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    Re: Meniscus lens iris "sweet spot"???

    Thomas Grubb pondered this back in the late 1850s and came up with a 'portable' (pillbox style mount) which gave reasonable definition and coverage when the stop was pushed as far forward as it was...
  2. Re: Advice needed for stuck lens retaining ring, please

    Fortunately Copal 1 shutter retaining rings are readily available for a few $.
  3. Re: Advice needed for stuck lens retaining ring, please

    You could always use a Dremmel or similar hand held grinder and cut into the retaining ring until you can snap it off but will obviously need a new one if you do.
  4. Thread: PPE lens

    by pgk
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    Re: PPE lens

    It looks very similar to a lens that I have, also made by Pilkington Perkin-Elmer - a UK/US collaboration which only lasted for a short time. The lens would have been made in St Asaph in North Wales...
  5. Re: Should I return this Dallmeyer Pentac 8" f2.9?

    Isn't it odd that many such sellers of photographic equipment have poor eyesight and seem unable to take sharp, correctly focussed photographs. Strange!
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    Re: How to attach bellows?

    I asked Custom Bellows what adhesive to use to attached a new set of bellows to a Gandolfi. They suggested impact adhesive - EvoStick - and its held fine for over 2 years so far. Cheap and effective.
  7. Thread: Servicing a lens

    by pgk
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    Re: Servicing a lens

    It seems to be a fairly common problem on Cooke lenses from TTH. I have a series III on which the diaphragm would hardly move and I simply sent to my local general camera repairer who sorted it out...
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    Re: Help identifying a lens

    I assume that you've waded through the information here: https://cookeoptics.com/t/compendium.html
  9. Re: Lens mounting flanges - measurements and other info

    Here is a shot illustrating the problem of measuring threads. The lens is an ~1860 Petzval which arrived minus flange. The gauge shown is a 22tpi Whitworth aligned with the flange thread on the lens...
  10. Re: Lens mounting flanges - measurements and other info

    My measurements suggest that you are applying very reasonable logic. However, in the early days of lens production, standards seem to have been a real rarity so my guess is that makers simply built a...
  11. Re: Lens mounting flanges - measurements and other info

    And FWIW I have an adapter flange for 1.712/28 to 1.912/36 - from ~1883ish and a pencil marking on the back cap which fits the larger male thread is marked Dallmeyer 1/4 plate. So although there was...
  12. Re: Lens mounting flanges - measurements and other info

    Some makers seem to have worked in fractions of an inch, so a good start point for some early lenses might be matching up the thousandths to fractions, depending on their country of manufacture .....
  13. Re: Lens mounting flanges - measurements and other info

    If only it was that easy. I tend to measure the lens thread as high up and near to the top as possible because lower down threads can be very worn indeed, especially softer brass ones. Even so I...
  14. Re: Lens mounting flanges - measurements and other info

    Its a long time since I had British motorbikes and worked on them but if I remember correctly they used UNC and UNF threads by the 50s and 60s. I think many threads 'approximated' Whitworth threads...
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    Re: MPP - newbie question

    I picked up a Linhof Colour very cheaply (~150) a few weeks back. MPPs and cheap Linhofs will be old though so you need to ensure that they are complete - NO missing or broken parts - and working...
  16. Re: Lens mounting flanges - measurements and other info

    That would be ideal and is potentially possible. But in the first instance this would be an information gathering excercise. Without information a database will go nowhere. So if anyone has lens/ring...
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    Re: Filthy Flange - possibilities.

    Its worth reading this: http://skgrimes.com/library/faq/how-to-measure-threads but older threads can be worn so a bit of adjustment or tolerance has to be applied.

    I have a couple of screw pitch...
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    Re: Filthy Flange - possibilities.

    I'll post some of mine in the sell/trade section soon. One thing I've realised is that older lenses and flanges can have well worn threads as the brass was quite soft. This means that measurements...
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    Re: Filthy Flange - possibilities.

    Sounds like a great idea - but might need moderator's approval. I've measured the spare flanges that I have and I think that the first thing required would be a 'how to measure and how to describe...
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    Re: Filthy Flange - possibilities.

    And FWIW, I have 4 lens housings which are from the same base lens, and three flanges (+ 3 complete lens sections). Despite this two of the flanges fit three of them but the other is just too tight...
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    Re: Filthy Flange - possibilities.

    Its cleaning up well - halfway!

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    Filthy Flange - possibilities.

    I received parts of an 1850s lens today (for spares). The flange does fit some of my other lenses as I'd hoped it would. However it was quite literally black. It was covered with a hard layer of...
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    Re: Trying to identify a film back.

    Here's the image of the back and the glass (which is upside down showing the brass sliders which fit together).

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    Re: Need Grubb Lens Expertise

    Yes. Although not marked as such (it probably pre-dated the code letters) it looks very much like it was probably what would later be coded as a B2 Petzval by Grubb - quite a popular lens I think.
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    Trying to identify a film back.

    I have a camera with a back on it which is designed to take a film holder which slides into a recess which is 3 5/8" wide and 1/16" thick - the holder must be in the region of 5 3/16" long (give or...
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    Re: Wet plate collodion spectral sensitivity?

    Thanks all, especially Nodda Duma (apparently very helpful). I have forwarded links and info and my friend is now looking at glass types with help from retired lens designers too. I think that he's...
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    Re: Information sought on a lens by C Burr, London

    Looks fairly similar but they are not identical - mine is 2" in diameter and never had a hood (no provision for one). I get 2 reflections from the front and 2 from the rear. I wonder if Mr Burr was a...
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    Re: Information sought on a lens by C Burr, London

    Yes. Tying specific photos to being taken on specific lenses during the 1850/60s is not easy, but I have certainly found a few, or have discovered specific photographers/locations/dates which I am...
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    Re: Information sought on a lens by C Burr, London

    Could you tell me the physical dimensions of your lens please?
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    Re: Information sought on a lens by C Burr, London

    Thanks Andrew. I hadn't looked at the VM as yet. The lens has no engraved specifications, nor address. Going from online info I'm thinking it may be a 'widish' RR from the 1870s?
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    Re: Information sought on a lens by C Burr, London

    August 15th 1860:
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    Information sought on a lens by C Burr, London

    I picked up, cheaply enough, what I thought was probably a Rapid Rectilinear lens by C Burr, of London. With a little persuasion it disassembled and after having cleaned decades of caked on muck off...
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    Re: Wet plate collodion spectral sensitivity?

    Thanks, it does and I've sent on the link.
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    Re: Wet plate collodion spectral sensitivity?

    I'd have thought it basic data myself (but then I have a photo science background) and having searched I've found some data, but I'm a bit dubious about some of its assumptions. I thought that...
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    Wet plate collodion spectral sensitivity?

    Can anyone tell me what the spectral sensitivity would have been like back in the 1850/60s. Was collodion simply just blue sensitive. I ask because I have a friend doing some lens software modelling...
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    Re: Fungus on antique Lens: Can it be fixed?

    And just to illustrate this further, here is a shot taken on an 1859 lens (using a step and repeat digital back I am building on a Gandolfi) and then stitched and processed in Photoshop) which,...
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    Re: Fungus on antique Lens: Can it be fixed?

    If you intend to use the lens then try it out before doing anything else. I have been using old lenses with many optical faults including balsam separation, scratches, yellowing of the balsam and so...
  38. Re: Lensboards for Macro Stereo :confused::confused::confused:

    Well, I have one of a pair of stereo lenses from the mid/late 19th century which came on a 'half-board' that was clearly intended to be adjusted. I assume that it was so that the inter lens distance...
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    Re: Show off your Large Format camera!

    Indeed you do. As it happens I know a lens designer who knows who designed the 210mm f/6.8 so I have been informed that it dates from '72-'75. It is a simple symmetrical double gauss type lens of 4...
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    Re: Show off your Large Format camera!

    Here's one of mine - a Welsh made Nesbitt along with 2 x Welsh made PPE lenses. A long term project which I might eventually sort out - the camera takes MPP lens boards which is handy. (the taking...
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