Nikon Z with astro filters

[UKAstroBill]

The weather has been so bad I have had the time to finish a video on using astro filters with the Nikon Z bodies and Nikon camera lenses. There is a manual alternative to the FTZ allowing 1.25 inch filters to be fitted between camera and F-mount lenses, and for some lenses and end of lens solution make sense. FAstroTZ is described here:
 

 

 

[davew]

That's a well presented video with most things covered I think. 

As a Nikon Z user myself I hope to see some more if you get the urge :) I don't use mine on a scope but only with lenses and not where I need filters. I find the layout of the body way better than any other camera ( DSLR ) I've used.

Dave.

[UKAstroBill]

Weather in UK is dire at moment. Biblical rain. I’ll get out eventually. But on the matter of “need” there are all kinds of projects. I picked up my Halpha filters today at the Astronomy show with a view to seeing if I can synthetically astro mod the Z6 in a less crude way, given that it appears to capture a bit over 20%. 
 

The layout is great and having focus peaking give you a first fix is amazing.

[sharkmelley]

That's a very informative video and an interesting solution to the problem of using filters with the Nikon Z cameras.

The approach probably works well for lenses but I think 1.25" filters will cause vignetting issues when attaching the camera to a scope.

Mark

Edited November 16, 2019 by sharkmelley

[Space Oddities]

There's a DSLR lens (Canon EF, Nikon F, Pentax K) to mirrorless camera (Nikon Z, Canon R/M, Fuji X, Sony E) adapter from Borg, that allows you to screw a 52mm or 2" filter inside of it. It's a bit pricey ($200), but well made. Here's the link for anyone interested!  

https://astrohutech.store/product/mirrorless-camera-adapters/

[UKAstroBill]

On 16/11/2019 at 15:39, Space Oddities said:

There's a DSLR lens (Canon EF, Nikon F, Pentax K) to mirrorless camera (Nikon Z, Canon R/M, Fuji X, Sony E) adapter from Borg, that allows you to screw a 52mm or 2" filter inside of it. It's a bit pricey ($200), but well made. Here's the link for anyone interested!  

https://astrohutech.store/product/mirrorless-camera-adapters/

That's great for the 2 inch case - thanks for pointing this one out. I was hoping this post would turn something up. Costs a bit more than my contraption though. My main concern is whether it allows adjustment of the back focus distance for the effect of the filter?  I've been doing some focus fine tuning and have discovered that if you do not correct for that you have to focus quite a bit short of where infinity was in the ordinary FTZ. 

Edited November 22, 2019 by UKAstroBill
Realised a possible issue

[UKAstroBill]

On 16/11/2019 at 08:14, sharkmelley said:

That's a very informative video and an interesting solution to the problem of using filters with the Nikon Z cameras.

The approach probably works well for lenses but I think 1.25" filters will cause vignetting issues when attaching the camera to a scope.

Mark

Thanks Mark - There is some discussion of this in the video. On the Nikon 200-500 there is hard vignetting at 500 but the 1:1 crop is fine. On a dedicated telescope you would almost certainly get the same. On my scopes (an APM 107/700 and a Celestron C6 with reducer) I have 2 inch filters in line and just do not use this contraption.

[Space Oddities]

1 hour ago, UKAstroBill said:

That's great for the 2 inch case - thanks for pointing this one out. I was hoping this post would turn something up. Costs a bit more than my contraption though. My main concern is whether it allows adjustment of the back focus distance for the effect of the filter?  I've been doing some focus fine tuning and have discovered that if you do not correct for that you have to focus quite a bit short of where infinity was in the ordinary FTZ. 

Sadly, no. It's some kind of bayonet mount, you can't really adjust the distance. At least on mine!

Also, the filter is placed upside down (so the front of the filter faces the sensor). I'm not sure it makes a difference though?

[UKAstroBill]

I’m not sure if direction matters! For a filter where it is the body of the material that does the job it can’t matter. I’ve been a bit anxious about whether a more complex layered design would be sensitive to it. Both the contraption in the video and my 2 inch prototype have the filter “right” way up but for the 1.25 case that was more to do with moving the filter away from the lens to kill the vignetting as much as possible. I’m more concerned about getting the right Backfocus though. A couple of days ago I spent some time calibrating the infinity focus on my gadget to various or no filters. The device seems to be a bit wider than the manufacturer data suggests and it was calibrating to close to FTZ infinity focus with a 0.8 mm spacer, and 1.4mm nailed it for the Optolong L enhance, with the Baader Halpha wanting a tiny bit more, though I left it at 1.4. 

[UKAstroBill]

On 22/11/2019 at 08:22, Space Oddities said:

Sadly, no. It's some kind of bayonet mount, you can't really adjust the distance. At least on mine!

Also, the filter is placed upside down (so the front of the filter faces the sensor). I'm not sure it makes a difference though?

Space Oddities: I think it would be sensible for me to compare the Borg device to my 2inch prototype when I get to the next stage. I’ve emailed AstroHutech to ask them some questions especially about its optical length. Eg is the fixed length the same as the FTZ or is it calibrated at eg around 2mm filters with a larger optical length. Can you tell me what lenses you Use it with and what the image quality is like edge to edge? 
 

When I first built the 1.25 gadget I calibrated it to the FTZ by matching infinity focus without filters. When I put an Optolong l enhancer or Baader Halpha in the image quality was good edge to edge on the Nikon 200-500 but poor on wide angles. I mean that if you focused in the middle the edges were fine on telephoto but way off for wide angle. Adjusting the spacer up to allow for the filter made a big improvement for the wide angles, especially UWA zone. So I’m curious how well you find a fixed length part works at various focal lengths. If you have time! I’ll probably buy it anyway to compare once I’ve heard back from them.  

[fwm891]

Great description and video.

Immediately made me grab my Panasonic Lumix (4/3rds chip) GX80. This has interchangeable lenses and I have a Nikon to Lumix 4/3rds adapter which at a quick glance looks like I too can insert 1.25" filters into... One of the exposed threads inside the adapter eyeba;lls at about 42mm - if so I can get a 42mm to 1.25" filter stepdown male to female ring. 🙏

[UKAstroBill]

On 27/11/2019 at 21:38, fwm891 said:

Great description and video.

Immediately made me grab my Panasonic Lumix (4/3rds chip) GX80. This has interchangeable lenses and I have a Nikon to Lumix 4/3rds adapter which at a quick glance looks like I too can insert 1.25" filters into... One of the exposed threads inside the adapter eyeba;lls at about 42mm - if so I can get a 42mm to 1.25" filter stepdown male to female ring. 🙏

All kinds of possibilities. Just make sure that when you screw in a filter it is clear of the sensor and the end of the lens. The Geoptik has plenty of clearance to ensure this and I screw the filter assembly well in to be clear of the lens. 1.25 is plenty for a 4/3 or DX sensor. 
 

meanwhile Borg have confirmed their part is fixed length and indicated they designed it with IDAS filters in mind. I hope to get more details after Thanksgiving. Don’t know the optical length yet.

[UKAstroBill]

Borg responded with the useful detail that their filter adapter has an optical length of 31.3mm and is designed for IDAS filters, of thickness 2.5mm and refractive index 1.5168. So they have decided to calibrate well for a certain thickness, which makes a lot of sense. I’m ordering one and will try it out in comparison with the 2 inch version of FAstroTZ. 

[UKAstroBill]

I’ve had the Astro Hutech part for a few weeks now and am really pleased with it. The optical length calibration for IDAS filters is perfect and the body lens interface is rock solid. Mine is the one coupling Nikon Z bodies to Nikon F lenses and it has a mechanical control for adjusting aperture on G type lenses. So you can adjust aperture from the adapter on non E Nikons and 3rd party lenses from Sigma for example. It’s calibrated for the IDAS range so that’s for filters that are 2.5mm thick. Thinner filters from other manufacturers will usually fit but you might not be able to achieve infinity focus as the optical path is too long. That’s not a fault in the design so much as the fact that AH have tuned the part to work perfectly with the par focal IDAS range. It works brilliantly with the IDAS set.