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120 film recommendation

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#1 balazs.benei

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Posted 07 August 2021 - 02:40 AM

Hi guys, I need advice. I'm gonna try medium format astrophotography with a Yashica Mat 124. I have a roll of Ektar 100 and Portra 400. Which one would you recommend to shoot with and what settings (minimum exposure time)? I've seen good results with both so far but I'm confused a bit now.

Thanks,
Balázs

#2 ngc7319_20

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Posted 07 August 2021 - 03:57 AM

According to Google that has a 80mm F/3.5 lens?  Judging from your nice photo album you already have a tracking mount.



#3 balazs.benei

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Posted 07 August 2021 - 04:20 AM

Indeed, 80mm f/3.5. And I can do guiding recently so technically 1 hour exposure is also possible.

#4 ngc7319_20

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Posted 07 August 2021 - 07:21 AM

Well I am not an expert on this film business.  But I thought this image of Orion on Ektar 100 was excellent -- good red response, and lots of nebulosity if you stretch the image in the computer.

 

https://www.cloudyni...0#entry10978008

 

So that image was taken with an F/6.5 telescope.  You could probably stop down your Yashica lens a little and do equally well.

 

You might want to test the image quality of the Yashica lens at different F-stops.  F/3.5, F/5.6, F/8 to see what makes an acceptable image.  Sometimes camera lenses are not so good wide open.


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#5 balazs.benei

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Posted 07 August 2021 - 09:40 AM

Yes I've seen that Ektar is great for AP, I just don't know wether push it or not during development. Trying to cover more f stops sounds good I just have to decide how long exposures to take for each.



#6 TxStars

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Posted 07 August 2021 - 03:25 PM

The Ektar does a fairly good job..

I would start with 10min exposure then do a 15min and 20 min test to see if your skies can take it before getting washed out.


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#7 balazs.benei

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Posted 07 August 2021 - 03:54 PM

Thanks, TxStars! 

 

What do you mean getting washed out? Light pollution? I'm gonna shoot in a protected night sky area in Hungary where the quality is around Bortle 2-3 I guess. Only distant villages cause some light pollution on the horizon. I've seen that some folks here did 1 hr exposure on Ektar with really good result under dark skies.

And what about pushing the film, would you recommend it?

 

Sorry for the many questions but I'm getting excited since the weather forecast predicts clear skies smile.gif



#8 TxStars

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Posted 07 August 2021 - 04:04 PM

I don't like to push process due to the loss of dynamic range.

If you are shooting under Bortle 2-3 skies, then go for some longer exposures, just be aware your will need guiding (not just tracking) for 1hr exposures.

Still do some shorter 10 / 15 / 20 min shots to look at the brighter areas.


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#9 balazs.benei

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Posted 22 July 2022 - 03:41 PM

I recently shot two astro targets on Portra 400 with P6 and 300 f/4.5 lens under Bortle 2 sky. I did 40 min.exposure for M16 and 60 min for NGC7000, wide open. I still have several shots left on the roll and going to continue with M8-M20, Scutum region and maybe M31 in the morning. How long exposures would you recommend?



#10 TxStars

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Posted 26 July 2022 - 09:44 PM

For M8-M20 @ f/4.5 I would go 30 and a good long 60min one if your southern skies are good.


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#11 Achernar

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Posted 30 July 2022 - 12:27 PM

Thanks, TxStars! 

 

What do you mean getting washed out? Light pollution? I'm gonna shoot in a protected night sky area in Hungary where the quality is around Bortle 2-3 I guess. Only distant villages cause some light pollution on the horizon. I've seen that some folks here did 1 hr exposure on Ektar with really good result under dark skies.

And what about pushing the film, would you recommend it?

 

Sorry for the many questions but I'm getting excited since the weather forecast predicts clear skies smile.gif

If you have significant light pollution, you will find at F/3.5 ten or fifteen minutes will fog the film badly. For the same reason, don't bother when the moon is up and at or near full moon. So you'll want to find the darkest location you can to take your photos. Also, I am familiar with this camera, the lens will be subject to dewing so you'll want to put one of those hand warmers on the camera near it to keep it from dewing up.

 

Taras


Edited by Achernar, 30 July 2022 - 12:27 PM.

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