View Full Version : Making Room in My 4x5 Pack...

Scott Rosenberg
19-Dec-2004, 08:02
good day...

when i got into 4x5 about a year ago, i set out to put together the most capable outfit i could afford, not really giving much thought to other variables like how much room all this stuff takes up. i told myself many times that i'd shoulder a few extra ounces for a better kit. with lots of help from this forum, kerry thalmann's site, mpex, etc, i assembled the following field kit:
-linhof technika IV
-ss110 xl
-sironar 150-s
-fujinon 240-a
-fujinon 300-a

after a year of backpacking my rig over the us, canada, and europe, i've now begun to think more practically about what is going into my bag - starting with my lenses. i'm extremely satisfied with the performance of all my glass, however, i have found that the 150 and 240 are very close. it's usually a toss up which one gets mounted... normally coming down to whichever is easier to get to.

as such, i'm giving serious consideration to replacing the 150 and 240 with something close to 180. my focal lengths would them change from 110 - 150 - 240 - 300 to 110 - 180 - 300. i know this a very personal decision, and everyone shoots differently, but i was wondering if any of you had gone through a similar progression and had any regrets. thinking back over the last year, i can't remember a time when there was an absolute need for the 150 or the 240. as such, i'm giving serious consideration to the fujinon 180-a (i'm concerned about edge sharpness with this one), sironar 180-s, 180 ss apo symmar, or the nikkor 200-m as a replacement for the 150 sironar-s and 240-a. before i did so, i figured i could profit by someone else's experience.


Glenn Kroeger
19-Dec-2004, 08:16

I have used the 110-180-300 set up and was very pleased with the ratios. I did use the 180 Fujinon-A and found it to be very sharp and its coverage is so large you won't have edge problems. Ultimately, I wanted a faster lens for my older eyes and switched to the Rodenstock 180 Apo-Sironar-S which I love... and it has the same filter size as the 110.

Ralph Barker
19-Dec-2004, 09:54
Personally, I'd lean toward just dropping the 150 and keeping the 240. The question then is how much you use the 300 in the field.

Scott Rosenberg
19-Dec-2004, 10:16
thanks for the tips glen. i do a fair amount of shooting while the sun is low in the sky, so lens brightnness is a concern to me as well. i've been meaning improve the gg on my technika, but didn't want to invest any more $$ into it, as i'm not sure i'll be sticking with this camera. a friend of mine recently suggested i look into a lighter field camera (canham or phillips) with 'real' rear movements and a better gg.

ralph... i only bought the fujinon 300-a because i got it for a song. for what i paid, i figured it couldn't hurt to have it in my pack. i have really suprised myself by how often i use it. i don't know how it compares to the fujinon 300-c, schneider 305 g-claron, or nikkor 300-m, as it's the only 300 i've used, but i've generally been pretty pleased with it... when the wind isn't blowing! the 240 isn't that far off from the 300, so i figured a 180 would be a nice comprimise.

thanks again, fellas,

Eric Leppanen
19-Dec-2004, 10:19

If you are primarily concerned with reducing weight, then the small and light 180 Fuji-A is clearly the best choice if you don't mind focusing at f/9. If your concern about edge sharpness stems from Chris Perez' lens test results, please note that there can be significant sampling variations among lenses (take a look at the 300 Nikon-M, for example, which in my experience is a razor sharp lens), so I suggest you test a lens yourself before drawing any final conclusions. Midwest Photo currently lists a 9+ 180 Fuji-A and 180 APO Symmar, maybe you can persuade Jim to ship you both for test purposes and keep the one you prefer?

The 180 Sironar-S is also a superb lens and the one I would personally prefer if weight was not an issue. For my taste the gap between 110 and 200mm is too large to go that route.

Mark Carstens
19-Dec-2004, 10:23
Scott, I own the same range of focal lengths that you do and have, in the last year, contemplated whether I should make room in my pack by “replacing” the 150 and 240 with a 180 (mostly to make room for a Fujinon 450-C, but that's another story).

I had used both lenses about equally, so there was no rationale for shedding one lens or the other because it was laying dormant in my pack. I soon discovered that I value the flexibility that having both lenses affords me. Maybe this comes from my days of shooting a Pentax medium format and using zoom lenses, but from my perspective at least, the 180 would be an inadequate compromise rather than a true replacement for the two lenses.

Another thought. I sometimes fall into the mindset that I can’t leave any of my lenses at home or back in the truck because I might “miss” an opportunity. Truth be told, this really hasn’t happened since my 35mm days when I shot wildlife and had a couple of occasions when I could have used a shorter telephoto, but had left it back in the truck. So, if weight is a primary consideration, you may consider leaving a lens behind for a hike or two and see if it changes you. The experience may force your hand one way or the other. Or not.

In the end, as you mentioned, this is a very personal decision and what works for others might not work for you. Know your shooting patterns and know that your lens choices don’t have to adhere to any prescribed “formula.”

Good luck!

Gem Singer
19-Dec-2004, 10:44
Hi Scott,

The Fuji 180A, 240A, and 300A are the most compact, light weight 6-element lenses that are available from any of the major lens manufacturers. The "A" stands for "Apo". They have ample image circles compared with other lenses of the same focal length. They have a similar lens design to the Schneider G-Clarons, except that the Fujis are smaller and lighter in weight. Since you will only be using them on the 4x5 format, you will probably be using the center (sweet spot) of the image circle of the lens. No need to be concerned about edge sharpness from any of them. The Nikkor 200M is a 4-element (Tessar) design. It's image size is fairly close to a lens of the 240 focal length.

Scott Rosenberg
19-Dec-2004, 10:57
the difference in weight between the 180-a and the 180's from schneider and rodenstock is about 1/2 a pound. i'd be willing to eat 1/2 a pound with this lens given that i'd estimate 40% of my shots will be taken using it if it meant better performance and a brighter gg. i keep each lens in identical rigid boxes with custom inserts sized to the rear element. so for me, the real gain here is not so much the 1/2 pound, but that i'd only need to make room for three boxes and not four. appealing to jim's more generous side is a great idea... he could probably come up with a Sironar-S for me to compare against the fuji if i give him a few weeks. the fuji seems priced right, which is another consideration for me.

again, thanks for the inputs. i've done just what you suggested, not exactly, but sort of. in considering my last several outings, there was never a time when i could not have gotten by with only the 150 or 240, and like i said, lens choice usually came down to whichever was closest. i've never owned a zoom lens, in any format, so am not accustomed to having such incremental control over my fov.

Scott Rosenberg
19-Dec-2004, 11:05
hi eugene...

good to hear from you. thanks for the background on the lens design. i agree that the nikkor 200-m is too close to the 240 that i already have... i'm not quite sure why i included it on my list. it's really not being considered. if i decide to go this route, i'd probably look very closely at the fujinon 180-a that you recommended and the 180 sironar-s.

Gem Singer
19-Dec-2004, 11:30

I am only referring to replacing the 150 Sironar-S with the Fuji 180A in your backpack. Keep the Schneider 110XL, the 240A, and the 300A. With the addition of the 180A, they will make a unique set of lenses to carry in your kit.
I was thinking in terms of the weight savings. Replacing the 150 Sironar-S with a 180 Sironar-S is only going to add weight to your pack and offers very little advantage in focal length spread.

Frank Petronio
19-Dec-2004, 11:49
Because you have a Technika I'd opt for a lens that is small enough that you can leave mounted on the camera. I'd look closer at the value of the 110XL, which has coverage to burn for 4x5. I'd consider building a lightweight set similar to Kerry's light weight set-up (i.e. 90 - 135 -240). By starting over with smaller, more backpack friendly lenses, you might also have more money left over for film and travel - or perhaps to purchase a lighter field camera (a Wista SP is a lot like the Technika in terms of quality, but lighter and more friendly, IMHO.)

I use a 90-180-300 set-up myself, but I don't backpack it. If I was a granola-muncher I'd do the Wista 90-135-240 outfit in a heartbeat.

Scott Rosenberg
19-Dec-2004, 12:37
regardless of what i ultimately decide to do here, i will definately keep the 240-a. it will cover 8x10, and i'm still on the fence on that issue. quite shaking your head! i'm thinking about buying the 180, selling the 150, and holding the 240. my field kit would then consist of the 110, 180, and 300. the 240 will stay at home while i decide if the 3 lens spread works for me. replacing the 150 and 240 in my pack with the 150-S would net me some extra room in my pack, as i'm only packing 3 lenses. i don't figure that i'll miss having two lenses between 110 and 300... there's really only one way to find out.

i gues i'm a granola-muncher... but one that prefers slightly longer lenses. the 110 is all the wide angle i've ever yearned for. not quite sure what i'd do with a 90 or 135 at this point. i've never felt the need to fill the gap between my 110 and 150/240 with anything shorter.

thanks for all the suggestions, all.

Gem Singer
19-Dec-2004, 12:52

I have no idea why you continually put down people who have more abundance than you do. It would probably take a professional many months, perhaps years, to get to the bottom of that deep- seated belief in your head. "Granola Muncher"?? I've never heard that one before! Maybe that's because I don't particularily like granola. How would you feel if the"wealthy" guys on this forum began to use those kinds of remarks about those who are less abundant ? After all, I got mine the old fashioned way, I worked hard for it for many years. I, for one, resent your snide remarks. Please refrain from using them. They only tend to make you appear to be a different person than you really are. Thanks.

Frank Petronio
19-Dec-2004, 12:54
Well, that granola must have lots of calories because packing a Tech 4 with that rack of lenses isn't for a wimp!

Brian Ellis
19-Dec-2004, 15:06
I don't see one lens as among the ones you mention saving enough weight to be worth the trouble. IMHO you should be looking at replacing your 6+ pound Technika with one of the 3-4 pound cameras such as a Tachihara, Horseman, Toho, et al. Then go to a three lens system consisting of the 110, the 300, and something small and light in between. The 300 would be pushing the bellows extension of some of the real light weights but mine worked fine on my Tachihara, I could focus to about ten feet. You don't mention what pack you're using but some of the camping packs such as a Kelty Red Wing usually weigh a good bit less than the dedicated photography packs.

I'm not familiar with the lenses you have now so I don't know how they compare in size and weight with some of the small, light weight lenses I've owned but the 150, 210, and 240mm G Clarons I've owned were excellent lenses and also were very small and weighed very little. I still have the 150. I use the Nikon M for my 300mm lens, it too is excellent and is also small and light. The only big lens I carry is the 210 APO Symmar. I've thought about getting rid of it since the 150 G Claron works about as well but when I've lifted my bag with and without the 210 I haven't noticed a discernable difference so I keep it even though it largely duplicates the 150.

Scott Rosenberg
19-Dec-2004, 16:54
your reply is spot on.. the technika is the next thing to go. i'm pretty sure about the direction i'm taking there; not so sure with my lenses. i thought that before i switched from 110-150-240-300 to 110-180-300 i might hear from some folks that have already gone down this path and profit by their collective experiences.

you are correct in that the weight savings with the lenses i'm looking at is negligable. what i'm really looking at here is freeing up a bit of room in my pack by going to a three lens kit.

i have two packs, both by dana designs. i was never able to find a photo pack that fit my frame comfortably, so i instead modified backpacking packs to work with my photo gear. the dana bags are light and have arguably the best suspension out there.

thanks for the inputs,

Leonard Metcalf
19-Dec-2004, 17:43
Dear Scott,

I used to have the following kit: 47, 90, 150, 210, 300, 450 mm and recently changed to 58, 80, 110, 180, 300 & 400mm.

I have no regrets and love the kit... the lenes I use most are the 110, 180 and the 300... in fact the 180 has quickly become my favorite lenes and most used lens... I hardly ever use the 58 or even the 80 mm, though you will already understand that lens choice is a personal thing... and can be subject or intent driven...

I made my choice primarly on image circles and weight... the fujion 180 mm is a fantastic lens, while the 110 XL schneider is amazing (and has a lovely feel when compared to the 90 5.6 anglulon it replaced)... I love the 300mm nikkor m... and bought the same lenes again... I would have bought another 450 fugion C... except that the camera I purchased didn't extend that far, and ended up getting the 400 schneider teli... instead...

In short... I love my new line up... and don't regret any of my choices...


Scott Rosenberg
19-Dec-2004, 17:56

thanks so much for the response - i'm glad to hear that you didn't find yourself for want of more options when you switched to your current lens set. can i assume that you are using the fujinon 180-a as your 180 lens?

thanks again,

Doug Meek
19-Dec-2004, 17:56
Hi Scott.

If you are more concerned with room than you are with weight, I'm going to make a suggestion which steers you in a somewhat different direction. I have the same lenses as you (110 150 240 300) and a few extras to boot. I have a Gnass 4-lens pouch which is quite compact and holds 5 (not 4) of the following lenses: 110xl Schneider, 150-s Rodenstock, 180A Fuji, 240A Fuji, 300C Fuji. This combination doesn't weigh a lot, but just as importantly, it takes up very little room in my pack. All of the glass is top quality and I always have the perfect lens available for the scene in front of me. After all, one of the main reasons for shooting large format is the size of the chrome. Why give away some of that quality by cropping if you don't have just the right lens available for a particular shot? You frequently can't move forward or backwards when composing your shot. Your large format lens can be reduced to medium format quality by cropping. I also have a second Gnass pouch - a 3 lens design which holds my Schneider 75SA, Nikkor 360T & 500 rear element. This second lens pouch stays in the truck on my extreme hikes. At any rate, I just thought that the 5-lens setup I have in one Gnass case might be perfect for you, especially considering the fact that you already have 4 of the lenses. Good luck in your decision!

Frank Petronio
19-Dec-2004, 18:23
Eugene - Huh? Munching granola isn't much of a put-down (I thought Scott would get a chuckle, really), and I don't exactly feel like I'm poor or jealous of people who own more than I do. Please re-read my post(s) - if I suggest a cheaper way to do something, it's because it is simply a cheaper and more practical way to do it. Not that I can't afford to buy some impractical, frivolous things from time to time... Honest, I'm a good consumer!

Gem Singer
19-Dec-2004, 19:42
O.K. Frank,

I over reacted. I interpreted your expression "granola muncher" as being in the same category as your other referrences to "cameras designed for wealthy old retired guys". I realize that it's probably your attempt to inject humor into your responses. I sometimes attempt to do that, myself.

Thanks for understanding that those types of remarks are insulting to us old retired guys who are able to afford the newer, and higher quality equipment. After all, someone has to buy that new stuff, so that younger, less affluent, guys can purchase it ,used, on E-Bay after we're tired of playing with it.

Frank Petronio
19-Dec-2004, 20:01
Well, I'll admit to smirking when I see a post about some newbie wanting to start with a $10,000 Ebony 8x10. But we're all addicted to the same expensive drug, whether it's a $100 Crown Graphic or something more.

19-Dec-2004, 21:12
Scott, I think it is a mistake to be pondering your lens set when you may be changing cameras soon. According to Badger Graphic, a Technika accommodates a 250mm whereas a Canham wood will accommodate a 600mm lens. Maybe these numbers are not precise, but the general point is clear, that your camera restricts what lenses are practical. If you were to make that switch, it opens up possibilities of longer lenses you may not have considered before.

I get by in landscape with 3 lenses. For me they are the widest I'd ever use, the 110mm, the longest my camera will accommodate, a 450mm, and one in the middle, a 240mm.

Scott Rosenberg
20-Dec-2004, 06:42
frank... the next time a newbie talks about buying a $10,000 8x10 ebony, send me his contact info. there's a good chance that camera will be available a few months later!

eugene... i for one am grateful that there are guys like you out there buying new gear. it keeps the market for used gear healthy, encourages manufacturers to continue to develop newer, better product, and makes forums like this possible, as who better to offer advice then folks with boat-loads of experience that have gone through boat-loads of gear!

cxc... since i'm pretty clear where i'm going with the new camera, i've already factored that into this decision. it's true i may one day want to go longer than my 300mm once i have a camera with enough bellows. at that point i'll probably start looking for a fujinon 450c, which is another reason to reduce my current field kit by one.

thanks for your suggestions,

arthur berger
20-Dec-2004, 09:06
Scott : Even though I own a number of lenses, I usually keep three in a gnass-gear three pack lens case ready for quick action. The three leses are... 110xl, 180 Fujinon ( f5.6) and 300mm Fuji A . I tried the 180-A but had trouble focusing in dim light and switched to the 180 Fuji W. The gnass gear case slips into my backpack along with my camera and other necessities. These three .lenses also cover 5x7.

Scott Rosenberg
20-Dec-2004, 10:37
arthur... sounds like you and leonard (and i'm sure many others) are happily using the spacing i am thinking about going to - that's quite encouraging. thanks for chiming in.

Kerry L. Thalmann
20-Dec-2004, 12:24

You've already gotten a lot of good advice. As other's have noted, and you have acknowledged, your greatest potential for weight savings is a lighter camera. Additionally, a camera that weighs 3 lbs., instead of 6 lbs., will allow you to use a lighter tripod and head - for even greater weight reduction.

Concerning your original question regarding your lenses... This may sound like blasphemy (especially coming from me, as I have spoken such high praise of this lens), but have you considered replacing your 110mm Super Symmar with something lighter? Don't get me wrong, it's a wonderful lens - one of the best ever, but do you really NEED the coverage? I love my 110 XL, but rarely take it backpacking. On my last backpacking trip, I left it home and took a little 120mm APO Symmar instead. Due to the limited coverage, I mainly use this lens for 6x12, but it will cover 4x5 with modest movements. On that recent backpacking trip, I actually found it was my most used lens. Other than the tight coverage, I doubt if you'd notice any difference in performance between it and the 110 XL unless you regularly make 40" x 50" prints. Coverage is tight, but performance superb. Schneider rates the image circle at 179mm, but they are usually very conservative in their specs. Filter size is 49mm. They list the weight at 200g, but my sample weighs 190g (compared to 430g for my 110 XL). They have a newer 120mm APO Symmar-L out now that is just a tad bigger (52mm filter size) and heavier (listed at 210g), but has a little more coverage (189mm published image circle). You may not be able to live with the tighter coverage of one of these smaller lenses in place of your wonderful 110 XL, but I just thought I'd bring it up as another possible solution to your weight reduction goal.

WRT to the 180mm len... Of course, the 180mm f9 Fujinon A is by far the smallest (46mm filters) and lightest (170g published, 190g actual) lens available in this focal length. Coverage is more than adaquate for general landscape use. I wouldn't wory too much about corner performance. Stopped down to normal working apertures, it should be fine. The real question is would you be comfortable with the f9 maximum aperture for focusing and composing. That's something only you can answer. I personally am willing to tolerate a smaller maximum aperture if it means I can carry a smaller, lighter lens when backpacking. I reguarly us a 150mm f9, a 200mm f8, and 240mm f9 and a 300mm f9 (not all at the same time, I either carry 90mm, 150mm, 240mm or 90mm, 135mm, 200mm, 300mm) and don't seem to have great difficulty focusing or composing. The 150mm f9 might be pushing it a bit, but it's such a TINY little lens (35.5mm filters, 130g) it's hard to leave home. If you don't think the Fuji is the lens for you, one other alternative would be the 180mm f5.6 APO-Symmar. I haven't used this particular lens, but in addition to the 120mm APO Symmar I mentioned above I've used a 210mm APO Symmar (not for backpacking, though) for years and have always been extremely pleased with the results. At 385g and a 58mm filter size, the 180mm APO Symmar is the smallest and lightest of the recent 180mm f5.6 plasmats.

Finally, you might also consider replacing the 300mm Fujinon A with a 300mm Nikkor M or 300mm Fujinon C. The 300mm Fujinon A is a great lenses, but really overkill for a 4x5 landscape shooter. The 300mm Nikkor M and 300mm Fujinon C will both have more coverage than you'll ever need for 4x5 and are both smaller and lighter. Since the 300mm Fujinon A is a very desirable lens, you could probably sell it and replace it with a new Nikkor M or Fujinon C for very little cash (or replace it with a used 300m M or C and put some cash in your pocket). In addition to being lighter, both of these lenses also more compact and take smaller filters than the 300mm A.

Here's a quick comparison of what you are currently carrying and an ultralight lens set based on the above recommendations:

110mm Super Symmar XL: weight = 425g (actual = 430g); filter size = 67mm
150mm APO Sironar-S: weight = 230g (actual = 215g); filter size = 49mm
240mm Fujinon A: weight = 225g (actual = 245g); filter size = 52mm
300mm Fujinon A: weight = 410g (actual = 420g); filter size = 55mm
Total weight = 1290 (actual = 1310g); filter size = 67mm

120mm APO Symmar weight = 200g (190g actual); filter size = 49mm
180mm Fujinon A: weight = 170g (actual = 190g); filter size = 46mm
300mm Nikkor M: weight = 290g (actual = 270g); filter size = 52mm
Total weight = 660g (actual = 650g); filter size = 52mm

If you want a bit more coverage, substitute the 120mm APO-Symmar-L and add about 10g, but keep the filter size at 52mm.

So, basically you can cut the weight of your lens kit in half and use smaller, lighter, less expensive 52mm filters. Of course, there is no free lunch. You give up the massive coverage of the 110mm XL and have to live with the f9 max. aperture of the 180mm Fujinon A. For general purpose use, the kit you already have is "better" and more versatile. It rally depends which you value more: coverage and usability or compact size and lightest possible weight. This is why I have two camera outfits - the Toho with a small selection of ultralight lenses for backpacking and teh ARCA-SWISS with a set of six wonderful lenses for everything else.

One possible compromise, that would save you a bit of weight and space in your pack would be to keep your 110mm SS XL, replace the 150/240 with a 180mm APO Symmar and replace the 300mm A with a 300mm Nikkor M. This will save you a couple hundred grams over your current kit, and all three lenses would offer outstanding performance and more than enough coverage.


Bruce Watson
20-Dec-2004, 14:40
Every group needs a naysayer, yes?

I started out with a 110mm SS-XL. The next lens I bought was a 240 Fuji-A. I used just these two lenses for well over a year. I began to get frustrated with some shots I was missing because I could only choose between an angle-of-view of 60 degrees, or 30 degrees. I needed something in the middle, and picked up a 150 Sironar-S, which gave me a 45 degree lens.

So, my base kit is just what you have now, and it works perfectly for me. But if it's not working for you, then you should change to something you are more comfortable with.

To me, it seems that the 240 and the 300 are way close - an angle-of-view difference of just a few degrees. You might want to consider what Kerry says - a 120/180/300 set might do what you need, very light, very small filters.

But the big weight savings is replacing the Technika with a Toho. But it sounds like you know that already ;-)

Scott Rosenberg
20-Dec-2004, 18:15
kerry... thanks so much for the thoughtful analysis and suggestions. as always, you're inputs are extremely helpful. a big thanks for all the work you and chris put into testing lenses... i have foud your sites to be invaluable.

as i said earlier, i only picked up the 300-A because i got it for an absolute song, but have since been very surprised at how often i use it. i have been kicking around the idea of stepping up to 8x10 for a little while now but remain undecided. this too is factoring into my decision on lens selection, and i won't be doing anything until i come to some resolution on that. a friend of mine has an 8x10 tachihara and i've already gotten him to commit to going shooting with me one day soon. i'm extremely fortunate to have someone local willing to spend an afternoon shooting with me. spending the day working with the tachi and then comparing the negs from his 8x10 and my 4x5 will be a very enlightening experience... though it may result in my pack getting anything but light! if i am positively stunned by the 8x10 then i'm looking at this a couple of ways... i'm going to want to build my lens kit around glass that can cover 8x10. the 300A will be useful, as it will cover that format nicely. add a fujinon 450-c and that would give me 3 (240-a, 300-a, 450-c) lenses that can cover 8x10 nicely. if i wanted to later on, i could then swap out the 240-a for a 210 APO-Sironar S (will also hit 8x10) just to spread the lenses out a bit (210-300-450 for 8x10 and 110-210-300-450 for 4x5)... it's too bad there isn't a 180 in a copal 1 that will cover 8x10!
if i decide that the weight of the 8x10 is not worth the gain in quality over my 4x5, which is how i think things will turn out, then i will very likely keep the 110-xl (it's such a pretty lens), replace the 150-S and 240-A with a 180 5.6 plasmat (whichever i can find the better deal on) and swap my 300-A for a 300-C or 300-M (again, whichever i can get a better deal on). WRT the filters, i've got a pretty good investment in 67mm glass already, so whichever lenses i end up with, i'll probably stay with that size.

hogarth... i appreciate the inputs, even from a 'nay-sayer'. sounds like we followed a similar path - i'm glad your kit is working so well for you.

thanks again, fellas! scott

Michael Chmilar
21-Dec-2004, 11:30
My kit is:

<LI>80 XL SS
<LI>110 XL SS
<LI>180 Apo-Sironar S
<LI>300 Fujinon C

I find this fulfills my needs for landscape photography perfectly. The most heavily-used is the 180, followed closely by the 110. Rarely, I might desire a wider or longer focal length than what I've got, but I never wish for a different "spacing" between lenses.