Enlarging lens question

[Doug A]

On 11/11/2021 at 1:44 PM, lukaszgryglicki said:

Yes 80 can be tricky - I miss maybe 2mm for infinity focus on Nikon when using 20-140mm bellows - but this 20mm isn't really 20 - if that *was* 20 I would be OK, it's rather 25mm.

 

@lukaszgryglickiI also have trouble getting the El-Nikkor 80 to reach infinity on a Pentax bellows. So close! Then I found an insert that screws into a M42 mount. This insert reduces to 32.5 (not normal 39) and adds no thickness. Unscrewing the Nikon's thick chrome 39 adapter reveals a 32.5 thread. This may gain you 2mm. Search on eBay for the insert. It is about $7.95. I'll order one asap.

 

Thanks,

Doug A

 

[lukaszgryglicki]

Good idea, thanks!

Just to be sure - it pokes inside the F-mount, but mirror won't hit it, right?

 

[Doug A]

@lukaszgryglickiit replaces the 39 insert. It won't be used directly on a Nikon body, because there wouldn't be even close to enough extension for focusing to infinity. Main use would be bellows or extension tubes. It just allows us to get rid of the really thick Nikon chrome adapter.

https://www.ebay.com/itm/M32-5-to-M42-Screw-Thread-Lens-Mount-Adapter-Inner-M32-5-x0-5mm-Outer-M42-x1mm-/274577705299?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=711-127632-2357-0

Thanks,

Doug A

[lukaszgryglicki]

OK, understood, thanks!

 

[Nate]

On 11/11/2021 at 10:05 AM, Andrea B. said:

17-31 mm helicoids available currently. That would be a much better choice

Thankyou Andrea, Lens arrived, 17-31mm arrived, still waiting on 39 to 42 adapter for the lens to helicoid, but fastened it temporarily to test, and exactly what I was looking for. The only problem I have now is when I was in my ordering frenzy, I bought a 35.5mm instead of a 34.5mm adapter for the filter 

I ordered the 34.5mm one rafcamera has, until I get that I'll probably use my Antilia U-Venus clip in filter, it goes past 400nm a bit but has max at 335-365nm website says.

[Andy Perrin]

Nate, you need additional IR blocking with that Antila filter. The specs say it’s only OD3 blocked outside the pass band, which is not enough in sunlight. There will be substantial IR contamination. 

[Nate]

1 minute ago, Andy Perrin said:

Nate, you need additional IR blocking with that Antila filter. The specs say it’s only OD3 blocked outside the pass band, which is not enough in sunlight. There will be substantial IR contamination. 

I think so too, The only some what of an ir blocker I have is the Kolari hot mirror. But it might just work. Web site says this 

[Andy Perrin]

I guess try it and see! You can’t tell from a linear graph like that how well the Kolari blocks IR. You need a logarithmic graph or diabatic like Schott’s. However since the Antilla is already adding OD3 of blocking it may not need much additional blocking to fully get rid of the contamination. 

[Nate]

4 minutes ago, Andy Perrin said:

I guess try it and see

A quick test with the industar 50-2 on the helicoid(need it for the 1.25in filter clip in) showed nothing with my IR torches and tv remotes, sounds a little promising. to use the nikkor 80, I need ups to show up. Today some time

[dabateman]

I hadn't heard of the Antilla filter before. 

The graph is promising but in Aavelength, so not sure what to make of it 

https://agenaastro.com/antlia-venus-ultraviolet-venus-u-filter-1-25.html

[Nate]

15 minutes ago, dabateman said:

The graph is promising

Too bad I don't have the fancy testing equipment

[Andy Perrin]

He is just making fun of the misspelling, Nate. Dabateman’s sense of humor sometimes requires interpretation. 

[Nate]

12 hours ago, Andy Perrin said:

He is just making fun of the misspelling, Nate. Dabateman’s sense of humor sometimes requires interpretation. 

Ah Ha. Makes sense now. Went back to the graph, I guess I blow by misspelling with all of it everywhere these days. This (an) that