to give really deep black areas in flowers where they are supposed to be just like a pure UV-Pass filter stack and also gives a bit more chromaticity as it includes some near UV-violet.

The UG2A, 1mm stacked with a S8612, 2mm or a BG39, 2mm gives images a bit like your ZWB3 stack, but with a really dark green centrum, instead of black.

 

---

The Aston image looks very promising.

 

 

 

[photoni]

10 hours ago, ulf said:

However it is essential for the understanding of less experienced members to realise that it is the combination of material and thickness that gives the final transmission characteristics. They might want to replicate what you have done and fail if they do not have the same filter thicknesses.

 

@ulf Yes you are right

 

it's just a curiosity otherwise I would buy measuring instruments.

but as a rookie I am satisfied with the results ... also because I have non-certified filters

and the curves provided are approximate, and very different from the schott ones.

by the way i looked at the 2021 catalog, schott UG2A and UG1 look like twins.
UG5 is very different from ZWB3 curve
the S8612 seems unsafe for IR .... maybe they are 1mm thick curves?

 

 

[ulf]

18 hours ago, photoni said:

by the way i looked at the 2021 catalog, schott UG2A and UG1 look like twins.
UG5 is very different from ZWB3 curve
the S8612 seems unsafe for IR .... maybe they are 1mm thick curves?

 

 

This is another example of how important it is to combine glass type and thickness when comparing or selecting filters like these.

The UG2A looks like a UG1 twin because it is displayed for 3mm thickness. The graphs for all the other filters are for 1mm filter glass.

 

I have been looking at the filter characteristics  for the filters above in Schott's filter calculation tool for Excel:

For universal usage in all kinds of filter stacks the S8612 should be 2mm thick to well block the IR contamination completely.

It is possible to tweak the filter thickness for specific glass combinations using thinner BG glass, but then it will not attenuate IR enough for other combinations.