Re: Orion Starblast vs 500mm mirror
- Original Message - From: "Darren Addy" I still say you will not enjoy the experience of trying astrophotography on a DSLR at f/8 though. Looking through a viewfinder at f/8, I'd agree. I'd even agree for f/4.5 with my eyes. :-( Using LiveView with its zoom function is the real enabler for me. I don't think an f/8 is going to be a problem with LiveView, but I'm all ears to people with actual experience. :-) Jostein -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Orion Starblast vs 500mm mirror
On 1/8/2013 9:20 AM, Darren Addy wrote: On Mon, Jan 7, 2013 at 3:03 PM, luiz felipe wrote: Tried the Orion Nebula with the 135/2.5 - too clear skies, lots of clouds, bad results - and purple fringing. I got to thinking that maybe you are referring to the Bayonet 135/2.5. If so, the purple fringing is certainly understandable. I'm talking about the last version of the Super-Multi-Coated Takumar 135mm f2.5, which also then became the original SMC K version (not the same as the later "Bayonet" version). The Bayonet version is a $50-60 lens. The v2 Takumar & SMC K version are more like $175-225 but bargains can be found. At $175-225 the SMC [K] 135mm lens is a bargain. If it were an A lens it would live on a camera as opposed to being used occasionally. -- Buy a Leica to get the full “Leica Experience”, (a quick reduction of funds in the bank account). -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Orion Starblast vs 500mm mirror
Jostein's words: Hi Luiz, My experience so far does not cover your alternatives, but I dare a comment anyway. I would suggest you find a manual focus mirror tele lens to try out first since it's the cheapest option and since it probably is easier to sell again if it proves to be the wrong choice. I've done a couple of astrophotos with the K-5 and the O-GPS-1, and can vouch for its convenience. But then again I'm a noob at astrophoto... :-) Jostein Glad you mention it, Jostein... been wondering about wich 500mm tele would you use in this scenario. The "selling a failure" idea is very interesting indeed - the fact some lens didn't work for me does not mean it won't be useful somewhere else. Come to think of it, the 500 mirror is probably easier to arrive safely and cheaper to ship... hmmm... I think I saw some 500mm f/6- somewhere. lf -- luiz felipe luiz.felipe at luizfelipe.fot.br -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Orion Starblast vs 500mm mirror
Darren's words: Tried the Orion Nebula with the 135/2.5 - too clear skies, lots of clouds, bad results - and purple fringing. I got to thinking that maybe you are referring to the Bayonet 135/2.5. If so, the purple fringing is certainly understandable. I'm talking about the last version of the Super-Multi-Coated Takumar 135mm f2.5, which also then became the original SMC K version (not the same as the later "Bayonet" version). The Bayonet version is a $50-60 lens. The v2 Takumar & SMC K version are more like $175-225 but bargains can be found. Darren, I'm talking exactly about the SMC Tak 135/2.5, m42 & 58mm filters. Mine gets purple fringes wide open, not so intense but noticeable. It's also rather battered, much used since 1976. Bought a K Takumar 135/ 2.5 but still got to test it - someday soon, not in a hurry... it's expected to be less than outstanding but useable. I'd delay my astro enablements if a VG K135/ 2.5 came my way... really like that lens and mine is getting old. I'm trying to repeat photo and processing, and re-processing the first test - did it quickly and didn't enjoy the results. lf -- luiz felipe luiz.felipe at luizfelipe.fot.br -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Orion Starblast vs 500mm mirror
Hi Luiz, My experience so far does not cover your alternatives, but I dare a comment anyway. I would suggest you find a manual focus mirror tele lens to try out first since it's the cheapest option and since it probably is easier to sell again if it proves to be the wrong choice. I've done a couple of astrophotos with the K-5 and the O-GPS-1, and can vouch for its convenience. But then again I'm a noob at astrophoto... :-) Jostein - Original Message - From: "luiz felipe" To: Sent: Monday, January 07, 2013 2:57 PM Subject: Orion Starblast vs 500mm mirror ok, I'm twice bitten. for the second time in my lifetime, I'm willing to enter astrophoto with more than casual approach. issue, the very same as 30yrs ago - still have less cash to use than a proper gear requires, problem added by the higher prices of BR stores. trying to fill gaps in my photo bag and start a more serious star trek, I'm considering both a 500mm mirror lens and a Starblast 4.5 by Orion. using the 500mm to shoot stars is far easier than using a reflector telescope to catch a sunset, mainly due to image orientation - something the Starblast would require an accesory to do, probably losing the image quality its simple construction offers. theory... I'd not try to handhold either, anyway. do you PDML'ers have any experience with 500mm mirror teles and astropix? would someone by chance have used both some 500mm mirror and a smaller telescope, and care to comment? optics is a small part of the star problem - I'm currently trying to start a home-made tracker, suitable I hope for my current lenses and the 500mm. so I'm avoiding more expensive glass as not sure of being able to track well enough to make the difference. well, even smaller steps count. tia, lf -- luiz felipe luiz.felipe at luizfelipe.fot.br -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Orion Starblast vs 500mm mirror
Darren's words: I know that f/8 is not unusual for a visual scope. (my 8" dob is f5.9) But f/8 is still f/8 photographically (exposure-wise). We've also switched subjects (more than a little) slightly when we are talking about using the telescope as the lens to the camera. That's called prime focus photography and it means that the projected image will need to reach the DSLR sensor (with no lens attached). I'm not wild about leaving my DSLR sensor exposed to the elements for any longer than necessary, but that's what you are doing when you use it on a reflecting telescope (as opposed to a catadioptric which is sealed like an over-sized mirror lens). You also need to have a way to really lock down that telescope focuser because it would be great (not) if the focusing tube with camera body attached worked its way right out of the focuser. And you are still back to the issue I originally raised as to How Good/Accurate the tracking unit is on the telescope you are mounting it on. Because now you are effectively using the focal length of the telescope the same as you would a lens. On my 8" dob that is 1200mm. Every step better be smooth or you are going to have a vibration. You also need to be perfectly polar-aligned or you will have issues with longer exposures. In short, prime focus photography is not done cheaply or easily. You should certainly "cut your teeth" on something easier and work your way up as you learn the various pieces of the puzzle. Well put. Some of those points I'm thinking about since december. the support question - since the Starblast comes without rings I've been thinking about a craddle, and imagined a support for the camera, something able to take the weight out of the adapter and yet allowing focusing. Not quite there yet, but some ideas are going to paper tonight. Never gave the open air condition a tought until now - but there is no way to avoid it, other than using a Barlow - not in my plans, really... as for the tracking unit... as soon as I finish it, we'll know. Will be an Isosceles mount, progressive tracking errors not relevant since I intend to keep exposures under 5 minutes and start from a closed unit. Do not plan to hand-turn it... and am very worried about motor and train vibration. FTR, the Starblaster is listes as 450mm, f/4 - not so long, not so dark - if only it turns out good... lf -- luiz felipe luiz.felipe at luizfelipe.fot.br -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Orion Starblast vs 500mm mirror
Steve's words: For an astronomical telescope, f8 is not that slow. Schmidt-Cassegrains - the most popular off the shelf optical system - are usually f10 (though focal reducers are available). I think what's more important is the optical quality of the lens. A lot of those inexpensive mirror lenses are not very good. As for astrophotography with the O-GPS1...I've gotta get one! -- Steve Sharpe Steve, those reflectors have been quoted as "useable" and "entry-level" by some. Orion's Starblaster gets cheaper as it comes without tube rings and we provide the mount - fine with me. Didn't browse other brands but that model in particular is not too long (optically) nor too dark and better some "useable" tool at hand than a proper in the store. So much for theory... and of course I'd add the O-GPS1 too as soon as possible! :-) -- luiz felipe luiz.felipe at luizfelipe.fot.br -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Orion Starblast vs 500mm mirror
On Mon, Jan 7, 2013 at 2:49 PM, Steve Sharpe wrote: > At 9:22 PM +0200 1/7/13, Boris Liberman wrote: >> >> On 1/7/2013 9:07 PM, Darren Addy wrote: >>> >>> Honestly, I think the best option is the Pentax O-GPS1 if you shoot >>> Pentax models that are compatible. What can be done with them is >>> amazing. Like any photography, wide field is easier to do than >>> telephoto (which gets increasingly more difficult with focal length). >>> But check out what this guy did with a K-5, an O-GPS1 and a 200mm f2.8 >>> lens: http://poirierstephane.free.fr/photos/index.php?/category/132 >>> AMAZING. I recently purchased an O-GPS1 to go with my K-5 and intend >>> to start with my Super-Multi-Coated Takumar 135mm f2.5 v2 along with >>> some more wide field stuff... just as soon as I get the fires in my >>> life put out. >>> : \ >> >> >> I should support year suggestion, Darren. It simply makes the most sense. >> However I wonder if 500mm lens is something that software on the camera and >> in the GPS module could work with. Mostly likely they will, but it needs to >> be double checked. > > > For an astronomical telescope, f8 is not that slow. Schmidt-Cassegrains - > the most popular off the shelf optical system - are usually f10 (though > focal reducers are available). I think what's more important is the optical > quality of the lens. A lot of those inexpensive mirror lenses are not very > good. > > As for astrophotography with the O-GPS1...I've gotta get one! > > -- > > Steve Sharpe > d...@eastlink.ca > • > > http://earth.delith.com/photo_gallery.html I know that f/8 is not unusual for a visual scope. (my 8" dob is f5.9) But f/8 is still f/8 photographically (exposure-wise). We've also switched subjects (more than a little) slightly when we are talking about using the telescope as the lens to the camera. That's called prime focus photography and it means that the projected image will need to reach the DSLR sensor (with no lens attached). I'm not wild about leaving my DSLR sensor exposed to the elements for any longer than necessary, but that's what you are doing when you use it on a reflecting telescope (as opposed to a catadioptric which is sealed like an over-sized mirror lens). You also need to have a way to really lock down that telescope focuser because it would be great (not) if the focusing tube with camera body attached worked its way right out of the focuser. And you are still back to the issue I originally raised as to How Good/Accurate the tracking unit is on the telescope you are mounting it on. Because now you are effectively using the focal length of the telescope the same as you would a lens. On my 8" dob that is 1200mm. Every step better be smooth or you are going to have a vibration. You also need to be perfectly polar-aligned or you will have issues with longer exposures. In short, prime focus photography is not done cheaply or easily. You should certainly "cut your teeth" on something easier and work your way up as you learn the various pieces of the puzzle. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Orion Starblast vs 500mm mirror
At 9:22 PM +0200 1/7/13, Boris Liberman wrote: On 1/7/2013 9:07 PM, Darren Addy wrote: Honestly, I think the best option is the Pentax O-GPS1 if you shoot Pentax models that are compatible. What can be done with them is amazing. Like any photography, wide field is easier to do than telephoto (which gets increasingly more difficult with focal length). But check out what this guy did with a K-5, an O-GPS1 and a 200mm f2.8 lens: http://poirierstephane.free.fr/photos/index.php?/category/132 AMAZING. I recently purchased an O-GPS1 to go with my K-5 and intend to start with my Super-Multi-Coated Takumar 135mm f2.5 v2 along with some more wide field stuff... just as soon as I get the fires in my life put out. : \ I should support year suggestion, Darren. It simply makes the most sense. However I wonder if 500mm lens is something that software on the camera and in the GPS module could work with. Mostly likely they will, but it needs to be double checked. For an astronomical telescope, f8 is not that slow. Schmidt-Cassegrains - the most popular off the shelf optical system - are usually f10 (though focal reducers are available). I think what's more important is the optical quality of the lens. A lot of those inexpensive mirror lenses are not very good. As for astrophotography with the O-GPS1...I've gotta get one! -- Steve Sharpe d...@eastlink.ca http://earth.delith.com/photo_gallery.html -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Orion Starblast vs 500mm mirror
On Mon, Jan 7, 2013 at 1:22 PM, Boris Liberman wrote: > On 1/7/2013 9:07 PM, Darren Addy wrote: >> >> Honestly, I think the best option is the Pentax O-GPS1 if you shoot >> Pentax models that are compatible. What can be done with them is >> amazing. Like any photography, wide field is easier to do than >> telephoto (which gets increasingly more difficult with focal length). >> But check out what this guy did with a K-5, an O-GPS1 and a 200mm f2.8 >> lens: http://poirierstephane.free.fr/photos/index.php?/category/132 >> AMAZING. I recently purchased an O-GPS1 to go with my K-5 and intend >> to start with my Super-Multi-Coated Takumar 135mm f2.5 v2 along with >> some more wide field stuff... just as soon as I get the fires in my >> life put out. >> : \ > > > I should support year suggestion, Darren. It simply makes the most sense. > However I wonder if 500mm lens is something that software on the camera and > in the GPS module could work with. Mostly likely they will, but it needs to > be double checked. It *can* do it, but with distended objects (like nebula, galaxies & clusters) the most important thing is getting photons to the sensor. You can only do that in two ways... faster optics or longer shutter speeds. When you increase the focal length you are decreasing the amount of time that the O-GPS1 can move the sensor to keep up (meaning your maximum shutter speed open time is reduced). In addition to reducing your "shutter speed" you are also losing 3/4 of the light with an f8 mirror lens over using a more common f4 200mm or 300mm. Put another way, you would need to stack 4 exposures taken with the 500mm f8 to equal the photons on the sensor with an f4 lens (8 if comparing to an f2.8 lens). -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Orion Starblast vs 500mm mirror
On Jan 7, 2013, at 11:22 AM, Boris Liberman wrote: > On 1/7/2013 9:07 PM, Darren Addy wrote: >> Honestly, I think the best option is the Pentax O-GPS1 if you shoot >> Pentax models that are compatible. What can be done with them is >> amazing. Like any photography, wide field is easier to do than >> telephoto (which gets increasingly more difficult with focal length). >> But check out what this guy did with a K-5, an O-GPS1 and a 200mm f2.8 >> lens: http://poirierstephane.free.fr/photos/index.php?/category/132 >> AMAZING. I recently purchased an O-GPS1 to go with my K-5 and intend >> to start with my Super-Multi-Coated Takumar 135mm f2.5 v2 along with >> some more wide field stuff... just as soon as I get the fires in my >> life put out. >> : \ > > I should support year suggestion, Darren. It simply makes the most sense. > However I wonder if 500mm lens is something that software on the camera and > in the GPS module could work with. Mostly likely they will, but it needs to > be double checked. Yes, it will work with any focal length that shake reduction will support. On the K-5 that goes up to 800mm. My friend Akkana used to do a bit of astrophotography and has some interesting, if a bit outdated, info on her website: http://shallowsky.com/ > -- Larry Colen l...@red4est.com sent from i4est -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Orion Starblast vs 500mm mirror
On 1/7/2013 9:07 PM, Darren Addy wrote: Honestly, I think the best option is the Pentax O-GPS1 if you shoot Pentax models that are compatible. What can be done with them is amazing. Like any photography, wide field is easier to do than telephoto (which gets increasingly more difficult with focal length). But check out what this guy did with a K-5, an O-GPS1 and a 200mm f2.8 lens: http://poirierstephane.free.fr/photos/index.php?/category/132 AMAZING. I recently purchased an O-GPS1 to go with my K-5 and intend to start with my Super-Multi-Coated Takumar 135mm f2.5 v2 along with some more wide field stuff... just as soon as I get the fires in my life put out. : \ I should support year suggestion, Darren. It simply makes the most sense. However I wonder if 500mm lens is something that software on the camera and in the GPS module could work with. Mostly likely they will, but it needs to be double checked. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
