greg_prior

Thanks for all the replies. Just to finish out the topic, I did see the aurora borealis from the

fan tail of the ship as we traveled South on August 9th out of Skagway. It turns out there

was another problem to photographing the event. That was the lights on the ship. It was

really quite bright, and even made eye viewing difficult.

The ship was fairly stable on the fan tail. The ships motion was mostly rolling rather than

pitching, so the motion would have shown up as a small amount or rotation rather than

the horizon raising and falling.

So, no pix this trip, but at least I got to see it!!!

-Greg

Well, I don't think 1/25 and 1/60 will work. With a f/1.4 lens I would need ISO 200,000 film for 1/60. Maybe I could find a f/1.0 lens and get it down to 100,000 ISO though. :-)

I have never seen the aurora borealis, but I was under the impression that it moves in the sky so that some motion from the ship wouldn't be that noticeable. Maybe I shouldn't set my expectations too high.

-Thanks, Greg

OK, I checked and Provia 400 isn't available in sheets. Is the next best Kodak E200 pushed to 800?

Now my exposure time (wide open) is 90 seconds?

Thanks again, Greg

I hear that the aurora borealis will be active while I am on an

Alaska cruise ship. I'll have my Linhof Technika along, so I thought

I'd try for a shot. Some of the questions I have are:

1. What film? Fuji Provia 400 pushed to 1600?

2. Long exposures on a cruise ship. I'm assuming that even the best

tripod won't stop the motion of the ship. :-) Will the motion have a

bad effect on a 30 sec. exposure?

3. I have a 90mm f/6.8 Apo-Grandagon N. Should I rent/buy something

faster/wider?

4. I found a web page that suggests ISO 800, f/4, for 30 sec. I think

that equates to ISO 1600, f/6.8 for 45 sec (+- bracketing of course)?

I like to scan and print these at about 3'x4' (largest size on my

Giclee printer).

Any advice would be appreciated.

Thanks for you help, Greg

For anyone that reads this thread, I found my own answer. The bottom brackets that hold the board have adjustment screws. They're hard to get to, but you can extend the bellows and tilt the lens to get to them. I may have used an angle screwdriver (it's been some time), but now all my boards fit tight...

-Greg

The Zig-Align is popular amongst Betterlight users doing art reproduction. It also aligns to the subject.

-Greg

I need to make an adapter to hold my Linhof boards on a Horseman

board, and want to use the sliding clamps like those used on the

Horseman/Sinar standards to hold the boards in place. Does anyone

know where I can buy these slider clamps?

Brian - you are right about slow deliberate devices like view cameras. I have a BetterLight that I use a lot. It is great. I got a great deal on it - not used, but less than half the new price.

As for good deals on used equipment, there looks like a good starter setup on that auction site - a Dicomed 6000 x 7520 field setup with laptop. Bid starts at 2k with buy-it-now at 3k.

FUN STUFF !!!!!!

-Greg

I'll second Brian's comment. You'll be absolutly amazed at the results you can get by adding a scan back to your 4x5. I went to the BetterLight user's group meeting a few months back and it was stated that if you compare Astia (the finest grain film available) to the pixel size of the 6000 scan back, you would need to shoot 30"x40" to get equivelant results. Plus you get 11-12 stops of dynamic range instead of 4-5 (for transparencies), etc, etc. You can do some really creative stuff. Just don't expect to snap lots of shots like the dslr's click off...

-Greg

I believe it is a stock MS screen. It has the diagonal split in the middle with the micro-prism around that. It seems like an after-market fresnel screen brightner would make the meter read overexposed, not under?

I have tried making readings by just scanning around at mid-day to get an average reading, and taking readings off of a gray card. The readings vary 1/2 stop or so, but it is -1.5 to -2.5 stops. This still isn't real scientific, but I don't see how I could be that far off either.

Maybe this is just all the closer the repair shop could get it, but that just doesn't sound right. I checked that I'm not in M mode on the lens, or that the lens is for some other reason stopping down. I have used 4 different lenses. I always check that they are engaged with the meter pin. I wish I had another body to compare with...

Thanks for the help - any other ideas?

-Greg

I bought a used Cds meter prism for my 1000s at a photo swap. It read

3-4 f/stops off (had to set ASA to about 1000 to get f/16 at 1/125

under 'sunny 16' conditions), so I had the seller send it out to his

repairman to calibrate it. It came back a little better, maybe 2.5-3

stops off. Now I'm wondering if there is something in the body that

is losing the light. Are there wrong focusing screens? Missing

fresnel lens? Any other ideas?

Thanks, Greg

I was curious what a 1:20 focus was, so I did a quick design on the simulator. For a 240mm lens, the object was at 4.2 meters to get 1:20. For a 305mm lens, the distance was 5.3m. So maybe the that doesn't make for an exact comparison to infinity. But if you look at the G-Claron data sheet, it shows data at two shorter focuses. Their numbers don't work out in the simulator, so I don't understand what magnification they are. Conflicting data puts them somewhere between 1:1 and 1:6. So it looks like the 1:20 data for the Ronar won't change that much as you approach infinity.

I've been trying to get patent data on these lenses so I can get accurate models into the simulator. Then I could really compare at infinity, get color data etc. Maybe someday...

I did get the patents on the new Schneider XL lenses. But they left out the aspherical coefficients. One of these days I'll see if I can do an optimization and get results similar to Schneiders...

Of course all of this only applies to a theoritcal lens. Yours will be different - just hopefully not too much. :-)

Hope that helps.

-Greg

The manufacturer's data sheets give a clue. I haven't been able to find a data sheet for the Ronar 300, but I have found one for the 240. Schneider's page has data for the 270 and 305 which show very similar MTF results. Schneider's data is at infinity, and the Ronar is at 1:20 so you'll have to figure if this is close enough to infinity to draw a conclusion. FWIW, the MTF is much better at 1:20 than 1:1 (it's going the right direction).

The G-Claron 305 at f/22, infinity focus, and 12 lp/mm spatial frequency managed 80% MTF on-axis, 55/50% out 75mm (4x5 no shifts) and 52/32% at 190mm (8x10 + some shifts).

The APO-Ronar 240 at f/22, 1:20 focus, and 10 lp/mm was 85% on-axis, 75/75% out 75mm, and 60/0% out 110mm (OK, so don't use this one for 8x10).

In case you think the Ronar's 10 lp/mm is wimpy compared to the Claron's 12, the APO-Ronar 240 at f/22, 1:20 focus, AND 20 LP/MM was 67% on-axis, 52/58% out 75mm, and 30/0% out 110mm. So DOUBLE THE RESOLUTION at 4x5, no shift.

Neither give color data, and I haven't tested them.

-Greg

If you don't find anything, let's start one. I'm interested in the same thing. There is a Yahoo group of SF bay area LF users. You might check there.

I'm going to the Betterlight user's conference in San Carlos tomorrow & Friday (9th and 10th). There will be lots of LF stuff there if you like (or don't mind) the use of scan backs on LF. You can find them at

www.betterlight.com

or me at

www.eleganteditions.com

-- Greg

I got a Betterlight 6000 scan back for scanning flat artwork. It does scans to

6000x8000 pixels. I've just started using it with a Linhof for outdoor shots, and like

the results a lot. I think there is one on eBay now. I've seen others go for around

$4000-$5000. It's a lot of money, but you get 11 stops of dynamic range, and I can

print 36x48 prints on my Colorspan drum printer with no upscaling. Also, I've been

experimenting with IR shots (just leave off the daylight filter).

--Greg

I have a Technika V, and I noticed that if you grab the lens, it

wiggles. There seems to be some play where the lens board seats at

the bottom where the two little clips are. The boards are not Linhof

brand. One is 'noname', and the other is Wista. The two castings look

identical, but with no Wista on the noname version. Has anyone else

seen this? Is there a fix?

Thanks, Greg

James- Thanks for the reply. You make a number of good points, but I don't believe that a reputable lens company would falsify technical data like MTF figures for some 'marketing' reason. They design new lenses because they can make them better than the old ones.

I'm not really too concerned with coverage specs since I don't do a lot of movements (my topic was just MTF). The data sheet says the 150mm (I think that's the only lens you were talking about) is tested out to 189mm. At f/9 you can see that the MTF starts to fall off considerable. At f/22 there is still MTF to burn, so it obviously carries a pretty good MTF past the 189mm spec. Of course you can use the lens out to any MTF value you choose. In my case, I need 42lp/mm, and would like that out to the corners of 4x5.

As far as time/money spent to analyze lenses, you are right. Since all lenses vary from their spec, I should buy one of each, test, and sell off the excess. I am looking for a 300 to 360mm lens, and have found over a dozen lenses is this size (both new and old). For a few thousand dollars and a few days time I could get data on the whole lot, then spend a few more days selling off the excess. I'd rather eliminate the ones that won't meet my requirements, and save a lot of time and money. I trust the manufacturers MTF specs for this.

I guess in general we are talking about different things. I am interested in a sharp lens for mostly on-axis distant use with a 4x5 scan-back. You are interested in close-up, 5x7, and coverage (or defending the G - both are fine). The G-claron may excell in all these areas, but they are outside my area of interest. I'm not saying the G is a 'bad' lens, just that there are better candidates for my purposes, and that I was surprised that a 'process' lens would only resolve 12 lp/mm at 50%+ when I was expecting 40+ lp/mm. Obviously the 12 lp/mm is more than adaquate (you're right, the spec sheet doesn't say this) for a lot of LF shooters, whereas I though >40 was needed.

I bought one of these (Xenar) in a barrel mount thinking I would use it with my Horseman view camera and scan-back for outdoor photos. Since then, I bought a Linhof V, and don't see how it will fit. The barrel is too big to fit thru the hole at the front of the camera. Also I found shooting film when very far from the car has its pluses (half the volume/weight without the scan-back), so a shutter would be nice. So I've given up on the 4.5 and am about to put it on ebay, and look for a 300-360 f/9-type with a shutter for quite a bit more $$$.

The 4.5 is really cool. A great looking piece of glass. I think mine is coated, and I'd love to try it out before selling. Any ideas on how to fit it to the Linhof V? Extension tube board? Mount to a shutter?

-- Greg

I use a UMAX PowerLook 3000. It scans 8.5x11 at 1200 dpi, and 3.4x11 at 3048 dpi (optical). It scans both transparencies/negatives and reflective. So if I'm looking to blow up a 4x5 to 30x40 or more, I scan a 'cropped' 4x5 (3.4x5) at 3048, or do two scans and 'stitch'. Haven't had to stitch yet though. Up to 24x30 I use 1200 dpi. I print at 200 dpi on a Colorspan Giclee drum printer.

HTH - Greg

www.ElegantEditions.com

Wow, what a bunch of great responses.

It sounds like Kelly's tests show that similar lenses perform better than the G-Claron spec. But maybe their specs are better than the G (although it doesn't seem likely that a 3-element would out-perform a 6-element lens). So this doesn't explain the G-Claron data.

Julio thought I was reading the wrong charts, but I'm look at the ones on the right labeled f/22 at infinity and conjugates of -2 and -1. The MTF is only 12 lp/mm at 40% to 80% over the entire 4x5 field.

David routed me to the APO-Ronar 240mm data (couldn't find 300 mm data, but it's probably similar). It is better than the G, but no by much. It is only 20 lp/mm at 40% to 65% over the 4x5 field.

Jim mentions the Perez/Thallman test results, but I think they state that their results are comparative, not absolute. They certainly are a lot different than what the manufacturers specify. None of my lens designs have measured 3x to 4x better resolution than the simulation results. But still the G compares well with other lenses tested by Perez/Thallman that are well regarded.

I did some more research and it turns out that the best lens performance I can find is at 20 lp/mm on the likes of APO-Symmar L, and APO-Sironar S. So I am guessing that the numbers reported by Perez/Thallman are at a very low MTF, maybe even 0% to get such a high spatial frequency. The same with Kelly's results.

Jeffrey might have the right idea. Try it and see if 12 lp/mm is 'good enough'. Obviously it is for a number of users.

Is the G-Claron a 'dog' at 12 lp/mm? Maybe not, but it looks like the APO-Ronar (a 4-element design - go figure!) has almost twice the resolution. I wish I had data on the Nikkor 300/9, Fuji 300, etc. A factor of almost 2 in resolution is pretty significant.

Now if I could just get lateral color data...

-Greg

I'm looking at the Schneider spec for a 150/9 and a 305/9 G-Claron.

The MTF tables are plotted at 3,6, and 12 lp/mm. These lenses are

best at f22 and a magnification of .5. But only show an MTF of 55-60%

for the 150, and 30-50% for the 300 at 12 lp/mm. The MTF does look

almost as good at infinity, but that's not saying much. Are these

lenses really that bad? I was expecting a lot more for a 6-element

design 'process' lens (like 50-60 lp/mm at 50%+).

Does anyone have specs for comptetive 300 - 360mm small lenses

(Nikkor 300/9, Fuji 300/8.5, APO-Ronar 300/9 etc.)? I kinda lost

interest in this one. I want to use it with both film and a scan-back

that has 84 pixels/mm (42 lp/mm).

Thanks, Greg

I'm looking into buying a 300mm or 360mm lens for my Linhof Technika

4x5. I want to use it with my scan back as well as film, so I'm

interested in a lens that is not only sharp, but has a minimum of

lateral color. This will be for travel use, so I'm looking for

something in a #1 shutter, or maybe a Compur #2. Any suggestions?

Thanks, Greg

I have a Tominon 105 and a 150 that I use in a MP-4 setup with a scan back for capturing fine art. I noticed the 105 has a lot of focus shift with changes in aperture. That may be why some are getting bad results. Try focusing at the taking aperture (yeah, just try it! :-) I see a pretty good shift just between f/11 and f/16. The scan-back makes this easy by using digital focus. The 105 performs about the same as my 150mm APO Sironar N in both resolution and lateral color. The scan back is 40 lp/mm, and lateral color shows up all too easily in copy work, so I think this lens is a keeper.

-Greg

Well there have been lots of suggestions for monorail cameras, but I have one of those now, and find it very difficult to hand-hold the thing while on the boat. :-) Maybe I'm missing something here. I have a Cambo. Are other monorails easier to hand hold?

All this has got me thinking that maybe some sturdy metal field camera like a Linhof III (almost in my price range), Super Graflex, or similar. As I look at the nice, light, wood (or carbon fiber) cameras, I'm thinking they are probably too light to work well with the scan back --- unless these lighter cameras mount with the tripod near the back so the weight of the camera and scan-back are on the tripod, with only the lens suspended by the camera base. Is this how they mount?