"BSI" or "No BSI" - that is the question

[BruceSD]

.
In the near future I plan to purchase either a Nikon Z5, or a Nikon Z6.  The Z6 has a BSI sensor, the Z5 does not.  I don't know if having a BSI sensor is worth the added cost (about $500 USD).

I have never used a camera with a BSI sensor.  For those of you who have used both, does a BSI sensor significantly improve image quality?  If you've ever done a side by side comparson, did the BSI image look noticeably better than the non-BSI image?

[Ilkka Nissilä]

There are a number of differences. The Z6 sensor has a faster read time so if you need to use the silent shutter capability or if you want to do video, it'll produce less banding in flickering lights and less rolling shutter if you pan the camera or if subjects move quickly. The Z6 has full sensor readout full-frame 4K video which is Nikon's highest quality video so far.

The Z6 sensor also has better dynamic range at high ISO whereas the Z5 is a bit better at base ISO, according to photonstophotos analysis.

I have not used the Z5 or Z6 but I have used the D750 and Z6 II which have closely related sensors. I would say in practice either works fine for still photography, they are both good sensors. I really like the output from the Z6 II image quality wise but didn't have any complaints with the D750's output, either.

On the other hand there are other differences between the cameras which may be important to you.

[BruceSD]

.
Thank you for the response Ilkka.

The only feature that I care about in my Z5/Z6 comparison is their sensors' image quality for base ISO stills. 

[David H. Hartman]

The Z6 II has a superior rear LCD monitor compared to the Z5: 2,100,000 Dot for the Z6 II v. 1,040,000 Dot for the Z5. If you review photos you've taken to check for critical focus this is very important. The Z6 II's rear LCD is probably superior in other aspects not easily ascertained by reading the specifications in the user manuals.

A BSI sensor makes better use of available light particularly in the shadows. [Wiring structure is placed behind the photo diodes thus allowing more light to reach the photo diodes (edited to remove errors).] I see BSI technology as a very desirable thing.

Base ISO isn't only ISO you should consider unless you will always use a tripod. By increasing the ISO just a little and using the 5-way in body image stabilization you may avoid carrying a tripod for use at dawn and dusk.

I'd investigate the many differences between the Z5 and Z6 II. Remember the old saying, "You get what you pay for." Some of what you pay for you may not care about such as better video but I'm sure there are other reasons pertaining to still photography only that make the Z6 II a better choice.

Dave

The price difference between the Z5 and Z6 (not Z6 II) is small enough that I would not even consider the Z5. I'm sure you will find enough advantages to the Z6 that easily make the extra $300.00 worth spending.

Here is a link with illustrations and such. I haven't read it but I glanced at it. Looked for a date...

https://www.ephotozine.com/article/digital-camera-image-sensor-technology-guide-16808

[BruceSD]

.
David H.  thanks for sharing your photo knowledge!

I only shoot at base ISO because I only shoot fast/expensive/premium/prime lenses wide open - so, no need for a tripod.  In fact, I mostly shoot handheld with an electronic shutter because the fastest mechanical shutter speed is not fast enough (even with a pola or ND filter attached).

The increased resolution on the back LCD is important because I use live view (often with a viewfinder) to achieve critical focus with such narrow DOF.

[Birna Rørslett]

Z5 is cheaper and uses SD cards. Z6/6.2 has XQD.

[Jack Dahlgren]

.
David H.  thanks for sharing your photo knowledge!

I only shoot at base ISO because I only shoot fast/expensive/premium/prime lenses wide open - so, no need for a tripod.  In fact, I mostly shoot handheld with an electronic shutter because the fastest mechanical shutter speed is not fast enough (even with a pola or ND filter attached).

The increased resolution on the back LCD is important because I use live view (often with a viewfinder) to achieve critical focus with such narrow DOF.

Backside illumination essentially gives better light gathering ability. I use cheap old large aperture lenses, but even then I appreciate the extended range as I like to shoot in places which may be deeply shaded or after/before the sun rises. The Z6 is a great camera for the price as you can often find it discounted or on sale since Z6II came out.

[Snoogly]

No top info screen on the Z5. But that doesn’t detract from the quality of images - it just annoyed me.

[David H. Hartman]

David H.  thanks for sharing your photo knowledge!

Well some of what I shared was misinformation. 

Here is a link...

https://www.ephotozine.com/article/digital-camera-image-sensor-technology-guide-16808

...that may help.

Dave

[Zang]

Hey Bruce,

I spent some time looking for the answer to the same question you are asking. I came to conclusion that the quality difference is negligible. I then decided to buy Nikon Z5. I soon discovered that Z5 has inferior card reading. Sometimes, it take 3 minute to switch to preview mode and the card reading led is showing red during that time. I know you mentioned you only care about the picture quality, but the reading speed issue could be some thing annoying.

Cheers,
Zang

[BruceSD]

.
Zang, I can live with the card reading issue.  With the IQ being similar, I think I'll probably go with the Z5.

[Birna Rørslett]

Turning power Off, then On, usually solves the delay in card reading & preview with my Z5. In all likelihood this is a bug that sooner or later will be fixed in a firmware update.

[Zang]

.
Zang, I can live with the card reading issue.  With the IQ being similar, I think I'll probably go with the Z5.

Z5 in your bag?

Let me know your experience with it.