Differences between a standard Sony A7 and a full spectrum

[photoni]

Differences between a standard and full spectrum Sony A7

Dried leaves and seeds + Jerusalem artichoke flower (topinanbur - Helianthus tuberosus)
The white balance was done on Teflon and gray white marble stone - Raw developed with Capture one
Lens - L. Meritar 50 mm @ f:8 /16 - Elinchrome flash light 500W > 4000W - flash tube with light yellow anti-UV layer

Original file 2000x2509 pixels - photoshop 8 compression (1.385 Mb)

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I did the same test with a Nikon F2 Photomic with 50 mm f 1.4 with "expired" black and white film, I hope to see something :)

[colinbm]

Very nice comparisons Toni.
Looks like the flowers have expired by the last photo.

[Unscenerie]

Nice. Didn't expect a standard Sony A7 could see UV. Exposure time must've been very long, right?

[photoni]

2 hours ago, Unscenerie said:

Nice. Didn't expect a standard Sony A7 could see UV. Exposure time must've been very long, right?

I haven't tried the filters that cut out everything visible, they are too dark.
I was interested in the QB29 ~ BG25
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Sony F.S.  it's 2 stops faster (2000W f:16)
the flower is colorful and there is a big difference between the UV-absorbing center and the lighter periphery of the petals.
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with the standard Sony it is 2 stops slower (2000W f:8)
the internal filter + QB29 cuts all the color.
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This doesn't happen with film BW.

[Andrea B.]

A useful series, Toni. Thanks!

 

Usually we recommend BG38 or its equivalent for visible work with a conversion. So it's good to see that the QB39 is also useful for this.

[Nate]

Nice comparisons Toni, your Sony performs well.

[Yves W]

Thanks Toni, always very interesting

[ulf]

On 10/31/2023 at 7:45 PM, Andrea B. said:

Usually we recommend BG38 or its equivalent for visible work with a conversion. So it's good to see that the QB39 is also useful for this.

Many BG-Glass filters are useful for "restoring" a converted camera to a VIS-only function.

Usually the BG38 2mm gives the best result as it allows all of the red light to pass.

 

Some flowers and maybe other materials have their peak reflectance closer to the first NIR-range at ca 700 nm.

Then a filter like S8612 or BG39 will render those reds very dull or weak.

 

In that aspect the BG38 is best followed by the BG40.

Worst are the S8612 or BG39.

 

Some other objects and flowers have red strong reflectance away from the NIR.

Then the red tones will be less affected like Tony showed above.

 

Using profiling with a colour chart for such VIS images can improve the image, but by limited experience doing so with an image taken with my S8612 is not working that well.

The cutoff wavelengths in red, by the S8612 and BG39 are quite similar and should be equivalent here, assuming a similar filter thickness.

[Doug A]

Great comparison @photoni. Didn't expect a stock camera to match FS so closely. Appreciate all the work you put into this experiment.

Thanks for sharing,

Doug A

[ulf]

1 hour ago, Doug A said:

Great comparison @photoni. Didn't expect a stock camera to match FS so closely. Appreciate all the work you put into this experiment.

Thanks for sharing,

Doug A

 

I would expect that the result would differ much more between a FS- and stock camera if the motif were different.

 

Here most were dried organic things and a few stones.

FS-colours from live matters and some other materials can be very different with a FS-camera.

 

That is what I have seen when returning to collected flowers that dried after I originally shot them in a vase when they were fresh.

[photoni]

On 10/31/2023 at 7:45 PM, Andrea B. said:

 

Usually we recommend BG38 or its equivalent for visible work with a conversion. So it's good to see that the QB39 is also useful for this.

 

I don't have the BG38
This QB39 from Tangsinuo is 1.5mm thick, it doesn't cut all IR - maybe that's why it works well for VIS.

To work with UV filters you need 2 stacked or TSN575

 

59 minutes ago, ulf said:

Here most were dried organic things and a few stones.

 

You're right, I'll do some tests with more colors and fresh subjects

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At that moment I was trying to understand why the same photo of that yellow flower,

which I had taken with "silver" = wet plate = collodion, the flower was all black.

(very similar to the standard Sony + BG25)

[ulf]

7 minutes ago, photoni said:

 

I don't have the BG38
This QB39 from Tangsinuo is 1.5mm thick, it doesn't cut all IR - maybe that's why it works well for VIS.

To work with UV filters you need 2 stacked or TSN575

 

That is likely the reason. I have not tried such a thin BG39 or QB39. My such filters are all close to 2mm thick.

 

I forgot that you some time ago told us that you had a 1.5mm QB39.

The thickness is just as important as the glass type when comparing transmission and photo results from these technical glass optical filters.

 

You should have the full recipe, just as you need the amounts of ingredients in a cooking or drink mixing recipe.

[Doug A]

15 hours ago, ulf said:

 

I would expect that the result would differ much more between a FS- and stock camera if the motif were different.

 

Here most were dried organic things and a few stones.

FS-colours from live matters and some other materials can be very different with a FS-camera.

 

That is what I have seen when returning to collected flowers that dried after I originally shot them in a vase when they were fresh.

Good point @ulf. I want to try UV with my stock Pentax 645Z. Coincidentally my adapter arrived allowing EL-Nikkors to fit the Pentax.

Thanks,

Doug A

[photoni]

Sony A7 standard - ABOVE
Sony A7 full spectrum - BELOW

the backdrop at the top right is Teflon with a Teflon tape

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Big= Jerusalem artichoke flower - Helianthus tuberosus
and three types of Bidens, white, yellow, and white + yellow
interesting to see how the Bidens white in UV becomes purple and the white of the two-tone one remains white.
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VIS - VIS with QB39 (1.5 mm t.)

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QB39+QB5

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QB39+QB29

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TSN575+QB29

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TSN+ZWB3 (oxidized)

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TSN+ZWB2 (does the photo above have an X caused by internal reflections of the helicoid?)

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[colinbm]

Good show Toni
The X is it internal or it looks like external, try wrapping something dark around it ?

[photoni]

it's black week
the latest Capture One in Italy costs 50% = €174.50
I can't use it because I have an old OS 10.15
Does anyone have version 22 to sell me?
Thank you

Toni

[photoni]

4 minutes ago, colinbm said:

Good show Toni
The X is it internal or it looks like external, try wrapping something dark around it ?

I hid the A7 with a lens hood, it doesn't change, the power used is 6 stops greater than the Full spectrum one, it's incredible that it sees around 380 nm

[ulf]

My guess is that the hazy X-pattern is from some light leakage in the adapter, helicoid or lens.

Just as Col suggests, try to wrap something light tight around your camera and lens. Many syntetic fabrics transmit IR even if they are black in VIS. 

There are traces of it in some of the other non-FS images too and I think the exposure times are quite long.