Velvia 50 vs Velvia 100 Film Speed

[kenneth_seidman]

I just finished a preliminary comparison of Velvia 50 vs 100 (non-F)

by shooting the same scenes using two different Pentax 67 bodies. One

body was loaded with Velvia 100, the other Velvia 50. I used a tripod

for all shots and switched camera bodies as quickly as possible to

minimize changes in outdoor lighting conditions.

 

Based on a comparison of 8 images at various shutter speeds it seems

to me that Velvia 100 is slightly more than 1 stop faster than Velvia

50 (perhaps ISO 125 instead of ISO 100)... BUT, I cannot be sure since

this difference may be due to the fact that I used different camera

bodies and there may be a bias in the shutter speeds. More testing

e.g. switching the film/camera combination for another round of

testing could answer this, but I am running out of time before a long

trip.

 

Has anyone else noticed a difference of more than one stop between

Velvia 50 and 100?

 

Ken

[marshall]

Haven't done enough testing yet. However, a lot of people routinely expose Velvia 50 at 40, so the extra stop may be more on the other side. Of course, your mileage may vary.

[keith_laban]

<a href="http://www.keithlaban.co.uk">Keith Laban Photography</a><p>The true ISO of Velvia 50 is more like ISO 40. If Velvia 100 is truly an ISO 100 film I would expect the difference between the two films to be more than one stop.

[wickedmartini]

I've had pretty good luck with rating my Velvia 100 at 100. I have shot about a dozen rolls of 35mm and 120 so far. There are alot of factors that can affect this--Camera, lenses, lab plots, etc.

[ellis_vener_photography]

I'm rating Velvia 100 at 80 and rated RVP 50 at 40.

[25asa]

Rating Velvia 100 at rated speed seems correct when I tried it.

[kenneth_seidman]

Thanks for your responses.

 

I like Keith Laban's explanation (and the photos on his website!):

"The true ISO of Velvia 50 is more like ISO 40. If Velvia 100 is truly an ISO 100 film I would expect the difference between the two films to be more than one stop."

 

If I did not have a direct comparison with both Velvias on the light table I would not have suspected there was anything 'wrong' with the exposures on either roll (Velvia 50 or 100). It is likely that over the last 10+ years I have learned to meter my landscape shots using Velvia 50 (with a Pentax digital spotmeter) to adjust for my 'personal' ISO setting of 50 instead of 40.

 

This weekend I will re-do my tests by switching the film/camera combination. If the Velvia 100 roll is still a bit more than one stop faster than the Velvia 50 roll I will have my answer. I expect to have results to post by mid week.

[discpad]

To do an accurate comparison, you need to use the SAME camera and lens: Shoot a roll of each - Quickly! - and bracket the exposures. If you shoot fast enough (outdoors), you don't have to worry about the sunlight/clouds changing.

 

Don't forget to take notes when you shoot these test rolls!

[ilkka_nissila]

To determine the film speed you can just shoot a gray card at different exposures _in constant light_ and compare the results between the two films. Since Velvia (50) has higher color density than gray density, you probably find in this test that the difference between the speeds of the two films is just that nominal 1 stop. If you want, you can then do the same with a color chart to see how it goes with different colored objects. It's very important to do this test so that you're in constant illumination.

[keith_laban]

<a href="http://www.keithlaban.co.uk">Keith Laban Photography</a><p>Kenneth, I haven't had a chance to use the new Velvia 100 yet. How do you (and others) find the colour and saturation in comparison with Velvia 50?

[kenneth_seidman]

>Kenneth, I haven't had a chance to use the new Velvia 100 yet. How do >you (and others) find the colour and saturation in comparison with >Velvia 50?

 

Saturation is high, similar to Velvia 50 (and not like Velvia 100F). Velvia 100 grain is definitely less. Yesterday I scanned the same images from Velvia 50 and 100: 6x7 image at 3200 dpi, 8x MultiSampling, ICE on - Minolta Multi Pro scanner. Screen comparisons in Photoshop at 100% showed much less grain in the highlights of the Velvia 100 scan (vs 50).

 

As best I can tell so far I agree with Ken Rockwell's color assesment:

http://www.kenrockwell.com/fuji/velvia100.htm

 

He says Velvia 50 is warmer in the tans, yellow, oranges. The few shots I have compared so far show this effect. I don't think there would be any problem changing the hue or saturation a bit in Photoshop if one wanted to mimic Velvia 50.

 

I shot another set of images today. I should get results back from lab on Tuesday.

 

Bottom line for me is that I like the reduced grain and high saturation of Velvia 100 and don't plan on stocking up on Velvia 50.

 

Ken

[kenneth_seidman]

>Bottom line for me is that I like the reduced grain and high saturation of Velvia 100 and don't plan on stocking up on Velvia 50.

 

Comparisons of film grain made with a 20x (?) magnifier directly on the film instead of a scan (as mentioned in my last post) do show somewhat reduced grain in Velvia 100 also... However, when using a 10x or 8x loupe the differences are very subtle. My earlier remark that the grain is 'much' reduced is too strong a conclusion.

 

BTW, in making comparisons with the same high power magnifier and the standard Air Force Test Targets indicate to my eyes that there is no difference in resolution.

Ken

[keith_laban]

<a href="http://www.keithlaban.co.uk">Keith Laban Photography</a><p>Kenneth, thanks for your observations.

[wickedmartini]

I've posted these in the past... Here are some Velvia 100 data sheets for those that are interested... Grain is definitely improved over Velvia 50 RVP... See the brochure for contrast and color samples...

 

Michael D. D'Avignon

[wickedmartini]

Brochure...

[kenneth_seidman]

I got back two more rolls of film, Velvia 50 and Velvia 100. As mentioned in my previous post, this time I switched the film/camera combinations, i.e. for my first comparisons Velvia 50 (Velvia 100) was in camera 1 (camera 2) and for this test Velvia 50 (Velvia 100) was in camera 2 (camera 1). Same lenses used for all pairwise comparisons. Light was constant for all pairwise exposures. I also bracketed several exposures by +/- 1/2 stop.

 

This allowed me to shoot a wide variety of naturally lit scenes throughout the day at various shutter speeds (1/125 to 1/2 sec). As with the first tests I compared images side by side on a light table.

 

Results: Same as with the first film/camera combination test, ALL the Velvia 100 images (regardless of scene or shutter speed) were slightly but noticeably lighter than the Velvia 50 images. The most reasonable explanation is that any differences between shutter speeds on both cameras is smaller than the more than 1-stop film speed differences.

I am ruling out secondary effects such as possible roll to roll variations or processing differences between these two tests (processing done by a professional lab, Calypso). I also had some independent observers compare the two sets... same conclusion. Sure, it would be useful to use the same camera and do more tests against gray cards (which I did include in many of my images) but what I am interested in is the relative film speeds under actual shooting conditions important to me.

 

My conclusion, Velvia 100 is approx 4/3 stop faster than Velvia 50. I'm going backpacking with the stuff next week, if all my shots are underexposed by 1/3 stop I'll let you know !

Ken

[lucas_wheat]

is it possible to do a densitometry test on this film? to check the rated speed? or is that only possible with black and white film?

 

also, has anyone taken photos of set color charts and compared them? as oposed to just general scenes?

[stephen_schoof1]

I just got my first test roll back, where I had shot Velvia 100 in a body I always set to ISO 50 for the old stuff. Each scene was bracketed +/- 0.5 and in almost all cases I preferred the -0.5. Unless future results change, I'll probably rate it at 125.

 

As far as color I noticed slightly less warmth in a couple of scenes (the 100 was shot alongside 50 in different bodies with the same lens), but overall I think the palette is similar enough I won't be stocking up on 50.

[kenneth_seidman]

Stephen,

Thanks for input on rating Velvia at 125. It gives me more confidence in my own observations.

Ken