where to find 105mm g-componon or rodagon-g lens?

[chris77]

hello all.
after doing some research i find that for big (up to wall size) enlargements these are the lenses to look for.
but i cannot seem to find them.
any advice?
thanks.

 

[ic-racer]

Try the 'poor-man's Rodagon-G." This is simply using a lens with more coverage. For example, if you are enlarging 6x9cm negatives, use a 135 or 150mm lens. So, even with very big magnification, a 6x9cm negative projection uses only the center of the image circle. In many cases this provides a projected image of excellent quality.

 

[chris77]

Try the 'poor-man's Rodagon-G." This is simply using a lens with more coverage. For example, if you are enlarging 6x9cm negatives, use a 135 or 150mm lens. So, even with very big magnification, a 6x9cm negative projection uses only the center of the image circle. In many cases this provides a projected image of excellent quality.

hello
yes, thanks for the good advice.
i must have misunderstood some posting on the way to find out about rodagon-g.
for the price these rare lenses are sold they are anyway out of reach atm!

i am shooting 6x7 and use a durst m800 to project vertically.
the enlarger came with the unicon 105 condenser.
i am not sure what range of focal lengths i could use with it. i guess somewhat between 80 and 150?

chris

 

[RobC]

You should know that most enlarging lenses are optimised for around 8X to 10X enlargement. They will go upto maybe 15X before quality really falls off.

Wall size enlargments are likely to be "soft" unless you have the absolute finest quality neg which is really fine detailed and sharp. They might look OK from half a mile away though.

 

[chris77]

You should know that most enlarging lenses are optimised for around 8X to 10X enlargement. They will go upto maybe 15X before quality really falls off.

Wall size enlargments are likely to be "soft" unless you have the absolute finest quality neg which is really fine detailed and sharp. They might look OK from half a mile away though.

sure. i am well aware of the degradation. at the same time, big prints are hardly looked at from 20 cm anyway.
and secondly, yes, i do produce very detailed negatives with high acutance.

most important for me is that the "degradation" is equal throughout the image.
when i stop my rodenstock trinar (came with the m800) down to f11, even f16 the image is still pretty soft in the corners, while the center sharpness is acceptable (although it seems that diffraction is already kicking in)
i am talking about 100x130 cm in this case..

 

[Patrick Robert James]

The Rodogon-G and the Schneider equivalent are going to cost you a fortune if you can even find one. You would probably be better off getting an APO lens from either company.

Leica used to optimize their enlarging lenses to your specific needs if you sent them in. I doubt they would still do that, but it may be worth your while to check.

 

[ic-racer]

hello
yes, thanks for the good advice.
i must have misunderstood some posting on the way to find out about rodagon-g.
for the price these rare lenses are sold they are anyway out of reach atm!

i am shooting 6x7 and use a durst m800 to project vertically.
the enlarger came with the unicon 105 condenser.
i am not sure what range of focal lengths i could use with it. i guess somewhat between 80 and 150?

chris

With the unicon 105 your maginifcation range with that enlarger and a 105 lens is 7.5x to 1.3x, so not 'mural size'. Lenses compatible with your setup are from 28mm to 105mm if you get the other condensers.

 

[chris77]

With the unicon 105 your maginifcation range with that enlarger and a 105 lens is 7.5x to 1.3x, so not 'mural size'. Lenses compatible with your setup are from 28mm to 105mm if you get the other condensers.

so, you are saying that with the m800 and 105 condenser + lens max. print from 6x7 neg is 45x50 cm? that doesnt sound right.
why would it be? if i go vertical? is the condenser causing the problem?

 

[ic-racer]

so, you are saying that with the m800 and 105 condenser + lens max. print from 6x7 neg is 45x50 cm? that doesnt sound right.
why would it be? if i go vertical? is the condenser causing the problem?

I'm just reading from the manufacturer's specifications, which are usually correct. Looking again at the manual, I do see they match the magnification to the baseboard size so that maximum I quoted might just apply to vertical enlargements. They do show the head projecting horizontal in the manual.

A few issues you may encounter projecting horizontal:
As you increase magnification, you need to focus the lens closer to the negative and therefore need a bigger image circle. I'm afraid using a 135mm lens as I mentioned above might not work, either due to limited bellows length or improper condenser match. The condenser focuses the light to the lens. As you change the lens position from where the condenser expects it to be you can move out of the condenser's focus and get dark edges or dark center. You won't have that problem of uneven illumination with the diffusion head, but the bellows may not focus the 135mm lens.

What would I recommend? Get a six-element 105mm lens, use the 105 condenser. Anticipate you might need some dodging or burning to even the light a little. Make sure the lens and negative are perfectly parallel (the wall is not as important). Find or make a glass carrier.

 

[chris77]

I'm just reading from the manufacturer's specifications, which are usually correct. Looking again at the manual, I do see they match the magnification to the baseboard size so that maximum I quoted might just apply to vertical enlargements. They do show the head projecting horizontal in the manual.

A few issues you may encounter projecting horizontal:
As you increase magnification, you need to focus the lens closer to the negative and therefore need a bigger image circle. I'm afraid using a 135mm lens as I mentioned above might not work, either due to limited bellows length or improper condenser match. The condenser focuses the light to the lens. As you change the lens position from where the condenser expects it to be you can move out of the condenser's focus and get dark edges or dark center. You won't have that problem of uneven illumination with the diffusion head, but the bellows may not focus the 135mm lens.

What would I recommend? Get a six-element 105mm lens, use the 105 condenser. Anticipate you might need some dodging or burning to even the light a little. Make sure the lens and negative are perfectly parallel (the wall is not as important). Find or make a glass carrier.

way to go.
i am going for a componon 105mm and when i have it i will do comparison with the 110mm mamiya taking lens.
will show the result here by the end of next month.
thanks
chris

 

[Muihlinn]

Wall size enlargments are likely to be "soft" unless you have the absolute finest quality neg which is really fine detailed and sharp. They might look OK from half a mile away though.

Mural printing usually need ( Require I should say ) proper masking to do not let the sharpness go away in the details.

 

[Muihlinn]

For this case you are looking for the shortest focal length which covers 6x7, as a tilted enlarger for wall projection with a larger than needed lens will increase all potential problems, like distance from negative to projection plane off room boundaries, no enough light to be able to focus, etc.

 

[chris77]

For this case you are looking for the shortest focal length which covers 6x7, as a tilted enlarger for wall projection with a larger than needed lens will increase all potential problems, like distance from negative to projection plane off room boundaries, no enough light to be able to focus, etc.

good point.
luckily the 110 taking lens that i have just mounted on the enlarger is fast (2,8) and i got a 150 watt bulb.
should work. if first tests dont succeed, i might build my own enlarger in the near future for horizontal work..