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UltravioletPhotography

Novoflex 35/3.5 possible light leak when extended


Andrea B.

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Added Later on 22 June 2021: One of my Noflexars does not seem to leak when extended. One leaks only at the longest extension. The leakage problem may depend on the age of the Noflexar and how much usage it has seen.


 

When extended for macro work the Novoflex 35/3.5 can sometimes light leak around the extension. There is a signature circular ring look to the light leak, so you would realize immediately what was happening. The light leak is easily cured by covering the extension area with a piece of dark towel or foil or whatever you deem usable for such things.

 

I know this light leak is not news to many, but we haven't talked about it or shown it for a long time. While I was working with the Novoflex yesterday, I captured some examples to show everyone.

 

In visible ambient light under 2-3 second exposures, I could not see the leak. In a couple of 8 second ambient visible exposures, I got a faint leak. When using the onboard flash (D610) for visible fill, I did get a slight light leak which is not surprising from a strong flash outburst.

 

In ultraviolet light from an SB-140 flash (filtered), the light leak is very strong. But then again, so is the flash. Using a 365 UV-LED (Convoy), the light leak was not as strong. This is probably because the LED light is more "directed", I was thinking.

 

Interestingly, I found that this circular ring light leak does not seem to affect the outcome of my particular UV photos because the leak is confined to the ring on the outer edge of the photo leaving the middle of the frame usable. Of course, that quite likely won't be the case with every UV composition.

 

In each of the example sets, there is an SOOC version, a raw composite, and a conversion. Both raw composites had minor endpoint adjustments and a bit of sharpening added so they would appear respectable besides the SOOC and converted versions.

 

Light leak when using Convoy 365 UV-LED Torch

I was pretty bad at the light painting in this one. Haven't done that for awhile! So the underexposed areas of the flower are my fault and not the fault of the torch.

 

penstemonPalmeri_uvBaad_365uvLed_20210620santaFe_23853.jpg

 

penstemonPalmeri_uvBaad_365uvLed_20210620santaFe_23853rawComp01pn.jpg

 

penstemonPalmeri_uvBaad_365uvLed_20210620santaFe_23853pn.jpg

 

 

Light leak when using SB-140 Flash with UV-Filter

 

penstemonPalmeri_uvBaad_sb140_20210620santaFe_2385501.jpg

 

penstemonPalmeri_uvBaad_sb140_20210620santaFe_23855rawComp01pn.jpg

 

penstemonPalmeri_uvBaad_sb140_20210620santaFe_23855.jpg

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I am sure that the typical light leak this lens is known to have is causing this.

The aperture blades are in the front section of the lens and even if they are shiny, the problematic light is not entering there.

The leakage problem is more likely the wider the gap is between front and rear part of the lens and can be very sensitive to from what direction the disturbing light comes from.

 

I have a rather efficient method of pin-pointing this type of light leaks.

I use a pointing laser and light paint the suspected areas from different directions.

It is important to change direction of the beam as sometimes the light is bounced around on internal surfaces and has to come in from a special angle to cause problems.

 

Normally I do that with a lens mounted on the camera and with a cap on.

It is done at high ISO setting while observing the live view on the camera.

 

It is possible to see some bigger leaks on lenses only, but it is much easier to do this with a complete camera and lens.

Then even smaller leakages are possible to spot.

 

Here the Noflexar 35mm:

post-150-0-67872200-1624345386.jpg

 

I tried in vain to find a way to fix the problem of this lens internally, but there was no space I could find to do so.

My way of covering the gap is to by place a wide Velcro-band around the exposed gap.

post-150-0-86235800-1624345415.jpg

 

It has to be applied after an extension position is selected. It is one more step, to do before taking a picture, but a rather easy one.

post-150-0-00293500-1624345472.jpg post-150-0-46248000-1624345442.jpg

 

Sometimes it is enough to just shade the gap from the light source with a hand.

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Very nice fix, Ulf.

I will look for some wide velcro because just covering with a dark cloth is not quite enough when using flash.

 

I added a note to my first post that one of my Noflexars does not leak. So leakage may depend on the wear and tear of a particular Noflexar over the years.

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Usually I don't notice as much leakage when using an extended Noflexar outside. But indoors when using an SB-140 or SB-14/mod or any UV-LED, I see the leakage. Probably because I'm using this concentrated UV light right up next to the extension.
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