13 replies to this topic

[slavicek]

I really like to look at the Emission Ha nebulas. Some of them are quite large so short focal length lens is needed to get relatively wide FOV. It seems to me that ideal focal lens for this application, using MOD3 NV, is around 200mm. That gives me magnification of around 8x and FOV around 5 deg. That FOV covers most nebulas. Looking at some telephoto lenses, both Nikon and Canon makes 200mm F/2 lens. Also, I found old Canon 200mm f/1.8 which is currently my favorite to get. But before I spend the money on it I want to make sure it will do the job so I begun experimenting with smaller (and cheaper) Cannon 200 mm f/2.8 lens. Unfortunately for the lens, to work with NV and regular eyepieces I had to “butcher” it - I've cut about an inch from the back of the lens and I've epoxied there a Baader ultra short 1.25” eyepiece holder:

 

 

(Due to sizes of the photographs and uploading limits I will have to spread this topic over several postings)
 

[slavicek]

This gives me enough back focus that I can install diagonal and use it as a fast telescope:

 

 

 

 

 

[slavicek]

One can also use it with a binoviwer:

 

 

[slavicek]

However to reach focus for NV I still have to use it without the diagonal:

 

GeezerGazer is working on NV diagonal which will come in handy for this set up once it becomes available.
So, there are multiple uses for this contraption and I am very excited about it. But again, before I spend the $$$$ on the 200mm F/1.8 I'd like to get some feedback and suggestions. Let me know what you think about it, what would be your "Ultimate telephoto lens"?

[slavicek]

And of course, for those really large nebulas (like Barnard loop in Orion)I still have the 3x setup which covers 13 deg FOV.
 

 

[chemisted]

I have used the Nikkor 200mm f/2 extensively and have referred to it as my 'Gold Standard' when it comes to viewing nebulae.  As you describe, it has just about the perfect FOV and a speed that provides incredible detail.  I use it routinely on a photographic tripod from the 70s that is lightweight but easily handles the load as the lens is rather short and stout.  If you can find one in good condition I highly recommend getting it.  I bought mine decades ago when they were quite plentiful and even got to choose between two contenders in a midwestern photo shop that had lots of used equipment at the time.

[Jeff Morgan]

I'm liking my Canon 300mm f/2.8 right now.

 

 

The 50mm f/1.4 is also quite good.

 

My third is a Canon 135mm f/2.8. Nice, but wish I had opted for a faster 135. The good news is it can still take a 2" filter over the front. When I replace it with a faster 135, I will lose that capability.

 

200mm and 85mm lenses are also in the plan.

 

There is a vendor with a recent thread (Vendor Forum) they make a filter box what would replace the usual C mount adapter.

[The Ardent]

The Nikon 180 and 135 vintage manual lenses are working good for me with the common $20 c-mount adapter. The 180 is a little more magnification for optimal handheld. 
 

[Jeff Morgan]

Filter drawer for telephotos:

 

https://www.cloudyni...-canon-adapter/

[nimitz69]

I currently use a f/.85 cctv 50mm lens and a Nikon f/2.8 135mm.  I need look into a 200mm to round out the collection 

Edited by nimitz69, 27 November 2019 - 08:45 PM.

[slavicek]

This is what I am working on right now: Canon 200mm F1.8

Once I have the focusing working I will have to get few narrow band Ha filters mounted into it's filter holder. So it will be few weeks before it will see it's "first light".

 

[GeezerGazer]

Slav, a 200mm f:1.8 used with H-a should be extraordinary.  If you look at jdbastro's gallery, many of his very wide field images are taken through a Zeiss 200mm f:2 lens.  

 

The thing about very fast camera lenses is the very thin depth of field when used with the aperture wide open... which can be very difficult to focus.  I occasionally use a Nikon 50mm f:14 and a 105mm f:1.8 and they are far more difficult to focus properly for images than my 300mm f:2.8.  This issue is not as problematic for visual use, but for photos, it is critical.  

 

I used a Nikon 180mm for a while but found its size and weight unmanageable for extended handheld use and it was much more difficult to attach to an alt/az mount because it had no mounting foot.  This is a caution, to make sure that the larger and heavier f:1.8 lens has a mounting foot.  For instance, the Nikon 200mm f:2 lens weighs abut 4.5 lbs., and my 300mm f:2.8 is 6+ lbs.  To mount them with NV attached, the mounting point must be on the lens, not the NVD.  Good luck with your efforts and I look forward to reading your results.  

[slavicek]

Slav, a 200mm f:1.8 used with H-a should be extraordinary.  If you look at jdbastro's gallery, many of his very wide field images are taken through a Zeiss 200mm f:2 lens.  

 

The thing about very fast camera lenses is the very thin depth of field when used with the aperture wide open... which can be very difficult to focus.  I occasionally use a Nikon 50mm f:14 and a 105mm f:1.8 and they are far more difficult to focus properly for images than my 300mm f:2.8.  This issue is not as problematic for visual use, but for photos, it is critical.  

 

I used a Nikon 180mm for a while but found its size and weight unmanageable for extended handheld use and it was much more difficult to attach to an alt/az mount because it had no mounting foot.  This is a caution, to make sure that the larger and heavier f:1.8 lens has a mounting foot.  For instance, the Nikon 200mm f:2 lens weighs abut 4.5 lbs., and my 300mm f:2.8 is 6+ lbs.  To mount them with NV attached, the mounting point must be on the lens, not the NVD.  Good luck with your efforts and I look forward to reading your results.  

Ray,

the lens has mounting leg (not shown in the picture) and it will be mounted on a tripod with NV and "your" diagonal. Lens weights 6lb.

[GeezerGazer]

Beautiful lens!  I'm sure you are going to love the performance.