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johnielvis
15-Dec-2011, 17:11
there is a converter that changes the 18" verito to like 22 inches or something

does anybody have the dimensions of this....does it mount IN PLACE of the exisiting front element/cell? or is it extended further out or closer in?

what is the diameter

any pics of it vs the regular 18" verito?

I have an idea I can make my own similar focal length extender using a different front cell/element and I want to see where to START from.

dimensions / pics if you got them, please, is what I want to see....I'm thinking that prety much any old meniscus can plug in there...just a little weaker than the existing one and you get longer focal length combined...should work...so I wish to try it

please post what you know about this attachment thanks

William Whitaker
15-Dec-2011, 17:25
The extension lens is 4 5/8" in diameter, the same as the standard 18" front element. It replaces the 18" element and is a positive meniscus lens of slightly less power which gives a 22 1/4" focal length. I do not have the means to measure the curves or the "bending" of the meniscus. You can see a photo of one in the image at the bottom of this page: http://wfwhitaker.com/tech/verito.htm.

johnielvis
15-Dec-2011, 17:33
heythanks....I think I can get a 23" lens combo to work then...direct replacement--perfect, that makesit next best as simple..THANKS...

now to figure if one of the front elements is available cheaper--anybody got a ballpark cost for one of them....if its in the 200 buck or less range then I may as well get the stock lens extender---if more than that, then I can do better by myself I think..

anybody know a ballpark Price on one of these front cells?? I KNOW availability is probably nill no matter WHAT the price is......

William Whitaker
15-Dec-2011, 17:41
I can't remember when the last time was I saw one on Ebay. It's been a long time. But another will show up just as soon as you spend your money on something else. You might try the usual suspects beyond Ebay, too.

I'll try to estimate the focal length when there's daylight again. Wish I could measure the radii, but I don't have access to a spherometer. The curves were probably chosen to keep some other aberrations in check, but leaving the spherical alone.

Of course, you do know that that lens is a 30" FL with the front element removed.

Tracy Storer
15-Dec-2011, 18:11
I am guessing that you're looking for something in the 1000mm fl, aka a +1 diopter to get a 23-ish efl. Will, I'll further guess the "normal" front cell for 18" is close to 600mm.
Going more on my gut rather than any real math.

johnielvis
15-Dec-2011, 18:49
I calculated the front to be about 36" fl....it infinitys on a far building at about 30 inches by yardstick....

I was thinking a +1/2 diopter...they're like 250 bucks minimum though....schneider makes +1/2 diopters...PLUS...can get them in like 6" diameters as well as 4.5 inches, 5 inches....the 6 inches in an inverted funnel the same distance as the stock barrel will give me EXTRA coverage since the front barrel vignettes the way it is...gotta talk to my machinist first, but it looks like an easy make...not the cone, but a straight chop thread in and it gets right to 6" to the end....it'll look WAY cooler that way..hell--I can use a COFFEE CAN....yeah...give it some CLASS, jack

..the +1/2 diopter will get me 23" combined with the 30" rear and the approx 6" space in between and will increase my coverage....think I'm gonna try that....got nothing to lose but money and time, right, PLUS I may then create the only verito that can be used on like 16x20 with the front and rear!!!!

braggin' rights...yeah!

c.d.ewen
15-Dec-2011, 19:35
I can't remember when the last time was I saw one on Ebay. It's been a long time. But another will show up just as soon as you spend your money on something else. You might try the usual suspects beyond Ebay, too.



They used to show up on eBay a couple times a year, but that early on in the devolution of eBay. As Will says, they seem to have gone to ground.

Keep your eyes open, however, as sometimes you get lucky. (http://www.largeformatphotography.info/forum/showthread.php?t=49310)

Charley

Louis Pacilla
16-Dec-2011, 00:13
They used to show up on eBay a couple times a year, but that early on in the devolution of eBay. As Will says, they seem to have gone to ground.

Keep your eyes open, however, as sometimes you get lucky. (http://www.largeformatphotography.info/forum/showthread.php?t=49310)

Charley

Yea but that way 2009 Charley. Way different today.

johnielvis
16-Dec-2011, 05:33
ahhhhhh...even THEN it was still in the ballpark of the diopter...now, I haven't EVERseen one of these for sale...of course this is the first time I'm looking...oh well...I'll assume it'll be hard...same price as diopter...PLUS I want to try the diopter--I think it will give better coverage...or at least illumination....although the possibility exists that all it will do is give more flare...SO...let's see.....

William Whitaker
16-Dec-2011, 07:26
I measure the 22 1/4" extension by itself to be around 57". But it's an approximation because of my crude technique. 57" equates to .69 diopter, but 1/2 diopter should be plenty close enough.

johnielvis
16-Dec-2011, 08:08
AHHHH...yes....and can be tuned by making a "variable extension" front barrel too!!

THANKS for measuring....57"....man...that significantly smaller than i thought...then again...who says the rear is EXACTly 30 and the total combined is EXACTLY 18"...and I just eyeballed the 6" separation for the front and back....so man them errors add up....BUT, you're right...close enough will work...it HAS to--it's all I can get right now