Orion 80mm Refracter : Need advice

[jammeymc]

Ok, so i had an idea as to how i would incorporate the following Orion 80mm short tube Refractor into my Ioptrion Skytracker set up. With the guide scope removed, this setup is roughly 5lbs. I have a couple things that i'm hoping you kind folks, who have used scopes, could clarify for me My prior experience has been ONLY camera/traditional lens combos

(Item link for reference : 80mm short tube refractor

1) When using refractors, is it the same as traditional camera lenses such that a MFT mounted will give you a 2X FOV?

2) When i use a F5 traditional lens on my sony A7S, I can literally do a live view of the sky due to the sensitivity of the camera. Is there any reason to think that this refractor view would be any different when mounted to the A7S?

3) Lastly, can anyone tell me how to mount a Canon EOS system to this Refractor (possibly provide a link to the right adapter)?

Thank you all very very much - i am taking a step into new waters here with this setup and appreciate and thank you all in advance for the help. I've already got a firm steady solution that will take this from dovetail to my Manfroto tripod.

 

[D L Fischer]

Ok, so i had an idea as to how i would incorporate the following Orion 80mm short tube Refractor into my Ioptrion Skytracker set up. With the guide scope removed, this setup is roughly 5lbs. I have a couple things that i'm hoping you kind folks, who have used scopes, could clarify for me My prior experience has been ONLY camera/traditional lens combos

(Item link for reference : 80mm short tube refractor

1) When using refractors, is it the same as traditional camera lenses such that a MFT mounted will give you a 2X FOV?

2) When i use a F5 traditional lens on my sony A7S, I can literally do a live view of the sky due to the sensitivity of the camera. Is there any reason to think that this refractor view would be any different when mounted to the A7S?

3) Lastly, can anyone tell me how to mount a Canon EOS system to this Refractor (possibly provide a link to the right adapter)?

Thank you all very very much - i am taking a step into new waters here with this setup and appreciate and thank you all in advance for the help. I've already got a firm steady solution that will take this from dovetail to my Manfroto tripod.

The use of a T-ring and spacer tube is usually effective.

An extension tube with 2 inch nose-piece interface on telescope side and male t-threads (42mm x 0.75mm) on camera side will also be required. The is often available at a kit with the T-ring which is designed with female T-threads on telescope side.

example:

Loading…

www.optcorp.com

Depending on the scope, one may need to correct for field curvature to get decent images without much distortion out to the edges of the sensor. If so, the instead of using the extension tube, use a Field Flattener in its place. It will have the same 2 inch noise-piece interface for the scope and same t-thread interface towards the camera. The T-ring will be a separate purchase.

Exactly which field flattener to use depends on the scope. Somebody else will have to answer regarding those specifics.

-- David F.

 

[JimH123]

Ok, so i had an idea as to how i would incorporate the following Orion 80mm short tube Refractor into my Ioptrion Skytracker set up. With the guide scope removed, this setup is roughly 5lbs. I have a couple things that i'm hoping you kind folks, who have used scopes, could clarify for me My prior experience has been ONLY camera/traditional lens combos

(Item link for reference : 80mm short tube refractor

1) When using refractors, is it the same as traditional camera lenses such that a MFT mounted will give you a 2X FOV?

2) When i use a F5 traditional lens on my sony A7S, I can literally do a live view of the sky due to the sensitivity of the camera. Is there any reason to think that this refractor view would be any different when mounted to the A7S?

3) Lastly, can anyone tell me how to mount a Canon EOS system to this Refractor (possibly provide a link to the right adapter)?

Thank you all very very much - i am taking a step into new waters here with this setup and appreciate and thank you all in advance for the help. I've already got a firm steady solution that will take this from dovetail to my Manfroto tripod.

The use of a T-ring and spacer tube is usually effective.

An extension tube with 2 inch nose-piece interface on telescope side and male t-threads (42mm x 0.75mm) on camera side will also be required. The is often available at a kit with the T-ring which is designed with female T-threads on telescope side.

example:

https://www.optcorp.com/catalogsearch/result/?q=canon+t-ring

Depending on the scope, one may need to correct for field curvature to get decent images without much distortion out to the edges of the sensor. If so, the instead of using the extension tube, use a Field Flattener in its place. It will have the same 2 inch noise-piece interface for the scope and same t-thread interface towards the camera. The T-ring will be a separate purchase.

Exactly which field flattener to use depends on the scope. Somebody else will have to answer regarding those specifics.

-- David F.

This is too big a scope for the iOptron SkyTracker.

In answer to another question you asked, yes, stars will look just like they would in using an equivalent camera lens at f5. If you were to compare this 400mm lens to a 400mm camera lens, they would be the same FOV with one qualifier. The Orion uses a 1.25" eyepiece holder, and you are very likely to see vignetting. And with the Sony A7S full frame camera, it will really vignette a lot.

Not sure what you mean with question #1. But if you use a camera with a 2x crop factor with camera lenses, you will have the same crop factor with this scope. And this scope does indeed have sufficient infocus range that you can focus to infinity with it. This is a problem that affects many spotting scopes, but not this scope.

 

[jammeymc]

Ok, so i had an idea as to how i would incorporate the following Orion 80mm short tube Refractor into my Ioptrion Skytracker set up. With the guide scope removed, this setup is roughly 5lbs. I have a couple things that i'm hoping you kind folks, who have used scopes, could clarify for me My prior experience has been ONLY camera/traditional lens combos

(Item link for reference : 80mm short tube refractor

1) When using refractors, is it the same as traditional camera lenses such that a MFT mounted will give you a 2X FOV?

2) When i use a F5 traditional lens on my sony A7S, I can literally do a live view of the sky due to the sensitivity of the camera. Is there any reason to think that this refractor view would be any different when mounted to the A7S?

3) Lastly, can anyone tell me how to mount a Canon EOS system to this Refractor (possibly provide a link to the right adapter)?

Thank you all very very much - i am taking a step into new waters here with this setup and appreciate and thank you all in advance for the help. I've already got a firm steady solution that will take this from dovetail to my Manfroto tripod.

The use of a T-ring and spacer tube is usually effective.

An extension tube with 2 inch nose-piece interface on telescope side and male t-threads (42mm x 0.75mm) on camera side will also be required. The is often available at a kit with the T-ring which is designed with female T-threads on telescope side.

example:

https://www.optcorp.com/catalogsearch/result/?q=canon+t-ring

Depending on the scope, one may need to correct for field curvature to get decent images without much distortion out to the edges of the sensor. If so, the instead of using the extension tube, use a Field Flattener in its place. It will have the same 2 inch noise-piece interface for the scope and same t-thread interface towards the camera. The T-ring will be a separate purchase.

Exactly which field flattener to use depends on the scope. Somebody else will have to answer regarding those specifics.

-- David F.

This is too big a scope for the iOptron SkyTracker.

In answer to another question you asked, yes, stars will look just like they would in using an equivalent camera lens at f5. If you were to compare this 400mm lens to a 400mm camera lens, they would be the same FOV with one qualifier. The Orion uses a 1.25" eyepiece holder, and you are very likely to see vignetting. And with the Sony A7S full frame camera, it will really vignette a lot.

Not sure what you mean with question #1. But if you use a camera with a 2x crop factor with camera lenses, you will have the same crop factor with this scope. And this scope does indeed have sufficient infocus range that you can focus to infinity with it. This is a problem that affects many spotting scopes, but not this scope.

Thanks David, i appreciate you taking the time to respond and providing this input. I here you, and you are correct, this is, according to the ratings of the skytracker, way too big. However, i've been pushing the boundaries way beyond the skytrackers ratings since i got the tracker with very good results. I tend to operate that way, it's a character flaw of mine

One thing that concerns me is the Vignette problem you outlined and thank you very much for pointing that out! Let me ask you - are there anything that can be done in order to prevent this with a full frame?

 

[swimswithtrout]

Ok, so i had an idea as to how i would incorporate the following Orion 80mm short tube Refractor into my Ioptrion Skytracker set up. With the guide scope removed, this setup is roughly 5lbs. I have a couple things that i'm hoping you kind folks, who have used scopes, could clarify for me My prior experience has been ONLY camera/traditional lens combos

(Item link for reference : 80mm short tube refractor

1) When using refractors, is it the same as traditional camera lenses such that a MFT mounted will give you a 2X FOV?

2) When i use a F5 traditional lens on my sony A7S, I can literally do a live view of the sky due to the sensitivity of the camera. Is there any reason to think that this refractor view would be any different when mounted to the A7S?

3) Lastly, can anyone tell me how to mount a Canon EOS system to this Refractor (possibly provide a link to the right adapter)?

Thank you all very very much - i am taking a step into new waters here with this setup and appreciate and thank you all in advance for the help. I've already got a firm steady solution that will take this from dovetail to my Manfroto tripod.

The use of a T-ring and spacer tube is usually effective.

An extension tube with 2 inch nose-piece interface on telescope side and male t-threads (42mm x 0.75mm) on camera side will also be required. The is often available at a kit with the T-ring which is designed with female T-threads on telescope side.

example:

https://www.optcorp.com/catalogsearch/result/?q=canon+t-ring

Depending on the scope, one may need to correct for field curvature to get decent images without much distortion out to the edges of the sensor. If so, the instead of using the extension tube, use a Field Flattener in its place. It will have the same 2 inch noise-piece interface for the scope and same t-thread interface towards the camera. The T-ring will be a separate purchase.

Exactly which field flattener to use depends on the scope. Somebody else will have to answer regarding those specifics.

-- David F.

This is too big a scope for the iOptron SkyTracker.

In answer to another question you asked, yes, stars will look just like they would in using an equivalent camera lens at f5. If you were to compare this 400mm lens to a 400mm camera lens, they would be the same FOV with one qualifier. The Orion uses a 1.25" eyepiece holder, and you are very likely to see vignetting. And with the Sony A7S full frame camera, it will really vignette a lot.

Not sure what you mean with question #1. But if you use a camera with a 2x crop factor with camera lenses, you will have the same crop factor with this scope. And this scope does indeed have sufficient infocus range that you can focus to infinity with it. This is a problem that affects many spotting scopes, but not this scope.

Thanks David, i appreciate you taking the time to respond and providing this input. I here you, and you are correct, this is, according to the ratings of the skytracker, way too big. However, i've been pushing the boundaries way beyond the skytrackers ratings since i got the tracker with very good results. I tend to operate that way, it's a character flaw of mine

One thing that concerns me is the Vignette problem you outlined and thank you very much for pointing that out! Let me ask you - are there anything that can be done in order to prevent this with a full frame?

No the ST80 will not work the same as a camera lens !!!!

The ST80 is an extremely cheap achromat, not an APO, and is not color corrected to use as a photographic lens. It is for visual use only, and even then, only if you can stand the color fringing around the Moon, planets, and any bright stars. It has extremely, EXTREMELY, severe CA and is not intended as an astrophotograghy OTA !


Might I add, I believe you are now officially "hooked" and need to start thinking about a real GEM mount.

 

[jammeymc]

Ok, so i had an idea as to how i would incorporate the following Orion 80mm short tube Refractor into my Ioptrion Skytracker set up. With the guide scope removed, this setup is roughly 5lbs. I have a couple things that i'm hoping you kind folks, who have used scopes, could clarify for me My prior experience has been ONLY camera/traditional lens combos

(Item link for reference : 80mm short tube refractor

1) When using refractors, is it the same as traditional camera lenses such that a MFT mounted will give you a 2X FOV?

2) When i use a F5 traditional lens on my sony A7S, I can literally do a live view of the sky due to the sensitivity of the camera. Is there any reason to think that this refractor view would be any different when mounted to the A7S?

3) Lastly, can anyone tell me how to mount a Canon EOS system to this Refractor (possibly provide a link to the right adapter)?

Thank you all very very much - i am taking a step into new waters here with this setup and appreciate and thank you all in advance for the help. I've already got a firm steady solution that will take this from dovetail to my Manfroto tripod.

The use of a T-ring and spacer tube is usually effective.

An extension tube with 2 inch nose-piece interface on telescope side and male t-threads (42mm x 0.75mm) on camera side will also be required. The is often available at a kit with the T-ring which is designed with female T-threads on telescope side.

example:

https://www.optcorp.com/catalogsearch/result/?q=canon+t-ring

Depending on the scope, one may need to correct for field curvature to get decent images without much distortion out to the edges of the sensor. If so, the instead of using the extension tube, use a Field Flattener in its place. It will have the same 2 inch noise-piece interface for the scope and same t-thread interface towards the camera. The T-ring will be a separate purchase.

Exactly which field flattener to use depends on the scope. Somebody else will have to answer regarding those specifics.

-- David F.

This is too big a scope for the iOptron SkyTracker.

In answer to another question you asked, yes, stars will look just like they would in using an equivalent camera lens at f5. If you were to compare this 400mm lens to a 400mm camera lens, they would be the same FOV with one qualifier. The Orion uses a 1.25" eyepiece holder, and you are very likely to see vignetting. And with the Sony A7S full frame camera, it will really vignette a lot.

Not sure what you mean with question #1. But if you use a camera with a 2x crop factor with camera lenses, you will have the same crop factor with this scope. And this scope does indeed have sufficient infocus range that you can focus to infinity with it. This is a problem that affects many spotting scopes, but not this scope.

Thanks David, i appreciate you taking the time to respond and providing this input. I here you, and you are correct, this is, according to the ratings of the skytracker, way too big. However, i've been pushing the boundaries way beyond the skytrackers ratings since i got the tracker with very good results. I tend to operate that way, it's a character flaw of mine

One thing that concerns me is the Vignette problem you outlined and thank you very much for pointing that out! Let me ask you - are there anything that can be done in order to prevent this with a full frame?

No the ST80 will not work the same as a camera lens !!!!

The ST80 is an extremely cheap achromat, not an APO, and is not color corrected to use as a photographic lens. It is for visual use only, and even then, only if you can stand the color fringing around the Moon, planets, and any bright stars. It has extremely, EXTREMELY, severe CA and is not intended as an astrophotograghy OTA!

As always, thank you swimwithtrout for your valuable insight.......do you have any lightweight APO recommendations at around 400mm that you could point too?

 

[rgibbons]

No the ST80 will not work the same as a camera lens !!!!

The ST80 is an extremely cheap achromat, ... not color corrected to use as a photographic lens.... It has extremely, EXTREMELY, severe CA and is not intended as an astrophotograghy OTA !

I have an ST80, and used it for astrophotography (once). While I agree it is not suitable for photography, it was not the color distortion that bothered me so much (I could correct much of this in Photoshop, it was tedious), rather it was the distorted star shapes, that turned stars in the corners into seagulls, that made me realize I wasted a night trying to use this for pictures.

The ST80 is a very nice scope, for other purposes. I use it for my auto guider, and as a bright finder scope on top of my big scopes.

For Photography, if you want the level of magnification and light gathering ability of the ST80, you will need to spend many times as much money.

Russ G.

 

[swimswithtrout]

No the ST80 will not work the same as a camera lens !!!!

The ST80 is an extremely cheap achromat, not an APO, and is not color corrected to use as a photographic lens. It is for visual use only, and even then, only if you can stand the color fringing around the Moon, planets, and any bright stars. It has extremely, EXTREMELY, severe CA and is not intended as an astrophotograghy OTA!

As always, thank you swimwithtrout for your valuable insight.......do you have any lightweight APO recommendations at around 400mm that you could point too?

Not for the iOptron. As I said, it's time to get a "real" mount instead of a new lens. ;-)

 

[JimH123]

One thing that concerns me is the Vignette problem you outlined and thank you very much for pointing that out! Let me ask you - are there anything that can be done in order to prevent this with a full frame?

No, there is nothing can be done with this scope to prevent vignetting with a full frame camera. The tube of the scope is too narrow.

I just looked through my picture collection to see where I put some test shots using a crop sensor camera with the Orion 80mm Refractor. I know I did it, but I can't find the pictures so maybe I didn't save them. Actually, the images turned out better than I would have guessed. I was shooting at some houses on a ridge at about 4 miles distance, and I did not get a lot of CA or a lot of corner distortion. But, to be honest, I tried the same shot using my Tamron 150-600mm lens, and the Tamron was better.

I intend to use the Orion as a guide scope, but haven't done it yet. Also, I don't seem to have clear nights very often this time of year either.

 

[skynoob]

Also consider the AT72ED. Its smaller, FL around 400mm range, ED glass and a 2in focuser. Might need a flattener for edge correction. I am considering this for my Star Adventurer.

Regards

 

[jammeymc]

Also consider the AT72ED. Its smaller, FL around 400mm range, ED glass and a 2in focuser. Might need a flattener for edge correction. I am considering this for my Star Adventurer.

Regards

Thank you Skynoob, great suggestion. After your suggestion, I quickly read about 5 reviews of the AT72ED and every one of them seems to be very good. At 5LBS, this is exactly what i'm looking for. Do you know what kind of adapters are required to mount a eos full frame camera too it?

 

[skynoob]

Also consider the AT72ED. Its smaller, FL around 400mm range, ED glass and a 2in focuser. Might need a flattener for edge correction. I am considering this for my Star Adventurer.

Regards

Thank you Skynoob, great suggestion. After your suggestion, I quickly read about 5 reviews of the AT72ED and every one of them seems to be very good. At 5LBS, this is exactly what i'm looking for. Do you know what kind of adapters are required to mount a eos full frame camera too it?

Hi,

I use both full frame and cropped. The one i found that work best for full frame is from here

Loading…

www.telescopeadapters.com

using their 2 inch "ultrawide" one piece adapter. It has minimal vignetting on my D610. It is a good quality one piece adapter. I call it one piece because the T-ring and adapter are one piece, unlike some.

I have used cheap T-rings+adapters before and it gave me some crazy vignetting and even internal reflection that caused circular halos on the pictures.

YOu also might or might not need a 2 inch extension tube in order to achieve proper focus.

I got mine from Orion, other brand may work as well.

But all these depends if you are planning to use a field flattener, and what type of flattener you will be using.

In my case, i use an 80mm scope with a "dedicated" field flattener" which accepts an M48 T ring (similar in size to the ultrawide adapter mentioned above), which is wider than the normal M42 T ring.

 

[D L Fischer]

Also consider the AT72ED. Its smaller, FL around 400mm range, ED glass and a 2in focuser. Might need a flattener for edge correction. I am considering this for my Star Adventurer.

Regards

Thank you Skynoob, great suggestion. After your suggestion, I quickly read about 5 reviews of the AT72ED and every one of them seems to be very good. At 5LBS, this is exactly what i'm looking for. Do you know what kind of adapters are required to mount a eos full frame camera too it?

If its OK with you, I'll go beyond the scope of your post to put the AT72 and similar scopes in perspective.

I've been using AT72ED for about a year and have been very satisfied by it. The setup for me is:

Mount = iOPTRON iEQ45-PRO - more than what is needed for such a small scope but will allow the scope be scaled up over time to perhaps 4.5 inch refractors or 8 inch reflectors and the focal length up to perhaps 1000 mm when my skills develop.

Scope = AT72ED

Field Flattener = ATFF from Astronomics. Works pretty well but there is some (a little) residual star distortion in the corners even after experimenting with spacing between the field flattener and the camera focal plane. At this point, I'm OK with it.

Cameras = Nikon D5300 (astro modified), SBIG STF-8300C (4/3 size sensor

Filters: IDAS LIGHT POLLUTION SUPPRESSION (LPS) FILTER - HU-LPS-D1-48

Compressors / expanders = Kenko 1.4X Tele-Expander, Nikon mount (sometimes)

Auto-Guider = Orion StarShoot Pro

Guide Scope = Orion 50mm f/3.2 guide scope

Capture Software = Back Yard Nikon, Nebulosity (for STF-8300C)

Guiding SW = PHD originally, now PHD 2.61

With D5300, I rely primarily on dithering for hot pixel removal but some darks are also shot and used.

With STF-8300C, dithering and dark library are used.

I can post a couple sample images to demonstrate system limitations for chromatic aberration and field curvature if you want.

-- David F.

 

[D L Fischer]

oops: Field Flattener = AT2FF

 

[skynoob]

Also consider the AT72ED. Its smaller, FL around 400mm range, ED glass and a 2in focuser. Might need a flattener for edge correction. I am considering this for my Star Adventurer.

Regards

Thank you Skynoob, great suggestion. After your suggestion, I quickly read about 5 reviews of the AT72ED and every one of them seems to be very good. At 5LBS, this is exactly what i'm looking for. Do you know what kind of adapters are required to mount a eos full frame camera too it?

If its OK with you, I'll go beyond the scope of your post to put the AT72 and similar scopes in perspective.

I've been using AT72ED for about a year and have been very satisfied by it. The setup for me is:

Mount = iOPTRON iEQ45-PRO - more than what is needed for such a small scope but will allow the scope be scaled up over time to perhaps 4.5 inch refractors or 8 inch reflectors and the focal length up to perhaps 1000 mm when my skills develop.

Scope = AT72ED

Field Flattener = ATFF from Astronomics. Works pretty well but there is some (a little) residual star distortion in the corners even after experimenting with spacing between the field flattener and the camera focal plane. At this point, I'm OK with it.

Cameras = Nikon D5300 (astro modified), SBIG STF-8300C (4/3 size sensor

Filters: IDAS LIGHT POLLUTION SUPPRESSION (LPS) FILTER - HU-LPS-D1-48

Compressors / expanders = Kenko 1.4X Tele-Expander, Nikon mount (sometimes)

Auto-Guider = Orion StarShoot Pro

Guide Scope = Orion 50mm f/3.2 guide scope

Capture Software = Back Yard Nikon, Nebulosity (for STF-8300C)

Guiding SW = PHD originally, now PHD 2.61

With D5300, I rely primarily on dithering for hot pixel removal but some darks are also shot and used.

With STF-8300C, dithering and dark library are used.

I can post a couple sample images to demonstrate system limitations for chromatic aberration and field curvature if you want.

-- David F.

Hi David,

Now that you mentioned IDAs can you tell me how's the color balance on your d5300? i have the same modded camera and ive been considering an IDAS filter. My other UHC-S is giving me a lot of blue color cast on my subs. I image in the suburbs.

Thanks!

 

[swimswithtrout]

Also consider the AT72ED. Its smaller, FL around 400mm range, ED glass and a 2in focuser. Might need a flattener for edge correction. I am considering this for my Star Adventurer.

Regards

Thank you Skynoob, great suggestion. After your suggestion, I quickly read about 5 reviews of the AT72ED and every one of them seems to be very good. At 5LBS, this is exactly what i'm looking for. Do you know what kind of adapters are required to mount a eos full frame camera too it?

Don't even try to mount it on the SkyTracker ! It can barely handle 3-4 lbs total @ 100mm.

The AT72ED is also NOT an APO either. It's just a cheap non Fluorite doublet like the Orion ST80. Don't get confused by by the ED label on the telescope, it's not even remotely light years close to the color correction in a camera lens and again is designed for visual use only. It's focuser is not even capable of carrying a full frame camera's , since it's not designed for AP as well.

In any event, did you give a thought that it's F6 !!!! You'll need 180-300 sec subs at bare min. to even crack 1/4 hisogram. The SkyTracker can't handle 60 sec subs reliably at 200mm.

If you REALLY want a "cheap" short focus APO, that can approach a good camera lens quality, the Stellarview 70mm along with it's dedicated field flattner ($295.00) is probably your best option. Next best would be to try and track down the suddenly discontinued Williams Optics Star71 that needs no flattner.

But none of these will work on the "little" SkyTracker. The SkyTracker is great for what it can do, unlimited exposures below 100mm fl, but it falls to pieces beyond that. I gave up even using it beyond 200mm fl long ago.

Give it up, you're hooked !

Get a decent GEM before you throw even more good money after bad.

 

[D L Fischer]

Here are some comparisons with and without filter. All images were shot with white balance = Direct Sunlight. If you use the dropbox link, you can get full RES TIFF, comapre histograms, and see EXIF data.

There are also some direct comparisons of ASTRO light subs and stacked / processed / finished images.

Loading…

www.dropbox.com

sky flat - no filter


sky flat - with Light Pollution Filter


nearby field without LPF

 

[jammeymc]

Also consider the AT72ED. Its smaller, FL around 400mm range, ED glass and a 2in focuser. Might need a flattener for edge correction. I am considering this for my Star Adventurer.

Regards

Thank you Skynoob, great suggestion. After your suggestion, I quickly read about 5 reviews of the AT72ED and every one of them seems to be very good. At 5LBS, this is exactly what i'm looking for. Do you know what kind of adapters are required to mount a eos full frame camera too it?

Don't even try to mount it on the SkyTracker ! It can barely handle 3-4 lbs total @ 100mm.

The AT72ED is also NOT an APO either. It's just a cheap non Fluorite doublet like the Orion ST80. Don't get confused by by the ED label on the telescope, it's not even remotely light years close to the color correction in a camera lens and again is designed for visual use only. It's focuser is not even capable of carrying a full frame camera's , since it's not designed for AP as well.

In any event, did you give a thought that it's F6 !!!! You'll need 180-300 sec subs at bare min. to even crack 1/4 hisogram. The SkyTracker can't handle 60 sec subs reliably at 200mm.

If you REALLY want a "cheap" short focus APO, that can approach a good camera lens quality, the Stellarview 70mm along with it's dedicated field flattner ($295.00) is probably your best option. Next best would be to try and track down the suddenly discontinued Williams Optics Star71 that needs no flattner.

But none of these will work on the "little" SkyTracker. The SkyTracker is great for what it can do, unlimited exposures below 100mm fl, but it falls to pieces beyond that. I gave up even using it beyond 200mm fl long ago.

Give it up, you're hooked !

Get a decent GEM you throw even more good money after bad.

Hooked, indeed. I hear you Swimwithtrout and i will indeed give up on the APO's & the AT72ED. However, I will challenge you on the 100mm and less threshold. I've been getting great results, tracking at 60sec +well over 600mm. Just as a few recent examples, one shot at 400mm and one at about 600mm:


600mm 60 Second Exposures 1HR


400mm 60 Second Exposures 1HR unmodded



The skytracker can handle up to 6lbs and i'm convinced it can handle longer focal lengths - i've changed courses hoever in my purchase and am considering buying an older Canon F4 400mmL lens to utilize on the skytracker.....

 

[skynoob]

Here are some comparisons with and without filter. All images were shot with white balance = Direct Sunlight. If you use the dropbox link, you can get full RES TIFF, comapre histograms, and see EXIF data.

There are also some direct comparisons of ASTRO light subs and stacked / processed / finished images.

https://www.dropbox.com/sh/rybiqxiks4oncbr/AADFjZNC1X3Ui3ZdVYLUDz-Ba?dl=0


sky flat - no filter


sky flat - with Light Pollution Filter


nearby field without LPF

Hey thanks for the samples. You are a big help. (Unlike some) =D

Will download them and see. My subs look similar in cast, i guess i just dont know what to expect. Another thing, is your mod full spectrum? Mine is just H alpha.

 

[swimswithtrout]

Also consider the AT72ED. Its smaller, FL around 400mm range, ED glass and a 2in focuser. Might need a flattener for edge correction. I am considering this for my Star Adventurer.

Regards

Thank you Skynoob, great suggestion. After your suggestion, I quickly read about 5 reviews of the AT72ED and every one of them seems to be very good. At 5LBS, this is exactly what i'm looking for. Do you know what kind of adapters are required to mount a eos full frame camera too it?

Don't even try to mount it on the SkyTracker ! It can barely handle 3-4 lbs total @ 100mm.

The AT72ED is also NOT an APO either. It's just a cheap non Fluorite doublet like the Orion ST80. Don't get confused by by the ED label on the telescope, it's not even remotely light years close to the color correction in a camera lens and again is designed for visual use only. It's focuser is not even capable of carrying a full frame camera's , since it's not designed for AP as well.

In any event, did you give a thought that it's F6 !!!! You'll need 180-300 sec subs at bare min. to even crack 1/4 hisogram. The SkyTracker can't handle 60 sec subs reliably at 200mm.

If you REALLY want a "cheap" short focus APO, that can approach a good camera lens quality, the Stellarview 70mm along with it's dedicated field flattner ($295.00) is probably your best option. Next best would be to try and track down the suddenly discontinued Williams Optics Star71 that needs no flattner.

But none of these will work on the "little" SkyTracker. The SkyTracker is great for what it can do, unlimited exposures below 100mm fl, but it falls to pieces beyond that. I gave up even using it beyond 200mm fl long ago.

Give it up, you're hooked !

Get a decent GEM you throw even more good money after bad.

Hooked, indeed. I hear you Swimwithtrout and i will indeed give up on the APO's & the AT72ED. However, I will challenge you on the 100mm and less threshold. I've been getting great results, tracking at 60sec +well over 600mm. Just as a few recent examples, one shot at 400mm and one at about 600mm:


600mm 60 Second Exposures 1HR


400mm 60 Second Exposures 1HR unmodded

The skytracker can handle up to 6lbs and i'm convinced it can handle longer focal lengths - i've changed courses hoever in my purchase and am considering buying an older Canon F4 400mmL lens to utilize on the skytracker.....

If that's all you're willing to settle for, go right ahead.