CCD, Nikon lens and EFW2

[tooth_dr]

I ordered a Nikon to M42 adapter, and it arrived yesterday.  It is about as slim as possible, with only 1/2m or less between Nikon lens protrusions and the metal of the adapter.

I'm not exactly sure where to measure from, I'm assuming that the Nikon body metal edge is where I need to achieve 46.5mm back focus.

 

EDIT: I've checked the flange point, and I was incorrect in my first measurement.  So my totals are 9.4mm for the adapter, the EFW is 22.0mm, and the back focus of the QHY9 is 17.3mm.  I've the EFW2 adapters arranged in such a way that that add 0.0mm to the connections.

So my total length is 9.4+22.0+17.3mm = 48.7mm.  If I add in the 1/3 of the 2.0mm filter thickness this gives me another 0.7mm to spare, which gets me to 48.0mm

However it isnt focusing, but very close.  I had hoped that the fact the lens focuses past infinity would give me a little bit to spare but it doesnt give me enough.

 

Either new filter wheel or new camera by the looks of things as I cant see anywhere to take 1.5mm off it.

What are my options and importantly do I have my calculations right?

Adam.

Edited November 23, 2019 by tooth_dr
Amendments to mesurements.

[tooth_dr]

Do you think it would be possible to cut an m54 thread into the outside of the Nikon adapter to screw it 1.5mm into the EFW2 cover. I have a spare EFW2 so I could modify it too.

 

[tooth_dr]

Anyone check over my figures please?

I'm in the process of chatting with a friend who works with metal, to modify the Nikon adapter.  If my measurements are right, I can free up at 4mm by threading my Nikon adapter direction into the EFW2 base plate, and still be clear of the filters.  This will give me a back focus distance of 44mm, so that should let me away?

[x6gas]

Your maths looks right to me Adam, but I'm surprised at the depth of your adapter.

I'll think I have one somewhere; I'll root around and see if I can find it and will send the measurements if I can...

Cheers, Ian

[tooth_dr]

2 hours ago, x6gas said:

Your maths looks right to me Adam, but I'm surprised at the depth of your adapter.

I'll think I have one somewhere; I'll root around and see if I can find it and will send the measurements if I can...

Cheers, Ian

Thanks Ian. Surprised as in big or small?

This is my current configuration. I have it at 46.5mm and was going to test it tonight  on street lights 5 miles away.  Can you believe we have heavy fog this evening of all things!!

 Agonisingly close

 

 

 

[david_taurus83]

Not sure if this is the correct type Adam. There are slim versions available on ebay?

[tooth_dr]

1 hour ago, david_taurus83 said:

Not sure if this is the correct type Adam. There are slim versions available on ebay?

Cheers David. Those are for connecting an m42 lens to a Nikon body.  I did look at those and nearly impulse bought it. No I’m going from Nikon lens to m42 body.

The photo below shows that my adapter is about as small as is possible, without fouling the lens itself  

 

[x6gas]

14 hours ago, tooth_dr said:

Thanks Ian. Surprised as in big or small?

This is my current configuration. I have it at 46.5mm and was going to test it tonight  on street lights 5 miles away.  Can you believe we have heavy fog this evening of all things!!

 Agonisingly close

I was surprised at how big it was.  Now I may have been thinking of the adapter that David pictured - I have both somewhere... as I've definitely connected a Nikon mount Sigma lens to my 383L+ in the past (though not with the OAG or filter wheel... I'll dig it out, just out of curiosity.

[tooth_dr]

2 minutes ago, x6gas said:

I was surprised at how big it was.  Now I may have been thinking of the adapter that David pictured - I have both somewhere... as I've definitely connected a Nikon mount Sigma lens to my 383L+ in the past (though not with the OAG or filter wheel... I'll dig it out, just out of curiosity.

Thanks Ian, I would appreciate it if you can find it.  I dont think it can physically be any shorter, if you see my photo above.  There are quite a few thin ones, but they are male Nikon to M42.  I need the female Nikon side/

[x6gas]

Hello Adam,

I finally managed to dig out the adapters I was thinking of...  They were both male Nikon bayonets as you figured.  I did have the female Nikon side at one point (and thinking about it that was considerably thicker...) but I think I must have sold it...

Anyway, hope by now you've managed to address the problem!

Best wishes, Ian

[tooth_dr]

On 15/12/2019 at 14:20, x6gas said:

Hello Adam,

I finally managed to dig out the adapters I was thinking of...  They were both male Nikon bayonets as you figured.  I did have the female Nikon side at one point (and thinking about it that was considerably thicker...) but I think I must have sold it...

Anyway, hope by now you've managed to address the problem!

Best wishes, Ian

Thanks Ian. I left the part off with my chap but the original part he struggled to modify. So he’s making a new one. I’ve not heard anything for a couple of weeks though will give him a shout after the hols.

[tooth_dr]

Just a wee update. It is made and awaiting anodising in black.