Mamiya 80mm f/1.9 for the night sky?

[alpenglow]

Greetings all,

 

I'm new to this forum, and I've very much enjoyed looking through your posts...

there is such a wealth of knowledge here.

 

I'm in the process of acquiring a new Mamiya 645 system that I intend to use for

both my landscape work, and astro-imaging (I specilize in aurora photography).

I was wondering about the fast 80mm f/1.9 lens and how it performs wide open.

My experience with fast 35mm lenses are that they show significant spherical

abberation and coma when shot wide open (especially noticable in the stars), and

I was wondering if anyone here has experience with this Mamiya lens...

especially in shooting the night sky.

 

Thanks in advance.

 

Mike K.

[mona_chrome]

Is this the AF or the older units? My experience is that the af lenses pretty much suck at any

aperture, especially with small detail and high resolution scans.

[ulrik]

Mike, the right tool for your application would be the Carl Zeiss Planar 3,5/100 mm lens, mounted to a purely mechanical camera with lock for the shutter release button like Hasselblad 500 CM. Extremely sharp, virtually no distortion, no problems with coma, excellent even wide open. Search the internet and the Carl Zeiss homepage for info on this unique lens. Maybe the lens could be adapted to a Mamiya but I doubt it would be cost effective. Prices are down. (I myself have a 500 C/M with 3,5/100 mm lens and A12 back FS for 750 Euros, if interested, contact me off list).

 

Ulrik

[alpenglow]

Thanks Mona...

I should have indicated that this is a manual focus lens and it's for a Mamiya 645 Pro TL body. I already have the 80mm f/2.8, but wondered of the f/1.9 would capture me a few more stars.

 

Thanks Ulrik for the suggestion...

That lens does sound wonderful, but I fear a bit out of my budget right now. I recently was given a Hasselblad SWA from 1954 in almost mint condition. I'm very curious to give this a try (I haven't yet). I understand that the lens is wonderful.

 

I also have other MF lenses for the Mamiya... the 35mm, 45mm and 55mm. But none are as fast as the 80 1.9. This winter will be my first experiment using them for night work. You can see some of the night imaging I've done with 35mm equipment on my website at www.aglowphoto.com

 

Thanks again,

Mike K.

 

Mike K.

[bueh]

The 80mm f/1.9 is a very nice lens, in fact, it's one of my favorites of the Mamiya 645 system. But it is not lightning-fast, and in my experience the effective aperture wide open is more like f/2.2 (it is definitively slower than f/2). For "normal" photography, I love the look this lens produces, but I have no clue how it performs for your kind of application. As it is not a super-fast "noctilux-type" lens, I guess optical abberation should not be too terribly obvious.

[jim_mcbride]

Mike: I own/use the Mamiya old-style c/n 80mm f1.9 lens. I agree that it is slower than

f1.9 but I have not computed an exact effective aperture and I estimate that Bueh's

calculation is a good number. The lens does not exhibit noticeable spherical aberration or

coma. The lens is sharp wide-open at infinity, but I have not used it for astrophotography.

I have a considerable variety of M645-compatible lenses and this one is one of my two

favorites, the other one being the Mamiya 80mm f4.0 macro.

[alpenglow]

Thanks Jim and Bueh for the input. Sounds like that lens has served you well. I will certainly consider getting one if and when I'm able to find a good deal.

 

Thanks all for taking the time to reply,

Cheers,

Mike K.

[ondebanks]

Mike,

 

I'm coming in late but I seem to be the only respondent who both actually owns an 80mm f1.9 and who actually uses it for astrophotography!

 

My sample (older C-type) does show coma and spherical abberation wide open. I would only use it at f1.9 for untracked, fixed camera shots where you are trying to "freeze" the stars' motion with a short exposure, and still capture a good bit of detail in terms of stars, aurorae, milky way, bright nebulae, comets and so on.

 

But in fact with a fast enough film (ISO 400+), I generally prefer the much sharper results I get with it at f2.8 - even in these same fixed-camera scenarios. At f2.8, the central 2/3 of the frame area cleans up very well: spherical aberration disappears and coma retreats towards the corners.

 

What this is showing is that the extra aperture I gain in going from 2.8 to 1.9 is merely adding spherical abberation blur and stronger coma aberrations. So although you are gaining light, it is not going to the right places on the image. Put another way, the ability to detect fainter stars does not seem to be increased when the additional light is basically defocussed.

 

With the luxury of an equatorial tracking mount, I use the lens at f4 where is in pin-sharp right into the corners. It is the only MF lens I have used, other than some telephotos, which can deliver that uniform excellence at such a fast f-stop as f4.

 

If you are not going to be using an equatorial tracking mount, one critical thing to think about is the availability of suitable fast film in MF rolls. Kodak Porta 800 is not bad for fixed camera shots. Fuji NPZ 800 should be avoided. Your best bet might be Fuji Provia 400x, which is excellent at ISO 400 and pushable as well.

 

Good luck!