D750 with SB-800 Flash and Telephoto Lens

A few days ago, "Fluffy", a California Brown Bat that has visited our front porch these past few years, returned. Fluffy is a small creature: even at close range, about 10 feet, my Tamron 70-200 was not getting all the detail I wanted.

It was time for the "big guns". I mounted my new Tamron 150-600 zoom and my SB-800 flash. The D750 is setup to use FP flash when the shutter speed is over 1/250. I was in aperture priority, with f/10 selected, and lens zoomed to 460 mm. I was surprised to see the camera had selected a shutter speed of 1/500 which put the flash in FP mode. When I changed to zoom to 550 mm , the camera changed shutter speed to 1/640. The ISO was selected to 400. In both cases the camera was trying set the shutter speed to one over the focal length to minimize lens shake, although the VC and the speed of the flash would have probably sufficed. With the flash off and the camera in "P" mode, the camera selected 1/125 sec at f/6.3 with the lens zoomed to 460 mm and punched the ISO to 12,800.

Smart camera the D750. Has anyone noticed other cameras selecting shutter speed in the FP region to compensate for lens shake?

By the way, I liked the images of Fluffy I got with the longer lens; I certainly got more detail. The one disadvantage of the longer lens is, even with flash and f/10, the DOF is quite limited to only a few centimeters. Fluffy's head and body are sharp, but the hind leg is definitely soft.

So where's Fluffy's pic?

I'd probably go full Manual for this kinda thing. Practice on a grey card hanging from a tree at about the same light level and distance.

ISO 1600, f11, 1/125 and adjust flash power.

Ensure flash is zoomed as much as possible. Maybe even get one of those snoots, to make a tighter beam.

Just as a note, I'd probably try to use as low power as possible to protect Fluffy's night vision...:)

I'd probably go full Manual for this kinda thing.

I'd definitely go full manual. Or at most use AA mode on the flash if I needed some exposure automation.

Getting into FP mode simply loses you flash power, and is totally needless if flash is the main source of light.

In short, those decisions that the camera is making are terrible! Lowering the flash 'power' will greatly shorten the flash duration, and do more to reduce vibration blur than raising the shutter speed. The flash should 'talk' to the camera and the camera should then be fully aware that flash is being used as the main illumination source.

Just another example of poor camera firmware/software I'm afraid.

It might be interesting to see what happens if you disable TTL-BL by putting the camera metering into spot or centre-weighted mode.

So where's Fluffy's pic?

 

I'd probably go full Manual for this kinda thing. Practice on a grey card hanging from a tree at about the same light level and distance.

 

ISO 1600, f11, 1/125 and adjust flash power.

 

Ensure flash is zoomed as much as possible. Maybe even get one of those snoots, to make a tighter beam.

 

Just as a note, I'd probably try to use as low power as possible to protect Fluffy's night vision...:)

The exposure of Fluffy was fine. It is my fault the DOF is shallow; I was in aperture priority and set f/10. I thought that would be sufficient; obviously I need to think again. This was the first time I had used the SB-800 with the 150-600. I was just surprised the camera would take lens shake into consideration. All in all, the D750 did a great job. It noted that FP was enabled, calculated I had sufficient power at the subjects distance to use it, and then took focal length into consideration and used FP, I ended up with a nice image.

As for Fluffy's night vision, if the quantity of guano is any indication, Fluffy's vision and sonar are perfect. The lily we have on the front porch will eat well, and the insect population has been reduced. Way to go, Fluffy!

I posted one image of Fluffy on the Nature forum, #4 in this thread:

Nature Unlimited, 2 April 2021 | Photo.net Photography Forums

I will post other images Wednesday in Nikon Wednesday thread.

The exposure of Fluffy was fine.

I'd say that Fluffy could use a bit more light. A stop, maybe even a stop and a half.

Ah OK. I thought we were BIF. A very much trickier genre!

Ah OK. I thought we were BIF. A very much trickier genre!

BIF??? The only entry in the dictionary is Banded Iron Formation.

BIF???

Bird In Flight

Bird In Flight

Thank you, Dieter

Hmm... BIF means Banana

In Flight... Hey, toss me a

banana, will ya...?

http://bayouline.com/o2.gif

FWIW: Re flash duration ('power')* control in X-synch versus FP-mode shutter speed.

Controlling shake through shutter speed in FP mode (HSS) just isn't as efficient as controlling the flash duration.

Suppose your maximum X-synch speed is 1/250th. Then halving the exposure time by setting 1/500th in FP mode also halves the effective flash brightness. But directly setting the flash to half 'power' immediately reduces the flash duration to typically just under 1/1000th of a second - with half the amount of potential shake as using FP/HSS mode at 1/500th, obviously.

Dropping the flash power to 1/4 gives you a duration of less than 1/2000th of a second in X-synch, as opposed to getting the same flash exposure at only 1/1000th of a second in FP mode.

The same happens in FP mode versus X-synch, all the way up to the maximum shutter speed on the camera. With a shorter duration always being got by reducing the flash power in X-synch mode. And that's why FP mode is a poor choice when exposure duration matters and flash is the main or only source of light.

* I'm putting the word 'power' into parentheses because it's actually the flash energy that's being controlled, not its power. But power is the more commonly used expression.

It was time for the "big guns". I mounted my new Tamron 150-600 zoom and my SB-800 flash.

You may want to investigate getting one of those Fresnel Flash Extenders (Better Beamer) if you are planning on using flash for bird photography. I have given up using those years ago though - too cumbersome to deal with. Most of the time, flash isn't the main light source but just some fill. In which case, shutter speed needs to be short in order to avoid motion blur/camera shake blur - which forces the use of FP mode. Which in turn reduces flash output - which makes the whole thing rather useless.

You may want to investigate getting one of those Fresnel Flash Extenders (Better Beamer) if you are planning on using flash for bird photography. I have given up using those years ago though - too cumbersome to deal with. Most of the time, flash isn't the main light source but just some fill. In which case, shutter speed needs to be short in order to avoid motion blur/camera shake blur - which forces the use of FP mode. Which in turn reduces flash output - which makes the whole thing rather useless.

Hi Dieter,

I have no intention of using flash with birds, unless they are very close. I am well aware of the inverse square law; one of the few things I still remember from my physics courses :-) . Fluffy was a different matter. It was stationary and about 10 feet away. I did state the range (2.99 meters) with the shooting data in my post in the Nature forum. The SB-800 had more than sufficient power even in FP mode.

As for the the exposure, it was my fault for having the metering mode set to Matrix; spot would have been more appropriate for a dark brown bat on a light stucco background. I was in a hurry to get the image before Fluffy departed. It was a "grab" shot. I looked out the front door at about 10 PM and there was Fluffy. I garbed my camera, changed lenses to the 150-600, got the SB-800, inserted the batteries, mounted the flash, and headed back to the front door. Fluffy was still there. Went for the shot and the camera did not focus. ??? Then I remembered I had changed to back button focus, but not used it yet. Pushed the button; and the camera focused (I do like back button focus; I think I'll keep it.) Took a shot; flash did not fire. Tried again, still no flash. I did not have the flash fully seated. As soon as I corrected the problem, I changed from P to A mode and selected f/10, That is when the camera selected the higher shutter speed and the flash went to FP mode. As for the two shots without flash and in P mode, the D750 selected 1/125 and f/6.3 (wide opened at that focal length) and push the ISO to 12800. I have two usable, albeit noisy, images, but not images I would care to post.

As for the exposure in the posted image, I shoot in RAW and process in Lightroom 6. I did some correction to the exposure and contrast. Any more exposure and the background became so bright as to be intrusive, at least to my eyes. I think I have good detail in Fluffy; even in the darker spots you can see each hair and in the lighter spots, its eyelashes.

All in all I am quite happy with the camera, lens and flash. When I moved from my FTn and Braun Flash to my F100 and SB-28, I thought the combination was "magic" - no more estimating range and dialing in guide numbers. The D750 and SB-800 exceed "magic". I just wondered if anyone else had noticed that, with long lenses the camera was also taking focal length into consideration.

I just wondered if anyone else had noticed that, with long lenses the camera was also taking focal length into consideration.

I suspect that the Tamron lens doesn't communicate its VC ability to the camera, hence the high shutter speed selected.

I think Tamron's VC is entirely lens-based and doesn't need any camera control, whereas Nikon's VR requires some camera input. So perhaps a Nikkor lens would get a completely different setting from the camera?

An expensive experiment to do to find out. Unless you just happen to have a similarly-specified Nikkor lens just lying around!

Incidentally, a standard speedlight will put out enough light to act as a decent daytime fill at up to about 50-60ft. I have a flash tele-extender for an old Sunpak flash - pretty useless. It might add half-a-stop if I'm lucky.

I suspect that the Tamron lens doesn't communicate its VC ability to the camera, hence the high shutter speed selected.

 

I think Tamron's VC is entirely lens-based and doesn't need any camera control, whereas Nikon's VR requires some camera input. So perhaps a Nikkor lens would get a completely different setting from the camera?

 

An expensive experiment to do to find out. Unless you just happen to have a similarly-specified Nikkor lens just lying around!

 

Incidentally, a standard speedlight will put out enough light to act as a decent daytime fill at up to about 50-60ft. I have a flash tele-extender for an old Sunpak flash - pretty useless. It might add half-a-stop if I'm lucky.

Mystery solved! It's not the camera or the lens; it's UBD (User Brain Damage).

A few days ago, I came across this video on YouTube by Steve Perry.

LINK:

He was explaining Auto-ISO on Nikon cameras. I had Auto ISO set, and in the Auto ISO setting I had selected AUTO for minimum shutter speed. For some reason I either missed reading or forgot the next to the last sentence in point 3 on page 137 of the D750 manual, "If Auto is selected, the camera will choose the minimum shutter speed based on the focal length of the lens." That is exactly what the camera did. Note no mention is made of VR on the lens. That is the safest way. For any given situation the VR capabilities can vary. The safest way is to assume there is no VR when setting shutter speed. That way the camera maximizes the probability of getting a sharp shot.

Go full Manual.

Don't let the machines dictate ANYTHING.

Maybe AF...:p

Don't let the machines dictate ANYTHING.

Not "dictate", but you pay the big bucks for "the machine" to do something to make life easier, right? ;)

Right!

Until they do something that makes you go... Eh?

I was playing with Face Detect on my Z6ii and it preferred a square-on portrait painting on the wall way, way behind my 3/4 on 'human' and it was a devil to dissuade it..:(

Went to centre point and all good...:)

A day or two ago, I saw a video of a Sony A1's eye-AF following a bird in flight - the performance was just stunning.

Use Manual Mode with Auto ISO, then you can set your shutter speed and F-Stop at will, and the appropriate ISO will follow.

That's what I do for quite some time now - dialing in exposure compensation as needed to help the matrix metering make the right decisions.

Go full Manual.

Hell no - why risk over- or underexposure?

I was playing with Face Detect on my Z6ii and it preferred a square-on portrait painting on the wall way, way behind my 3/4 on 'human' and it was a devil to dissuade it..:(

 

Went to centre point and all good...:)

dialing in exposure compensation as needed to help the matrix metering make the right decisions.

I have used Center-Point as the default for a long time now. It is more accurate than Matrix.

Use Manual Mode with Auto ISO, then you can set your shutter speed and F-Stop at will, and the appropriate ISO will follow. Just keep an eye on the ISO level and adjust your speed and/or F-stop downward if it gets too high. Believe Steve Perry talks about this too.

I use Manual Mode with Auto ISO for most of my daylight images and have been since I saw Mr. Perry's YouTube video on the subject. It works well, although I may have to revisit setting minimum shutter speed to AUTO in the Auto ISO settings.

Fluffy was a grab shot. I went to the front door just before bedtime and looked out. There was Fluffy! Get to the bedroom, go to the closet, get my camera bag. I keep my camera setup with the 24-70 f/2.8 lens mounted, and the camera in P mode. If I need the camera in a hurry, in most cases this gives me the best chance of getting something versus nothing. This was not most cases. Grab the 150-600 lens (it is in its own case), dismount the 24-70 and mount the 150-600 in its place. Take the SB-800 out of its case and and insert batteries, mount the flash. On the way back to the front door, switch to A mode and dial in f/10. Shoot and get very usable images of Fluffy. And a puzzle about why the camera did what it did to get those images.

Now I know. I thought I would share the solution with all the others who responded to the original post. One thing I dislike about people who ask questions on PN is that many just "disappear". We never find out which, if any, of the solutions worked. So now you know - none of the proposed solutions was correct. I am glad to know that I am not the only D750 user who "forgot the next to the last sentence in point 3 on page 137 of the D750 manual." :-) I thought old age was catching up with me.

Go full Manual.

 

Don't let the machines dictate ANYTHING.

Hey Mike, I paid good money for all those High-Tech bells and whistles. I have to get my money's worth. :-) All joking aside, I can remember full manual without even a coupled light meter. I'll take automation everyday. The current auto exposure with both camera and flash is nothing short of "magic" compared to my first 35mm - a Zeiss Contaflex IV with flash bulbs. At least it had a light meter although it was neither TTL nor coupled to the camera/lens. It was take a reading, and set the shutter speed and f-stop manually. (BTW it still works.) If you were using flash, it was manually focus with the split image range finder, lower the camera, read the distance off the lens, set the guide number on the analog disk on the back of the flash gun, read the f-stop, set it on the lens, take the picture (if your subject is still there). I like automation - especially with my old eyes.

I was suggesting full manual for something like small, dark furred Fluffy on an off-white (cream?) wall!!

That scenario is a auto-metering mishap waiting to happen.

Ordinarily, i like auto features too.....:D

As soon as you have 2 competing auto features running together, such as auto flash exposure AND auto ISO, you have to be sure you get what you want, not what it wants.