Win a Pentax Limited Lens: Raffle Now Live!

**Rorschach** · 12-12-2007, 09:43 PM

Has anybody tries these with an adapter? It sometimes seems that used Pentax medium format lenses could be had cheaper than 35mm stuff. Is there something to be aware of before getting these? Will a 300mm still be 300mm on a K100D for example?

Best regards,
Boucicaut

clawhammer · 12-12-2007, 09:59 PM

I don't think the focal lengths will be the same. Also be aware that it will be full manual everything. You should get extremely good IQ because you definately would be shooting in the 'sweet spot' of the lens (right in the center of the image circle). If you can, try it out. I'd love to hear how it works.

figmental1978 · 12-12-2007, 10:35 PM

Yeah, it would be cool beacuse I always see 645 lenses for auction at yahoo japan at decent prices.

**Canada_Rockies** · 12-12-2007, 11:14 PM

Originally posted by clawhamemr

I don't think the focal lengths will be the same. Also be aware that it will be full manual everything. You should get extremely good IQ because you definately would be shooting in the 'sweet spot' of the lens (right in the center of the image circle). If you can, try it out. I'd love to hear how it works.

The focal lenth will be the same, it's 300mm. The adapter puts the lens in the correct position to focus to infinity. A caveat would be that medium format lenses do not necessarily resolve the same degree as a smaller image circle lens. It's not needed when the negative is 6 x 7 cm, the magnification ratio is so much less. Also the lens design is somewhat different - the elements have to cover an image circle nearly 5 x the diameter. That is a super challenge for the lens designer.

**Rorschach** · 12-12-2007, 11:30 PM

Originally posted by clawhamemr

I don't think the focal lengths will be the same. Also be aware that it will be full manual everything. You should get extremely good IQ because you definately would be shooting in the 'sweet spot' of the lens (right in the center of the image circle). If you can, try it out. I'd love to hear how it works.

Manual doesn't bother me that much. Manual focusing is fine by me and I use aperture priority a lot anyways, so all is good. What worries me though is will I get a similar angle of view as I would with a normal 35mm lens, i.e. will a 300mm 645/6X7 lens give me the same reach a 35mm format 300mm lens would? If this works, I may try to do it. Don't worry, I'll report back if I go through with it

Best regards,
Boucicaut

**Canada_Rockies** · 12-12-2007, 11:31 PM

Originally posted by Boucicaut

Manual doesn't bother me that much. Manual focusing is fine by me and I use aperture priority a lot anyways, so all is good. What worries me though is will I get a similar angle of view as I would with a normal 35mm lens, i.e. will a 300mm 645/6X7 lens give me the same reach a 35mm format 300mm lens would? If this works, I may try to do it. Don't worry, I'll report back if I go through with it

Best regards,
Boucicaut

The 300mm focal length will give you the same angle of view as a 300mm made for the 35mm format. It just doesn't use the whole image circle. You can be 200% guaranteed not to have any vignetting!

**Rorschach** · 12-12-2007, 11:32 PM

Originally posted by Canada_Rockies

The focal lenth will be the same, it's 300mm. The adapter puts the lens in the correct position to focus to infinity. A caveat would be that medium format lenses do not necessarily resolve the same degree as a smaller image circle lens. It's not needed when the negative is 6 x 7 cm, the magnification ratio is so much less. Also the lens design is somewhat different - the elements have to cover an image circle nearly 5 x the diameter. That is a super challenge for the lens designer.

Thanks. This is something to consider, especially regarding the upcoming K10D replacement with it's 14mp sensor. I would imagine that the resolving power would be enough for a K100D Super though.

Best regards,
Boucicaut

**Rorschach** · 12-12-2007, 11:33 PM

Originally posted by figmental1978

Yeah, it would be cool beacuse I always see 645 lenses for auction at yahoo japan at decent prices.

Do you have experience of buying from there?

Best regards,
Boucicaut

**Rorschach** · 12-17-2007, 03:23 AM

...because I ordered a vintage/retro 400mm f6.3 Komura (m42) so I won't need another long tele for a while (unless the Komura turns out to be a complete bust, of course).

Best regards,
Boucicaut

figmental1978 · 12-18-2007, 06:30 PM

Yeah, I've bought some stuff through Yahoo Auctions Japan and Rakuten. But I don't think they send internationally, domestic orders only.

12-12-2007, 09:43 PM	#1
Rorschach Site Supporter Join Date: Nov 2007 Location: Kuusamo, Finland Photos: Gallery Posts: 652	Pentax medium format lenses on a DSLR? Has anybody tries these with an adapter? It sometimes seems that used Pentax medium format lenses could be had cheaper than 35mm stuff. Is there something to be aware of before getting these? Will a 300mm still be 300mm on a K100D for example? Best regards, Boucicaut

12-17-2007, 03:23 AM	#9
Rorschach Site Supporter Join Date: Nov 2007 Location: Kuusamo, Finland Photos: Gallery Posts: 652 Original Poster	Medium format lens plans on hold for now... ...because I ordered a vintage/retro 400mm f6.3 Komura (m42) so I won't need another long tele for a while (unless the Komura turns out to be a complete bust, of course). Best regards, Boucicaut

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pros/Cons of using medium format lenses on Pentax DSLRs?	hangu	Pentax SLR Lens Discussion	49	04-15-2011 01:24 PM
PENTAX announces a medium format DSLR, the 40MP 645D	Ole	Homepage & Official Pentax News	18	03-17-2010 05:53 PM
Medium format lenses	Atindra	Pentax SLR Lens Discussion	3	08-12-2009 11:54 PM
Medium Format to DSLR?	Jewelltrail	Pentax DSLR Discussion	26	06-11-2008 11:17 PM

12-12-2007, 09:59 PM	#2
clawhammer Veteran Member Join Date: Sep 2007 Location: Logan, Utah Photos: Gallery Posts: 971	I don't think the focal lengths will be the same. Also be aware that it will be full manual everything. You should get extremely good IQ because you definately would be shooting in the 'sweet spot' of the lens (right in the center of the image circle). If you can, try it out. I'd love to hear how it works.

12-12-2007, 10:35 PM	#3
figmental1978 Veteran Member Join Date: Feb 2007 Location: Melbourne Posts: 789	Yeah, it would be cool beacuse I always see 645 lenses for auction at yahoo japan at decent prices.

12-12-2007, 11:14 PM	#4
Canada_Rockies Loyal Site Supporter Join Date: Nov 2007 Location: Sparwood, BC, Canada Photos: Gallery \| Albums Posts: 12,385	Originally posted by clawhamemr I don't think the focal lengths will be the same. Also be aware that it will be full manual everything. You should get extremely good IQ because you definately would be shooting in the 'sweet spot' of the lens (right in the center of the image circle). If you can, try it out. I'd love to hear how it works. The focal lenth will be the same, it's 300mm. The adapter puts the lens in the correct position to focus to infinity. A caveat would be that medium format lenses do not necessarily resolve the same degree as a smaller image circle lens. It's not needed when the negative is 6 x 7 cm, the magnification ratio is so much less. Also the lens design is somewhat different - the elements have to cover an image circle nearly 5 x the diameter. That is a super challenge for the lens designer.

12-12-2007, 11:30 PM	#5
Rorschach Site Supporter Join Date: Nov 2007 Location: Kuusamo, Finland Photos: Gallery Posts: 652 Original Poster	Originally posted by clawhamemr I don't think the focal lengths will be the same. Also be aware that it will be full manual everything. You should get extremely good IQ because you definately would be shooting in the 'sweet spot' of the lens (right in the center of the image circle). If you can, try it out. I'd love to hear how it works. Manual doesn't bother me that much. Manual focusing is fine by me and I use aperture priority a lot anyways, so all is good. What worries me though is will I get a similar angle of view as I would with a normal 35mm lens, i.e. will a 300mm 645/6X7 lens give me the same reach a 35mm format 300mm lens would? If this works, I may try to do it. Don't worry, I'll report back if I go through with it Best regards, Boucicaut

12-12-2007, 11:31 PM	#6
Canada_Rockies Loyal Site Supporter Join Date: Nov 2007 Location: Sparwood, BC, Canada Photos: Gallery \| Albums Posts: 12,385	Originally posted by Boucicaut Manual doesn't bother me that much. Manual focusing is fine by me and I use aperture priority a lot anyways, so all is good. What worries me though is will I get a similar angle of view as I would with a normal 35mm lens, i.e. will a 300mm 645/6X7 lens give me the same reach a 35mm format 300mm lens would? If this works, I may try to do it. Don't worry, I'll report back if I go through with it Best regards, Boucicaut The 300mm focal length will give you the same angle of view as a 300mm made for the 35mm format. It just doesn't use the whole image circle. You can be 200% guaranteed not to have any vignetting!

12-12-2007, 11:32 PM	#7
Rorschach Site Supporter Join Date: Nov 2007 Location: Kuusamo, Finland Photos: Gallery Posts: 652 Original Poster	Originally posted by Canada_Rockies The focal lenth will be the same, it's 300mm. The adapter puts the lens in the correct position to focus to infinity. A caveat would be that medium format lenses do not necessarily resolve the same degree as a smaller image circle lens. It's not needed when the negative is 6 x 7 cm, the magnification ratio is so much less. Also the lens design is somewhat different - the elements have to cover an image circle nearly 5 x the diameter. That is a super challenge for the lens designer. Thanks. This is something to consider, especially regarding the upcoming K10D replacement with it's 14mp sensor. I would imagine that the resolving power would be enough for a K100D Super though. Best regards, Boucicaut

12-12-2007, 11:33 PM	#8
Rorschach Site Supporter Join Date: Nov 2007 Location: Kuusamo, Finland Photos: Gallery Posts: 652 Original Poster	Originally posted by figmental1978 Yeah, it would be cool beacuse I always see 645 lenses for auction at yahoo japan at decent prices. Do you have experience of buying from there? Best regards, Boucicaut

12-18-2007, 06:30 PM	#10
figmental1978 Veteran Member Join Date: Feb 2007 Location: Melbourne Posts: 789	Yeah, I've bought some stuff through Yahoo Auctions Japan and Rakuten. But I don't think they send internationally, domestic orders only.

Pentax medium format lenses on a DSLR?

Win a Pentax Limited Lens: Raffle Now Live!