filter size for Dagor 6"?

[rippo]

yes i did a search, and couldn't find anything. too many instances of "dagor", "thread" etc. sorry if this is a repetitive request.

i have a dagor 6 inch lens in a rapax shutter. i bought a LisJon kit 4x5 field camera a few months ago, mostly so i could have the lens and 6x6 roll film back. i've used the camera a couple of times as a test, but i think the film plane isn't aligned with the gg. so i'm going to pull the dagor and mount it for my toyo-view.

long-winded intro to say: what's the filter size? i don't have any accurate way of measuring it, and with a ruler it looks to be about 28mm or so.

what's the best way to use filters on this, as it's pretty small? i've got cokin A and P holders, and a fair collection of cokin A filters. just get a 28mm (if that's what it is) to 37mm step up, and then a 37mm cokin adapter ring to work with the A-series?

or are there pitfalls i'm unaware of?

thanks!

[Ash]

I remounted my own Dagor 180mm, it's tiny in the shutter. I would use oversized filters for personal preference.

That's mainly due to a large filter thread I used mounted to the front element - I wanted a lens hood so I used an oversized thread for good measure. Any filters will need to be P's to screw onto the correct holder on that thread.

See what works for you. I'm sure with a correct holder A filters will be large enough. Just avoid vignetting?

[rippo]

thanks ash. i don't think the A series will give me vignetting. this lens is tiny compared to modern lenses...i even used my A series filters on my Caltar 210mm lens before i got rid of it, which i think was 49 or 52mm filter diameter. i'd need multiple step up rings to get it working on my P series...i don't think i can go from 28mm (if that's what it is. anyone?) to say 67mm in one fell swoop.

good point on the lens shade. i don't use them as of yet, preferring (for reasons of economy) to hover like an expectant father over the lens, blocking the sun with my large head.

btw ash, i'm going to try your packard mod very soon now. i have the packard, have some melamine, and just need a wide-holed toyo lensboard and some way to drill through metal.

[Ash]

The Caltar is a longer lens however, the Dagor is a bit wider (210 vs 150-ish) so it takes from a wider field that might clip the corners of an A filter if it's not super-close.

Good luck with the mod :)

[Ash]

Oh here's the link to my personal mod for my own Dagor. You can see how tiny the lens elements are http://www.largeformatphotography.info/forum/showthread.php?t=29097&page=2

You could possibly do something along those lines (with a bit of a mod and machining) to avoid necessary filter step-ups?

You could go so simple as a friction/spring clamp to hold a P series holder in place over the element?

[rippo]

i just tried a ballpark test with the holder, holding out from the lens a good distance, and checking the corner of the gg through the lens. looks like the actual filter holder won't vignette even if it's 3/4 of an inch in front of the lens (2cm). that doesn't account for any step up rings in between though, so i won't truly know until i try.

i had looked at the P series universal adapter before, which has three screw posts radiating from the lens, which tighten down around the lens. (i have a ilex-caltar 90mm lens with no filter threads.) however i can't find the *minimum* size the cokin universal adapter will handle. their site only gives the max size. also, i don't know if the posts will have sufficient grip, as the ring around the lens is not very wide. also from the few posts i can find in other forums on the adapter, it sounds a little fiddly and/or unreliable.

unfortunately, there's no built-in gap behind the front element, as there is on your lens. :(

other research on the forum points out that some lenses only appear to have filter threads, but in fact the threads are just to assemble the lens with. that doesn't appear to be the case here, but i'm no expert.

another option just occurred to me: the P series holder fits completely around the rapax shutter. i could mount an appropriately sized ring between the shutter and the lensboard. i could then use the holder with one filter only, and i couldn't rotate the holder for grad filters. however i think cokin sells an extender, so i could put a second holder on front, rotate it, and have multiple filters and/or round filters if i wanted. the only possible deal-breaker is whether i have enough threading on the rear mounting flange to allow for the extra space up front. in the kit camera with its wood lensboard, i think not. but a metal lensboard, perhaps....

[Robert A. Zeichner]

My lens guide indicates this lens takes a 32.5mm filter. It doesn't indicate whether this is the inner threaded diameter or the outer diameter. You can measure this with a metric ruler if you are careful. If it's the outer diameter, I can sell you a 33mm push-on adapter that will take you to series 6, a very common size for drop-in filters. What kind of filters are you wanting to use?

[rippo]

that's got to be the outer dimension.

so if i get a series-6 on the business end, where do i go from there? i own one 'series' filter that came with my Argus C4. that's the extent of my experience using series filters. i've done some reading before, but it's a bit confusing without actually seeing what's going on.

can i then use a threaded step-up ring to get me into either my cokin A or P, or my set of 67mm round filters? or do i need to get series filters? thanks.

i'm guessing if your lens guide lists the outer dimension, then those inner threads might not be for filter attachment.

[Bill_1856]

My 6" Dagor in Rapax takes a 1.25"/31.5mm Kodak Seriea VI adapter.

[Robert A. Zeichner]

that's got to be the outer dimension.

so if i get a series-6 on the business end, where do i go from there? i own one 'series' filter that came with my Argus C4. that's the extent of my experience using series filters. i've done some reading before, but it's a bit confusing without actually seeing what's going on.

can i then use a threaded step-up ring to get me into either my cokin A or P, or my set of 67mm round filters? or do i need to get series filters? thanks.

i'm guessing if your lens guide lists the outer dimension, then those inner threads might not be for filter attachment.

If Bill_1856 is correct, I also have a 31.5mm push-on series 6 adapter as well. You can confirm the dimension with a metric ruler.

How the Series filter system works is pretty simple. The filters are trapped between the adapter and either a retaining ring which comes with the adapter or a series shade of the appropriate size. You could get a step up adapter to go from 6 to 7 and then 7 to 8, which will allow you to attach 67mm screw-in filters directly. You would have to attach a shade to the front of the 67mm filter, which will make quite a pile of adapters, glass and shade. The weight may be such that the whole mess could fall off, especially if you are aiming downward. I've done the series 6 to 7 step up with a lightweight shade and that seems to work fine. The other thing you could do is simply get some series 6 filters which are cheap and plentiful and available in just about any color you need. From left to right, lens, series 6 push-on adapter, 6-7 step up, 7-8 step-up, 67mm filter, shade; pic 2 is that whole mess together on the lens (tends to fall off); pic 3 is the lens, series 6 push-on adapter, series 6 filter and series 6 shade; pic 4 is that whole assortment attached to the lens (very serviceable). I hope this helps.

[Keith Fleming]

I use 1.25-inch filters from the Orion telescope catalog. The eyepieces for amateur astronomy scopes come in 1.25 and 2.0 inch sizes, and Orion provides filters in various colors for these scopes. The disadvantage is that Orion sellls the filters in sets rather than individually. However, I've been able to "borrow" a yellow filter from an unused set that belongs to my wife (who no longer has a scope).

Keith Fleming

[rippo]

wow, yeah robert, that helps a lot. very clear now, thanks! i can see how the lens is going to have a lot of stuff dangling off the front end. could be dangerous, as you say.

rather than go to a 67mm thread, which is what my 'classy' filters are, could i do just a series 6 and then buy a cokin 'A' adapter ring to fit it? that would save on weight and let me use what i've already got. is the retaining-ring thread size standard on series filters, or just the lens-end of the filter holder?

pictures too! wow, full service. thanks again.

[rippo]

keith: i saw you mention those in an earlier post (see, i did do some research before postin! :) ). however i didn't understand whether it pertained to me or not. will the 1.25" filters fit? do they slip on, screw in, or what? if they slip on, i just get to use one at a time i would think.

thanks!

i'd like to have the ability to use my grad filter from time to time, even if it's the cokin A series one. although i can live without if necessary.

[Robert A. Zeichner]

wow, yeah robert, that helps a lot. very clear now, thanks! i can see how the lens is going to have a lot of stuff dangling off the front end. could be dangerous, as you say.

rather than go to a 67mm thread, which is what my 'classy' filters are, could i do just a series 6 and then buy a cokin 'A' adapter ring to fit it? that would save on weight and let me use what i've already got. is the retaining-ring thread size standard on series filters, or just the lens-end of the filter holder?

pictures too! wow, full service. thanks again.

Series size threads are not really the equivalent to any modern screw-in filter sizes except the series 8, which is very, very close to 67mm. So, much so, that 67mm screw-in filters almost with out exception, fit right in. For series 6, I don't think you will find an off-the-shelf Cokin ring that will fit. But, there is Gorilla Glue. You can get a 46mm Cokin adapter ring if they make one, remove the retaining ring on a 31.5mm push-on adapter and glue one to the other with the aforementioned adhesive or some other epoxy. If you find that a 46mm is only available in the Cokin A size, I think you could get an A to P adapter, but Cokin is not my forte, so perhaps others can guide you in that.

[Keith Fleming]

Rippo,

The Orion filter I'm using screws into the 6-inch Dagor.

Having read comments elsewhere today by Sandy King, I am mindful that many variations of Dagors exist as they were manufactured by various entities over a long time. While the Orion filters screw into mine, such filters may not fit other 6-inch Dagors. For clarity, I have a coated version, serial number 77XXXX, in a Copal O shutter, by C. P. Goerz Am. Opt. Co.

Keith Fleming

[rippo]

robert: i'd probably go the glue route, otherwise i'd have a lot of things hanging off the front. must think on this a bit.

keith: thanks for the heads up. 31.5 would definitely have to be the outer diameter on this lens. perhaps i have a smaller one. i seem to recall the serial started wit 784, but i'm at work now and can't check it.


the easiest thing might be for me to get a 28mm filter and just try it. i think that's a vidcam standard, and they're cheap on ebay. i'll check around locally and see if i can find something to try first. if that works, i know i can step up to 47mm, then get a cokin adapter for the P. but i don't think your 1.25 filters are going to work here.

thanks.