flash for deep stack

mawyatt · Post by **mawyatt** » Mon May 18, 2020 10:39 am

Adalbert wrote:Hello Mike,
Flash can help with vibration issues

yes, at 1/128 of the power you get very short light-impulse (about 1/40000s)
so that no vibration can be registered during the exposure.

BR, ADi

Hi Adalbert,

I think if you measure the optical burst output you will find that's it's not a simple rectangular "pulse". It's more of a faster rise exponential with a slower decay exponential, looking more distorted triangular that rectangular. Many use the 1/2 power points t.5 between the rise a fall edges as the "exposure time", the better strobes reference the t.1 times since the falling edge can tail off for an extended period.

Either way they are quicker at lower powers but likely not 25 microseconds at 1/128. I was never able to get enough optical power at 1/128 with a speedlight, and usually ended up around 1/16~1/32, but was using lots of diffusion which eats the optical power.

Believe it or not, many modern strobes (AD600, Rapid 600) are actually faster than speedlights at a given moderate output power level. These of course employ the same techniques (IGBT) as a speedlight but at 10X the power levels and quicker recharge times without the hassle of batteries.

Best,

metebalci · Post by **metebalci** » Mon May 18, 2020 11:03 am

I measured both t0.5 and t0.1 flash duration of V1, if you are interested to see: https://metebalci.com/blog/flash-duration-godox-v1/

I agree that 1/128 would not be sufficient with normal camera flashes, but maybe 2 or 3 of them would be enough. If not, that is exactly why I consider AD600. By the way, I am already and often using two small LED continuous lights, and I am happy with them, but I am not sure about the vibration issues, which problem to solve first (big flash is easier of course, having a fixed setup takes more time).

Mete

Adalbert · Post by **Adalbert** » Mon May 18, 2020 11:41 am

Hello Mate,
Yes, for the high NA as 0.75 or 0.95 I need 4 flashes with 1/128 power and zoom 200.
Sometimes I have to go to the 1/64 but only in special cases (e.g. high NA and small WD).
BR, ADi

Adalbert · Post by **Adalbert** » Mon May 18, 2020 11:47 am

Hi Mike,
But what about the price

You can get YN660 for $70 :-)
https://www.ebay.com/itm/YongNuo-YN660- ... Swfl9XAztG
BR, ADi

metebalci · Post by **metebalci** » Mon May 18, 2020 11:51 am

Adalbert wrote: Yes, for the high NA as 0.75 or 0.95 I need 4 flashes with 1/128 power and zoom 200.
Sometimes I have to go to the 1/64 but only in special cases (e.g. high NA and small WD).

What is the pros and cons of having multiple (and also more than 2) flashes ? I guess it gives flexibility, and I assume synchronization is not a problem. Is matching/mismatching color temp. a problem ?

Mete

Adalbert · Post by **Adalbert** » Mon May 18, 2020 11:59 am

Hello Mete,

I guess it gives flexibility

yes, of course.
You get diffuse light with a thin diffuser and can illuminate as you want :-)
e.g.
https://www.facebook.com/photo.php?fbid ... =3&theater
The YN660 flashes have an internal transceiver and can be triggered wireless exactly at the same time.

BR, ADi

metebalci · Post by **metebalci** » Mon May 18, 2020 1:26 pm

Thanks for the link. Always good to see a setup.

Mete

mawyatt · Post by **mawyatt** » Tue May 19, 2020 1:36 pm

Adalbert wrote:Hi Mike,
But what about the price
You can get YN660 for $70 :-)
https://www.ebay.com/itm/YongNuo-YN660- ... Swfl9XAztG
BR, ADi

Maybe you get what's it's worth

Generally when I was using the YongNuo products many years ago they worked OK but I had numerous problems. Had one completely melt the lens assembly (failed thermal overload sensor), burnt my hand on another with very hot overheated batteries, and was always having problems with the RF triggers not working, intermittent and causing black images during long stacking sessions. The RF "Trigger" system was very unreliable, others had reported similar results. Back then my time was more valuable (not retired), so these issues were more painful.

These issues were also one of the main reasons I moved to Godox products strobes and speedlights, which Adorama offers under their brand in some cases. The Godox RF system is generally common among most of their products, and was much better and more reliable than YongNuo RF system. From what I saw with the YongNuo products I had, the build quality of Godox was overall better.

Maybe YongNuo has improved their products and specifically their RF triggers lately, but I've been very happy with the Godox products, not that I haven't had some issues, but much less than with YougNuo products.

Best,

metebalci · Post by **metebalci** » Tue May 19, 2020 1:55 pm

I am also quite happy with Godox flashes but not with RF triggers (RF is working fine I think but I do not like the trigger unit). I like and often use optical triggering. Fuji has a great little flash that works without batteries, I wish Sony also has something similar so I do not need to use any cable or RF or batteries to trigger flashes.

Mete

Adalbert · Post by **Adalbert** » Tue May 19, 2020 2:13 pm

Hello Mike,
I have been using the YN660 for some years for all my stacks.
The only one problem is the cover of the battery :-)
Everything else has worked in the perfect way up to now.
BTW, I use the flashes 430EXII too but in the ETTL mode (not for macro).
BR, ADi

mawyatt · Post by **mawyatt** » Tue May 19, 2020 2:55 pm

metebalci wrote:I am also quite happy with Godox flashes but not with RF triggers (RF is working fine I think but I do not like the trigger unit). I like and often use optical triggering. Fuji has a great little flash that works without batteries, I wish Sony also has something similar so I do not need to use any cable or RF or batteries to trigger flashes.

Mete

The Godox RF system isn't perfect, there were cases of missed triggers (much less frequent than YungUno) that were attributed to receiver overload. A solution was an undocumented command to reduce the transmitted power and turn off the receiver LNA, thus desensitizing the receiver....this is what I thought the command did. The overload was caused by the trigger and strobe/speedlight being very close together like in a stacking setup.

Anyway, I can't remember the details but Google should show something.

BTW really like what you've shown with the Sekonic L-858D, wish I had got that instead of the L-308DC I have. Got this to save $ but should have went ahead with the L-858D, not realizing how beneficial "seeing" the optical waveform is!!

I've learned over the years, the cheapest solution isn't always the best, but still keep relearning this!!

Good example, I got a Porsche 911 C2 (My Avatar) in 1996, certainly not the cheapest car then. This was my daily drive until I got another 911 Twin-Turbo in 2007, which then became my daily drive. The 911 C2 (993) is the last of the famous air-cooled flat boxer 6 engine and worth more today than I paid 24 years ago!! And I still have it

Best,

mawyatt · Post by **mawyatt** » Tue May 19, 2020 4:18 pm

Adalbert wrote:Hello Mike,
I have been using the YN660 for some years for all my stacks.
The only one problem is the cover of the battery :-)
Everything else has worked in the perfect way up to now.
BTW, I use the flashes 430EXII too but in the ETTL mode (not for macro).
BR, ADi

Hi,

You must have some good really ones

I was using them about 5~6 years ago, maybe longer I think. Nothing horrific but a constant annoyance with various issues, mostly variation in output or just complete misfires. Like you I was using 3~4 and a single misfire would underexpose, but sometimes all 3 or 4 would misfire leaving a black image.

Was just getting into very long sessions so the likelihood of this was reasonable. Often I would cut the step size in half so if a misfire occurred I wouldn't loose the session or have extensive rework in post.

This is why I moved to strobes, and have never regretted it once I discovered the Godox brand.

I do like the small size of the speedlights, and one reason I'm looking into the modified Jansjo...these work really well but nowhere near as powerful!!

Recycle time has become an important issue, especially with long S&S sessions, speedlights just can't keep up and will overheat and the batteries die.

I'm down around ~1 second per exposure now, but working towards a goal of rates near 10 exposures per second or higher. This involves quite a bit of serious custom development work. If you follow my posts here on the Trinamic controllers, LED controllers, and Piezo controllers, these are all related. Lots going on behind the scenes at Mike's Lab but not ready to disclose details just yet.

Keep posting your wonderful images.

Best,