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80mm f/15 performance

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#1 BillP

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Posted 28 December 2010 - 12:15 AM

If anyone owns or owned an 80mm f/15 Achromat would be interested in hearing your impressions of its use and performance. Considering getting one of the 80mm f/15 objectives from Sheldon.

#2 7331Peg

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Posted 28 December 2010 - 01:31 AM

I've got two of them - one is an old Mizar tube with the Carton f15 lens in it, and the other is a Sears model with the Towa lens. I use them mainly for double stars, which is where they really do well. They both provide sharp, crisp images. I compared them side by side once, and would give the Carton a slight edge, but at the time I had a 1 1/4" TV diagonal in it and a hybrid .965 to 1.25" diagonal in the Sears scope which I'm sure didn't come up to the level of the TV model. Since that time I've found a conversion unit at Agena which will allow a 1 1/4" diagonal in the Towa, but rain and clouds and more rain have prevented me from giving it a try.

They'll both show quite a bit of detail on Jupiter, and last year when Mars was at its closest, I could see quite a lot of detail on it as well - rather amazing for as small as the image was. Both scopes handle up to 150x rather well, but the seeing here rarely allows going much higher than that, so that's been the limit on them.

The question everyone asks of course is about color, and the answer is I really don't notice any. It's there, but you have to go searching for it. I've seen it on Jupiter on nights of poor seeing when it wasn't quite in focus, but otherwise, it just isn't noticeable. Can't comment on the moon because I haven't looked at it with either scope.

They're a great compromise between a 60mm and a 100mm refractor, and you can always stop one down to 60mm and have a 60mm f20! Haven't done that yet, but I intend to give it a try when the weatherman gets the weather straightened out around these parts.


The Sears is on the left in the attached photo, Mizar/Carton on the right. Not the best picture, but hey - it was dark! The moon was for effect - it was full so I didn't look at it.

John :refractor:

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#3 Wes James

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Posted 28 December 2010 - 06:06 AM

Bill-
I'm sure you've read about the Cartons... I have the 80mm that used to belong to Doug76, the only reason he got rid of it was because he had several other Carton objective scopes. I've got 3 myself (built the other two- a 60 and a 100mm), and there is a Carton group- I have NEVER heard a negative comment about one of Sheldon's Carton objectives. Being long f/l scopes (most of them- there are some short ones), false color is minimal at best, they have all star tested superbly, and give great views. Very enjoyable scopes to use. I use mine mainly for lunar viewing, and I highly recommend them.

#4 astroneil

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Posted 28 December 2010 - 09:12 AM

Not exactly what the doctor ordered but close enough;

http://www.cloudynig...hp?item_id=2428

Cheers,

Neil. :cool:

#5 Doug76

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Posted 28 December 2010 - 10:51 AM

Bill-
I'm sure you've read about the Cartons... I have the 80mm that used to belong to Doug76, the only reason he got rid of it was because he had several other Carton objective scopes.


Yep, that was my 80mm f/15. Loved the view, but when I got the 100mm f/13 Carton I figured the 80mm would be neglected.
I may have been a bit hasty in that assessment! Miss it still.

#6 mikey cee

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Posted 28 December 2010 - 11:46 AM

I've always felt that this Selsi 80mm x 1200mm was an APO in disguise.

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#7 mikey cee

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Posted 28 December 2010 - 11:53 AM

But there is no doubt with the Sans & Streiffe 76mm x 1200mm! :shocked:It is an APO in disguise for about 1/20th the cost! :thewave: :whee:Mike

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#8 astroneil

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Posted 28 December 2010 - 11:53 AM

Schweet Scope Mike!

Doug; you bear an uncanny resemblance to the late Ronald Reagan:lol:

Regards,

Neil. :)

#9 mikey cee

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Posted 28 December 2010 - 12:00 PM

Schweet Scope Mike!

Doug; you bear an uncanny resemblance to the late Ronald Reagan:lol:

Regards,

Neil. :)

Hey read the TOS! No politics or opinions displayed!:shameonyou:But I'll make an exception for this! :grin:Mike

#10 lightfever

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Posted 28 December 2010 - 12:08 PM

I just ordered one of the 80mm lenses and a 60mm from Sheldon this last weekend. Based on what I have read I have high hopes the quality will be good.

#11 Erik Bakker

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Posted 28 December 2010 - 01:17 PM

Hi Bill,

A well figured 80mm f/15 is a very fine lens, easily capable of splitting tight and unequal doubled. My first serious scope was a 1981 built 76mm f/12 achromat, which was also sold by A-P as a guide scope many years ago. It has insanely good spherical correction, though quite some chromatic abberation. Lowest power/widest field is in the 35x / 2 degrees area, so it can be used from say 35x to any power you want without barlow. That is a big plus in my book. All that said, it has been safely stored in it's trunk for almost 15 years now. Perhaps it is time to pull it out and set it up next to my 70mm f/8 fluorite to find out how the two compare. If i find the time to do so, I will report back what came out of that.

Clear skies,

Erik

#12 Trever

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Posted 28 December 2010 - 01:45 PM

Schweet Scope Mike!

Doug; you bear an uncanny resemblance to the late Ronald Reagan:lol:

Regards,

Neil. :)

Hey read the TOS! No politics or opinions displayed!:shameonyou:But I'll make an exception for this! :grin:Mike


Maybe he is a Ronald Reagan movie fan?

#13 astroneil

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Posted 28 December 2010 - 02:46 PM

Hi Bill,

A well figured 80mm f/15 is a very fine lens, easily capable of splitting tight and unequal doubled. My first serious scope was a 1981 built 76mm f/12 achromat, which was also sold by A-P as a guide scope many years ago. It has insanely good spherical correction, though quite some chromatic abberation. Lowest power/widest field is in the 35x / 2 degrees area, so it can be used from say 35x to any power you want without barlow. That is a big plus in my book. All that said, it has been safely stored in it's trunk for almost 15 years now. Perhaps it is time to pull it out and set it up next to my 70mm f/8 fluorite to find out how the two compare. If i find the time to do so, I will report back what came out of that.

Clear skies,

Erik


Hi Erik,

I for one would love to see that old scope. I recently acquired an 80mm F/11 achromat and it too was sold by A-P back in the day. It has excellent optics. Some CA but it is within the Sidgwick standard, so not bothersome to me in the least.

Best wishes,

Neil. :cool:

#14 sarastro

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Posted 28 December 2010 - 02:59 PM

I've got two of them - one is an old Mizar tube with the Carton f15 lens in it, and the other is a Sears model with the Towa lens. I use them mainly for double stars, which is where they really do well. They both provide sharp, crisp images. I compared them side by side once, and would give the Carton a slight edge, but at the time I had a 1 1/4" TV diagonal in it and a hybrid .965 to 1.25" diagonal in the Sears scope which I'm sure didn't come up to the level of the TV model. Since that time I've found a conversion unit at Agena which will allow a 1 1/4" diagonal in the Towa, but rain and clouds and more rain have prevented me from giving it a try.

John :refractor:


John,
I also have an 80mm Sears and would like to use a 1 1/4" diagonal. What conversion unit did you purchase from Agena?

Roger

#15 eric_zeiner

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Posted 28 December 2010 - 04:27 PM

I've got a 76/1200 Sears 6344 on the way that I cannot wait to try out. I was going to do a Carton 80/1200 but this one came at a wonderful price from a wonderful CN member. I will do a Carton later on in 2011.

#16 Doug76

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Posted 28 December 2010 - 05:15 PM

Doug; you bear an uncanny resemblance to the late Ronald Reagan:lol:

Regards,

Neil. :)


Now why would you say that? Has my icon changed? I tried to change it to RR, but I am still seeing the observatory icon.

#17 jrbarnett

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Posted 28 December 2010 - 05:22 PM

"Maybe he is a Ronald Reagan movie fan?"

Impossible. There are none. Now if the picture was of Bonzo... :grin:

- Jim

#18 Scott Beith

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Posted 28 December 2010 - 05:28 PM

Doug you need to refresh your cookies to see the new one.

EXCELLENT avatar sir! :bow: :waytogo:

#19 Doug76

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Posted 28 December 2010 - 05:30 PM

Not true Jim. He made a few goodies.
But that isn't why I'm a fan.

#20 jrbarnett

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Posted 28 December 2010 - 07:06 PM

Bill:

I'd think an 80mm f/15 would be just about ideal for someone wanting to try the "long focus" experience, but not willing to radically adjust their other gear to live with a 4" or longer long focus instrument. It's about the longest refractor OTA I'd consider reasonably easy to transport by car.

My 2.4" f/16.7 Cartons are waiting for first light, but 2.4" is kinda tiny honestly. 80mm is actually a fun double star scope, and just begins to resolve the edges of globulars, and also show wisps and ripples in the Orion Nebula.

Regards,

Jim

#21 eric_zeiner

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Posted 28 December 2010 - 07:13 PM

Bill:

I'd think an 80mm f/15 would be just about ideal for someone wanting to try the "long focus" experience, but not willing to radically adjust their other gear to live with a 4" or longer long focus instrument. It's about the longest refractor OTA I'd consider reasonably easy to transport by car.

My 2.4" f/16.7 Cartons are waiting for first light, but 2.4" is kinda tiny honestly. 80mm is actually a fun double star scope, and just begins to resolve the edges of globulars, and also show wisps and ripples in the Orion Nebula.

Regards,

Jim


Jim, don't underestimate your 60mm Cartons, they are as I have been saying all along amazing scopes!!!

#22 Nemrod

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Posted 28 December 2010 - 07:57 PM

Royal Astro Scope, no color here, 76mm X 1200mm. I also have a new Carton 80mm f15 project, just picked up an aluminum tube to match the Carton cell.

Posted Image

JR

#23 eric_zeiner

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Posted 28 December 2010 - 08:15 PM

That is a gorgeous scope and that is why I am so anxious to get me Sears 76/1200 :jump:

#24 Doug76

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Posted 28 December 2010 - 09:52 PM

Doug you need to refresh your cookies to see the new one.


Never had to before. How do I do that?

#25 eric_zeiner

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Posted 28 December 2010 - 10:24 PM

I can see Mr. Reagan so I am not sure where the problem is.






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