Flash artifact?

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Sulafat
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Flash artifact?

Post by Sulafat »

This may be a simple problem, but it's stymied me today. Maybe someone can help me get back on track again.

I was experimenting with a couple of cheap Chinese speedlites, using one as Master and other as Slave. I took a stack using them with a Canon M6MII in manual mode on a WeMacro rail. I used a shutter speed of 1/200 sec, the maximum shutter speed recommended when using external flash on this camera. I set the Master flash to manual and second curtain as is my habit. I took a few preliminary shots to adjust the flash output and achieve the exposure I wanted. Everything appeared routine.

Upon processing the images from the stack (both Helicon & Zerene), the results were similar to the attached image. I thought to myself, "Hmmm, could the cheap speedlites have a problem sync'n with each other and the camera creating shutter-like artifacts?" I decided to "canex" the cheap Chinese speedlites and used my old but dependable Canon MT-24EX. I set it to manual and second curtain. I confirmed my camera shutter mode was "mechanical" and the external flash settings were "manual" and second curtain. I ran another stack. The result is the attached image.

I reviewed the individual images in Lightroom, and I could not see any "shutter artifacts." However, when reviewed in Helicon, they were visible as narrow black strips on a handful of images.

Has anyone had similar problems? Is it indeed related to my flash? Or is the source of the problem different? Any hypotheses? I suspect this is a typical novice's problem.

Thanks
Attachments
2021-06-22 16-59-30 (C,Smoothing3).jpg
Flickr page: https://flic.kr/ps/3eJvz5

I'm an amateur photographer in the gentle persuit of modest competency.

rjlittlefield
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Re: Flash artifact?

Post by rjlittlefield »

This is not a typical novice's problem.

In fact, I cannot recall having seen this problem before, either in the forum or in any email to support@zerenesystems.com .

Even more weird, it sounds from your description that both Helicon & Zerene produce output like this, but no problem is obvious when you look through the source images.

At this moment, I have no idea what's going on.

Is it possible for you to upload the source images so I can look at them and hopefully reproduce the problem? (I'm thinking Google Drive, Dropbox, or wetransfer.com to support@zerenesystems.com )

--Rik

Lou Jost
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Re: Flash artifact?

Post by Lou Jost »

How does the Canon flash trigger? Master/slave? There is always a slight delay between master and slave flashes, usually negligible but maybe not always. The shutter curtain may be cutting off one but not the other flash. I suggest lowering your synch speed slightly and see what happens..

Sulafat
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Re: Flash artifact?

Post by Sulafat »

I should have noted that I have the shutter release connected to the WeMacro controller and I'm using WeMacro's software to control the stack. In the past I used Helicon Remote, but got out of the habit since Helicon seems to have difficulty keeping their software up to date whenever Canon changes it's image format.

Anyhow, I believe the problem is good ole fashioned operator error. I suspect I had the flashes in ETTL rather than manual. I have a mental check list I follow before starting a stack and checking the flash's mode is part of it. For these stacks, I changed the configuration of my equipment and the LED on the flashes were hard to see. I think that the mode may have been switched to ETTL while I was fumbling with them. I set up a subsequent stack and confirmed the flash mode before starting it. The attached image is the result. The image illustrates other stacking problems, but not the flash artifacts.

Sorry for the snafu. Next time I'll sleep on the problem before panicking. Regardless, thanks Lou and Rik for your help.
Attachments
210601_Tiger_Beetle_Head.jpg
Flickr page: https://flic.kr/ps/3eJvz5

I'm an amateur photographer in the gentle persuit of modest competency.

rjlittlefield
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Re: Flash artifact?

Post by rjlittlefield »

Thanks for the update.

I can understand how ETTL could produce prominent banding. But then I would expect that banding to be obvious in the source images, even in Lightroom.

Did I understand incorrectly that the banding was not obvious in source, and only appeared prominently in the stacked outputs?

--Rik

Sulafat
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Re: Flash artifact?

Post by Sulafat »

Yes, the bands were not obvious in Lightroom CC. I reviewed each image at full screen and no obvious bands. I loaded the images into Helicon Focus and reviewed the individual images again. I discovered about a dozen photos out of 120 images that had bands. I'm no sure why the bands weren't obvious in the Lightroom CC previews. Lightroom CC is a mystery to me.

Anyhow, now that I confirm my flash mode before I start photographing, I haven't had anymore issues, doh! So embarrassing... :oops:
Flickr page: https://flic.kr/ps/3eJvz5

I'm an amateur photographer in the gentle persuit of modest competency.

rjlittlefield
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Re: Flash artifact?

Post by rjlittlefield »

OK, thanks. I'll just file this under "Unresolved Mysteries". It's a pretty thick folder, so no worries!

--Rik

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