Is there a difference 6x6 ->6x9 cm?

[MattKing]

Early Riser is correct when he uses the word "might" - many people find it easier and get better results shooting 6x6 TLRs or rangefinders when using the camera handheld.

 

[Ko.Fe.]

6x6 has plenty of cameras to choose from and almost any enlarger will do.
6x9 is mostly folders with primitive lenses and Texas Leica. And it is specialty enlarger.
6x9 originally was for contact prints. So, lens doesn't need to be super.

 

[Thorpelyon]

Can’t add much to what’s already here... except to say the lens on my Fuji GW690 is STUNNING. I mean jaw-dropping STUNNING.

 

[Early Riser]

I never realized that a 6x6 Hasselblad was a lousy camera and that no photographer professional or amateur has ever been able to hold the camera stable. What load of horse manure did you dig up that little gem from???

Where did I say Hasselblads were a lousy camera? Why have you so overreacted to what I said?

I've used Hasselblads on and off for 40 years. I currently own and use very extensive systems of Hasselblad, Rolleiflex 6008i and AF, Mamiya 7II, Fujica GL690, Fuji GX680III, and Fotoman 612. I also owned a Fuji GX617II system. I currently own more than 70 lenses. As I need to make large prints, prints measured in feet not inches, I need to be able to get as much resolution out of a camera system as possible. Therefore I test my cameras and lenses very critically. Recent tests include Hassy 80mm planar v Rollei 80mm Schneider PQS v 80mm Rollei xenotar AF. Hassy zeiss 100mm w 1.4XE v Rollei 150mm Schneider v mamiya 150mm v Fujica 150mm. Hassy 180mm sonnar w 1.4 XE v 250mm Sonnar v rollei 300mm APO Schneider. I literally use a microscope to test resolution. These tests are comprised of shooting the same distance scene and test targets side by side.

What I have learned is that an MF SLR hand held creates sufficient vibration to lower the resolution versus a hand held TLR or Rangefinder and that if you want to optimize the resolution of a Hasselblad or a Rolleiflex 6008i you need to have them on a tripod and use mirror lock up.

 

[NedL]

There actually is a difference in negative sizes in different brands of 6x6 camera's. A Hasselblad will only produce negatives of 5,5 x 5,5cm, while a Rollei will illuminate a area of 5,8 x 5,8 cm. Other brands may vary too.

Same w/ 6x9. I've got three different negative carriers for my 3 different folders. Although lately I've been using a glass carrier that crops a bit around the edges of all of them. I love my old folders, but I suspect a high quality 6x6 or 6x7 non-folding camera might do better due to holding the lens more rigidly parallel to the film. BTW you can print 6x9 with a Beseler 23 just fine, so it's not all that specialized an enlarger!

 

[Slixtiesix]

It´s simple. If you put prints from a 6x6 and a 6x9 negative next to each other, the resolution would be the same (as long as lenses of the same quality had been used), but of course the 6x9 frame will show more from the scene (provided the same focal length had been used). If you use a wider lens with the 6x6 camera and crop the image so it would fit the 6x9 frame, the resolution would be lower, as you would practically end up with a 4x6 negative. However, you need to enlarge quite some bit to see the difference.

 

[bernard_L]

I never realized...horse manure...

No need to shout. Our ears are all right. And no need to get excited. Nobody intends to hurt your darling hassy.

 

[Dan Fromm]

Hmm. When I went up from 35 mm (never shot 6x4.6) I went straight to 2x3 (6x9 in metric, nominal 2x3 camera/roll holder gates range in size from 56 x 78 mm to 56 x 84 mm) for three reasons. In his lovely book Field Photography A. A. Blaker made the point that going up in format without at least doubling both dimensions of the gate isn't worth the trouble and expense. 24 x 36 doubled on both dimensions is 48 x 72, a little lower and a hair longer than nominal 6x6, but close enough. For me that was enough to rule out nominal 6x6 (56 x 56). I like 24x36's aspect ratio, 2x3's is the same. And 2x3 gives more cropping opportunities than smaller roll film formats.

As for going up from 645, one of my friends shot 645 before he went digital. I showed him some of my 2x3 Ektachromes. His response? They blew away his 645s. Remember, 645 is half frame 2x3. To be fair, 2x3 Ektachromes look pretty punk next to 4x5s.

About lenses. There were many relatively inexpensive crappy 2x3 cameras with inexpensive lenses, some quite good. There were few good fixed lens 2x3 cameras and fewer 2x3 system cameras. But there are 2x3 press, technical and view cameras. Quite a few very good lenses were made for them.

If you want to shoot 2x3 snapshots a fixed lens camera will do just fine. If you want interchangeable lenses with a rangefinder think Linhof or Horseman. If you're willing to focus on a ground glass, 2x3 Graphics will do very well. To learn more about what can be done with 2x3 Graphics, read http://www.galerie-photo.com/telechargement/dan-fromm-6x9-lenses-v2-2011-03-29.pdf

 

[trendland]

Good morning everyone, as it rains here in Chicago I'm wrestling with a question of medium format film sizing - namely, do people have an opinion about the appreciable difference in photo "crispness" and resolution going from 6x6 -> 6x7 or 6x9?

I currently have used a 6x45, and found it not quite the resolution I was hoping for, so went to a 6x6 TLR, which while quirky I enjoy (except the difficulty focusing on the ground glass in low light with a F3.5) - so I'm thinking of heading into a 6x7 SLR, like the RB, or a rangefinder like the Fuji GW690 (not similar cameras at all).

I know the size differences for sure, but am looking for input from the forum about what appreciable difference you've had experience with using 6x7, or if the difference is not worth the switch, and I should jump to 6x9.

Thanks in advance!

-Rick

More resolution than 4,5 x 6 has been the subject of many within the past.
If they changed to 6x6 they were confronted with a special 6x6 philosophy of some : Your decision on portrait or landscape is coming when the shot is done (comming later).
I personaly was no friend of such kind of workflow because : " 4,5 x 6 is the resulting format again "
So you might see a real advance in negative format and resolution with 6x7.
Art directors loved this format over many many years.
4 x 5 inch is near the double of 6 x 9 but it is a little expensive in comparison.
The disadvantige of 6 x 9 are the old lenses.
You might love the special (older) technology of that lenses comming from the 20th - 50th because of a nice characteristic.
But in concern of resolution they mostly are real "oldfashiones" (I have shot against the sun with 6x9 lenses (uncoated) there is no resolution of 6 x 9 remaining (caused from optical issues ).
It is more like pocket110.
At last the resolution can just as high as the sum of all parametern.
As there are f-stop, speed and type of films, quality of lenses, tripot, and wheather conditions (lighting,dust a.s.o.)
This all may concern the resolution more than the advantage of higher formats - so a Hasselbladt with modern lens on 6x6 (reduced to 4,5 x 6) can result much more resolution in comparison to 6x9 with open f 7,7 (lens - uncoated out of the year 1929).
But to answer your question :Best resolution with midt format is definitivly with format 6 x 8 (a real nice format) with Fuji GX680 and highest (and expensive ) quality lenses (all lenses of that systems from my point are like Hasselbladt Zeiss quality).
With low speed films and ( of course ) best tripot.
with regards

 

[flavio81]

Where did I say Hasselblads were a lousy camera? Why have you so overreacted to what I said?

I've used Hasselblads on and off for 40 years. I currently own and use very extensive systems of Hasselblad, Rolleiflex 6008i and AF, Mamiya 7II, Fujica GL690, Fuji GX680III, and Fotoman 612. I also owned a Fuji GX617II system. I currently own more than 70 lenses. As I need to make large prints, prints measured in feet not inches, I need to be able to get as much resolution out of a camera system as possible. Therefore I test my cameras and lenses very critically. Recent tests include Hassy 80mm planar v Rollei 80mm Schneider PQS v 80mm Rollei xenotar AF. Hassy zeiss 100mm w 1.4XE v Rollei 150mm Schneider v mamiya 150mm v Fujica 150mm. Hassy 180mm sonnar w 1.4 XE v 250mm Sonnar v rollei 300mm APO Schneider. I literally use a microscope to test resolution. These tests are comprised of shooting the same distance scene and test targets side by side.

What I have learned is that an MF SLR hand held creates sufficient vibration to lower the resolution versus a hand held TLR or Rangefinder and that if you want to optimize the resolution of a Hasselblad or a Rolleiflex 6008i you need to have them on a tripod and use mirror lock up.

Wow, great post.

The swedish thing, at least in the original 500C version, is infamous for a brute mirror slap. I would have expected the Rolleiflex 6008i to fare better!!

 

[Early Riser]

Wow, great post.

The swedish thing, at least in the original 500C version, is infamous for a brute mirror slap. I would have expected the Rolleiflex 6008i to fare better!!

The Rollei 6008i does have less mirror slap and shutter vibration than the blads, but compared to a TLR or a rangefinder like the Mamiya 7 you're still getting enough vibration around 1/2 to 1/30th to affect image quality. So even on a tripod MLU is required if you want to get the most from those optics. I will hand hold if necessary a Mamiya 7 or Rolleiflex TLR at shutter speeds I'd never consider if it were a blad or 6008i.

 

[Oldwino]

You all know that 6x6 is God’s format, right?

 

[Ian Grant]

I personaly was no friend of such kind of workflow because : " 4,5 x 6 is the resulting format again "
So you might see a real advance in negative format and resolution with 6x7.
Art directors loved this format over many many years.
4 x 5 inch is near the double of 6 x 9 but it is a little expensive in comparison.
The disadvantige of 6 x 9 are the old lenses.

Dan Fromm mentions comparing 645 Ektachromes to 6x9 but that's a visual comparison where the size helps, a comparison of prints would be less conclusive, obviously a slight improvement but less of a difference compared to 35mm to 645 or 6x6.

My experience knowing a few art directors who worked with friends is they were happy with 645, 6x6 or 6x7 where LF wasn't practical, Two friends were to advertising photographers and one shot 6x6 the other 6x7.

I don't no why the disadvantage of 6x9 is old lenses, there were plenty of good Multi-coated lenses from many manufacturers all very capable lenses, I'm talking about Rodenstock, Schneider, Nikon, Fuji etc, and even earlier coated lenses are excellent performers.

While I don't have a 6x9 camera with inter-changeable lenses I could very easily modify my home-made 6x7 camera to take one and I use lenses that I also use for 5x4 so image circle/coverage isn't an issue, nor is resolution/sharpness or contrast/ I used the camera with a very late US 203mm f7.7 Ektar in a Compur #1 18 months ago in Canada and the results on Delta 100 are excellent in terms of sharpness/resolution. Are they better than those made on my Mamiya 645 yes but these days I only use the Mamiya hand held (when working with models) the 6x7 camera was on a tripod. Compared to when I shot the 645 on a tripod with AP100/APX100 or Tmax 100 it#s much less of a difference.

I may well look for a Graflex 6x9 back and modify the camera, I do like the format and regardless what format I shoot I compose to it.

Ian

 

[Paul Howell]

I have a Mamyia Universal with 6X7 and 6X9 backs. As mentioned the 6X7 prints full to a 8X10, but I print a lot at 1X14 so I prefer 6X9.

 

[Early Riser]

As a side bar in case anyone is interested in what my lens testing has led me to regarding what I would carry in each focal length. I have not tested every lens there is, and while I already own a ridiculous amount of gear I narrowed it down to Mamiya 7II, Hasselblad 5xx and Rolleiflex 6608i, I consider those the best non panoramic MF systems for my needs. I shoot landscape and want as much detail and resolution as possible. I am not looking for a "look" I am looking for detail, I can fake a look after the exposure. I view negatives under a microscope, the minimum magnification I accept is 20x. While I would not carry all these lenses at the same time, if I had to fill a specific lens slot here are what I have concluded are the best choices among what are all really great lenses:

43mm Mamiya 7
50mm Mamiya 7
65mm Mamiya 7
80mm Mamiya 7, then 80mm rollei Schneider both PQS and AF, then 80mm Zeiss planar ( these two are close) the Mamiya 7 lens is clearly higher resolving.
90mm Schneider APO Makro for Rolleiflex
100mm 3.5 Zeiss Planar, the 100mm on the Fujica 690 camera is good for about 15x if you crop the sides to about a 6x7cm
150mm Mamiya 7 then 150mm Rollei Schneider, then 150mm sonnar, then 100mm 3.5 zeiss with 1.4XE TC (140mm) is surprisingly good
180mm Zeiss Sonnar
210mm Mamiya 7
250mm Zeiss superachromat, 250mm zeiss sonnar, 180mm zeiss sonnar with 1.4 XE is acceptable if not enlarging more than 12x
300mm Schneider APO for Rolleiflex

Simply put the Mamiya 7 lenses are amazing. They are brutally sharp, there's nothing else like them for MF. I assume not having to compromise with retrofocus combined with a vibrationless shutter is the reason. By this one might well assume that similar rangefinder MF cameras of similar time frame should also yield great results.

Hasselblad's best lens by far is the 100mm 3.5. It's super sharp edge to edge. Their next best lens is the 180mm sonnar. It is the fact that these lenses are so good that make them reasonable choices to use with the 1.4XE. With the TC they are almost equal to the 150mm zeiss and the 250mm zeiss (not the superachromat).

I also did extensive testing of lenses for the Fujica GL690. I tested the 65mm, two 100mm's, 150mm and the 180mm. These lenses test more like LF lenses, they tend to need f 16 in order to have enough sharpness towards the edges of the frame. They can be tack sharp in the center but the sharpness fall off towards the edges is noticeable. However if one sticks to no more than a 10x enlargement, which still results in a 30"+ print, they can yield very satisfying results, especially as the added film size means less apparent grain and smoother gradations.

 

[Bill Burk]

I've occasionally been surprised by how well prints from 6x9 compare with prints from 4x5. It's logical, since the film is only half the area. It's a lot easier to handle and develop rolls, so it's a good choice.

Of course I've been surprised how well an occasional 35mm negative compares to 4x5. (11x14 prints ... 4x5 on the left, 35mm on the right)...

 

[sixby45]

More resolution than 4,5 x 6 has been the subject of many within the past.
If they changed to 6x6 they were confronted with a special 6x6 philosophy of some : Your decision on portrait or landscape is coming when the shot is done (comming later).
I personaly was no friend of such kind of workflow because : " 4,5 x 6 is the resulting format again "
So you might see a real advance in negative format and resolution with 6x7.
Art directors loved this format over many many years.
4 x 5 inch is near the double of 6 x 9 but it is a little expensive in comparison.
The disadvantige of 6 x 9 are the old lenses.
You might love the special (older) technology of that lenses comming from the 20th - 50th because of a nice characteristic.
But in concern of resolution they mostly are real "oldfashiones" (I have shot against the sun with 6x9 lenses (uncoated) there is no resolution of 6 x 9 remaining (caused from optical issues ).
It is more like pocket110.
At last the resolution can just as high as the sum of all parametern.
As there are f-stop, speed and type of films, quality of lenses, tripot, and wheather conditions (lighting,dust a.s.o.)
This all may concern the resolution more than the advantage of higher formats - so a Hasselbladt with modern lens on 6x6 (reduced to 4,5 x 6) can result much more resolution in comparison to 6x9 with open f 7,7 (lens - uncoated out of the year 1929).
But to answer your question :Best resolution with midt format is definitivly with format 6 x 8 (a real nice format) with Fuji GX680 and highest (and expensive ) quality lenses (all lenses of that systems from my point are like Hasselbladt Zeiss quality).
With low speed films and ( of course ) best tripot.
with regards

Thank you for this well thought out and written response and a great thanks to everyone weighing in - much appreciated!

 

[mshchem]

One thing to consider. If you want to shoot color prints at a shop, many only print up to a 6x7 negative. This aside, I have, Fuji 6x9 rangefinders and love them. Bronica and Hasselblad 6x6, both are lovely, Bronica cameras and lenses are cheap, and the SQ-AI is quite sophisticated, auto exposure ,ttl flash etc. Hasselblad is a thing of beauty especially with the Acute-Matte screen. I also have a RZ67 II and a bunch of lenses , I walked around a lot with the waist level finder and a grip, wonderful camera, also quite available. The great medium format purge from professional photographers in the last 15 years has put a lot of incredible equipment on the market at bargain prices.

If you are printing your own negatives in the dark , bigger the negative the better.

My first real new pro medium format camera is a Bronica ETRSi, what a wonderful camera 645 is a great format.
Good hunting!

 

[guangong]

I have never had a problem holding Hasselblads, Rollei TLR, or Kodak Medalist, although for 150/200mm or more I prefer a tripod to hand held. My 300mm Olympic Sonnar plus camera weighs too much for hand held, even on a Nikon F, so tripod is a necessity with Hassy.
For folders, ZI Super Ikonta B is easy to hold steady. I don’t feel confident with folding Fuji 645 because of plasticy feel and holding camera on side for landscape. The folding Fuji GF 670 is a challenge because it lacks the heft of my Super Ikonta B but the whole point of a folder is readiness.
Shooting with a camera is no different than shooting with a gun...loose, relaxed and calm. Like a gun, a camera can’t be muscled.

 

[Alan Gales]

Good morning everyone, as it rains here in Chicago I'm wrestling with a question of medium format film sizing - namely, do people have an opinion about the appreciable difference in photo "crispness" and resolution going from 6x6 -> 6x7 or 6x9?

I currently have used a 6x45, and found it not quite the resolution I was hoping for, so went to a 6x6 TLR, which while quirky I enjoy (except the difficulty focusing on the ground glass in low light with a F3.5) - so I'm thinking of heading into a 6x7 SLR, like the RB, or a rangefinder like the Fuji GW690 (not similar cameras at all).

I know the size differences for sure, but am looking for input from the forum about what appreciable difference you've had experience with using 6x7, or if the difference is not worth the switch, and I should jump to 6x9.

Thanks in advance!

-Rick

Hello Rick. I see that you are a glamour and portrait photographer. If you decide on 6x7 then I'd recommend the RZ or RB because of the revolving backs. They are so quick and easy to use on a tripod. If you plan on using the camera handheld then I highly recommend buying a Mamiya "L" grip. Both of these cameras are heavy so the "L" grip makes the cameras so much easier to shoot hand held.

I've owned the RZ but not the RB. I prefer the RZ because when you advance the film you also cock the shutter so it's a little quicker when shooting people. On the RB you cock the shutter with a lever like the RZ but then you have to wind the film separately. The RZ is also a little lighter in weight. Of course the RZ is also battery dependent where the RB is not. Read up on both cameras before you buy one.

 

[sixby45]

Hello Rick. I see that you are a glamour and portrait photographer. If you decide on 6x7 then I'd recommend the RZ or RB because of the revolving backs. They are so quick and easy to use on a tripod. If you plan on using the camera handheld then I highly recommend buying a Mamiya "L" grip. Both of these cameras are heavy so the "L" grip makes the cameras so much easier to shoot hand held.

I've owned the RZ but not the RB. I prefer the RZ because when you advance the film you also cock the shutter so it's a little quicker when shooting people. On the RB you cock the shutter with a lever like the RZ but then you have to wind the film separately. The RZ is also a little lighter in weight. Of course the RZ is also battery dependent where the RB is not. Read up on both cameras before you buy one.

Thank you for this great perspective - much appreciated! I'm leaning towards a RB - die to cost per lens and equipment factor as well.

 

[Poisson Du Jour]

Resolution and clarity are inherent strengths of the medium format base measurements such as 6x 'xxxx'. I settled on 6x7 and happily and easily crop to 6x6 from this as circumstances occasionally present.

The 6x7 format has for a very long time been referred to as the ideal format, with 6x6 often described as perfect, particularly in the portrait/fashion genre.
Obviously the larger format allows a lot of flexibility while the smaller one does not and not everything will be appropriate for just one format.

 

[xtolsniffer]

Resolution and clarity are inherent strengths of the medium format base measurements such as 6x 'xxxx'. I settled on 6x7 and happily and easily crop to 6x6 from this as circumstances occasionally present.

The 6x7 format has for a very long time been referred to as the ideal format, with 6x6 often described as perfect, particularly in the portrait/fashion genre.
Obviously the larger format allows a lot of flexibility while the smaller one does not and not everything will be appropriate for just one format.

This is a very wise assessment. I can always crop 6x7 from my RB67 to 6x6 or crop 6x7 to 6x4.5 (or 4.5x7 if you want to think of it in landscape!) so it's a very good versatile format. Also enlargers for 6x7 are not too hard to find while going up to 6x9, they tend to get harder to find (though there are some good ones). The RB67 is a wonderful camera with a wonderful system and I think you'll find that with good technique you'll get great 16"x20" prints and above (I only print to 12"x16" due to my darkroom size and they are stunning). The downside to the RB is the weight. If you are using a tripod, it's a great camera, handheld I have trouble as the huge mirror makes quite a noise, and even though the lenses have leaf shutters, I never get as sharp an image with the RB as I do with my TLR. I would say that if your photography is planned, i.e. you go out to take photos or are in the studio, the RB is fabulous, if it's just a walk-around, a TLR will give you almost (i.e. probably indistinguishable resolution on a 12"x16" print) resolution. I have to say that if I'm in a public place, getting the RB out is more likely to cause a stir than the TLR!

 

[trendland]

Dan Fromm mentions comparing 645 Ektachromes to 6x9 but that's a visual comparison where the size helps, a comparison of prints would be less conclusive, obviously a slight improvement but less of a difference compared to 35mm to 645 or 6x6.

My experience knowing a few art directors who worked with friends is they were happy with 645, 6x6 or 6x7 where LF wasn't practical, Two friends were to advertising photographers and one shot 6x6 the other 6x7.

I don't no why the disadvantage of 6x9 is old lenses, there were plenty of good Multi-coated lenses from many manufacturers all very capable lenses, I'm talking about Rodenstock, Schneider, Nikon, Fuji etc, and even earlier coated lenses are excellent performers.

While I don't have a 6x9 camera with inter-changeable lenses I could very easily modify my home-made 6x7 camera to take one and I use lenses that I also use for 5x4 so image circle/coverage isn't an issue, nor is resolution/sharpness or contrast/ I used the camera with a very late US 203mm f7.7 Ektar in a Compur #1 18 months ago in Canada and the results on Delta 100 are excellent in terms of sharpness/resolution. Are they better than those made on my Mamiya 645 yes but these days I only use the Mamiya hand held (when working with models) the 6x7 camera was on a tripod. Compared to when I shot the 645 on a tripod with AP100/APX100 or Tmax 100 it#s much less of a difference.

I may well look for a Graflex 6x9 back and modify the camera, I do like the format and regardless what format I shoot I compose to it.

Ian

Thanks Ian - the issues you mentioned about the 6 x 9 format is nearly the same what I felt about.
6 x 9 is realy not bad (it is the best from my point).And there is of course the oportunity to shot 6 x 9 with sheed film and a mass of very good (and modern lenses).An other exeption ist the Fuji Gw/Gsw avaible in 6x7 And 6 x 9. The lenses of that cameras seams to be quite good but they are not to switch. The pre war folder cameras in 6 x 9 (for example bessa) beginning around the year 1934 had more and more better lenses (zeiss) - with advantage of 1) to the first time coating and 2) more speed f 3,5/f3,8 for example.The last issue seams to be more inportant from my point because you simple higher the optical performance by closing the lens to f5,6 / f 8. The hyperfocal distance to each lens allows also best performance with relative old systems. That isn't real possible in my example - I mentioned with much older lenses of folder cameras ( before 1930 ).There you find most systems with open lens at f8/f7,7/f6,3 and to higher the performance while closing the lens would mean here : To shot with f11/f22 wich isn't an advance in regard of resolution from the other side.(compensating the 6x9 format advantage with high speed films).So a Hasselbladt with cheap 70th zeiss lens croped to 4,5 x 6 will bring much more resolution than 6 x 9 then (Serious Glass like to hear this).The advantage is generally the case with enlargements min. 1m × 1,40 m AND 6x9 vs 4,5 x 6 (normal smal sized englargements don't need this discussion about max. possible resolution).Well Ian - the issue with Art Directors best baby 6x7 was different from the format of the magazines of each period.May be they loved also 6 x 9 within the 40th/50th perhaps some others had made experience.During the 70th and later 6 x 7 made a good deal in regard of the letterset. There 6 x 7 was the ideal format. (to most magazines of that time I would like to say).
6 x 7 is 6 x 6 in reality (with a smal additional space on one side) but if you don't need to crop 6 x 7 (the normal case) you still have nearly the double of negative space in regard of croped 6x6. (6 x 9 would be the real double)
But 6 x 8 would be my favorite - much sad to realize : there is just one camera outside the expensive FujiGX680 system : "THE motorized MAMIJA RB 67". (with 6 x 8 Magazine).
with regards

 

[narsuitus]

I use 6x6cm, 6x7cm, 6x9cm, and 4x5 inch.

To me, their difference in image quality is insignificant compared to their difference in ergonomics.

When compared to 35mm, their difference in image quality was so significant that I no longer shoot 35mm black & white.

My favorite for landscape is 6x9.

My personal favorite is 6x6 because I do not have to worry about portrait vs. landscape orientation while shooting.

Even though I have never used it, if I had to use only one medium format aspect ratio for the rest of my life, I would be 6x8.

My favorite for architecture is 4x5 because I can shift/tilt/swing the lens and/or back when needed.

I have never used 6x4.5cm. However, based on the Alaskan landscape images I have seen from a photographer who uses a pair of Pentax 645 cameras, I would not hesitate using 645.