How to find filter size of lens?

W_Taylor76 · Mar 1, 2022

I have two lenses for my 4x5 camera and I am wanting to buy contrast filters for b&w photography. However, I don't have any idea what the filter size would be for the lenses. One is 210 mm and the other is 135 mm. The cap on the 135 mm has ø42 on the inside of the front cap, and the 210 mm does not have anything written on the front cap. Does the ø42 mean the filter size? How would I tell the size of the filter for the 210 mm? Any suggestions are welcome.

shutterfinger · Mar 1, 2022

What make/vintage are the lens? Lens from the 1940's to the 1960's used series filters which fit into slip on adapters to fit various lens.
Newer lens use screw in filters and 42 will be the filter size in millimeters.

Kodachromeguy · Mar 1, 2022

1. 135mm. If the lens cap fits over the lens, then the filter size is likely 40.5mm. That was a common size in mid-century German lenses for large format and smaller format.
2. 210mm. Not enough information.
Brand and model of lenses? Do they have filter threads?

W_Taylor76 · Mar 1, 2022

shutterfinger said:
What make/vintage are the lens?

The 135 mm is a Caltar II-N 1:5.6 MC Copal 0 and the 210 mm is a Horseman Topcor 5.6/210 Copal 1

bdial · Mar 1, 2022

You need to measure the inside diameter of the lens in millimeters. The number on your cap is likely the inside diameter of the cap, assuming it’s a slip-on, more or less the outside diameter of the lens. But not always, sometimes it’s just a number.

W_Taylor76 · Mar 1, 2022

Kodachromeguy said:
1. 135mm. If the lens cap fits over the lens, then the filter size is likely 40.5mm.

It does fit over the front of the lens.

Kodachromeguy said:
Why didn't you write the brand and model of lenses?

Got distracted from the rugrats and didn't go back and reread the post to see if it made sense. When the kids want attention, they want attention and they want it now. Plus I don't use forums that much so I am just winging it on what to include in the post.

Kodachromeguy said:
Do they have filter threads?

Yes, they have threads.

shutterfinger · Mar 1, 2022

Sometimes those threads are for the front element retainer ring and not for a filter.
These lens should be new enough to use screw in filters, measure the inside diameter of the lens in millimeters. Sometimes the filter/snap in lens cap size is printed on the front element trim ring.
xxø

Sirius Glass · Mar 1, 2022

Slip on filter adapters use Series Filters such as series 5, series 6, series 7, series 8 which do not have threads.

Oren Grad · Mar 2, 2022

W_Taylor76 said:
The 135 mm is a Caltar II-N 1:5.6 MC Copal 0 and the 210 mm is a Horseman Topcor 5.6/210 Copal 1

The 135 Caltar II-N is a relabeled Rodenstock Sironar-N. Filter spec is 40.5 mm. Filter spec for the 210mm LF Topcor is 67 mm. Put a ruler across them to verify.

mrosenlof · Mar 2, 2022

Most 210mm f/5.6 lenses take 67mm filters. But I am not familiar with yours.

Ah, Owen beat me to it!

AgX · Mar 2, 2022

A caliper and and a thread-profile gauge anyone into photographic threads should have in house. They meanwhile cost only few dollars. Together with a thread table even the size of female threads can be establised.

AgX · Mar 2, 2022

This does not exclude that threads may keep some enigma... I once presented here the case of three large filters from KMZ, seemingly out of one set, which only could be stacked together in one certain sequence. Other than this it is of practically no effect, but still something that even with my various tool I could not get right.

Alan Edward Klein · Mar 2, 2022

Courtesy of Large Format Photography forums: (third column from the right.)
https://www.largeformatphotography.info/lenses/LF4x5in.html

Doremus Scudder · Mar 3, 2022

At the risk of sounding flippant...

Take them to your local camera store and "try on" a few filters and see what fits. (Digital cameras use the same sizes.)

Doremus

AgX · Mar 3, 2022

W_Taylor76 said:
The cap on the 135 mm has ø42 on the inside of the front cap. Does the ø42 mean the filter size?

No. Push-on caps are not related to threads at all. Their designation refers to front-ring outer-diameter they will fit on.

xya · Mar 3, 2022

Doremus Scudder said:
At the risk of sounding flippant...

Take them to your local camera store and "try on" a few filters and see what fits. (Digital cameras use the same sizes.)

Doremus

very good idea!!!

igmolinav · Mar 3, 2022

Hi,

@OP - Would you please be so kind to tell us the make and the lens focal length, including its aperture and any other description you may want to give us?

Thank you, kind regards!

runswithsizzers · Mar 3, 2022

Every threaded part can be described by two numbers: the diameter of the male threaded part, and the spacing of the thread teeth, called the thread pitch. Fractional threads are given as threads per inch (tpi) and metric thread pitch is given as a peak-to-peak measurement in millimeters. With camera filter threads, sometimes the pitch number is not given, because for most modern filters, a given diameter wiil come in only one pitch. But there may be exceptions, so beware.

If you had a filter, you could use a caliper to measure across the top of the threads - which would give the nominal diameter of the filter.

With female filter threads it is harder, because you would need to measure to the bottom of the female threads, and the caliper is not designed to do that. Usually you can come up with a "close-enough" estimate by measuring inside the lens to the top of the threads - and then estimating how tall the threads are. If the threads are about 1mm tall, then add 2 millimeters to your inside measurement to approximate the outside diameter of the filter.

The thread pitch can be determined by finding which toothed gauge fits the threads best. For general thread measuring you should have both a metric thread pitch gauge and a fractional one.
---
"One accurate measurement is worth a thousand expert opinions" - Grace Hopper, computer pioneer and naval officer.

BrianShaw · Mar 3, 2022

igmolinav said:
Hi,

@OP - Would you please be so kind to tell us the make and the lens focal length, including its aperture and any other description you may want to give us?

Thank you, kind regards!

You might want to review post #9. All is there

John Earley · Mar 20, 2022

My Horseman Topcor 5.6/210 Copal 1 takes a 67mm filter

abruzzi · Mar 20, 2022

I have bought a lot of LF lenses without caps, and my filter system for my LF cameras is a Cokin P, so all my filters are the same size, but I have a series of rings from 49mm to 82mm, but semi frequently I get a lens that doesn't have a matching mounting ring, so I'll get a step-up filter adapter to adapt to the Cokin sizes (49, 52, 58, 67, 72, 82. Cokin has a few others but I haven't had a need for them yet.) So the most useful LF tool for me has become the cheap $10 digital calipers that I use to measure the outside for push on lens caps, and the inside to measure the threads. If I can't find a listing for the lens, first I try test fitting some close ring sizes that I already have, if that doesn't work, I do what runwithsizzers mentions above.

campy51 · Mar 21, 2022

Doremus Scudder said:
At the risk of sounding flippant...

Take them to your local camera store and "try on" a few filters and see what fits. (Digital cameras use the same sizes.)

Doremus

That's too easy, we must complicate this to keep the thread going.

abruzzi · Mar 21, 2022

I live in a city of 200k, and our local camera store is Best Buy. These days, the local camera store isn't worth 2 cents.

Kodachromeguy · Mar 21, 2022

Doremus Scudder said:
At the risk of sounding flippant...

Take them to your local camera store and "try on" a few filters and see what fits. (Digital cameras use the same sizes.)

Doremus

Many (most) Americans have no convenient access to a real camera store. So at the risk of sounding flippant, where is this store with a variety of filters to be found? Drive to New York?

Doremus Scudder · Mar 22, 2022

Kodachromeguy said:
Many (most) Americans have no convenient access to a real camera store. So at the risk of sounding flippant, where is this store with a variety of filters to be found? Drive to New York?

Any store that sells digital SLRs with interchangeable lenses will have a good supply of filters in many sizes (I don't know if that's a "real camera store," rather electronics/photo). I don't think you need to go to B&H to find a filter selection. Maybe a larger city, though...

Doremus

How to find filter size of lens?

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