Long exposure reciprocity failure on fujifilm instax

[hiroko]

Anyone care to share how to calculate the reciprocity failure for fujifilm instax film? Cant seems to find it in fujifilm datasheet. What i have noticed is that it will turn blue cast for anything more than 1s exposure. Its more for experimental and fun project use.

 

[Donald Qualls]

I've done limited pinhole in Instax Wide; I used 3 for 2 exposure time (i.e. every stop got 3x the time instead of twice) starting at 0.1 seconds -- my prints still came out on the dark side, so I might be tempted to give another stop on top of that (likely by metering at lower EI).

 

[xya]

I have taken an ordinary film factor which has worked fine for me:

1s x 1.25
5s x 1.5
15s x 2
45s x 2.5
2m x 3
5m x 4
10m x 5
20m x 6

But there is another factor for Instax film to take into account. The 800 ISO are only valid for medium light. It's 400 for dimly lit situations and 1600 for brightest sunshine, pinhole or normal lens.

 

[hsandler]

Some more info in this earlier thread: https://www.photrio.com/forum/threads/reciprocity-and-long-exposure-on-instax-film.143619/

 

[cukon]

Thanks for sharing your findings with instax.

 

[illawarraflametree]

But there is another factor for Instax film to take into account. The 800 ISO are only valid for medium light. It's 400 for dimly lit situations and 1600 for brightest sunshine, pinhole or normal lens.

Is there more info available on this variability in the ISO of Instax film?

 

[hsandler]

Is there more info available on this variability in the ISO of Instax film?

I'm not convinced there really is a variable ISO to Instax film. It's just that it has such a narrow dynamic range that in bright situations scenes tend to be contrasty, so the highlights will easily blow out and underexposure can help, equivalent to considering the ISO as 1600. In dim situations, the reciprocity begins to kick in, and that's equivalent to lowering the ISO. Also, dim situations tend to be lit by tungsten light and perhaps there is reduced sensitivity to yellow light. The definitive experiment would be to expose a uniform middle grey scene in variable daylight or with various neutral density filters, but that's not real life. The bottom line is that Instax is a very fiddly film in terms of exposure. Trial and error is often called for. If I nail the exposure one in two or one in three times I feel I'm doing OK.

 

[RandomViews]

I'm not convinced there really is a variable ISO to Instax film. It's just that it has such a narrow dynamic range that in bright situations scenes tend to be contrasty, so the highlights will easily blow out and underexposure can help, equivalent to considering the ISO as 1600. In dim situations, the reciprocity begins to kick in, and that's equivalent to lowering the ISO. Also, dim situations tend to be lit by tungsten light and perhaps there is reduced sensitivity to yellow light. The definitive experiment would be to expose a uniform middle grey scene in variable daylight or with various neutral density filters, but that's not real life. The bottom line is that Instax is a very fiddly film in terms of exposure. Trial and error is often called for. If I nail the exposure one in two or one in three times I feel I'm doing OK.

That’s an interesting way to think about this, and a good framework for taking a properly exposed image. I completely agree that Instax is a tricky film to shoot manually.

The info here and in the link above is the best info I’ve come across on this topic. There’s nothing in the Instax specification sheet about ISO variability.

I’ve arrived at the same patterns indicated here by my own trial and error. Operating on the guidelines that medium light is about ISO 800, darker situations is ISO 400, but I’ve even gone down to ISO 200, and bright light is at least ISO 1200. In my experience, reciprocity failure starts to show up around 1/30 of a second, so if that’s what my meter reads, then I think twice about taking the image. I also found that Instax has, at most, 2.5 stops of underexposure latitude and at most 1.5 stops of overexposure latitude (other folks have arrived at a similar pattern).

By keeping “ISO variability,” reciprocity failure, and poor exposure latitude in my head when taking an image, I’ve been able to get some good images, on purpose, using Instax.

Like hsandler, it usually takes me more than one try to find a “sweet spot” using these concepts with Instax film.

 

[illawarraflametree]

I'm not convinced there really is a variable ISO to Instax film. It's just that it has such a narrow dynamic range that in bright situations scenes tend to be contrasty, so the highlights will easily blow out and underexposure can help, equivalent to considering the ISO as 1600. In dim situations, the reciprocity begins to kick in, and that's equivalent to lowering the ISO. Also, dim situations tend to be lit by tungsten light and perhaps there is reduced sensitivity to yellow light. The definitive experiment would be to expose a uniform middle grey scene in variable daylight or with various neutral density filters, but that's not real life. The bottom line is that Instax is a very fiddly film in terms of exposure. Trial and error is often called for. If I nail the exposure one in two or one in three times I feel I'm doing OK.

This was kind of the impression I was getting as well. Instax is kind of famous for having terrible reciprocity, maybe the reciprocity failure is even worse than what is commonly said. ISO is technically about density anyway, so if there were a way to measure the density at different exposures, you'd be able to really tell if it actually is variable ISO or not... I think.

Functionally though it doesn't really matter all that much, what's important is how you go about responding to your scene and your light meter. Changing the exposure index in a fairly linear manner in response to particular lighting conditions may be an easier rule of thumb than accounting for reciprocity in low light. But of course the more meticulous approach will probably lead to better results.

I would be curious to see the results in a dimly lit scene with a wide open aperture but decently high shutter speed. Something like a street at night time with a wide open aperture. I'm going to get an Instax square back for my RB67 soon, and I'm planning on doing some tests to see how the film responds once I finally have a camera that lets me manually control how the instax is exposed.

That’s an interesting way to think about this, and a good framework for taking a properly exposed image. I completely agree that Instax is a tricky film to shoot manually.

The info here and in the link above is the best info I’ve come across on this topic. There’s nothing in the Instax specification sheet about ISO variability.

I’ve arrived at the same patterns indicated here by my own trial and error. Operating on the guidelines that medium light is about ISO 800, darker situations is ISO 400, but I’ve even gone down to ISO 200, and bright light is at least ISO 1200. In my experience, reciprocity failure starts to show up around 1/30 of a second, so if that’s what my meter reads, then I think twice about taking the image. I also found that Instax has, at most, 2.5 stops of underexposure latitude and at most 1.5 stops of overexposure latitude (other folks have arrived at a similar pattern).

By keeping “ISO variability,” reciprocity failure, and poor exposure latitude in my head when taking an image, I’ve been able to get some good images, on purpose, using Instax.

Like hsandler, it usually takes me more than one try to find a “sweet spot” using these concepts with Instax film.

Yeah even with the very limited manual controls on the Instax cameras I've got, I find that getting a good exposure can be pretty difficult. I plan to eventually do a whole battery of tests in different lighting conditions to get a good idea of how the film will respond in scenes with different ranges and at different EV. I don't imagine I'll be too surprised by the results, but it's more about hoping to reduce wasted exposures in the future as much as I can. Instax might be cheaper than colour negative film, especially once accounting for dev costs, but it's still expensive (at least in Australia).

 

[Donald Qualls]

Yeah even with the very limited manual controls on the Instax cameras I've got, I find that getting a good exposure can be pretty difficult.

As far as I know, the only Instax camera that corrects for the reciprocity characteristics of Instax film is the Mint folder. All the others (from Fuji, even!) do poorly when the exposure exceeds 1/10 second, at most (and the comment above about starting at 1/30 might well be more correct that my 1/10).

 

[ic-racer]

Anyone care to share how to calculate the reciprocity failure for fujifilm instax film? Cant seems to find it in fujifilm datasheet. What i have noticed is that it will turn blue cast for anything more than 1s exposure. Its more for experimental and fun project use.

The film has not been made for years, it is all expired. April fools??

 

[xya]

As far as I know, the only Instax camera that corrects for the reciprocity characteristics of Instax film is the Mint folder. All the others (from Fuji, even!) do poorly when the exposure exceeds 1/10 second, at most (and the comment above about starting at 1/30 might well be more correct that my 1/10).

Yes, I agree, but only the later editions. The first, the "founders" edition, did not have that correction. Mint listened to its customers, improved the circuits and eventually even exchanged the camera. So I had both.

To my opinion Fuji improved their cameras as well in the same way. Their 400 wide is MUCH better than the 300 although the 400 is simpler. And their Neo 90 gets it right under most circumstances.

Of course you cannot compare the Fujis to an all manual camera. So I look forward to the tests of our members...

 

[xya]

The film has not been made for years, it is all expired. April fools??

??? I just bought loads of recent Instax film. So who is the fool here?

 

[illawarraflametree]

The film has not been made for years, it is all expired. April fools??

Are you sure you're not thinking of FP100C?