Speeding up live view (tethered Nikon D7100)

[trilobutt]

Hi all, I want to pick your brains about the problem of live view lags. Context: I am responsible for a mass digitisation effort, taking high-resolution stacks of carabid type specimens. My setup uses a Nikon D7100 with bellows, connected to a Stackshot, and tethered and controlled by ControlMyNikon (CMN).

The setup works great but one problem from the start has been the slow speed of taking the individual stack photos, because CMN doesn't allow you to use the stacking workflow without live view. Live view makes a big delay that basically doubles the amount of time to make each shot. It's fine for most specimens that require ~50 shots (good time to prepare the next specimens!), but when I have a deep specimen with 100+ photos needed, the delay is too much.

What solutions do you have that allow you to take stacked shots while tethered, without live view?

The only solution I can think of is to buy the Stackshot-Nikon shutter release cable, use the CMN live view to set the distance, and use Stackshot to do the shutter release instead of CMN. The camera will be turned off live view and the big delay should't be there.

Is there any other solution, one that maybe doesn't involve buying this cable? I know that live view lags are part of the package with DSLRs, but I figure there must be a way to stack without live view.

(I realise that getting rid of the lag might introduce extra vibrations and also runs the risk of frying the flashes if too fast. But I would rather have control of the timing of the shots and experiment than be hamstrung by weird firmware limitations.)

Thank you very much for any help!

[mawyatt]

I use Stackshot with a Nikon D800 and D500, controlled through Zerene Stacker. The camera is connected to the Stackshot controller via a cable, and the controller is connected by a USB cable to computer with Zerene.

Zerene has a very good built-in interface for the Stackshot controller with lots of ability to configure parameters like rail pitch, steps per rotation, trigger pulse width, delay, acceleration rate, rail velocity, and so on. This scheme works well and allows you to control the usual timing between things like shutter trigger, rail movement and settling time. The Stackshot controller to camera cable is a simple modification to an inexpensive eBay remote for your particular camera body. Cognisys will provide the details if you request such.

Best,

Mike

[ray_parkhurst]

trilobutt...are you using flash, or continuous light? If continuous, then if you use the D7100 in non-Live View mode, mirror slap may cause you problems with image blur. Live View eliminates the problem by actuating the shutter before cycling the mirror. You still need to wait a little for the system to settle after each shot. If you're using flash, then "never mind"...

[trilobutt]

Ray, I am using flash (rear flash in an almost fully darkened room). I understand the issue of vibrations, but the live view lag is far too long.

As it is, I have 1s shutter speed and 500ms settling time, and it can take between 3-5s per shot because of the live view lag. The live view therefore doubles the time per shot at least.

Mawyatt, thanks a lot for the hint about the cable. I will try asking Cognisys then. Their version of the cable is €80 over here, I figured they would just try to sell it to me instead of giving me instructions on how to make it...

[ray_parkhurst]

Ray, I am using flash (rear flash in an almost fully darkened room). I understand the issue of vibrations, but the live view lag is far too long.

As it is, I have 1s shutter speed and 500ms settling time, and it can take between 3-5s per shot because of the live view lag. The live view therefore doubles the time per shot at least.

Mawyatt, thanks a lot for the hint about the cable. I will try asking Cognisys then. Their version of the cable is €80 over here, I figured they would just try to sell it to me instead of giving me instructions on how to make it...

3-5sec sounds unusual. When using Helicon Remote with my D7000, the delays were at most 2sec. I don't remember having much luck with CMN and converted to Canon before solving the problems. Hope mawyatt's suggestions help...Ray

[mawyatt]

If you are using flash, then you just need the shutter period to be 1/160 sec or so, no need for full second. That alone should save 1 second per image.

Cognisys just has a schematic, which is simple. If you are reasonably proficient with a soldering iron this should be no problem. I recall you need a RCA type plug and cable (this end plugs into the Stackshot controller) and the other end is soldered to the remote which has a Shottkey Barrier diode between a couple terminals. I built one about 7 years ago, so my recollection is probably not very good. I have no idea what the diodes purpose is though (may work without). If you contact Coginsys you might want to buy a couple of their special connectors for the stepper motor, then you can configure another focus rail such as the surplus THK KR types, or others to work with the Stackshot controller. I've done this with a few different stepper motor based focus rails (most with 400 step/rot motors) and the Stackshot controller works fine, especially with Zerene stacker controlling things.

Best,

Mike

[Chris S.]

Trilobutt,

Like you, I do studio macro with a Nikon D7100 body, Cognisys StackShot controller, and ControlMyNikon tethering software. Then I use Zerene Stacker to stack the acquired images. This said, my workflow differs substantially from yours—I never use CMN to control image acquisition. And I was not aware that doing so throughout acquisition would require constant use of live view. Yuck! Ack!

It's easy to see how this requirement would slow things down. In my experience, if one triggers the shutter during live view, live view first shuts down (which takes time), then the camera takes the picture (which takes time), then live view boots up again (which takes time); all these time-takings add up to an annoying-long delay for even for a single shot, let alone a stack.

To my mind, you should use live view only to set up the shot—framing, lighting, and begin/end points for the stack. Then--importantly--shut down live view while actually shooting your stack. From what you’re saying, CMN seems not to support this approach. If so, this is not acceptable.

The only solution I can think of is to buy the Stackshot-Nikon shutter release cable, use the CMN live view to set the distance, and use Stackshot to do the shutter release instead of CMN. The camera will be turned off live view and the big delay shouldn't be there.

This is precisely what I do—works great.

I use Stackshot with a Nikon D800 and D500, controlled through Zerene Stacker. The camera is connected to the Stackshot controller via a cable, and the controller is connected by a USB cable to computer with Zerene.

Zerene has a very good built-in interface for the Stackshot controller with lots of ability to configure parameters like rail pitch, steps per rotation, trigger pulse width, delay, acceleration rate, rail velocity, and so on. This scheme works well and allows you to control the usual timing between things like shutter trigger, rail movement and settling time.

This seems an equally-good approach, and differs only in Mawyatt's use of the Zerene Stacker interface for the Cognisys controller versus my use of the physical buttons on Cognisys controller. Zerene Stacker’s interface for driving the Cognisys StackShot controller is user-friendly and powerful. I’ve tested it and consider it very good, but don’t use it myself—only because I became accustomed to the StackShot controller's buttons before Zerene Stacker added this feature. Either path produces the same results, so long as the user is accustomed to it. I tend to stick with old habits, unless a change offers substantial reward. But if you're acquiring new habits, I'd recommend using Zerene Stacker's interface for the Cognisys controller.

In either case, you need a cable to connect your camera with the Cognisys controller. I agree with Mike (Mawyatt) that making one’s own such cable need not be difficult for anyone accustomed to reading pinout diagrams and doing basic soldering. Still, I chose to purchase this cable, because I prefer making photographs to making cables (even though I do actually enjoy making cables). Plus Cognisys is a small company that has done a world of good for macro-photographers, and is exceptional with customer support. Spending a few dollars their way strikes me as supporting the community.

But as Mike said, Cognisys will likely help you make your own cord, even if this works against them financially. In my experience, the folks at Cognisys are good people, very supportive of the macro community.

--Chris S.

[trilobutt]

Hi all,

Thank you very much for the detailed comments. Chris, what you describe with the live view is exactly how CMN does it. I hope they will fix it in some next version.

In any case, I will go ahead with the cable and follow Chris and mawyatt's workflow. I love contributing to Cognisys of course, my only issue was that we have so many arcane bureaucracies over here for acquiring new equipment (that cable will run up to €90, they gave me trouble for buying a €50 used microscope objective!) that I always try to DIY anything to avoid all the paperwork

I have two extra questions, not worth making a new thread about them:

- Do mirrorless cameras suffer from this extra live view lagginess? I'm guessing not since they have no mirror, but just want to make sure in case I ever get the chance to upgrade the camera.

- Mawyatt, you mention that 1/160 is a good speed when using flash. Are there no issues with mirror slaps and other vibrations at such fast speeds?

[trilobutt]

FWIW I have been playing around and have found a not-so-elegant but working solution to enable Zerene Stacker's Stackshot control to capture images using ControlMyNikon's settings, without live view, without the need for a shutter release cable.

All you need is for both the Stackshot and the camera to be connected by USB to your computer, and a powerful program called Autohotkey.

In ControlMyNikon, set a keyboard shortcut for photo capture (in my case, Numpad 0). Then make the following Autohotkey script:

Code: Select all

WinActivate, ControlMyNikon 5.3 Pro
SendInput {Numpad0}

First line puts the focus on the CMN window. Second line presses the keyboard shortcut for photo capture.

You can run this script from Zerene's StackShot controller, under Configuration/Device Settings/External trigger command. In my case, it's

Code: Select all

"C:\Program Files\AutoHotkey\Autohotkey.exe" "C:\Users\edicoll\Desktop\shutter.ahk"

First command calls the Autohotkey program, second points it to your script.

As long as the settling time of the Stackshot is equal to or longer than your shutter speed, it will work perfectly.

Small victories...

(Theoretically this can be expanded to do any number of things - I can envision potentially automating the entire process until retouching the final stack.)

[mawyatt]

Hi all,

Thank you very much for the detailed comments. Chris, what you describe with the live view is exactly how CMN does it. I hope they will fix it in some next version.

In any case, I will go ahead with the cable and follow Chris and mawyatt's workflow. I love contributing to Cognisys of course, my only issue was that we have so many arcane bureaucracies over here for acquiring new equipment (that cable will run up to €90, they gave me trouble for buying a €50 used microscope objective!) that I always try to DIY anything to avoid all the paperwork

I have two extra questions, not worth making a new thread about them:

- Do mirrorless cameras suffer from this extra live view lagginess? I'm guessing not since they have no mirror, but just want to make sure in case I ever get the chance to upgrade the camera.

- Mawyatt, you mention that 1/160 is a good speed when using flash. Are there no issues with mirror slaps and other vibrations at such fast speeds?

I use the delay trigger option within the Nikon D800 and D500. I also use TIFF files created within the camera, this takes some time to create, so my stack period is about 4~5 seconds, especially with the D800 since it takes about 4 seconds to create the TIFF file.

Since you now can control things from Zerene (clever solution), you can optimize the timing with overlaps like moving the rail while the files are being written and using this time for settling to get the fastest possible stack. Also, you might not need to wait as long for lower magnifications, I might expect less than 3 seconds per shot with everything optimized.

BTW I agree with Chris, Cognisys is a great company that has done everything they can to help their customers, including providing schematics for the cable and connectors so other rails (like THK) can be used with their controller. They make the Porsche of stacking rail systems IMO, the other systems are more in line with the VW (here in the US we use Cadallic and Chevolet)

Best,

Mike

[mawyatt]

FWIW I have been playing around and have found a not-so-elegant but working solution to enable Zerene Stacker's Stackshot control to capture images using ControlMyNikon's settings, without live view, without the need for a shutter release cable.

All you need is for both the Stackshot and the camera to be connected by USB to your computer, and a powerful program called Autohotkey.

In ControlMyNikon, set a keyboard shortcut for photo capture (in my case, Numpad 0). Then make the following Autohotkey script:

Code: Select all

WinActivate, ControlMyNikon 5.3 Pro
SendInput {Numpad0}

First line puts the focus on the CMN window. Second line presses the keyboard shortcut for photo capture.

You can run this script from Zerene's StackShot controller, under Configuration/Device Settings/External trigger command. In my case, it's

Code: Select all

"C:\Program Files\AutoHotkey\Autohotkey.exe" "C:\Users\edicoll\Desktop\shutter.ahk"

First command calls the Autohotkey program, second points it to your script.

As long as the settling time of the Stackshot is equal to or longer than your shutter speed, it will work perfectly.

Small victories...

(Theoretically this can be expanded to do any number of things - I can envision potentially automating the entire process until retouching the final stack.)

Very clever solution sir!! Sure beats purchasing or building a custom cable!!

Best,

Mike

[Lou Jost]

To answer the question about mirrorless cameras, there is no delay. For low m (say, up to 2x or maybe 3x), you can stack by moving the focus ring instead of by rail, and take a hundred or more shots per minute. There are costs though. You'd have to use continuous light to achieve that speed (unless you have a very special strobe), making vibration reduction important. This may not be possible in a big building with lots of vibration sources that are out of your control.

And these Olympus cameras have sensors that are 17mm across instead of 24mm so the image quality is not as good. It is still pretty good though, and very very easy.

I think someone could make a script to do focus stacking on a Nikon camera (if CMN doesn't already have such a function).

[trilobutt]

Thanks for the information Lou, good to know!

Just to make it clear, CMN does have focus stacking built into it, both through Stackshot control and through lens focusing (that obviously doesn't work with a bellows or microscope objective so not too useful for higher mags). I personally love the software and all the features it offers, definitely worth a buy. The only drawback is that, for whatever reason, live view must be kept on, or it doesn't allow you to start focus stacking. You can take individual photos without live view though, so I'm really not sure why CMN has this limitation.