canned
Hello everyone,
Where can I measure the lens diameter?
When I look into the lens from the front, should I measure from the outside or the inside of the barrel?
The inside diameter is ~40mm, and the outside diameter is ~43mm.
Best regards,
Canned
canned
Additional questions:
What are the differences in quality between
- ND filter sheets
- ND neutral density filters
- ND HTMC-coated neutral density filters?
Best regards and thanks!
Canned
canned
Follow-up question II:
At the moment, I’ve reached my limit with an aperture of f/16 and an exposure time of 2–5 seconds. What ND factor (filter film or neutral density filter) would you choose?
Best regards and thanks,
Canned
MirkoBoeddecker
Canned,
You’ll need to measure the filter thread if you want to screw a filter in. The spacing between the thread diameters is large enough that you don’t really need to take the depth of the thread cut into account. So measure from centre to centre and see which one fits best.
As for the coating: the plastic filters aren’t coated, of course. But that’s not a problem. You’re using this ND filter under the lens in the darkroom, not for taking photographs. There’s hardly any light more perfectly directed than the beam coming out of the bottom of your enlarger lens. The coating becomes important when light rays strike the surface of the filter at an angle and cause reflections or a reduction in contrast.
I doubt you’ll be able to tell the difference between a plastic filter and an SHPMC-coated Heliopan filter when enlarging.
As I said, this applies to filtering UNDER THE ENLARGING LENS.
Not for filters used for photographic purposes!!
You’ll need at least two of our filters.
Mirko
canned
Hi Mirko!
Thanks for your reply (and your patience).
The thread diameter is ~37mm.
-> So, does that mean the ND filter goes on first, then the lens? (and not the other way round)
Can the filter sheets be cut to size with scissors?
Best regards,
Canned
MirkoBoeddecker
Canned,
I think we’re a bit talking at cross-purposes here...
The neutral density filter I’m talking about goes where your red filter is at the moment.
So just below the magnifying lens (through which the light from the top of the enlarger falls).
No, you can’t cut it to size – they’re Lee Filters, so they’re those sturdy, clear plastic discs.
Of course, you can also screw a standard screw-in neutral density filter into the filter thread at the bottom of your lens if you can’t attach this plastic disc.
You’ll have to choose whatever works best for you.
Regards,
Mirko
canned
I’ve got you perfectly:
Unfortunately, the Lee Filters filter sheet isn’t an option, as only round sheets fit into the filter holder below the lens (the red filter is round with a diameter of 50 mm).
But I have another question about neutral density filters that screw onto the lens thread: are there any lens designs that don’t allow this? As far as I know, the thread runs lengthways (not around the circumference!) and is at the very end of the lens. With my enlarger lens (Rodegon 50mm, thread diameter ~37mm), there is a smaller tube inside the threaded tube which is ~1cm longer lengthwise; in other words, when screwed in, this part apparently protrudes into the enlarger.
To put it another way: are there different types of filters that can be mounted onto the lens in different ways?
I’ll probably have to take the lens to a specialist shop at some point :blink: . Perhaps someone knows the answer anyway?
Regards,
Canned
Gast
Hold on, :rolleyes:
Lee filter sheets are designed for lamps; they aren’t gelatine filters like the Kodak Wratten ones and (strictly speaking) aren’t meant or suited to being placed anywhere in the optical system! Sure, they’re not bad, but they’re still lamp filters – you just have to weigh up the cost against the result; I know people who, for want of a red filter, have held something like that by hand in front of the lens and the result is still impressive. I, however, would opt for a proper filter – be it gelatin or glass – if in doubt.
What Mirko was trying to sell you in the other thread is probably a resin filter, i.e. solid-coloured plastic; that’s probably fine too, but don’t cut it up – perhaps it’s enough simply to remove the red filter from its holder and place the ND filter on top – just be careful not to scratch it.
ND grey filter – the ‘ND’ stands for Neutral Density.
ND filters with ‘HTMC’ simply means they have a multi-coating (MC = Multicoating); Mirko has already made the differences clear.
0.3 = 1 stop
0.6 = 2 stops
0.9 = 3 stops
1.2 = 4 stops
and so on, but normally there’s nothing above 1.2; you’d have to stack several filters on top of each other – and that’s where the differences between Tiffin glass filters and some HAMA rubbish become apparent; with budget amateur photography suppliers, a distinct brown colour cast is usually noticeable. Lee light filter sheets won’t fare any better in this respect. Does it matter? No idea :blink:. But imagine you want to print the same image again on a larger scale – because the exposure times would be too long, you decide to remove the ND filters – and voilà, a colour cast in the opposite direction, as you’d already counteracted the brown colour cast with a filter when printing the smaller version.
Regards
Matthias
P.S.: Take the lens to the camera shop and try screwing in different filter sizes... as a last resort, you can sometimes find those plastic filter holders for gelatine filters on eBay (they look like a ring with four white plastic screws, which let you adapt the thing to almost any lens size), add an ND filter and you’re sorted.
