XPAN 45mm lens - light fall-off versus aperture

[reisenberger]

Can the XPAN 45mm lens be shot without the centre filter at one end

of the aperture range or the other (either wide open or fully stopped-

down), on transparency film, and still get acceptable results without

too much light fall-off at the edges? And if so at which end?

 

 

I have the opportunity to hire an XPAN&45mm lens at around 100GBP

only for a 7-day stock shoot to Italy next week - excellent chance to

try out the kit before spending at the 1000+GBP starting price - but

the hire company unclear whether they have the 45mm centre spot

filter available, and I want to know what my shooting options are

without it.

 

I mainly shoot tripod-based landscape, so if results were acceptable

at the f/16-f/22 end but not wide open, for instance, that would bar

handheld shots but could still be very workable for my general

practice (tripod-based landscape). If the other way round, I guess

one could shoot handheld or f4-5.6 landscapes where most of the

subject was at a distance/infinity but not resort to f/22 for near-

far/front-to-back sharpness... Fuji Velvia/Provia is my emulsion of

choice.

 

Many thanks for all info. Have searched hard for the answer on this,

but find conflicting info - some like

http://shutterbug.com/equipmentreviews/35mm_cameras/0403sb_hasselblad/

stating that ok at the wide open end, others like hasselblad's own QA

http://www.hasselblad.co.uk/faq/faqFirst.asp?secId=580

stating ok at f/11-f/16.

 

(I would assume the Hasselblad QA should be definitive, but am not

entirely clear from: "is free from vignetting at apertures smaller

than f/8" followed by "however, natural light fall-off reduces the

exposure at the corners by 1-stop"...)

 

Many thanks

 

Dylan Reisenberger

[ilkka]

Hasselblad does not say that the filter should be removed at small apertures and that seems to confirm their statement that natural light fall off remains 1 stop even at F/22. If the light were even without the filter at F/22 then with the filter the corners should be clearly lighter. I found the fall off objectionable after trying without for a few rolls and have since then used the filter for every shot regardless of aperture, apart from a few rare exceptions when the light is just not enough (at full F/5.6 effective aperture). But many people use it without the filter so it depends partly on how critical you are and what type of photography you do. Sometimes slight darkening can help focus the attention to the centre part of the image.

[reisenberger]

Many thanks Ilkka!

 

I subsequently found this

http://www.naturfotograf.com/xpan_rev.html

which suggests that f/22 is the end to work at to reduce the light fall-off.

 

Would still be interested in anyone else's views on the results working at f/22 without the filter...?

[nick_evans1]

Hi

 

I use a Hassleblad Xpan alot and do not have a centre filter (mainly because I think they are not worth the money) and shoot mainly at apertures f8 - f22.

 

I think the 'uneven exposure' is more of a problem when shooting at the wider apetures.

 

There is a very slight fall off at the edges but this seems common with panoramic cameras, sometimes I will use a ND filter (cokin or ND 4 Nikon held in front of the camera) which will even the exposure out.

 

As the other chap said, there can be little darkening at the edges but it can be used to highlight the centre of the image.

 

HTH

 

Nick

[bob_cook]

Dylan - I use the 45mm quite a lot. Just got back from two weeks shooting water landscapes in the mountains in Tennessee. I don't own the center filter. Because of my subject matter, I always shoot at f16.5. My subjects have a lot of variation in content, with green foliage out to the corners, so the light falloff is not noticeable, it it is there. I also shoot some more general landscapes and have noticed it to be objectionable, but I'm always at a small aperture.

[stephen_scardamalia]

I've run maybe 4 rolls through my new (to me) XPan. I started with just the 45mm lens and no filter. I haven't noticed any significant light falloff. If you're just testing the camera for now, I'd think you could get a very good idea of it's value to you regardless (knowing you could add the center filter if you buy). I don't think you'll see anything so extreme as to ruin an image.

 

So far I've loved the camera, just haven't had enough time to use it! Next step is the 90mm...

[bob_cook]

Correction - sentence should read "I've shot some more general landscapes and have NOT noticed it to be objectionable...

Sorry for the mistake.

[db1]

I have the xpan II and have never used the center filter, but I only shoot b&w.

 

I believe the Hasselblad website states the filter should be used with POSITIVE film and apertures larger than f8.

 

Do you have time for a test roll?

[tony_estcourt]

Hasselblad advice is to stick with small (F22 end) apertures to minimise light fall-off. All wide angle lenses suffer from un-even illumination and personally I'd only invest if I shot a lot of evenly illuminated subjects where it would start to become obvious.

 

When I shoot lanscape on tranny film the problem I find is that the subject is often not that evenly illuminated (naturally), the letterbox format seems to magnify this effect (left hand side brighter than right etc). The effect of the lens un-evenly transmitting light to the film is a marginal effect for me.

[Rob F.]

I don't own a centre filter for my 45mm, and do not notice any objectionable light falloff at any aperture when using Provia 100. Perhaps a contrastier film, like Velvia, would make a difference.

 

As a comparison, I find that the light falloff, shooting with Velvia 50, with my 21mm Leitz Super-Angulon, is unacceptable. That might give you an idea of about how much falloff I can and can't tolerate.

 

With my 30mm on the XPAN, then the filter becomes necessary.

 

I'd suggest starting out without a filter, only adding one if your requirements demand after seeing the results. I doubt you'll need it at all, least of all at f/22.

[neil_grant]

Using an XPAN 45 mm lens at f/22 doesn't sound great from a lens performance POV. I used

my 45 for several weeks w/o centre spot - but rapidly got tired of the vignetting. Typical

apertures were f 8-11. Film, in those days would have been Fui RDP 2 (Provia). Needless to

say, bought the filter.

[michael_briggs2]

I what I think is a good guess at what Hasselblad means by the combination of the sentences "is free from vignetting at apertures smaller than f/8" and "however, natural light fall-off reduces the exposure at the corners by 1-stop". Photographic lenses normally don't deliver their rated maximum aperture over the image image area. If you buy an f4 lens, most likely, it is really only an f4 lens at the center of the film, and probably f8 at the corners. The manufacturers do this because very large glass elements would be needed so that the rays of the f4 aperture would reach all portions of the film without being blocked by barrel. Probably the sentence "is free from vignetting at apertures smaller than f/8" means that this effect is at apertures smaller than f8. It is probably almost gone at f8.

 

You can check for this by looking at the lens through the film gate, moving your head around: can you always see all of the aperture, as a circle or ellipse, or does some portion of it get cutoff?

 

There are remaining optical reasons that no lens (which renders perspective in a normal way) delivers perfectly uniform illumination, even when well stopped down (which means past f8 for this lens). For example, the rays to the corner of the film have to travel further. I discuss this at http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=005gK2. This is what Hasselblad means by the "natural light fall-off" and why the lens still has a 1-stop reduction of light at the corners no matter how far you stop down.

 

So most likely you will reach the most uniform illumination that this lens delivers by stopping down to f8, or just past f8. At this point

only the non-uniformity due to the optical laws that apply to all lenses remain.

 

You can see some examples of how this works for other lenses in the PDF datasheet for Rodenstock LF lenses at http://www.linos.de/en/prod/obj_analoge_fotogr.html. The graphs show how the illumination improves as the vignetting is gradually reduced as the lens is stopped down, until at some aperture it reaches the best illumination-uniformity that the lens delivers.

[35mmdelux]

i just bought an xpan I few months ago and didn't realize just how great this little camera is. I read that the filter wasn't really nec with the 45mm, unless you're shooting chromes. Be that as it may, I'll take it without the filter.

 

Any of you checked out the Lois Conner's panos? She uses old banquet cameras - her work is quite great.

[35mmdelux]

is here:

 

http://www.amazon.com/gp/product/093511257X/qid=1147282429/sr=1-1/ref=sr_1_1/103-3287465-0511847?s=books&v=glance&n=283155