750mm Apo-Germinar

[mosndup]

Hi,
I just got a 750mm Apo-Germinar. This huge heavy lens has a particularity that I don't understand. Besides the apperture ring there is another larger ring that can make a quarter of a turn, but nothing changes (seems to change on the ground glass) when you manipulate it. Does any one knows what is this ring for. There is a picture of this lens at http://www.skgrimes.com/lenspics/750zeiss.jpg.
Thanks,
Charles.

[Gene McCluney]

That ring opens up a slot in the lens barrel to allow you to insert waterhouse stops or a thin filter. This is quite common on Repo Lenses. For certain graphic arts processes, the shape of the hole in the waterhouse stop needs to be "shaped" a certain way.

[mosndup]

That is a nice fast answer, thanks a lot.
Do you think this repro lens could be use to take 8x10 pictures in the wild, like a tele?
I am ready to try, but am not sure of the result. Is there any contra-indication apart from the fact that this less is heavy and difficult to attach safely (to my old Sinar P2)?
By the way I dont know what a waterhouse is.
Thks.

[Mark Sampson]

A waterhouse stop is a thin shim of metal with a hole in it corresponding to a given f/stop. There would be several different ones for each lens. This system was popular in the 19th century, before iris diaphragms were common, and are still used in graphic arts.That's because they can be made with extreme precision (unlike an iris). The slot also may have been used to hold filters.
You could use that lens in the field if you have enough bellows extension- which you can add to your Sinar. You'll also want the Sinar shutter and two very large tripods. See the work of the late Reinhart Wolf, especially his book "New York". He used a similar setup, with spectacular results.

[mosndup]

Nice, I bought two used metallic heavy weight Gitzos tripod for that purpose (very heavy); A question I am wondering about the bellows: I have a 4X5 bellows connected to a 4x5-8x10 bellows (that I have not received yet from ebay) and I am wondering if I will see the whole circle in the ground glass or if the bellows will shade off the lens borders. I did some test with the 5x7 bellows it is OK (I am obliged to cut the film since the 5x7 color film does not exist anymore). The final aim is to reproduce a picture I took with a digital camera two years ago but this time with a very high definition: www.zenobie.be/Architecture. Cross the fingers....

[Gene McCluney]

You will need 30" of Bellows to focus this lens at infinity (almost a yardstick). For semi-close up shots you will need almost a couple of yards. You will need extension rails for the sinar, and possibly 2 4x5 bellows with 2 intermediate standards, and they might crop on close up work.

Best field camera design for this lens might be an old Agfa/Ansco triple extension 8x10 camera.

[Joerg Krusche]

Hi Charles,

congrats to that 9/750mm lens, it is regarded as one of the best lenses in that focal length range. I believe I can say that because I played and am playing with quite a few lenses in that focal length range i.e. up to the 47"/1200mm range.

The positive thing about this lens is the f=9 which does give you a bright image on the focussing screen, I am using on a Sinar a Bossscreen, which allows to see also very fine details.

Since it is a barrel lens you need a shutter, I do not have experience with the "hat method", "the Galli shutter" .. the simplest solutions but with their natural limitations.

I tried 3 systems which worked, the Sinar behind-the-lens shutter, the Compur 5FS behind the lens shutter and the Compur 5FS carrying front and rear elements on both sides.

In your case the first two approaches do work, for the Sinar/Copal behind-the-lens I took a Sinar board and mounted in front of it a 110mm flange ring together with a distance ring to allow for the rear lens extension of the Apo Germinar. This modified flange takes the 750mm lens with its 110mm thread and is monted on the Sinar front standard which towards the film side carries the Sinar/Copal shutter. The rear element of the lens is just about 10mm away from the shutter.

Now you may ask ...will the front standard carry the weight of the lens and will it keep the lens reliably in its postion vertical to the film plane ?.. The good answer is :YES .. I tried that with a P frontstandard .. but to my surprise even a F2 standard did it .. I am now using a F front standard from a Sinar F5x7/13x18(cm) .. this one is heavier in design.. .. the same approach was done with the 5FS shutter .. in this case I had an adapter made with 110mm thread on the lens side and the wide diameter thread on the shutter side .. this mounted again on a Sinar board .. in this case without the Sinar/Copal shutter of course. This last set up allows control from behind the camera, wide open for focussing, closed to the taking f-stop for control, then closed/cocked and fired with time range between 1/60 of a second to 32seconds, .. a very smooth shutter .. allowing for multiple exposures if wanted .. and the added option to use the iris of the shutter to act as a mechanical f-stop to avoid the light bouncing around on the bellows interior.

Above options hold a lenses like the Apo Germinars 9/750 and 12/1000 reliably. In case of a Apo Ronar CL 16/1000, a true heavy weight champion, I had adapters made for the 16/1000 and mounted on both sides of the 5FS shutter to have at that weight a better balanced lens, had to chose though a Sinar F 5x7 rear standard (not the intermediate standard !!) via a Sinar 5/7 to 4/5 reducing adapter connected to a 5/7 to 4/5 bellows to accommodate the larger diameter of the rear element .. from there onto a 4/5 intermediate standard which towards the film side either had a 4/5 -8/10 bellows or other variations .. but this was for the 1000mm combo. In your case all you need is a 4x5 straight bellows to an intermediate standard .. and from there with a 4/5 to 8/10 bellows ..or if you have one of the longer 4/5 bellows you may as well go via an intermediate standard to a 4x5-5x7 bellows if you want to use the smaller format .

The P2 is a heavy weight, you can get away very well with the stronger F-standards of the Sinar's F 5x7 or 8x10.

I recommend two tripods, that is more important than one heavy tripod, I believe that good practice allows to work successfully with two tripos of moderate weight. It is good to have more weight on the front of the rail when it postions itself onto the front tripod. ... etc.

I am sure there are more things to be said, but I want to encourage you to do it, you will develop certain work practices specific to working with the long lenses .. but you will be rewarded with some outstanding performance .. the system is very powerful.. and you will leave far behind all digital systems .. with the technique of our fathers. Have fun !

Joerg

if you have specific questions please feel free to ask.

[mosndup]

Thanks, I have some questions.

First of all let me describe the system: two heavy tripods, a three pieces rail, a 8x10/4x5 bellows, a 4x5/4x5 bellows, a Sinar shutter, the lens supported by its flange on a P2 standard and another front standard to support the front side of the lens (security first, I already dropped a smaller lens one day) that will also carry a 4x5 bellows for shading purpose.

My question about this 750mm lens which has a f/128 iris closure, that I would like to try for making very long pause pictures, so the crowd disappears magically from the scene. I usually measure the light in the distance with a Nikon D200 and I should say it is quite accurate, I do not exactly know how to convert a 1/60s, f16 to the resulting speed at f/128. Any existing tables?

One problem is left, the weight of all that equipement causes surcharge fees in some airways companies.

Cheers,
Charles.

[Ole Tjugen]

.. I do not exactly know how to convert a 1/60s, f16 to the resulting speed at f/128. Any existing tables?...

Since one stop is one step on the time setting, the 6 stops from f/16 to f/128 requires 6 steps longer time.

The mathematical way is T=T0 * (f/f0)^2 where T0 and f0 are the initial settings and T and f are the result. In your example that works out to T= 1/60 * 8^2, which is 64/60 second or just about one second.

[Emmanuel BIGLER]

Joerg Krusche and his 750mm Apo Germinar in action at the 2006 LF conference in Fontfroide abbey, France
http://farm1.static.flickr.com/152/358087941_4f9f1a9dca_b_d.jpg

[Joerg Krusche]

Charles,

I am not sure whether I understood your question .. as you close under constant lighting condtions the iris by one f-stop, say from f=16 to F=22 you have to double your exposure time e.g. from 1/60 sec to 1/30 sec .. with further closing the iris you will end at f=128 and exposure time of 1 second .. hope I made no mistake .. 1 second is still too short than to make clouds disappear from the scene. .. if that was your question.?

Best

Joerg.

[Joerg Krusche]

Joerg Krusche and his 750mm Apo Germinar in action at the 2006 LF conference in Fontfroide abbey, France
http://farm1.static.flickr.com/152/358087941_4f9f1a9dca_b_d.jpg

Emmanuel,

those were happy days at Frontfroide that I will never forget and I look forward to enjoy hopefully soon again the beauty of your country and the hospitality of your LF group.

Joerg

[mosndup]

Are there any syllabus, or printouts about the 2006 conference in Fontfroide? When is the next conference planned?

[mosndup]

Joerg, what an interesting picture posted by Emmanuel, what type of bellows are these?

[Gene McCluney]

Charles,

I am not sure whether I understood your question .. as you close under constant lighting condtions the iris by one f-stop, say from f=16 to F=22 you have to double your exposure time e.g. from 1/60 sec to 1/30 sec .. with further closing the iris you will end at f=128 and exposure time of 1 second .. hope I made no mistake .. 1 second is still too short than to make clouds disappear from the scene. .. if that was your question.?

Best

Joerg.

That is the correct concept, yes. In bright sunlight, if you want clouds to disappear, then you will have to use a neutral density filter to get your exposure times very long.
If you use an ISO 25 film, your outside sunny starter exposure would be 1/25 (round up to 1/30) @ f16, so at F128 you would have an exposure of 1 sec. "IF" your film does not have reciprocity, and "IF" the lens transmits "true" f128 when set to f128.

[Emmanuel BIGLER]

Are there any syllabus, or printouts about the 2006 conference in Fontfroide?
Unfortunately, not as far as the formal technical sessions are concerned.
I had prepared with Henri Gaud something on "bokeh" so I can get the slides if you wish, but it is in French !
There was a really interesting presentation by Mr. Régis Martin, chief architect of the French historical buildings (who was in charge of Fontfroide abbey for several years) about the use of photography in the preservation and renovation and documentation of historical monuments.

There was an informal and very friendly trade show and a really fruitful informal meeting between amateur camera builders, etc...

And we had the privilege to meet Mr. and Mrs Krusche, discover the 750 apo germinar and its outstanding sharpness even at infinity, be converted by propagandists of the Church of the Holy Compur Electronic Five etc... (I'm not yet converted to the 18x24 cm Plaubel Monorail, but who knows ? ;) )

We could meet and admire the work of the Swiss people of Atelier de Saint Prex, one of the rare places in Europe where the photogravure technique is maintained to the highest level.

HOWEVER ! There is something really substantial that has been produced for the conferece : a book.
It is a collective workabout Fontfroide abbey by 12 photographers, working with medium and large format cameras and different techniques, attempting to renew the classical genre of pictures taken in an abbey.

The reference to the book is here and you can get it through some well-know on-line bookstsores.
Or contact me if you have trouble to get it.

Fontfroide(s) : Douze regards/twelve viewpoints
bi-lingual text in French and English, 204 pages
Published by : Editions Gaud (2006)
ISBN-10: 2840801604 / ISBN-13: 978-2840801603

[Joerg Krusche]

Joerg, what an interesting picture posted by Emmanuel, what type of bellows are these?


Charles,

on that occasion I am using just one tripod, a Berlebach UNi-6, I believe this is the correct name, and it works if there is very little wind, today I prefer two tripods though, but they are lighter.

On the pic is shown the 750 lens mounted before the 5FS shutter and showing the control unit. The camera is a Plaubel Peco Profia which holds the lens on the front standard. The bellows is the standard 4x5 - 8x10 bellows.

@ Emmanuel

I will certainly try to be present this year in Bourges/2008 .. no need to take a note in my calender .. I will not forget it !!

Joerg

[Emmanuel BIGLER]

Bourges/2008
The dates are decided for the French LF conference this year
Organised by the http://www.galerie-photo.com volunteers in Bourges, France this autum.
Conference dates : Friday 10, Saturday 11 and Sunday , October 12 2008.
Details when known will be posted here on the appropriate forum.

The Bourges conference will be a good opportunity to meet a large group of French LF aficionados.
Including, hopefully, Joerg "Germinar" Krusche of course and many other friends not scared by the idea of coming to France in person ;)

[mosndup]

Nice to know that a conference will ocur in France next autum.
Thanks to you all for your help, if my future LF pictures are nice I will post them somewhere.

(@Emmanuel so I can get the slides if you wish, but it is in French
I am also french so if you have time to post them somewhere on the net or mail them to me at 'mosndup arobas gmail dot com' I would appreciate.)

To continue on the LF discussion and as I am new to LF I am wondering how to solve the following issue: I am going by the end of February in the french Alps and I want to picture the Mont-Blanc from the top of a Meribel hill with the Germinar. All my equipment is dismantled in a huge Stormcase. I'll have to open the case and remount the camera in the wild (it will be a sunny day, but the temp is near or below zero), take my pictures and re-put everything back in the case, in an order that make everything to fit in the case (it is tight). What do the masters recommend, not to loose anything in the snow, how does react this type of equipment in the cold etc...

[Emmanuel BIGLER]

(@Emmanuel so I can get the slides if you wish ...I am also french so if you have time to post them somewhere
PM sent

[Dave Wooten]

Is coverage similar to Nikkor 760 mm, which can be put into shutter. The Toyo G with the 1200 mm bellows handles these lenses nicely.

[mosndup]

Dave I dont have the answer to your question, sorry.

[mosndup]

That is the correct concept, yes. In bright sunlight, if you want clouds to disappear, then you will have to use a neutral density filter to get your exposure times very long.
Gene, do you have a pointer to these neutral density filters?

[Michael Kadillak]

On the pic is shown the 750 lens mounted before the 5FS shutter and showing the control unit.

Can you share with us any details of the shutter mentioned above? I am not familiar with this and have a barrel 750mm Apo Germinar that I would like to mount it to. Where does one acquire this shutter and what is the cost?

I have a Linhof Color Karden that could manage this lens very nicely.

Many thanks

[Emmanuel BIGLER]

Can you share with us any details of the shutter mentioned above?
Michael
After manipulating Joerg's equipement I started hunting for a Compur 5FS and got one.
They show up from time to time on ****, and of course, more often from ****-Germany.
The main problem is to find somebody able to repair them. Depending on where you live on the planet, this can be straightforward (probably Joerg's situation ;) ) or a real nightmare. One of the major issues is the depletion of parts for repair, we are in the situation of the last years when European companies operating the Concorde had to cannibalize non-flying Concordes in order to get repair parts ;)
---
Not kidding. The shutter is useless without its special cable and without its control unit.
So if you look for one, be sure that you have a starter-kit with the 3 items that actually woirk ; the shutter itself, the cable and the control box. Erratic contacts at the plug level are a real soure of concern.
The control box is supplied by standard big 1.5V batteries easy to find worldwide, this is at least a non-issue ;)

The box is a remote control that operates the f-stop and the shutter. Shutter speeds up to 1/60-th, superb for a shutter of this size. No problem for slow speeds, the timing is old-fashion electronic... when the electronics works (typical transistor technology from the sixties, the Apollo mission relied on such electronics, this can be rock-solid for decades but who could repair now the control boxes in an Apollo vessel ?)
Setting the maximum aperture when mounting a new lens without f-stop scale is done mechanically by positioning a small sliding part on the shutter, this is easy and accessible to anybody who wishes to remount new cells on the shutter.
f-stop spacing are equidistant. The control box starts at 5.6 and is valid for all lenses when the max aperture setting has been done on the shutter. A switch probably prevents any damage when you request 5.6 on a f/9 apo-ronar. A typical situation seemed that users had more shutters than control boxes, so the control box had to be somewhat universal for all different maximum apertures of various lenses.

Beware however that you might not know the proper spacing between lens cells, a #5 is not as standard as #0,1 and 3 where cell spacing is common to most manufacturers.
This problem of course does not occur when remounting a barrel lens in front, like Joerg's 750mm Germinar.

When everything works, it is a pleasure to use.
When something goes wrong, however, you regret not to to have hunted for a Compound #5 or an Ilex#5 !!
As the saying goes in France, we say : you'll be like a hen that has found a knife.

I do not have the sizes for lensboard mounting threads and lens-cell mounting threads handy right now, but I can find the info upon request.
To give you an idea: the vintage 5.6-360mm convertible Symmar cannot be mounted on a #3 but is mounetd on the Compur 5FS through reducing rings.
The 600mm apo ronar fits directly inside the Compur 5FS.

[Joerg Krusche]

Emmanuel,

merci for your most competent answer .. there is little I can add so I expand on some other aspects of this shutter/lens combination. Whenever someone gets hold of a barrel lens the question is .. which shutter and how to mount the lens on shutter .. and both onto the camera. Since I am playing for some time with repro lenses from various manufacturers with some preference of the long ones 600mm and up to 1200mm (47") I ran into that dilemma. Methods like hat/cap, Galli shutter .. or other lack of reproducibility, linearity etc. .. were discarded.

Two options -- both work

1. Sinar/Copal as behind the lens shutter .. does work .. just need to mount an adapter on Sinar Board (see my previous post).. lens is carried by front standard.

2. Compur 5FS, smooth shutter, strong threads to mount lens before shutter or front and rear elements, use as between the lens shutter. great performance when it works, electrical components may be ageing, if I went on that long distance trip with all the gear, as back up I would take that all mechanical slim Sinar/Copal shutter with an adapter with me as back up.

@ Emmanuel .. I expect/hope to obtain a drawing of the shutter electronics .. perhaps you can read it .. will send you a copy once I have it .. may also eventually meet with someone who knows how to service .. a CLA after 30 years of opration may be advisable.

Re camera system .. I have played with two systems, first a Plaubel Peco Profia system, the standard for german professionals next to the Sinar system, can be had today for little money .. good camera, the front standard holds the 750 with 5FS easily.

The Sinar system front standard holds both systems (see previous post). The Kardan will just smile ...it was a surprise to me that the F standard (5x7) on the Sinar is suitable, used it up to 1000mm and beyoond.

BTW the Rodenstock high resolution repros 16/1000 and 16/1200 are both all-air spaced 6-element lenses .. very similar/though not identical to the long Apo Germinars which means that Zeiss moved ahead earlier and added this to the proven >100 year old Goerz design.

There are also very rare Apo Germinars 14/750 in Copal 3.

Best

Joerg

[Michael Kadillak]

Emmanuel,


There are also very rare Apo Germinars 14/750 in Copal 3.

Best

Joerg

I have acquired an Apo Germinar 14.5/750 in a Copal #3 but it is a Doctor Optics lens. Is this the lens you are making reference to as being rare or did Zeiss put some in a Copal #3 that are few in number?

How they got this into a Copal #3 is beyond me, but they did.

Cheers!

[Joerg Krusche]

I have acquired an Apo Germinar 14.5/750 in a Copal #3 but it is a Doctor Optics lens. Is this the lens you are making reference to as being rare or did Zeiss put some in a Copal #3 that are few in number?

How they got this into a Copal #3 is beyond me, but they did.

Cheers!

Michael,

sorry my fault, I assumed you had bought one of the 9/750's in barrel that were sold by Kerry, if you have the 14,5/750 ...that is the identical lens design .. it is mounted into a Copal 3 shutter, the housing of the lens is made to fit the shutter, the max opening goes down from 9 to 14,5, that is clear, it was made by Carl Zeiss/Docter .. and it is a pretty rare and desirable lens, so forget my comments on the various shutter options for barrel lenses, thought it was for thr 9/750 in barrel for which I have a further interesting option which I am going to test this weekend, weather permitting, that will allow to mount that 9/750 lens on a simple board incl. shutter onto all camera sytems. Enjoy the 750, it is one of the better 750's.

Best,

Joerg

[Michael Kadillak]

Michael,

sorry my fault, I assumed you had bought one of the 9/750's in barrel that were sold by Kerry, if you have the 14,5/750 ...that is the identical lens design .. it is mounted into a Copal 3 shutter, the housing of the lens is made to fit the shutter, the max opening goes down from 9 to 14,5, that is clear, it was made by Carl Zeiss/Docter .. and it is a pretty rare and desirable lens, so forget my comments on the various shutter options for barrel lenses, thought it was for thr 9/750 in barrel for which I have a further interesting option which I am going to test this weekend, weather permitting, that will allow to mount that 9/750 lens on a simple board incl. shutter onto all camera sytems. Enjoy the 750, it is one of the better 750's.

Best,

Joerg

In addition to the 750mm Doctor lens in shutter that we are talking about above, I also acquired one the 750mm Zeiss lenses from Kerry as I wanted to support someone that was doing something very creative in bringing these into the market. I have not used the lens in barrel yet so that was why I was exploring the options.

Thanks or the information.

Cheers!

[Gene McCluney]

Gene, do you have a pointer to these neutral density filters?

Any of the filter manufacturers, either optical glass, or acetate or gel filters such as Lee make Neutral Density filters.

Here is a selection of Gel type 4" x 4" neutral density filters available from B&H photo.

http://www.bhphotovideo.com/bnh/controller/home?O=search&A=search&Q=&sb=bs%2Cupper%28ds%29&sq=asc&ac=&bsi=&bhs=t&ci=5038&shs=&at=Type_Neutral+Density&basicSubmit=Submit+Query


Here is a selection of round glass neutral density filters.

http://www.bhphotovideo.com/c/shop/114/Standard_Filters_Neutral_Density.html

[mosndup]

Thanks Gene,

There is a huge thread on this 750mm ApoGerminar, I'll give a try if I find a filter.

(I can may be place the filter after the lens, I hope this is not a strange idea, ... ah these newbies!)

[Joerg Krusche]

In addition to the 750mm Doctor lens in shutter that we are talking about above, I also acquired one the 750mm Zeiss lenses from Kerry as I wanted to support someone that was doing something very creative in bringing these into the market. I have not used the lens in barrel yet so that was why I was exploring the options.

Thanks or the information.

Cheers!

Michael,

I know the Apo Germinar's quite a bit, the 750 as you know comes as f=9 and f=14,5 while the Apo Germinar 1000 comes as barrel lens as 12/1000 and in a Copal 3 as 19/1000 .. this is a bit dim, unless its is a bright day and you are using a Bossscreen. Critical focussing is easier with the f=9 or F=12 also due to the shallower depth of field. Michael, enjoy the long ones .. you have the right countryside over there !

Joerg

[Gene McCluney]

Thanks Gene,

There is a huge thread on this 750mm ApoGerminar, I'll give a try if I find a filter.

(I can may be place the filter after the lens, I hope this is not a strange idea, ... ah these newbies!)

Yes, you can place the Neutral density, or for that matter, any filter you want, before or after the lens. It doesn't matter to the film.

[David Vickery]

If your lens has the filter slot then you could use the gel filters in the slot. I think this would be much better than using a filter on the rear of the lens.

[mosndup]

Yes it has a slot. Do you have an idea of the type of gel filter to be used, I personally have never used it.

[Gene McCluney]

Yes it has a slot. Do you have an idea of the type of gel filter to be used, I personally have never used it.

You can get most filters in Gel form. I suggest looking at the website of a big vendor, such as Adorama or B&H and you would have to get a filter larger than the slot probably, and cut it to size with scissors.

[Kerry L. Thalmann]

Yes, you can place the Neutral density, or for that matter, any filter you want, before or after the lens. It doesn't matter to the film.

Actually, it can matter. If you plan to use a filter behind the lens be sure to focus with the filter in place. Otherwise you will get a focus shift equal to 1/3 the thickness of the filter. This isn't really a problem for gel filters as they are so thin, but can be an issue for glass filters in some situations.

For very long lenses, that have greater depth of focus, it's probably not much of an issue even with a single glass (stacking glass filters behind a lens isn't a very good idea if you can avoid it). But better safe than sorry.

It really starts to be a significant issue with wide angle lenses like the 80mm or 110mm Super Symmar XL that have filter threads on the rear for glass filters. Whenever I use a rear mounted filer on one of these lenses I always make sure to focus with the filter in place.

Kerry

[Asher Kelman]

Michael,

I know the Apo Germinar's quite a bit, the 750 as you know comes as f=9 and f=14,5 while the Apo Germinar 1000 comes as barrel lens as 12/1000 and in a Copal 3 as 19/1000 .. this is a bit dim, unless its is a bright day and you are using a Bossscreen. Critical focussing is easier with the f=9 or F=12 also due to the shallower depth of field. Michael, enjoy the long ones .. you have the right countryside over there !

Joerg

How challenging is it to focus the 750 mm F12 Apo Germinar in a Copal shutter at f 12. Is it still practical for most work. Also how much extension is needed to focus at 4 feet?

Asher

[Joerg Krusche]

Asher,

no problem to focus that lens .. great performer at longer distances due to coverage..other than tele designs.. and resolution.. although designed for 1:1 .. due to symmetrical design vg from 1:1 to infinity.. this lens and siimilar ones will give you more resolution than you may be able to handle or you may actually need on the larger formats..working with these long ones is fun.. may need an adequate scanner to exploit and manage amount of information of even standard LF formats.

Why would you want to focus at 4 feet ? ..extension is quite a bit .. a shorter focal length will cover and be easier to work with ..

best regards,

joerg

[Dan Fromm]

Is it still practical for most work. Also how much extension is needed to focus at 4 feet?

Asher

There are extension calculators.

But since you can't find answers to your silly questions yourself, in round figures focusing a 750 mm lens at a subject 48" in front of the lens requires 79" extension. If you meant film-to-subject distance = 48", not possible with a 30" lens.

By the way, why are you fixated on an Apo Germinar? There are other good process lenses with focal lengths around 750 mm that are easier to find and less expensive.

[Asher Kelman]

Asher,

no problem to focus that lens .. great performer at longer distances due to coverage..other than tele designs.. and resolution.. although designed for 1:1 .. due to symmetrical design vg from 1:1 to infinity.. this lens and siimilar ones will give you more resolution than you may be able to handle or you may actually need on the larger formats..working with these long ones is fun.. may need an adequate scanner to exploit and manage amount of information of even standard LF formats.
Joerg,

Thanks for your helpful response! Have a Topaz II and love wall to make size prints viewable for detail at 25 cm.



Why would you want to focus at 4 feet ? ..extension is quite a bit .. a shorter focal length will cover and be easier to work with ..

The distance is what I use for portraits in my studio. That's where I want to use the 750mm for ULF. I have to translate from 35 mm cameras and 6x6., my areas of comfort. (8x10 landscapes and still life with the 150 mm SSXL and portraits with the PS 945 on 8x10 is my limited LF experience to date.) So this 750mm lens would be a very wide angle on a direct to ULF wall print. I'll try first with a 600 mm lens. The extensions I'll just have to buy and these are available for my camera.

I also have a 450 Apo Germinar, but the 750 mm is interesting to me because it has been used very successfully by another photographer.

Asher

[Joerg Krusche]

Asher,

keep up your enthusiasm !! .. the Topaz II is a beautiful scanner but it has 8000 pixels across the moving bed .. that is 4000 dpi max (in an ideal world 4000 linepairs) for the short side of your negative .. for your wall sized prints to be looked at from 25 cm to discover even more details .. there may be just a linepair per mm .. for me at my age that is more than enough but perhaps not for you ...

joerg

[Asher Kelman]

Asher,

keep up your enthusiasm !! .. the Topaz II is a beautiful scanner but it has 8000 pixels across the moving bed .. that is 4000 dpi max (in an ideal world 4000 linepairs) for the short side of your negative .. for your wall sized prints to be looked at from 25 cm to discover even more details .. there may be just a linepair per mm .. for me at my age that is more than enough but perhaps not for you ...

joerg

Hi Joerg,

I appreciate the encouragement! There's a lot work out. For the 750 mm lens, I plan to hang Ilfochrome paper on the wall of a camera obscura and process them n one step. So no scanning. For smaller nagatives, the Topaz will be fine and the best will be drum scanned.

Asher