Hi all -

I am looking for a camera body to mount on an astro scope for high-focal-length photography. To that end, I need a body that has sensor IS and which will provide focus confirmation (beep or flashing AF point... preferably the latter) when used with manual focus lenses or with lenses mounted via adapters.

Any suggestions?

Thanks,
Vandit

Pentax K20D would be a good start. IS, seen great stuff with it and scopes. Killer camera. Love mine. Adorama has a deal for 699 with 18-55mm right now. Insane.

But then again, the Olympus E bodies have the IS and 2x crop which would extend your focal length even more.

Any Pentax with SR or Oly with IS.

The astro photo guys are super equipment geeks. Any of the astro forums will be able to give you highly detailed answers.

There are 2 dedicated forums for astrophotography on cloudynights:

Beginners:

http://www.cloudynights.com/ubbthreads/postlist.php/Cat/0/Board/low

DSLR:

http://www.cloudynights.com/ubbthreads/postlist.php/Cat/0/Board/DSLR

Even though I am mounting it on an astro scope, this is not for astro photography - it is for birds. As such, my requirements are a bit different from astro guys. My question was more of a camera feature question, which is why I posted here, instead of on CN. Still, thanks for the links anyway.

mawz - are you sure that the Oly cameras provide AF confirmation with manual focus bodies or when using lenses via adapters?

The in-body IS is easy to figure out, the AF confirmation with MF is a bit harder.

Thanks,
Vandit

vkalia wrote:
Even though I am mounting it on an astro scope, this is not for astro photography - it is for birds. As such, my requirements are a bit different from astro guys. My question was more of a camera feature question, which is why I posted here, instead of on CN. Still, thanks for the links anyway.


Do you intend to focus and shoot this scope Lord Nelson style? If not, and I strongly recommend not, then you're going to be tripod bound and should forget about IS. Focus confirmation is also hit-or-miss with typical slow yet long spotting scopes. What you want is a camera with live view, and a heavy tripod.

I don't know if you already have a scope, but any 60-90mm (aperture, not focal length!) scope, f/8 or faster, with a 2" focuser will do. A rotateable focuser is a big plus found on the better scopes, so you don't have to constantly loosen and retighten your T adaptor's drawtube to level your horizon. There is a fairly good correlation between price and performance, but semi-apo fpl-53 (fluoro-ed) based doublets seem to be the sweet spot on the entry level these days.

Seriously, save some money for a good tripod and a gimbal head. A carbon fibre survey tripod, or other dual tube based model will both make up for the lack of IS, and aid your manual focusing by damping out vibration.

Dutch Hill makes a suitable mount which takes standard photographic heads:

If you can find a Canon 20DA, they are supposed to be pretty neat! They have the Inferred filter removed and offer a primitive version of live view I believe.

maxima302 wrote:
If you can find a Canon 20DA, they are supposed to be pretty neat! They have the Inferred filter removed and offer a primitive version of live view I believe.

The 20Da drops its IR cut just beyond H-alpha versus typical cameras which fully attenuate that emission line. It's of great interest for astronomical imaging, but the extra red can be a liability in normal terrestrial work.

body IS with existing cameras won't work well or possibly at all on tripod mounted systems. the vibration frequency spectrum is completely different from hand-held. also, all of these systems have an upper limit for what focal lengths they will function. you have to correctly specify that focal length to the system so that it knows how much to move the sensor for system motion. if the difference is too far off, you will get worse results than without it engaged even if you could match the vibration frequency. that limits you to about 400mm on all the body-based IS bodies.

the focus confirmation on these bodies doesn't work very well on telescopes unless your effective aperture is no smaller than about f6.3. you will get better than that only if you use an eyepiece and focus both the telescope and the camera with lens. using an adapter that replaces the eyepiece, you will be at around f8 for the short focal length telescopes and f11 or smaller for the long focal length ones. Live View, even a relatively poor one, works better for focusing.

Herb...

vkalia wrote:
I am looking for a camera body to mount on an astro scope for high-focal-length photography. To that end, I need a body that has sensor IS and which will provide focus confirmation (beep or flashing AF point... preferably the latter) when used with manual focus lenses or with lenses mounted via adapters.

olyacme wrote:
Do you intend to focus and shoot this scope Lord Nelson style? If not, and I strongly recommend not, then you're going to be tripod bound and should forget about IS. Focus confirmation is also hit-or-miss with typical slow yet long spotting scopes. What you want is a camera with live view, and a heavy tripod.

Actually, I know quite well what I want - a camera with IS and focus confirmation with manual focus lenses.

I appreciate your advice on tripods & support, but you are preaching to the choir here - I own 2 Gitzos, including a 1548 (which is about as sturdy a portable tripod as you are going to get) as well as a Wimberly and a Sidekick. Trust me, I take my stands very seriously - and besides, my scrawny arms would fall off if I was shooting the scope handheld.

However, I find that IS helps even on a tripod, especially if you are shooting with the head not fully locked down. That is the case with my 500/4 and TCs, and that is the case with the scope. Even on the sturdiest tripod, IS can make an improvement outdoors. I realize that in-body IS will not be as useful on a scope as it is on a shorter lens, but it is better than nothing and certainly will not hurt.

And mainly, I would like focus confirmation. Again, it may be hit or miss, but it is better than nothing. At the shutter speeds/relatively high EVs in which I will be using the scope for shooting wildlife, I dont think there will be problem getting focus confirmation (or so I hope, anyway).

You are right about Live View - that is probably going to be the most-used way of checking focus. However, virtually all current DSLR models have it, so I didnt bother listing it in my requirements.

I don't know if you already have a scope, but any 60-90mm (aperture, not focal length!) scope, f/8 or faster, with a 2" focuser will do. A rotateable focuser is a big plus found on the better scopes, so you don't have to constantly loosen and retighten your T adaptor's drawtube to level your horizon. There is a fairly good correlation between price and performance, but semi-apo fpl-53 (fluoro-ed) based doublets seem to be the sweet spot on the entry level these days.

I have a Televue 85 and 2" extension tubes, barlow and T-adapter. Works quite well and provides magnifications far greater than what I have gotten so far.

Nice photo of the longspur, btw. Excellent detail... that's the Nikon ED80, you said? I have the ED50 which I use as a portable scope and ever since I got it, my Pentax 65 hardly sees the light of the day. Am thinking of selling the Pentax and getting an 80mm scope for those low-light days. The ED80 may be the one (or the Pentax 80).

Vandit

HerbChong wrote:
body IS with existing cameras won't work well or possibly at all on tripod mounted systems. the vibration frequency spectrum is completely different from hand-held. also, all of these systems have an upper limit for what focal lengths they will function. you have to correctly specify that focal length to the system so that it knows how much to move the sensor for system motion. if the difference is too far off, you will get worse results than without it engaged even if you could match the vibration frequency. that limits you to about 400mm on all the body-based IS bodies.

the focus confirmation on these bodies doesn't work very well on telescopes unless your effective aperture is no smaller than about f6.3. you will get better than that only if you use an eyepiece and focus both the telescope and the camera with lens. using an adapter that replaces the eyepiece, you will be at around f8 for the short focal length telescopes and f11 or smaller for the long focal length ones. Live View, even a relatively poor one, works better for focusing.

Herb...


Herb, thanks for that info. I understand the bit about tripod-based vibration, but I am hoping to control the vibration caused by wind (for example) and even the human hand on the rig when it is mounted on an unlocked head. Even with lens-based IS, they say to switch it off when on a tripod... and my experience has been that IS has never harmed an image: it has either helped or had no effect.

As for focus confirmation - wouldnt it be a function of EV values? Enough contrast and light, and the focus confirmation *ought* to work.

The way I see it - it doesn't really matter what body I put on the setup, so I might as well put something that has the above 2 features - even if they dont work all the time, something is better than nothing.

Vandit

even if you ignore the vibration effect, the focal length problem remains. unless you stay within the designed focal length range of the body IS, it's not going to work. the results can be much worse than no IS.

as for EV values for focusing, the bodies focus with ordinary lenses wide open. when directly attached to a scope, you are looking at f8 or worse. the confirmation indication will light when the the body thinks that it is in focus, but without enough light, the indication will be mostly meaningless.

Herb...

vkalia wrote:
my experience has been that IS has never harmed an image: it has either helped or had no effect.

As for focus confirmation - wouldnt it be a function of EV values? Enough contrast and light, and the focus confirmation *ought* to work.

vkalia wrote:
However, I find that IS helps even on a tripod, especially if you are shooting with the head not fully locked down. That is the case with my 500/4 and TCs, and that is the case with the scope. Even on the sturdiest tripod, IS can make an improvement outdoors. I realize that in-body IS will not be as useful on a scope as it is on a shorter lens, but it is better than nothing and certainly will not hurt.


I don't want to call you wrong, because experience always trumps theory, but I can lay out some reasons which might cause you to second guess your requirement for in-body IS. The first and most fundamental concern is that the accelerometers that the IS system uses to determine what it must do are located in the body only. Rather than seeing pitch and yaw, as rotations occurring close to the body will produce, the sensors will instead see lateral shifts, as the lens rotates across its relatively distant gimbal point. Without knowledge about where the axis of ration lies (now at the balance point of the system, rather than near or even behind the body as in hand held use) the system will make bad decisions about how far to move the sensor. As far as I can see, it could only be luck that allows the system to have a consistently positive effect when used this way.

The other issue is that the type of vibration found on when mounted on a tripod is significantly different from the kind humans generate. Unlike human induced pitch and yaw, which sways back and forth about an average position as the photographer maintains framing, a locked down tripod shows resonant vibration at much higher frequencies (tens to hundreds of Hz rather than Hz to tens of Hz). Rather than carrying the sensor in only a single direction through a whole exposure, the IS system may be called upon to repeatedly correct and come back, without under or overshoot. This is an extremely demanding task - the system would have to maintain a running history of how long the vibrations were in order to get ahead of them during the exposure. I've not experimented with Sony or Pentax's implementations, but I'd be surprised if any IS systems manage this feat.

Even with gimbals relaxed and resonant vibration at a minimum, typical digiscoping focal lengths are quite extreme relative to the amount of correction sensor shake style IS can provide. The sensor will quickly run out of travel.

vkalia wrote:
And mainly, I would like focus confirmation. Again, it may be hit or miss, but it is better than nothing. At the shutter speeds/relatively high EVs in which I will be using the scope for shooting wildlife, I dont think there will be problem getting focus confirmation (or so I hope, anyway).


You're probably correct that focus priority is better than nothing, but you have to bear in mind that an 85mm scope combines narrow DOF (comparable to a 85mm f/1.2 lens) with a speed (f/7) where parallax based AF systems are running out of steam. It's a very demanding task you're asking of any body, and I think you'll be disappointed if you base your choice on this feature working reliably. Mirror-less "EVIL" cameras might be better adapted to this task, where the viewfinder could highlight high contrast edge transitions while maintaining a full frame view.

vkalia wrote:
I have a Televue 85 and 2" extension tubes, barlow and T-adapter. Works quite well and provides magnifications far greater than what I have gotten so far.


Unless your quarry is both torpid and demanding of every last bit of focal length you can muster, you might be happier swapping the barlow for a focal reducer / flattener. Even if you only get a mild reduction (0.8x) the flatter field should expose itself positively in the corners of an APS sensor, and the higher shutter speeds and closer to diffraction matched resolution should allow cropping to deliver just a much detail on the subject.

vkalia wrote:
Nice photo of the longspur, btw. Excellent detail... that's the Nikon ED80, you said? I have the ED50 which I use as a portable scope and ever since I got it, my Pentax 65 hardly sees the light of the day. Am thinking of selling the Pentax and getting an 80mm scope for those low-light days. The ED80 may be the one (or the Pentax 80).


That shot was with the humble Skywatcher 80mm f/7.5 (1200mm EFL) and a modified survey tripod, live view focus, and patient bird.

Olyacme -

Thanks for that excellent post. Lots of useful info there, and lots of things for me to chew on. A few questions/comments...

olyacme wrote:
I don't want to call you wrong, because experience always trumps theory, but I can lay out some reasons which might cause you to second guess your requirement for in-body IS. The first and most fundamental concern is that the accelerometers that the IS system uses to determine what it must do are located in the body only. Rather than seeing pitch and yaw, as rotations occurring close to the body will produce, the sensors will instead see lateral shifts, as the lens rotates across its relatively distant gimbal point. Without knowledge about where the axis of ration lies (now at the balance point of the system, rather than near or even behind the body as in hand held use) the system will make bad decisions about how far to move the sensor. As far as I can see, it could only be luck that allows the system to have a consistently positive effect when used this way.

The other issue is that the type of vibration found on when mounted on a tripod is significantly different from the kind humans generate. Unlike human induced pitch and yaw, which sways back and forth about an average position as the photographer maintains framing, a locked down tripod shows resonant vibration at much higher frequencies (tens to hundreds of Hz rather than Hz to tens of Hz). Rather than carrying the sensor in only a single direction through a whole exposure, the IS system may be called upon to repeatedly correct and come back, without under or overshoot. This is an extremely demanding task - the system would have to maintain a running history of how long the vibrations were in order to get ahead of them during the exposure. I've not experimented with Sony or Pentax's implementations, but I'd be surprised if any IS systems manage this feat.

That makes sense. My experience has been with DSLR+long lenses, and there, there is enough vibration at lower frequencies (hand shake, wind shake, etc) that the IS system has proved to be effective. I can see what you are saying above.

However - and here, I am merely speculating, as opposed to arguing a particular position - I wonder if in-body IS mechanisms have some kind of logic controller (or even a dampener) built in which would compensate or ignore the high frequency vibration? I personally have no experience with in-body IS cameras mounted on scopes, but I have heard from a couple of people at Birdforum that it has occasionally helped their image. So I am merely investigating the possibilities here.

You're probably correct that focus priority is better than nothing, but you have to bear in mind that an 85mm scope combines narrow DOF (comparable to a 85mm f/1.2 lens) with a speed (f/7) where parallax based AF systems are running out of steam. It's a very demanding task you're asking of any body, and I think you'll be disappointed if you base your choice on this feature working reliably. Mirror-less "EVIL" cameras might be better adapted to this task, where the viewfinder could highlight high contrast edge transitions while maintaining a full frame view.

Possibly. I just find it hard to open myself up to using an EVF - each one I have used to date has been a hideosity (to coin a phrase) in terms of ease of use. I gather the G1 and others have a much better EVF implementation, but I am inherently biased against them. Give me an optical finder any day of the week.

Another option might be to get a Katz Eye or similar MF screen installed on one of my bodies.

Unless your quarry is both torpid and demanding of every last bit of focal length you can muster, you might be happier swapping the barlow for a focal reducer / flattener. Even if you only get a mild reduction (0.8x) the flatter field should expose itself positively in the corners of an APS sensor, and the higher shutter speeds and closer to diffraction matched resolution should allow cropping to deliver just a much detail on the subject.

Thank you for that tip. I will most certainly give it a shot. Any recommendations on a good focal reducer/flattener?

That shot was with the humble Skywatcher 80mm f/7.5 (1200mm EFL) and a modified survey tripod, live view focus, and patient bird.

Hardly humble - that is a very nice scope indeed. And obviously being put to work by an knowledgeable user.

Cheers,
Vandit

HerbChong wrote:
even if you ignore the vibration effect, the focal length problem remains. unless you stay within the designed focal length range of the body IS, it's not going to work. the results can be much worse than no IS.

as for EV values for focusing, the bodies focus with ordinary lenses wide open. when directly attached to a scope, you are looking at f8 or worse. the confirmation indication will light when the the body thinks that it is in focus, but without enough light, the indication will be mostly meaningless.


I see a distinct trend here... perhaps I should just stick with my Canon body on the scope after all.

May I ask if either of you are saying based on theory or have you tried this on a scope? I should make it clear - I dont ask this to cast doubts on what you are saying (what you said above makes a lot of sense to me), but just so I understand what's what.

Regards,
Vandit

vkalia wrote:
HerbChong wrote:
even if you ignore the vibration effect, the focal length problem remains. unless you stay within the designed focal length range of the body IS, it's not going to work. the results can be much worse than no IS.

as for EV values for focusing, the bodies focus with ordinary lenses wide open. when directly attached to a scope, you are looking at f8 or worse. the confirmation indication will light when the the body thinks that it is in focus, but without enough light, the indication will be mostly meaningless.


I see a distinct trend here... perhaps I should just stick with my Canon body on the scope after all.

May I ask if either of you are saying based on theory or have you tried this on a scope? I should make it clear - I dont ask this to cast doubts on what you are saying (what you said above makes a lot of sense to me), but just so I understand what's what.

Regards,
Vandit

In-body IS is best suited for shorter lenses (which require less deflection of the sensor). Effectiveness drops off the longer the lens gets and the further the actual focal length is from what the camera thinks you're using. The combination of both will render in-body IS useless.

I'm speaking from experience here (K10D, K100D with lenses up to 420mm). Also the in-body IS does not have a 'tripod' mode like most modern lens-IS systems which optimises response for tripod use instead if handheld use. My experience with tripod use of in-body IS setups is that in-body IS is of no use in that situation (even with unlocked tripods)

Also note that most AF systems are only rated to f5.6

Technical and practical theory is certainly covered here.

I'll just say that I use a Takahashi FS-60C 355mm f/6 APO scope with my XSi, and Teegul/Bogen3036 tripod, for daytime and nighttime photos and visual. This is a relatively short focal length, 60mm scope that is only about a foot long. In additon to wildlife daytime shots, I've hand tracked the ISS/Shuttle across the sky at dusk and been able to detect the solar panels.

i have used my K10D on my Pentax PF-100ED spotting scope with the PF-CA35 K-mount adapter for an effective 1250mm/12.5 lens. in body SR must be turned off because the focal length is far beyond what the body is designed to handle. the correct focus indication operates over such a wide range of focus settings that it is meaningless. after having done all that, the amount of light needed to make it work well combined with the unsteadiness of the air column at that FOV and typical working range for fitting a larger bird like a bald eagle means that you get blurry images anyway. the results are inferior to my Nikkor 600/4 and 1.7X extender on my D300 even when i crop to the same FOV. nowadays, i use the spotting scope only with a compact digital camera and high power fixed eyepieces for low resolution captures.

Herb...

vkalia wrote:
May I ask if either of you are saying based on theory or have you tried this on a scope? I should make it clear - I dont ask this to cast doubts on what you are saying (what you said above makes a lot of sense to me), but just so I understand what's what.

Ok thanks for that info, guys. When theory AND practice both say the same thing, it is time to accept the conclusions and move on. No IS needed, and doubtful utility on the focus confirmation. That does open up my options a bit more - I guess I'll get a body with the best VF (either a Noink or a Pentax).. Liveview is pretty much a given anyway. The K20D might just be that body anyway. Regardless, the 20D needs replacement.

Herb, I agree that long focal-length photography is ultimately limited by atmospheric conditions. However, a high-mag scope gives the option to get high quality shots of a lot of little birdies within 50m or so.

Cheers,
Vandit