Re: Lenses for 645D?
Hi Jens, - Original Message - From: Jens Bladt [EMAIL PROTECTED] Sharper is also a COF issue, which means 35mm lens shots don't get enlarged as much as MF shots. I thought this was the other way around. With a larger format you can enlarge more without revealing the COF. A clever guy who has money to spend would start buying up Pentax 645 lenses in order to sell them at very good prices a year from now :-) This way one could make enought money to buy a Pentax 645D - for free, actually. LOL - Well, you may be right about that, if the prices of 645 lenses inflate the way as it has for K-mount lenses. Jostein
Re: Lenses for 645D?
- Original Message - From: Jens Bladt [EMAIL PROTECTED] 35mm lenses sharper than MF-lenses? No way. The DOF is greater due to the smaller format. That's all. The rest is a question of polishing glass. Of course the 35-mm lenses are smaller, thus smaller tolerences - in order to obtain a CORRESPONDING quality measuere. That doesn't make them sharper, though. Well, my experience is still that MF lenses from Pentax are less sharp than comparable 35mm K-mount lenses as long as we keep the basement consumer stuff out of the discussion (equivalents to these doesn't exist in MF). Pål
RE: Lenses for 645D?
Oh, this is about Pentax MF stuff - as opposed to Pentax 35mm. Why is that an issue? You want to use MF lenses for 35mm cameras or DSLR's? Pentax MF lenses (645) should be excellent if Pentax wants to be compeditive in the digital MF segment, ehre others are alrady miles ahead (Hasselblad, Rolleiflex, Mamiya, Fuji, Sinar and who else...). I guess Pentax MF lenses are quite good, although perhaps not the best there is. Regards Jens -Oprindelig meddelelse- Fra: Pål Jensen [mailto:[EMAIL PROTECTED] Sendt: 11. februar 2006 13:17 Til: pentax-discuss@pdml.net Emne: Re: Lenses for 645D? - Original Message - From: Jens Bladt [EMAIL PROTECTED] 35mm lenses sharper than MF-lenses? No way. The DOF is greater due to the smaller format. That's all. The rest is a question of polishing glass. Of course the 35-mm lenses are smaller, thus smaller tolerences - in order to obtain a CORRESPONDING quality measuere. That doesn't make them sharper, though. Well, my experience is still that MF lenses from Pentax are less sharp than comparable 35mm K-mount lenses as long as we keep the basement consumer stuff out of the discussion (equivalents to these doesn't exist in MF). Pål
RE: Lenses for 645D?
Jostein. I guess that's what I meant. COF is defined according to the wanted englargement. So, a plausible COF should not be the same for MF and 35mm. Or should it? Jens Bladt http://www.jensbladt.dk -Oprindelig meddelelse- Fra: Jostein [mailto:[EMAIL PROTECTED] Sendt: 11. februar 2006 11:12 Til: pentax-discuss@pdml.net Emne: Re: Lenses for 645D? Hi Jens, - Original Message - From: Jens Bladt [EMAIL PROTECTED] Sharper is also a COF issue, which means 35mm lens shots don't get enlarged as much as MF shots. I thought this was the other way around. With a larger format you can enlarge more without revealing the COF. A clever guy who has money to spend would start buying up Pentax 645 lenses in order to sell them at very good prices a year from now :-) This way one could make enought money to buy a Pentax 645D - for free, actually. LOL - Well, you may be right about that, if the prices of 645 lenses inflate the way as it has for K-mount lenses. Jostein
Re: Lenses for 645D?
- Original Message - From: Jens Bladt [EMAIL PROTECTED] Oh, this is about Pentax MF stuff - as opposed to Pentax 35mm. Why is that an issue? You want to use MF lenses for 35mm cameras or DSLR's? Pentax MF lenses (645) should be excellent if Pentax wants to be compeditive in the digital MF segment, ehre others are alrady miles ahead (Hasselblad, Rolleiflex, Mamiya, Fuji, Sinar and who else...). I guess Pentax MF lenses are quite good, although perhaps not the best there is. I personally don't think it matters for the same reasons as doesn't matter for MF film. Lens quality is more crucial the smaller the format as the final quality depends on an interaction of the resolution of the medium (film or sensor) + the resolution of the lens. Pål
Re: Lenses for 645D?
A 645 original is 2.5 times the size of a 35mm original. So I suppose that any COF that is less than 2.5 times as large in a 645 optic will make a print of a given size look sharper than a corresponding print made from a 35mm optic. But I'm on thin ice here...:-) I would suspect that other factors may influence the apparent sharpness as well, such as chromatic aberrations. I imagine that a 645 lens would have to be better CA corrected than a corresponding 35mm lens. Jostein - Original Message - From: Jens Bladt [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Saturday, February 11, 2006 2:26 PM Subject: RE: Lenses for 645D? Jostein. I guess that's what I meant. COF is defined according to the wanted englargement. So, a plausible COF should not be the same for MF and 35mm. Or should it? Jens Bladt http://www.jensbladt.dk
Re: Lenses for 645D?
On Feb 11, 2006, at 10:30 AM, Jostein wrote: A 645 original is 2.5 times the size of a 35mm original. So I suppose that any COF that is less than 2.5 times as large in a 645 optic will make a print of a given size look sharper than a corresponding print made from a 35mm optic. But I'm on thin ice here...:-) Kraakk! Watch out! The ice is breaking and the water is cold!! I would suspect that other factors may influence the apparent sharpness as well, such as chromatic aberrations. I imagine that a 645 lens would have to be better CA corrected than a corresponding 35mm lens. You have that backwards. More CA is tolerable in a MF lens, because the final image is enlarged less. It has been a matter of pride with designers of MF lenses in Germany to make them better than they needed to be. The Japanese wanted theirs to be as good, so they followed the example. Bob
Re: Lenses for 645D?
By reputation, the very best 35 mm. lenses are said to be sharper than corresponding medium format lenses because they have to be (i.e., to get good image quality in the smaller negative). For the reason given in the first paragraph, I don't know this personally. It is just something I have read. Check out the test results from Rob Studdert's comparison of a few top-notch 35mm Pentax lenses against similar-focal-length 645 lenses: http://home.swiftdsl.com.au/~distudio/mfv35lenstest/ The 35mm lenses look better, but not by all that much --Mark
Re: Lenses for 645D?
On Sat, Feb 11, 2006 at 01:16:44PM +0100, P?l Jensen wrote: - Original Message - From: Jens Bladt [EMAIL PROTECTED] 35mm lenses sharper than MF-lenses? No way. The DOF is greater due to the smaller format. That's all. The rest is a question of polishing glass. Of course the 35-mm lenses are smaller, thus smaller tolerences - in order to obtain a CORRESPONDING quality measuere. That doesn't make them sharper, though. Well, my experience is still that MF lenses from Pentax are less sharp than comparable 35mm K-mount lenses as long as we keep the basement consumer stuff out of the discussion (equivalents to these doesn't exist in MF). It rather depends on how you define measure comparable, though. If the measurement consists of taking two lenses with a comparable angle of view, one on a 35mm body, and one on a 645 body, and making the same sized print using each system, then I think most people here would expect the larger negative to produce the sharper print. If, though, we're taking two lenses of identical focal length, and cropping to just use the central 36x24 portion of the 645 negative, then most would expect the result of using the 645 lens would be not quite as good - the increase in image circle comes at some cost.
Re: Lenses for 645D?
- Original Message - From: Bob Shell [EMAIL PROTECTED] Kraakk! Watch out! The ice is breaking and the water is cold!! LOL I would suspect that other factors may influence the apparent sharpness as well, such as chromatic aberrations. I imagine that a 645 lens would have to be better CA corrected than a corresponding 35mm lens. You have that backwards. More CA is tolerable in a MF lens, because the final image is enlarged less. You're probably right that the lesser magnification is the most important here too. When I wrote the above, I was thinking that the longer register distance would accentuate CA... Speaking of which... How are the optics of 645 and K-mount related with regards to optical construction? If you have, say, a 300mm for 645; which would be its closest sibling in K-mount, constructionwise? I'd like to think that it's simply following the focal length to the number, but I suspect that AOV enough significance to make it more akin to a 200mm in 35mm. Jostein
Re: Lenses for 645D?
On 11 Feb 2006 at 11:48, Mark Erickson wrote: Check out the test results from Rob Studdert's comparison of a few top-notch 35mm Pentax lenses against similar-focal-length 645 lenses: http://home.swiftdsl.com.au/~distudio/mfv35lenstest/ The 35mm lenses look better, but not by all that much I haven't done any semi-scientific testing of my Mamiya 7 lenses as compared to my best 35mm gear but after staring at many chromes I'd guess that most would measure up a lot better than their Pentax equivalents in 35mm or MF so I don't think it's wise to generalize. However I don't think it matters too much in the context of the 645 lenses being suitable for use on an MF digital body either. The pixel pitch of the MF DSLR sensor will be somewhat larger than that of the current K-mount DSLRs (Sony ICX413AQ), ie 9m vs 7.8m (that is if they stick with the previously announced 18.6MP KAF-18000CE image sensor from Kodak). Assuming that they apply to this an anti-aliasing filter with similar (and desirable) cut-off frequency ratio as they have employed in the K-mount bodies this would translate to a maximum practical resolution of about 38.6lp/mm, I'm sure most of the 645 lenses can deliver better than that through out their aperture range . Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: Lenses for 645D?
On 2/12/06, Rob Studdert [EMAIL PROTECTED] wrote: The pixel pitch of the MF DSLR sensor will be somewhat larger than that of the current K-mount DSLRs (Sony ICX413AQ), ie 9m vs 7.8m (that is if they stick with the previously announced 18.6MP KAF-18000CE image sensor from Kodak). Assuming that they apply to this an anti-aliasing filter with similar (and desirable) cut-off frequency ratio as they have employed in the K-mount bodies this would translate to a maximum practical resolution of about 38.6lp/mm, I'm sure most of the 645 lenses can deliver better than that through out their aperture range 9-7.8m? No wonder my shots come out blurry :-) Dave
Re: Lenses for 645D?
On 12 Feb 2006 at 9:49, David Savage wrote: On 2/12/06, Rob Studdert [EMAIL PROTECTED] wrote: The pixel pitch of the MF DSLR sensor will be somewhat larger than that of the current K-mount DSLRs (Sony ICX413AQ), ie 9m vs 7.8m (that is if they stick with the previously announced 18.6MP KAF-18000CE image sensor from Kodak). Assuming that they apply to this an anti-aliasing filter with similar (and desirable) cut-off frequency ratio as they have employed in the K-mount bodies this would translate to a maximum practical resolution of about 38.6lp/mm, I'm sure most of the 645 lenses can deliver better than that through out their aperture range 9-7.8m? No wonder my shots come out blurry :-) Grr, mongrel mail system masticated my mu! Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: Lenses for 645D?
- Original Message - From: jtainter [EMAIL PROTECTED] But if MF lenses are less sharp than 35 mm. lenses, I wonder if existing MF lenses will be good enough for a digital sensor? As we know, some lenses that do well (or okay) in 35 mm. do not perform so well on APS-C. Will 645D buyers need new lenses? Yes, but you still have more real estate just like for film so you do not depend as much on lens quality. The smaller the format the larger the input of the lens in the final quality. Few Pentax 645 lenses are as good as the good K lenses. Pål
Re: Lenses for 645D?
On Feb 10, 2006, at 2:27 PM, jtainter wrote: But if MF lenses are less sharp than 35 mm. lenses, I wonder if existing MF lenses will be good enough for a digital sensor? As we know, some lenses that do well (or okay) in 35 mm. do not perform so well on APS-C. Will 645D buyers need new lenses? Probably not. We may need some wider wide-angle lenses depending on the crop factor. This whole thing about MF lenses being less sharp is largely mythical. Bob
Re: Lenses for 645D?
- Original Message - From: Bob Shell [EMAIL PROTECTED] This whole thing about MF lenses being less sharp is largely mythical. Nothing mythical about my lenses. I have the 645 - K adapter and compare the lenses with K mount lenses of similar focal lenght on a K mount body. Both the FA645 45/2.8 and standard lens 75/2.8, which Swdish test performed by Hasselblad claims are just as good as the Carl Zeiss 80mm for the Hasselblad, are about K mount consumer zoom quality. Lenses like the FA645 120/4 Macro is up along the best short K mount telephotos; indistinguishable from the A* 135/1.8 lens. Pål
Re: Lenses for 645D?
Not less sharp, but of lower resolution ... that's my understanding. Shel [Original Message] From: Bob Shell This whole thing about MF lenses being less sharp is largely mythical. On Feb 10, 2006, at 2:27 PM, jtainter wrote: But if MF lenses are less sharp than 35 mm. lenses, I wonder if existing MF lenses will be good enough for a digital sensor?
Re: Lenses for 645D?
On Feb 10, 2006, at 3:28 PM, Pål Jensen wrote: Nothing mythical about my lenses. I have the 645 - K adapter and compare the lenses with K mount lenses of similar focal lenght on a K mount body. Both the FA645 45/2.8 and standard lens 75/2.8, which Swdish test performed by Hasselblad claims are just as good as the Carl Zeiss 80mm for the Hasselblad, are about K mount consumer zoom quality. Lenses like the FA645 120/4 Macro is up along the best short K mount telephotos; indistinguishable from the A* 135/1.8 lens. Depends on the lens. The 80mm f/2.8 Planar, for example, that Rollei uses in their medium format TLR cameras is also offered in rangefinder coupled mount for Leica type cameras. It has been rated as the best lens in the 75 to 90mm focal length available in Leica mount. Medium format/35mm, same lens. Excellent for both. I used to use my 50, 80, 120, 180 and 300 mm Carl Zeiss Jena lenses on my 35mm cameras via Zörkendorfer adapters and got exceptional results. I have more recently used them on my EOS 10D and also gotten excellent results. I've used 50, 75 and 150 Mamiya lenses from my 645PRO system on 35mm, also via Zörkendorfer adapters, also with excellent results. I have not shot with Pentax 645 lenses, so maybe they aren't as good as CZJ or Mamiya. In the days when I used Pentax 67, I used some of the longer lenses on 35mm as well, and they were certainly up to the task. Bob
Re: Lenses for 645D?
On Feb 10, 2006, at 3:31 PM, Shel Belinkoff wrote: Not less sharp, but of lower resolution ... that's my understanding. Perhaps, but the resolution is high enough for digital, and for most film. Bob
Re: Lenses for 645D?
saying that MF lenses are less sharp than 35mm lenses is the same as saying that motorcycles are faster than cars. that is, too broad a generalization. best, mishka On 2/10/06, jtainter [EMAIL PROTECTED] wrote: But if MF lenses are less sharp than 35 mm. lenses, I wonder if existing MF lenses will be good enough for a digital sensor? As we know, some lenses that do well (or okay) in 35 mm. do not perform so well on APS-C. Will 645D buyers need new lenses? Any thoughts? Joe
Re: Lenses for 645D?
On 2006-02-10, at 20:27, jtainter wrote: By reputation, the very best 35 mm. lenses are said to be sharper than corresponding medium format lenses because they have to be (i.e., to get good image quality in the smaller negative). For the reason given in the first paragraph, I don't know this personally. It is just something I have read. But if MF lenses are less sharp than 35 mm. lenses, I wonder if existing MF lenses will be good enough for a digital sensor? As we know, some lenses that do well (or okay) in 35 mm. do not perform so well on APS-C. Will 645D buyers need new lenses? Jostein made some tests. FA645 35/3.5 is about as sharp as 31/1.8 Ltd. Most of lenses for 645 is of very high optical quality, just a few are weak - for instance FA 45/2.8, which is actually worse than FA 45-85/4.5 zoom... So I think majority of P645 lenses will work very good on big sensor. -- Best regards Sylwek
Re: Lenses for 645D?
That's right, I tested some 645 lenses on the *istD. The FA645-35/3.5 and the A645-45/2.8, to be exact. I have played around with my other 645 lenses as well, but not in a very systematic way. I'd really like to repeat the test with all the 645 lenses I have, and compare them to the K-mount lenses I have available in the same AOV. It may be a while before I get around to that, though. :-( Meanwhile, let me share with you a slightly different finding. I have been experimenting with different optical solutions for shooting snow crystals at around 4x life size. I've tried 4-5 different setups with K-mount lenses. Currently, I use a 645-A*300/4 with a reversed 645-FA75/2.8, a #2 extenstion tube, and K-mount adapter. This solution gives a very good optical quality. However it would probably be awkward on a 645-based camera because of vignetting. Jostein - Original Message - From: Sylwester Pietrzyk [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Friday, February 10, 2006 10:39 PM Subject: Re: Lenses for 645D? On 2006-02-10, at 20:27, jtainter wrote: By reputation, the very best 35 mm. lenses are said to be sharper than corresponding medium format lenses because they have to be (i.e., to get good image quality in the smaller negative). For the reason given in the first paragraph, I don't know this personally. It is just something I have read. But if MF lenses are less sharp than 35 mm. lenses, I wonder if existing MF lenses will be good enough for a digital sensor? As we know, some lenses that do well (or okay) in 35 mm. do not perform so well on APS-C. Will 645D buyers need new lenses? Jostein made some tests. FA645 35/3.5 is about as sharp as 31/1.8 Ltd. Most of lenses for 645 is of very high optical quality, just a few are weak - for instance FA 45/2.8, which is actually worse than FA 45-85/4.5 zoom... So I think majority of P645 lenses will work very good on big sensor. -- Best regards Sylwek
Re: Lenses for 645D?
Hi Joe, I'm quite optimistic about the Pentax 645 lenses regarding digital. I have very little evidence to substantiate my opinion, but some randomly obtained shots with the *istD suggests that they're not much worse than their K-mount counterparts with corresponding AOV. Of course, how they will perform with a larger area chip may be a different story all together, but as I said, I'm optimistic. Jostein - Original Message - From: jtainter [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Friday, February 10, 2006 8:27 PM Subject: Lenses for 645D? Here's something I am idly thinking about. I have not used medium format, except for a very old Rolleicord TLR that I bought used in 1967 and last used in 1991. By reputation, the very best 35 mm. lenses are said to be sharper than corresponding medium format lenses because they have to be (i.e., to get good image quality in the smaller negative). For the reason given in the first paragraph, I don't know this personally. It is just something I have read. But if MF lenses are less sharp than 35 mm. lenses, I wonder if existing MF lenses will be good enough for a digital sensor? As we know, some lenses that do well (or okay) in 35 mm. do not perform so well on APS-C. Will 645D buyers need new lenses? Any thoughts? Joe
RE: Lenses for 645D?
35mm lenses sharper than MF-lenses? No way. The DOF is greater due to the smaller format. That's all. The rest is a question of polishing glass. Of course the 35-mm lenses are smaller, thus smaller tolerences - in order to obtain a CORRESPONDING quality measuere. That doesn't make them sharper, though. Sharper is also a COF issue, which means 35mm lens shots don't get enlarged as much as MF shots. A clever guy who has money to spend would start buying up Pentax 645 lenses in order to sell them at very good prices a year from now :-) This way one could make enought money to buy a Pentax 645D - for free, actually. Jens Bladt http://www.jensbladt.dk -Oprindelig meddelelse- Fra: jtainter [mailto:[EMAIL PROTECTED] Sendt: 10. februar 2006 20:28 Til: pentax-discuss@pdml.net Emne: Lenses for 645D? Here's something I am idly thinking about. I have not used medium format, except for a very old Rolleicord TLR that I bought used in 1967 and last used in 1991. By reputation, the very best 35 mm. lenses are said to be sharper than corresponding medium format lenses because they have to be (i.e., to get good image quality in the smaller negative). For the reason given in the first paragraph, I don't know this personally. It is just something I have read. But if MF lenses are less sharp than 35 mm. lenses, I wonder if existing MF lenses will be good enough for a digital sensor? As we know, some lenses that do well (or okay) in 35 mm. do not perform so well on APS-C. Will 645D buyers need new lenses? Any thoughts? Joe
