Nikon 39mm drop in filters, DIY mod of gel filter holders

[toups]

I recently acquired a nice 600mm f/5.6 ED IF AI lens at a price point I couldn't pass up.  It came with a gel filter holder (with no filter element) installed.  In spite of the Nikon claim that the lens is designed to be used with a filter, I do not believe that image quality could be positively impacted by using a filter.  The 39mm slide in normal filter holder and the C-PL1S polarized filter filter are pretty much "unobtanium." Also the filter holder only works with the special Nikon 39mm filters.  Strangely enough, the gel filter holders are very cheap and relatively easy to find.

I have managed to acquire an additional pair of gel filter holders fairly inexpensively (less than $15 US each.)  My plans are to machine the holders to take 40.5mm filters which are reasonably common.  I'm not sure that I have a great need for filters with this lens, except for a circular polarized filter. 

So my plan is to mill off the back surface of the holder after removing the thin gel holder to make room for a 40.5mm filter.  So basically the filter holder will be mounted reversed from how the gel holder is normally inserted.  One could be a simple 40.5mm filter holder that could take standard 40.5mm filters while the other would emulate a C-PL1S.

Not sure I have an easy way to cut the needed filter threads but will cross that bridge later.

I have a Neewer 40.5mm Polarizing Filter Ultra Slim arriving next week.  So the thought is to machine the gel holder, and thread or glue the filter to the holder.  Will mill a slot for a small thumb wheel to rotate the filter.  Will see if I need an idler gear or rubber roller to rotate the filter.

One interesting observation, is that the gel filter holders I recently acquired do not have any screws on the top side while the one that came with the lens has 2 screws on top.  So the former ones should be more convenient for milling a slot for a thumb wheel.

I'll post pictures and updates when I can find time to proceed with this project.

I suppose someone with a 3-D printer could also easily design and emulate a C-PL1S but I figure it will be just as quick for me to machine down an existing gel filter holder.

[Birna Rørslett]

I'm glad to be ensured I own a piece of 'unobtanium' .... aka C-P1S using this with 300/2.8 ED-IF Ais, 500/4Ai-P and the 600/5.6 ED-IF. The polariser is surprisingly effective for landscape scenes with these long lenses. And are the drop-in filter holders really that rare? I have a number of them. If these also are classified as 'unobtanium' I must be very lucky then? The 39mm filter set is shared ith the 500 Mirror lenses if memory serves, at least that was the route by which they arrived to me.

Otherwise, I agree that a filter in the little holder isn't strictly necessary. Nikon is very conservative of behalf on the users. It does prevent some dust inside, though.

I mounted a B+W IR filter 39mm in one of the holders so these lenses can be used for IR photography. By the way, the 600/5.6 ED-IF is very good for IR.

[toups]

Maybe not completely unobtanium for either, but the price point can be a bit to a lot higher than I like.  Actually there is a C-PL1S located in Japan on eBay for over half of what the lens cost me.  So one can still obtain one at the moment and maybe I am spoiled by my lens purchase price.

Actually I also couldn't pass up a Nikkor 500mm f/8 Reflex C lens with its set of filters. Now I  just need to remember where I safely stored the spare filters.

Regarding whether a filter is necessary, I played around a little bit in the OSLO EDU ray tracing software and for a long perfect lens, I don't see any real measurable changes in image quality by placing a plane parallel piece of glass at that point in the image path other than shifting the focus point by a fraction of the filter thickness.  Agree one role of the filter may be to keep dust out.

Thanks for the note regarding IR and the 600/5.6.  Very interesting!

P.S. Thanks for reminding me what the best camera is.   

[ARTUROARTISTA]

I'm glad to be ensured I own a piece of 'unobtanium' .... aka C-P1S using this with 300/2.8 ED-IF Ais, 500/4Ai-P and the 600/5.6 ED-IF. The polariser is surprisingly effective for landscape scenes with these long lenses. And are the drop-in filter holders really that rare? I have a number of them. If these also are classified as 'unobtanium' I must be very lucky then? The 39mm filter set is shared ith the 500 Mirror lenses if memory serves, at least that was the route by which they arrived to me.

Otherwise, I agree that a filter in the little holder isn't strictly necessary. Nikon is very conservative of behalf on the users. It does prevent some dust inside, though.

I mounted a B+W IR filter 39mm in one of the holders so these lenses can be used for IR photography. By the way, the 600/5.6 ED-IF is very good for IR.

Birna, can I do IR with a Nikon D750? I have never done infrared photography and would like to try.

[Birna Rørslett]

Birna, can I do IR with a Nikon D750? I have never done infrared photography and would like to try.

I don't think that'll work well, as long as the original internal AA/anti-IR filter is in place. Older Nikons such as the D70 and similar unmodified cameras allowed IR shooting, however exposure times were long and images became noisy.

There are several companies which can modify most cameras for either IR, UV, or "full spectrum".

[ARTUROARTISTA]

I don't think that'll work well, as long as the original internal AA/anti-IR filter is in place. Older Nikons such as the D70 and similar unmodified cameras allowed IR shooting, however exposure times were long and images became noisy.

There are several companies which can modify most cameras for either IR, UV, or "full spectrum".

Okay, understood. Thanks Birna.

[toups]

I have a spare D50 or D70 that I can remove the UV/IR filter from on top of the sensor.  I wonder if a quartz window is needed to replace the filter for a full spectrum mod where the IR (or UV) filter is used on or in the lens.

I have removed the CCDs from a few cameras but never stripped one down that I wanted to reassemble.

Of course the astrocamera I built (here is a link to my build inside the original thread https://www.cloudynights.com/topic/497530-diy-astro-ccd-16-bit-color-6mpx-camera/?p=9228294) mentioned in the "Introduce Yourself" forum has no filter, but is not convenient for normal photo use since it requires cooling and a laptop to use.

[toups]

Regarding IR or UV use, since a D70 or D50 doesn't support live view, the best option may be to mount the IR filter in place of the filter at the CCD.  So a UV only, IR only or full spectrum version would be useful, but putting a UV or IR filter at the lens means it would be impossible to frame the photo before taking it.

[Birna Rørslett]

My first years shooting IR was with a "blind" camera, i.e. no LiveView. D1, D1H, D70, D40 were used back then.One quickly learned to frame the scene nonetheless. Of course, long lenses posed more severe issues (85-135mm)  thus I used a flip-up holder allowing for pre-focusing and framing. My first D40X, presented to me courtesy of Vivek Iyer, had the Baader UV filter over the sensor thus allowed direct focusing from the viewfinder. Very nifty combination with the UV-Nikkor. I have transferred the filter now to a modified D3200 instead to get LiveView and more pixel resolution.

Being able to frame and focus a camera without looking in a finder is beneficial for any photographer. Try it.

I have a spare D50 or D70 that I can remove the UV/IR filter from on top of the sensor.  I wonder if a quartz window is needed to replace the filter for a full ...

Unless you own a specialist lens designed for UV,  no dedicated quartz window is required. I believe using WG280 is popular.

[toups]

Birna, no I don't own a special UV lens like a UV-Nikkor 55 or 105.  But from ultravioletphotography.com I guess you do.

Ordered some IR and UV filters from Tangsinuo to play with.  (Like I needed more projects,  )  Did grab some JGS1 UV Grade Fused Silica Quartz Glass Windows that I believe are the right size to replace the UV/IR filter in the Nikon D50 or D70 to make it full spectrum.   Overkill, but unlike the ZBW1 bare glass disk I grabbed for the camera, the JGS1 won't require any cutting.  I know, too many projects.  Anyway testing and use of the filters and seeing if any lens I have can get to the UV will have to be a future post for a thread in the proper forum.

Back on topic, I need to find time to machine the gel holders to turn one into a CPL assembly and the other into a 40.5mm filter holder.  More to come, but need to find some time so don't expect any updates soon.