duncan_kirkwood2

Now realise the 1000mm Nikkor received is different to the one advertised … I copied the dealer's original photo before ordering . The lens received does not have a front element retaining ring / 'tidying' ring … so it's going back. The lens bezel might also be missing. At some stage after the dealer's sale listing photo was taken , one or more front rings has been removed . I have advised the dealer and await a reply . Not mentioning the dealer's name because their s/h wares are usually OK . Could be several reasons why the lens has a missing ring(s)

On examining the Nikkor 1000mm slightly fungused front element, its retaining ring has only one slot for removal / tightening … thus could be difficult to remove safely. Most lenses' front retaining rings have 2 slots enabling use of a spanner wrench for removal. To remove the Nikkor 1000mm retaining ring would likely require use of a suitable tool to fit the single slot - which might have to be custom made - and a small hammer. I'm not prepared to risk using such a combination but will consult an engineer friend for a second opinion. Might be better to leave the lens on a window shelf and let the Sun kill the fungus … or use a UV lamp on it for a few days. Fungus is noticeable but slight so unlikely to affect the image. UV light will not remove the fungus but once neutralised it should not get any worse.

Nikkor 1000mm arrived today … build quality including internal baffling is superb compared to e.g. Chinese astro telescopes … thus will not require internal flocking. Many Chinese astro reflectors are built to a price and have inefficient shiny black internal baffling which compromises image contrast. Hence many astronomers improve the baffling of their Chinese 'scopes. dunk

Self adhesive black velour is recommended and used by astronomers for improving astro telescopes performance and I've seen no reports of dust or fungus … I have used it myself on my own modified astro reflector 'scopes. Check out Neil English's astro telescope modification articles. dink

All mirror lenses need to acclimate to ambient temperature in order to prevent internal thermals compromising the image. When stored in a warm environment the primary mirror absorbs heat and the mirror then acts like a radiator when taken into cooler environment … when the heat is radiated from the primary mirror the resultant 'internal thermals' will blur the image … imagine the thermals from e.g. a jet aircraft engine when the plane is stationary on a runway awaiting take-off. Astronomers always allow at least 30 minutes for their reflector telescopes to acclimate before commencing astro observing / astro imaging … longer acclimation times are required for Maksutov reflectors. I have just ordered a s/h Nikkor 1000mm f11 Mk II complete with minor fungus on the rear of the front element . I plan to remove the front element to clean off the fungus … and will also flock the lens interior with matt black self adhesive velour to improve image contrast. dunk

<p>EL Nikkors are suitable for UV photography:<br> http://www.savazzi.net/photography/el-nikkor_uv.htm</p> <p>dunk</p>