Geoptik Adapter and Nikon G Lenses

[edjrgibbs]

Looking for some advice. I'm interested in a CCD widefield setup for my AstroTrac. I've got a Nikon DSLR thus want to use my Nikon glass coupled with my QHY163c. If I got a Geoptik Nikon adapter though (https://www.rothervalleyoptics.co.uk/geoptik-nikon-slr-lens-ccd-adaptor.html) how do you set the aperture on a G lens with no aperture ring?

Thanks 

[Uranium235]

Try this:

Attach the lens to your DSLR camera as normal, set the aperture. Turn the camera off, remove the lens.... done!

[edjrgibbs]

8 minutes ago, Uranium235 said:

Try this:

Attach the lens to your DSLR camera as normal, set the aperture. Turn the camera off, remove the lens.... done!

Is this from personal experience with a Geoptik adaptor and Nikon G lens? There are conflicting accounts on the internet some of which say the lens defaults to max aperture when the camera is turned off...

Thanks

[Uranium235]

Ok, try removing the lens while the camera is switched on. It shouldn't break anything,  though the camera will report an error. 

I've no experience with nikon lenses, but with canon lenses that have no manual aperture setting, that's the way I would set it (setting up with dslr, then remove).

[davew]

I thought that lens trick only applied to Canon lenses ?

Re the adaptor. I was going to get a similar adaptor a few years ago and had worked out that the best way to use it was rather convoluted. 

Buy a Canon Geoptic adaptor and a Canon to Nikon G adaptor. Something like this - https://www.lensadaptor.com/nikon-g-canon-eos-adaptor  Ignore the price there are much cheaper ones !!

Then you can operate the aperture mechanism.

I've heard of people jamming bits of match stick in their lens but I wouldn't do it personally ! ( Jam the linkage open ) 

Unless Geoptic now make a proper adaptor I can't really help.

Dave.

Edited March 12, 2018 by davew

[edjrgibbs]

Thanks Dave. It seems odd to sell an adapter that looks nice but is totally non-functional. I cant really see the benefits of imaging at f16-22...

[davew]

I know what you mean ! Look at the sales pages for this adaptor and it doesn't tell you what will and won't fit, that I've seen anyway. It will fit an Ais style lens.

The G adaptor trick at least means you wouldn't have to keep changing the aperture by removing the lens and starting up your camera. Swings and roundabouts I suppose. Double check with Geoptik to see if they do in fact have a proper adaptor.

Dave.

 

Edited March 12, 2018 by davew

[1DegreeN]

Cyclops Optics have custom adapters to connect Nikon lenses to the 163c - https://www.cyclopsoptics.com/cyclops-adapter/cyclops-optics-blade-n-camera-lens-adapter-nikon/ I have their adapter for mounting Canon lenses on the 163M and the quality is very good. I use step down rings to reduce the effective aperture of my Canon lenses and avoid the diffraction spikes that the lens' iris blades introduce. 

[giorgio_ne]

Why don’t you create your own aperture mask? In this way you will also avoid diffraction spikes.

[edjrgibbs]

7 hours ago, 1DegreeN said:

Cyclops Optics have custom adapters to connect Nikon lenses to the 163c - https://www.cyclopsoptics.com/cyclops-adapter/cyclops-optics-blade-n-camera-lens-adapter-nikon/ I have their adapter for mounting Canon lenses on the 163M and the quality is very good. I use step down rings to reduce the effective aperture of my Canon lenses and avoid the diffraction spikes that the lens' iris blades introduce. 

Thanks but the same issue with G lenses. There's no way to change the aperture

 

[edjrgibbs]

On 12/03/2018 at 15:27, Uranium235 said:

Ok, try removing the lens while the camera is switched on. It shouldn't break anything,  though the camera will report an error. 

I've no experience with nikon lenses, but with canon lenses that have no manual aperture setting, that's the way I would set it (setting up with dslr, then remove).

Unfortunately it doesn't work... Defaults to min aperture on taking the lens off. 

[edjrgibbs]

4 hours ago, giorgio_ne said:

Why don’t you create your own aperture mask? In this way you will also avoid diffraction spikes.

Thanks but it doesn't solve the issue. Unfortunately Nikon lenses basically close to their min aperture when taken off the body so f16 on a nikon 50mm afs.

[edjrgibbs]

On 12/03/2018 at 16:50, davew said:

I know what you mean ! Look at the sales pages for this adaptor and it doesn't tell you what will and won't fit, that I've seen anyway. It will fit an Ais style lens.

The G adaptor trick at least means you wouldn't have to keep changing the aperture by removing the lens and starting up your camera. Swings and roundabouts I suppose. Double check with Geoptik to see if they do in fact have a proper adaptor.

Dave.

 

Hi Dave

I think this is probably the best/only option short of paperclips which i'm not keen on. Seems odd to sell an adaptor for £90 that can't be used on most current lenses. 

[UKAstroBill]

I've got the Geoptik working with various Nikon and 3rd party F-mount lenses. I have had no problems keeping the aperture wide open.

1. There is a pin in the Geoptik that holds the aperture wide open for those lens that support mechanical aperture control; e.g. Nikon 20mm f/1.8; Samyang 12mm Fisheye, Sigma 35mm Art

2. For lenses like the Nikon 200-500, the pin does not work, but if you detach the lens from a camera before turning the power off the aperture stays in the last position. I have had no problems using this at f/5.6 on the Geoptik. Nothing bad has happened to lens or camera doing this. 

My issue with the Geoptik is its attaching mechanism, my least favourite. Hard to see why they could not have a secure click option rather than the annoying orange tightening screw.

*** QUESTION ***

But I do have another question about the Cyclops Nikon lens adapters as I am looking for 2 inch compatibility which the Geoptik does not have. Can any one tell me the camera side interface, in terms of thread AND gender and depth if you know for

(a) the Cyclops Blade-N Nikon gadget

(b) the simpler M54 Nikon adapter (part 020073)

(c) the simpler M42 Nikon adapter (part 020074)

For the last two it is obviously the gender I am after!

 

By the way, if anyone has a Nikon Z and some F mount glass, the Baader wide T mount for Z attaches to the Geoptik and lets you have 1.25in filters in line. They screw together to create an optical path about 1.2mm shorter than the Nikon FTZ, but it allows the filters and you can space it out if you are fussy.

 

Thanks

 

William

[wuthton]

On 12/03/2018 at 13:40, edjrgibbs said:

Looking for some advice. I'm interested in a CCD widefield setup for my AstroTrac. I've got a Nikon DSLR thus want to use my Nikon glass coupled with my QHY163c. If I got a Geoptik Nikon adapter though (https://www.rothervalleyoptics.co.uk/geoptik-nikon-slr-lens-ccd-adaptor.html) how do you set the aperture on a G lens with no aperture ring?

Thanks 

Sorry, I'm a bit late to this.

I went though the same exact process you have, I ended up throwing in the towel and buying an 85mm Samyang. No regrets, the lens is superb.

The aperture mask is a good idea, I haven't touched the aperture ring for 18 months.