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03-07-2019, 12:36 PM - 1 Like   #1
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Medium Format Lenses on Pentax ME

So, I have this Pentax ME. I also have a Mamiya 645 pro tl with a set of lenses. For a couple of bucks, I bought an adapter to mount the Mamiya lenses on the Pentax. Of course, everything is manual and the only shutter speed available is 100. I used my spotmeter, set at 1/125 to determine the lens aperture for a given exposure at 1/125 sec. With HP5+, this approach seemed to work pretty well. This gives me access to a 45, 55, 80, 150, and 210 mm lens on my Pentax ME.

A cheap way to extend my lens inventory. (Excuse the dust on some of the negatives, the static electricity is bad here, today.)

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03-07-2019, 12:55 PM - 1 Like   #2
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03-07-2019, 02:48 PM - 3 Likes   #3
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Whether using lenses intended for a larger format on a smaller one is always a murky topic. While many will point to the professional pedigree of medium format lenses (which were always intended for professional portraiture, etc.) and boast of their "amazing" sharpness, the fact is they seldom are as sharp as lenses intended for smaller formats.

The very best lenses intended for 35mm use (typically macro lenses) could resolve some 100 lines per millimeter. Not even the very finest best-of-the-best medium format lenses did that well - but of course they were intended to cover a bigger piece of film. Large format lenses (for 4x5 film etc.) typically didn't resolve as well as medium format optics, so they were even a worse idea for mounting onto 35mm cameras. But some did, and none of the results I've seen ever seemed worth the effort.

I've heard it argued that putting an MF lens onto a 35mm or DSLR body means you are only using the central area of the image circle, and therefore the sharpest part of the image. But still, the resolution of that image likely only matches the sharpness of a decent zoom lens - not a top grade prime.

Then you've just got the whole practicality of the thing. It may make sense to make use of a MF telephoto - maybe a 300mm or so, and get excellent results on a 35mm or DSLR. But MF normal lenses just turn into clunky portrait-range lenses with ho-hum apertures. And MF wide angles fall into the normal range on a 35mm format body and make no sense at all.
03-07-2019, 07:18 PM   #4
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QuoteOriginally posted by Ontarian50 Quote

The very best lenses intended for 35mm use (typically macro lenses) could resolve some 100 lines per millimeter.
Out of interest, do you know what the best sub-35mm format lenses resolved? For instance, the sharper lenses for the Pen F half frame system?

03-08-2019, 02:56 AM   #5
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QuoteOriginally posted by Ontarian50 Quote
Then you've just got the whole practicality of the thing. It may make sense to make use of a MF telephoto - maybe a 300mm or so, and get excellent results on a 35mm or DSLR
Agree with Ontarian50 completely here. Got the 645 adapter to K mount only to use with the A*300. Don't want to spend huge amounts on the highest quality 300 for 35mm or APSC but the 300 for 645, which I got at a great low price, gives a better result than cheap lenses and it's great for my purposes. The use of any of my other 645 lenses with the adapter would never make sense for the reasons already mentioned.
03-08-2019, 04:04 AM   #6
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Why all that categorical denial when it can be a great economical option?

I also had an existing 80mm 1.9 sekor c and adapted it on K-1. It puts all my other lenses to shame, even the Tamron 90mm SP, in terms of sharpness. I don't need to buy any new fancy 85mm 1.4 Superstar, I'm very happy with this.
03-08-2019, 06:08 AM   #7
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QuoteOriginally posted by Ontarian50 Quote
Whether using lenses intended for a larger format on a smaller one is always a murky topic. While many will point to the professional pedigree of medium format lenses (which were always intended for professional portraiture, etc.) and boast of their "amazing" sharpness, the fact is they seldom are as sharp as lenses intended for smaller formats.

The very best lenses intended for 35mm use (typically macro lenses) could resolve some 100 lines per millimeter. Not even the very finest best-of-the-best medium format lenses did that well - but of course they were intended to cover a bigger piece of film. Large format lenses (for 4x5 film etc.) typically didn't resolve as well as medium format optics, so they were even a worse idea for mounting onto 35mm cameras. But some did, and none of the results I've seen ever seemed worth the effort.

I've heard it argued that putting an MF lens onto a 35mm or DSLR body means you are only using the central area of the image circle, and therefore the sharpest part of the image. But still, the resolution of that image likely only matches the sharpness of a decent zoom lens - not a top grade prime.

Then you've just got the whole practicality of the thing. It may make sense to make use of a MF telephoto - maybe a 300mm or so, and get excellent results on a 35mm or DSLR. But MF normal lenses just turn into clunky portrait-range lenses with ho-hum apertures. And MF wide angles fall into the normal range on a 35mm format body and make no sense at all.
Ontarian50 raises several excellent points, and I agree with them. However, one point that was missed is that fact that I have these MF lenses - and I don't have the longer 35mm lenses. Most of my film work is medium format.(Mamiya 645 and 6X7). I see no reason to spend hundreds of dollars on 35 mm lenses that won't be used very often, so adapting the lenses I have makes sense.

I'm certainly not advocating the use of medium format lenses in place of 35mm lenses, I simply noted that the use of medium format lenses is possible and can provide acceptable results in many cases. The little Pentax ME is small enough that, even with a MF lens on it, it can be easily carried in a satchel of larger coat pocket. This makes taking it out for casual strolls more likely.

03-08-2019, 08:36 AM   #8
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QuoteOriginally posted by nickthetasmaniac Quote
Out of interest, do you know what the best sub-35mm format lenses resolved? For instance, the sharper lenses for the Pen F half frame system?
I don't recall seeing any lpm information on half frame lenses (which are actually not that far removed from our current APS-C lenses in coverage). I have seen crop-sensor specific lenses out perform their full-frame rivals (but only on the smaller format, of course) - for instance, the 35mm 1.8 DX Nikkor is smaller, lighter and cheaper than the full frame 35mm 1.8, but it is certainly the better bet on the smaller format.

However, I do remember Minox boasting their lenses for the tiny 8x11mm format spy cameras were designed to resolve 300 lpm. Also, the test reports that came with the instruction manuals for the Russian medium format lenses often showed resolutions reaching into the 40s in the centre, and the 30s at the edges, which seemed shockingly poor, but given the large amount of film they put their images on, the results could be lovely.
03-08-2019, 05:23 PM   #9
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QuoteOriginally posted by Jim70 Quote
So, I have this Pentax ME. I also have a Mamiya 645 pro tl with a set of lenses. For a couple of bucks, I bought an adapter to mount the Mamiya lenses on the Pentax. Of course, everything is manual and the only shutter speed available is 100. I used my spotmeter, set at 1/125 to determine the lens aperture for a given exposure at 1/125 sec. With HP5+, this approach seemed to work pretty well. This gives me access to a 45, 55, 80, 150, and 210 mm lens on my Pentax ME.
I'm curious about the adapter - which one are you using? The manual focus Mamiya 645 lenses have an A/M aperture switch (similar to the P6x7) to stop down the aperture for DoF etc, is there a reason why you can't focus wide open then stop the aperture down with the switch to use Av and the camera's metering?

Medium format lenses don't resolve the same IQ as the best 35mm format lenses, but there are no 'consumer' grade medium format lenses, apart from the odd exception, they're all good, very good or excellent. As stated you're only using the centre of the lens, on film I'm pretty sure they're capable of good or better results. The biggest drawbacks are the additional size/weight, larger filters and the lack of automation.

Last edited by johnha; 03-08-2019 at 05:32 PM.
03-09-2019, 10:03 AM   #10
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QuoteOriginally posted by johnha Quote
I'm curious about the adapter - which one are you using? The manual focus Mamiya 645 lenses have an A/M aperture switch (similar to the P6x7) to stop down the aperture for DoF etc, is there a reason why you can't focus wide open then stop the aperture down with the switch to use Av and the camera's metering?

Medium format lenses don't resolve the same IQ as the best 35mm format lenses, but there are no 'consumer' grade medium format lenses, apart from the odd exception, they're all good, very good or excellent. As stated you're only using the centre of the lens, on film I'm pretty sure they're capable of good or better results. The biggest drawbacks are the additional size/weight, larger filters and the lack of automation.
The adapter I use is from Photodiox. It has no electrical connections, so everything is manual. However, since the Pentax ME only has 1 manual speed (1/100) that makes the rig essentially aperture priority. I've been using my Sekonic Dual Spot F (Model 778) which is a bit of overkill - but again, it's the one I have. (One advantage is that I can shoot film at iso greater than 800 - a limitation on the ME.)

I set the iso on the Sekonic and fix the shutter speed at 1/125. On B&W film (see above) the difference in shutter speed doesn't seem to matter. I'm trying some Ektar 100 now and I'll let you know how that turns out.

The size/weight isn't too bad, with a 45, 55, or 80mm lens, it's pretty easy to carry around. I imagine it's similar to attaching a big lens to a micro 4/3 camera in terms of weight and size.

Again, this isn't the rig I'd recommend to anyone starting out but it allows me to have some fun with existing equipment, while using an old camera to good effect. So, if you have some decent MF lenses and want to expand your shooting repertoire, you might give this approach a whirl. All you will be out is the cost of the adapter (and maybe some film if you really muck it up.)
03-13-2019, 04:47 AM   #11
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Lens equivalent chart

For those of you considering the use of M\F lenses on your Pentax cameras, here's a chart showing rough equivalent focal length of MF Format lenses:
645 Lens 35mm Equivalent
45mm 28mm
55mm 34mm
60mm 37mm
55-110mm zoom 34-68mm
80mm (normal angle of view)* 50mm
80-160mm 50-100mm
100mm 62mm
120mm 75mm
150mm 93mm
200mm 124mm
210 mm 130 mm

(Sorry for the formatting - I couldn't figure out how to fix it.)

I found this info at" https://www.*******************/2016/02/06/understanding-medium-format-crop-factors/. The site also has similar tables for other MF lenses, RB67, Hassy, etc.

The reason I posted this is that it helped me realize that I already have a 28mm and a 135mm equivalent to add to my existing 50mm Pentax lens. By using a Photodiox adapter (~$40), I'm able to expand the use of my Pentax ME.

Downsides are that shutter speed is fixed at 1/100 and that the use of a hand held meter is required. Upsides are that I can shoot film that has ISO vales greater than 800. Since I have some rolls of Delta 3200 (which I rate at 1600), this is interesting. Looking forward to some street photography once the weather warms up.

Last edited by Jim70; 03-13-2019 at 04:59 AM. Reason: additional comments, formatting
03-13-2019, 08:01 AM   #12
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Keep in mind that if you put a 45mm 645 lens on a 35mm camera, it will be a 45mm lens. No crop factor or adjustment needed. The table you posted above is useful if you want to know an approximate field of view of a 45mm lens when used on a 645 camera.
03-13-2019, 10:12 AM   #13
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Agreed!

QuoteOriginally posted by abruzzi Quote
Keep in mind that if you put a 45mm 645 lens on a 35mm camera, it will be a 45mm lens. No crop factor or adjustment needed. The table you posted above is useful if you want to know an approximate field of view of a 45mm lens when used on a 645 camera.
Yep - that's exactly right. Nobody has yet developed an adapter that can change the focal length of a lens!
03-13-2019, 06:00 PM   #14
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QuoteOriginally posted by Jim70 Quote
Yep - that's exactly right. Nobody has yet developed an adapter that can change the focal length of a lens!
Umm, Pentax did with the 1.7x AF adapter...
04-03-2019, 01:22 PM   #15
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MF Lenses with Ektar 100 film

Here's a result with the 80mm MF lens (50m equivalent):
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