Jupiter 9 is a low cost alternative to the to much hyped helios 40
If you need a 85mm fast prime, there is not a wide choice of M42 lenses. The most famous is the Helios 40 (85mm f/1.5) But this lens is not a low cost item for your DSLR because it is to much hyped. Certainy because of it's vintage(and massive) look.
So the alternative is the Jupiter 9. This short telephoto (85mm) russian lens is opticaly based on the Carl Zeiss 85 Sonnar. This is a pre-war optical formula.
We can consider it as a fast prime lens because of it's wide aperture (f/2.0)
For portraiture wide opened you will get a very small dept of field (just on eye!)
Jupiter 9 was my second M42 lens after the Helios 44-2. I found the build quality awesome. Considering the compact size of this lens, it is heavy.
Jupiter 9 has a preset ring. The iris blade is oily on my copy (this is comon on M42 lenses)
If you plan to purchase this lens, be aware that it is available in M42 and M39 mount.
In terms of image quality, the Jupiter 9 is soft wide opened and it becomes sharp when stopped down to f/4. This softness wide opened is nice for portraiture maybe because it is well combined with the bokeh.
Clearly, the Jupiter 9 is excellent for portraiture. I have not noticed flare issues (my copy seems to be multicoated). The color rendition is good (very neutral) and the bokeh is very nice.
This lens is clearly less expensive than the Helios 40. But in this focal lenght there is not a wide choice of lenses, so the prices are higher than for 50mm or 135mm M42 lenses.
I do not consider the Jupiter 9 is a low cost lens (considering it is a manual focus lens). When I bought my Minolta AF 35-105 f/3.5-4.5 (beercan like) I stopped to use the Jupiter 9 because the image quality was roundly the same but the versatility was not the same. The J9 and the Minolta AF 35-105 were paid the same price. If I would have to keep only one of the twoo I would keep the Minolta zoom. Even if the Jupiter 9 can produce slightly better images in certain conditions. Difficult to describle why (the real life photo is not the same as studio test charts): better color neutrality, nicer bokeh and other points difficult to describle with usual words. Also it is faster than the zoom lens but deep of field is to narrow when used wide opened (f/2.0). I think that for this focal lenth, f/4.0 provide the right deep of field for portraiture at usual subject disances.
Jupiter 9 mounted on a Sony A700 : (with a Braun BVC 370 flash)
I tested this lens on APS-C DSLR : Konica Minolta D5D, SONY A300 and SONY A700
You should have a look to this match@85mm where the Jupiter 9 is compared to Minolta great lenses.
Hereafter, a few samples of pictures with the Jupiter 9
Jupiter 9 samples pics with Konica Minolta D5D (6Mpix)
Jupiter 9 samples pics with Konica Minolta D5D (6Mpix) (nice lens for portraiture)
Jupiter 9 sample pics with Sony A300 (aperture wide opened : f/2.0)
Jupiter 9 sample pics with Sony A700 (aperture wide opened : f/2.0)