Need help finding the best aerial lens for 6x17

[Maple]

Hi guys,

Love the forum guys thanks, its a true gold mine of information! anyway

I am an aerial photographer with a landscape and wildlife focus. I shoot both digital and 6x17 and currently I am having a really hard time setting up the 6x17 format to do all the things i need it too. I really need some advice on a wide lens (below 140mm) that will work the way i need it to work which i find is the opposite to what these lenses are built for. I need shutters speeds at a minimum of 1/250 on velvia 100 or at a maximum prov 400x with as little as possible light fall off for reef and tropical island scenes! I know its a big ask. one thing on my side is that the dof is not critical. I shoot at infinity all the time so can work at f4.5 if the lens will allow but as you know they dont.

I have been using a Nikkor 4.5 SW at f5.6 - f8 and seems to work well except it has terrible fall off. A center filter could just work with prov 400x but its really at its limits and would like to stick to the velvia if possible!

So what i really need to know is what if any lens would work the best for this application, something that will preform well close to wide open (without mechanical Vig) has no really noticeable light fall off has a copal 0 or 1 shutter (3 is not fast enough) and is wider then 140mm?

Any advice would be greatly appropriated!! and i mean that! it has been a long and expensive road.

cheers
ben

[Dan Fromm]

Ben, it all depends on the focal length you want to use.

I don't, off the top of my head, know the size of your 6x17 roll holder's gate. If it is 56x170, the diagonal (= normal focal length for the format) will be approximately 180 mm.

With a 140, the half-angle covered (theta) will be around 33.5 degrees and the corners will be around half a stop down from the center. I assume falloff as cos(theta)^4, some lenses do cos(theta)^3.

With a 110, around a stop and a half.

With a 75 (a 75/4.5 Biogon won't quite cover 6x17), 2 (Biogon) to 2 1/2 stops (most others).

Schneider and Rodenstock publish falloff curves for their current LF lenses. Look 'em up, curse your cruel, cruel fate.

[Joshua Dunn]

What is the focal length of the Nikkor SW you are using now? I use my 120mm f/8 Schneider Super Angulon all the time on my 6x17 but I use a center filter. Have you looked at the Schneider 110mm Super Symmar XL? Again you would probably need a center filter.

I have never used one but a Schneider 120mm Apo Symmar L (I think it would have to be the never "L" version to really cover) will cover 6x17 but with little movements. The lack of movements doesn't sound like an issue for the way you are shooting. I mention that lens because it is not a traditional wide angle lens so it should have less light fall off but will cover 6x17. See if you can borrow or rent one and test it.

How wide did you want to go?

-Joshua

[Dan Fromm]

I just looked at Schneider's data sheets. The Apo Symmar L covers 189 mm, a bit more than needed for 6x17; at the edge it is down more than 1 stop from the center. The Super Symmar XL has much much more coverage, at the edge of a 180 mm circle is down around three quarters of a stop from the center. [edited to correct an arithmetic error in converting % down to stops down. I'm glad no one pounced on me for it}

So much for the conventional wisdom as expressed by Joshua.

[Maple]

Wow thanks for the fast reply guys! Sorry Joshua i didn't mention, it is a 90mm nikkor.

So dan what you are saying is if i use anything around 140mm i should only experience 1/2 a stop in fall off? Because half i could deal with. At the moment its about 1 and 1/2 and i loose too much quality with returning it in post.

I cant really use a CF because at f/8 it will barely work as i understand it.

Does excess coverage help? would a 135mm with 200mm coverage still leave me with 1/2 a stop fall off? I am using the http://www.largeformatphotography.in.../LF6x17cm.html charts to narrow down my choices.

Thanks Again for the fast and timely advice.

ben

[Maple]

Sorry i forgot to ask, the image circle stats are at f22. Can i pay any attention to those figures when i will be almost exclusively shooting at f11 and below.

ben

[Dan Fromm]

Um, ben, are there modern 140 mm lenses that will cover 6x17? And what focal length do you need?

Re coverage, if you're thinking about modern lenses from Rodenstock and Schneider, in alphabetical order, look at the MTF curves. I think they're given for a range of stops, I know, having just looked at some, that the illumination curves are. The MTF curves are a guide to coverage.

[Maple]

Thanks mate i will mull over the mtf data, there are 135mm and 150mm lenses that will cover 6x17 at f22, as for what i need, wider would be better but i have to find a balance between fall off and wide angle. 135 if only producing 1/2 a stop of loss will be great.

thanks again.
ben

[Peter York]

A few suggestions:
1. Experiment with pushing velvia 1/3 to 2/3. This might tip the balance, allowing you to use a center filter.
2. With E-6 and 1/250, the condition and care of the shutter will be important. Schedule regular CLA's, and/or buy a shutter speed tester.
3. Take a look at the Schneider 110mm XL. An outstanding lens, nice and wide with less falloff than the 90mm lenses.

[Maple]

Hey Thanks peter i will give that a try.

I did have a look at the 110xl but its really expensive! I guess if all else fails i will invest!

thanks again